Node:Run Time System, Next:GPC Units, Previous:Notes for Debugging, Up:Programming

### Pascal declarations for GPC's Run Time System

Below is a Pascal source of the declarations in GPC's Run Time System (RTS). A file `gpc.pas` with the same contents is included in the GPC distribution in a `units` subdirectory of the directory containing `libgcc.a`. (To find out the correct directory for your installation, type `gpc --print-file-name=units` on the command line.)

    { This file was generated automatically from gpc-pas.in.
      DO NOT CHANGE THIS FILE MANUALLY! }

    { Pascal declarations of the GPC Run Time System that are visible to
      each program.

      This unit contains Pascal declarations of many RTS routines which
      are not built into the compiler and can be called from programs.
      Don't copy the declarations from this unit into your programs, but
      rather include this unit with a uses statement. The reason is
      that the internal declarations, e.g. the linker names, may change,
      and this unit will be changed accordingly. @@In the future, this
      unit might be included into every program automatically, so there
      will be no need for a uses statement to make the declarations
      here available.

      Note about protected var parameters:
      Since const parameters in GPC may be passed by value *or* by
      reference internally, possibly depending on the system,
      const foo* parameters to C functions *cannot* reliably be
      declared as const in Pascal. However, Extended Pascal's
      protected var can be used since this guarantees passing by
      reference.

      Copyright (C) 1998-2003 Free Software Foundation, Inc.

      Authors: Jukka Virtanen <jtv@hut.fi>
               Peter Gerwinski <peter@gerwinski.de>
               Frank Heckenbach <frank@pascal.gnu.de>
               J.J. v.der Heijden <j.j.vanderheijden@student.utwente.nl>
               Nicola Girardi <nicola@g-n-u.de>
               Prof. Abimbola A. Olowofoyeku <African_Chief@bigfoot.com>
               Emil Jerabek <jerabek@math.cas.cz>
               Maurice Lombardi <Maurice.Lombardi@ujf-grenoble.fr>
               Toby Ewing <ewing@iastate.edu>

      This file is part of GNU Pascal.

      GNU Pascal is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published
      by the Free Software Foundation; either version 2, or (at your
      option) any later version.

      GNU Pascal is distributed in the hope that it will be useful, but
      WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
      General Public License for more details.

      You should have received a copy of the GNU General Public License
      along with GNU Pascal; see the file COPYING. If not, write to the
      Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
      02111-1307, USA.

      As a special exception, if you link this file with files compiled
      with a GNU compiler to produce an executable, this does not cause
      the resulting executable to be covered by the GNU General Public
      License. This exception does not however invalidate any other
      reasons why the executable file might be covered by the GNU
      General Public License. }

    {$gnu-pascal,I-}
    {$if __GPC_RELEASE__ <> 20030507}
    {$error
    Trying to compile gpc.pas with a non-matching GPC version is likely
    to cause problems.

    In case you are building the RTS separately from GPC, make sure you
    install a current GPC version previously. If you are building GPC
    now and this message appears, something is wrong -- if you are
    overriding the GCC_FOR_TARGET or GPC_FOR_TARGET make variables, this
    might be the problem. If you are cross-building GPC, build and
    install a current GPC cross-compiler first, sorry. If that's not the
    case, please report it as a bug.

    If you are not building GPC or the RTS currently, you might have
    installed things in the wrong place, so the compiler and RTS
    versions do not match.}
    {$endif}

    { Command-line options must not change the layout of RTS types
      declared here. }
    {$no-pack-struct, maximum-field-alignment 0}

    module GPC;

    export
      GPC = all;
      GPC_SP = (ERead { @@ not really, but an empty export doesn't work
      } );
      GPC_EP = (ERead { @@ not really, but an empty export doesn't work
      } );
      GPC_BP = (MaxLongInt, ExitCode, ErrorAddr, FileMode, Pos);
      GPC_Delphi = (MaxLongInt, Int64, InitProc, EConvertError,
                    ExitCode, ErrorAddr, FileMode, Pos, SetString,
      StringOfChar,
                    TextFile, AssignFile, CloseFile);

    { Pascal declarations of the GPC Run Time System routines that are
      implemented in C, from rtsc.pas }

    const
      MaxLongInt = High (LongInt);

      { Maximum size of a variable }
      MaxVarSize = MaxInt div 8;

    { If set, characters >= #$80 are assumed to be letters even if the
      locale routines don't say so. This is a kludge because some
      systems don't have correct non-English locale tables. }
    var
      FakeHighLetters: Boolean; attribute (name = '_p_FakeHighLetters');
      external;

    type
      PCStrings = ^TCStrings;
      TCStrings = array [0 .. MaxVarSize div SizeOf (CString) - 1] of
      CString;

      Int64 = Integer attribute (Size = 64);
      UnixTimeType = LongInt;  { This is hard-coded in the compiler. Do
      not change here. }
      MicroSecondTimeType = LongInt;
      FileSizeType = LongInt;
      SignedSizeType = Integer attribute (Size = BitSizeOf (SizeType));
      TSignalHandler = procedure (Signal: Integer);

      StatFSBuffer = record
        BlockSize, BlocksTotal, BlocksFree: LongestInt;
        FilesTotal, FilesFree: Integer
      end;

      InternalSelectType = record
        Handle: Integer;
        Read, Write, Exception: Boolean
      end;

      PString = ^String;

      { Max so the size of the array is not zero for Count = 0 }
      PPStrings = ^TPStrings;
      TPStrings (Count: Cardinal) = array [1 .. Max (Count, 1)] of
      PString;

      GlobBuffer = record
        Result: PPStrings;
        Internal1: Pointer;
        Internal2: PCStrings;
        Internal3: Integer
      end;

    { Mathematical routines }

    function  SinH (x: Real): Real; attribute (const); external
      name '_p_SinH';
    function  CosH (x: Real): Real; attribute (const); external
      name '_p_CosH';
    function  ArcTan2 (y: Real; x: Real): Real; attribute (const);
      external name '_p_ArcTan2';
    function  IsInfinity (x: LongReal): Boolean; attribute (const);
      external name '_p_IsInfinity';
    function  IsNotANumber (x: LongReal): Boolean; attribute (const);
      external name '_p_IsNotANumber';
    procedure SplitReal (x: LongReal; var Exponent: Integer; var
      Mantissa: LongReal); external name '_p_SplitReal';

    { Character routines }

    { Convert a character to upper case, according to the current
      locale.
      Except in --borland-pascal mode, UpCase does the same. }
    function  UpCase (ch: Char): Char; attribute (const); external
      name '_p_UpCase';

    { Convert a character to lower case, according to the current
      locale.
      Except in --borland-pascal mode, UpCase does the same. }
    function  LoCase (ch: Char): Char; attribute (const); external
      name '_p_LoCase';
    function  IsUpCase (ch: Char): Boolean; attribute (const); external
      name '_p_IsUpCase';
    function  IsLoCase (ch: Char): Boolean; attribute (const); external
      name '_p_IsLoCase';
    function  IsAlpha (ch: Char): Boolean; attribute (const); external
      name '_p_IsAlpha';
    function  IsAlphaNum (ch: Char): Boolean; attribute (const);
      external name '_p_IsAlphaNum';
    function  IsAlphaNumUnderscore (ch: Char): Boolean; attribute
      (const); external name '_p_IsAlphaNumUnderscore';
    function  IsSpace (ch: Char): Boolean; attribute (const); external
      name '_p_IsSpace';
    function  IsPrintable (ch: Char): Boolean; attribute (const);
      external name '_p_IsPrintable';

    { Time routines }

    { Sleep for a given number of seconds. }
    procedure Sleep (Seconds: Integer); external name '_p_Sleep';

    { Sleep for a given number of microseconds. }
    procedure SleepMicroSeconds (MicroSeconds: Integer); external
      name '_p_SleepMicroSeconds';

    { Set an alarm timer. }
    function  Alarm (Seconds: Integer): Integer; external
      name '_p_Alarm';

    { Convert a Unix time value to broken-down local time.
      All parameters except Time may be Null. }
    procedure UnixTimeToTime (Time: UnixTimeType; var Year: Integer; var
      Month: Integer; var Day: Integer; var Hour: Integer; var Minute:
      Integer; var Second: Integer;
                                    var TimeZone: Integer; var DST:
      Boolean; var TZName1: CString; var TZName2: CString); external
      name '_p_UnixTimeToTime';

    { Convert broken-down local time to a Unix time value. }
    function  TimeToUnixTime (Year: Integer; Month: Integer; Day:
      Integer; Hour: Integer; Minute: Integer; Second: Integer):
      UnixTimeType; external name '_p_TimeToUnixTime';

    { Get the real time. MicroSecond can be Null and is ignored then. }
    function  GetUnixTime (var MicroSecond: Integer): UnixTimeType;
      external name '_p_GetUnixTime';

    { Get the CPU time used. MicroSecond can be Null and is ignored
      then. Now, GetCPUTime can measure long CPU times reliably on most
      systems (e.g. Solaris where it didn't work before). }
    function  GetCPUTime (var MicroSecond: Integer): Integer; external
      name '_p_GetCPUTime';

    { Signal and process routines }

    { Extract information from the status returned by PWait }
    function  StatusExited (Status: Integer): Boolean; attribute
      (const); external name '_p_StatusExited';
    function  StatusExitCode (Status: Integer): Integer; attribute
      (const); external name '_p_StatusExitCode';
    function  StatusSignaled (Status: Integer): Boolean; attribute
      (const); external name '_p_StatusSignaled';
    function  StatusTermSignal (Status: Integer): Integer; attribute
      (const); external name '_p_StatusTermSignal';
    function  StatusStopped (Status: Integer): Boolean; attribute
      (const); external name '_p_StatusStopped';
    function  StatusStopSignal (Status: Integer): Integer; attribute
      (const); external name '_p_StatusStopSignal';

    { Install a signal handler and optionally return the previous
      handler. OldHandler and OldRestart may be Null. }
    function  InstallSignalHandler (Signal: Integer; Handler:
      TSignalHandler; Restart: Boolean; UnlessIgnored: Boolean;
      var OldHandler: TSignalHandler; var OldRestart: Boolean): Boolean;
      external name '_p_InstallSignalHandler';

    { Block or unblock a signal. }
    procedure BlockSignal (Signal: Integer; Block: Boolean); external
      name '_p_BlockSignal';

    { Test whether a signal is blocked. }
    function  SignalBlocked (Signal: Integer): Boolean; external
      name '_p_SignalBlocked';

    { Sends a signal to a process. Returns True if successful. If Signal
      is 0, it doesn't send a signal, but still checks whether it would
      be possible to send a signal to the given process. }
    function  Kill (PID: Integer; Signal: Integer): Boolean; external
      name '_p_Kill';

    { Constant for WaitPID }
    const
      AnyChild = -1;

    { Waits for a child process with the given PID (or any child process
      if PID = AnyChild) to terminate or be stopped. Returns the PID of
      the process. WStatus will contain the status and can be evaluated
      with StatusExited etc.. If nothing happened, and Block is False,
      the function will return 0, and WStatus will be 0. If an error
      occurred (especially on single tasking systems where WaitPID is
      not possible), the function will return a negative value, and
      WStatus will be 0. }
    function  WaitPID (PID: Integer; var WStatus: Integer; Block:
      Boolean): Integer; external name '_p_WaitPID';

    { Returns the process ID. }
    function  ProcessID: Integer; external name '_p_ProcessID';

    { Returns the process group. }
    function  ProcessGroup: Integer; external name '_p_ProcessGroup';

    { Returns the real or effective user ID of the process. }
    function  UserID (Effective: Boolean): Integer; external
      name '_p_UserID';

    { Tries to change the real and/or effective user ID. }
    function  SetUserID (Real: Integer; Effective: Integer): Boolean;
      external name '_p_SetUserID';

    { Returns the real or effective group ID of the process. }
    function  GroupID (Effective: Boolean): Integer; external
      name '_p_GroupID';

    { Tries to change the real and/or effective group ID. }
    function  SetGroupID (Real: Integer; Effective: Integer): Boolean;
      external name '_p_SetGroupID';

    { Low-level file routines. Mostly for internal use. }

    { Get information about a file system. }
    function  StatFS (Path: CString; var Buf: StatFSBuffer): Boolean;
      external name '_p_StatFS';
    function  CStringOpenDir (DirName: CString): Pointer; external
      name '_p_CStringOpenDir';
    function  CStringReadDir (Dir: Pointer): CString; external
      name '_p_CStringReadDir';
    procedure CStringCloseDir (Dir: Pointer); external
      name '_p_CStringCloseDir';

    { Returns the value of the symlink FileName in a CString allocated
      from the heap. Returns nil if it is no symlink or the function
      is not supported. }
    function  ReadLink (FileName: CString): CString; external
      name '_p_ReadLink';

    { The result of the following function is a pointer to a *static*
      buffer! }
    function  CStringRealPath (Path: CString): CString; external
      name '_p_CStringRealPath';

    { File mode constants that are ORed for BindingType.Mode, ChMod,
      CStringChMod and Stat. The values below are valid for all OSs
      (as far as supported). If the OS uses different values, they're
      converted internally. }
    const
      fm_SetUID           = 8#4000;
      fm_SetGID           = 8#2000;
      fm_Sticky           = 8#1000;
      fm_UserReadable     = 8#400;
      fm_UserWritable     = 8#200;
      fm_UserExecutable   = 8#100;
      fm_GroupReadable    = 8#40;
      fm_GroupWritable    = 8#20;
      fm_GroupExecutable  = 8#10;
      fm_OthersReadable   = 8#4;
      fm_OthersWritable   = 8#2;
      fm_OthersExecutable = 8#1;

    { Constants for _p_Access() and _p_OpenHandle() }
    const
      MODE_EXEC     = 1 shl 0;
      MODE_WRITE    = 1 shl 1;
      MODE_READ     = 1 shl 2;
      MODE_FILE     = 1 shl 3;
      MODE_DIR      = 1 shl 4;
      MODE_SPECIAL  = 1 shl 5;
      MODE_SYMLINK  = 1 shl 6;
      MODE_CREATE   = 1 shl 7;
      MODE_TRUNCATE = 1 shl 8;
      MODE_BINARY   = 1 shl 9;

    { Check if a file name is accessible. }
    function  Access (FileName: CString; Request: Integer): Integer;
      external name '_p_Access';

    { Get information about a file. Any argument except Name can
      be Null. }
    function  Stat (FileName: CString; var Size: FileSizeType;
      var ATime: UnixTimeType; var MTime: UnixTimeType; var CTime:
      UnixTimeType;
      var User: Integer; var Group: Integer; var Mode: Integer; var
      Device: Integer; var INode: Integer; var Links: Integer;
      var SymLink: Boolean; var Dir: Boolean; var Special: Boolean):
      Integer; external name '_p_Stat';
    function  OpenHandle (FileName: CString; Mode: Integer): Integer;
      external name '_p_OpenHandle';
    function  ReadHandle (Handle: Integer; Buffer: Pointer; Size:
      SizeType): SignedSizeType; external name '_p_ReadHandle';
    function  WriteHandle (Handle: Integer; Buffer: Pointer; Size:
      SizeType): SignedSizeType; external name '_p_WriteHandle';
    function  CloseHandle (Handle: Integer): Integer; external
      name '_p_CloseHandle';
    procedure FlushHandle (Handle: Integer); external
      name '_p_FlushHandle';
    function  DupHandle (Src: Integer; Dest: Integer): Integer; external
      name '_p_DupHandle';
    function  CStringRename (OldName: CString; NewName: CString):
      Integer; external name '_p_CStringRename';
    function  CStringUnlink (FileName: CString): Integer; external
      name '_p_CStringUnlink';
    function  CStringChDir (FileName: CString): Integer; external
      name '_p_CStringChDir';
    function  CStringMkDir (FileName: CString): Integer; external
      name '_p_CStringMkDir';
    function  CStringRmDir (FileName: CString): Integer; external
      name '_p_CStringRmDir';
    function  CStringChMod (FileName: CString; Mode: Integer): Integer;
      external name '_p_CStringChMod';
    function  CStringChOwn (FileName: CString; Owner: Integer; Group:
      Integer): Integer; external name '_p_CStringChOwn';
    function  CStringUTime (FileName: CString; AccessTime: UnixTimeType;
      ModificationTime: UnixTimeType): Integer; external
      name '_p_CStringUTime';
    function  SeekHandle (Handle: Integer; Offset: FileSizeType; Whence:
      Integer): FileSizeType; external name '_p_SeekHandle';
    function  TruncateHandle (Handle: Integer; Size: FileSizeType):
      Integer; external name '_p_TruncateHandle';
    function  LockHandle (Handle: Integer; WriteLock: Boolean; Block:
      Boolean): Boolean; external name '_p_LockHandle';
    function  UnlockHandle (Handle: Integer): Boolean; external
      name '_p_UnlockHandle';
    function  SelectHandle (Count: Integer; var Events:
      InternalSelectType; MicroSeconds: MicroSecondTimeType): Integer;
      external name '_p_SelectHandle';

    { Constants for MMapHandle and MemoryMap }
    const
      mm_Readable   = 1;
      mm_Writable   = 2;
      mm_Executable = 4;

    { Try to map (a part of) a file to memory. }
    function  MMapHandle (Start: Pointer; Length: SizeType; Access:
      Integer; Shared: Boolean; Handle: Integer; Offset: FileSizeType):
      Pointer; external name '_p_MMapHandle';

    { Unmap a previous memory mapping. }
    function  MUnMapHandle (Start: Pointer; Length: SizeType): Integer;
      external name '_p_MUnMapHandle';

    { Returns the file name of the terminal device that is open on
      Handle. Returns nil if (and only if) Handle is not open or not
      connected to a terminal. If NeedName is False, it doesn't bother
      to search for the real name and just returns DefaultName if it
      is a terminal and nil otherwise. DefaultName is also returned if
      NeedName is True, Handle is connected to a terminal, but the
      system does not provide information about the real file name. }
    function  GetTerminalNameHandle (Handle: Integer; NeedName: Boolean;
      DefaultName: CString): CString; external
      name '_p_GetTerminalNameHandle';

    { I/O routines }

    { Sets the process group of Process (or the current one if Process
      is 0) to ProcessGroup (or its PID if ProcessGroup is 0). Returns
      True if successful. }
    function  SetProcessGroup (Process: Integer; ProcessGroup: Integer):
      Boolean; external name '_p_SetProcessGroup';

    { Sets the process group of a terminal given by Terminal (as a file
      handle) to ProcessGroup. ProcessGroup must be the ID of a process
      group in the same session. Returns True if successful. }
    function  SetTerminalProcessGroup (Handle: Integer; ProcessGroup:
      Integer): Boolean; external name '_p_SetTerminalProcessGroup';

    { Returns the process group of a terminal given by Terminal (as a
      file handle), or -1 on error. }
    function  GetTerminalProcessGroup (Handle: Integer): Integer;
      external name '_p_GetTerminalProcessGroup';

    { Set the standard input's signal generation, if it is a terminal. }
    procedure SetInputSignals (Signals: Boolean); external
      name '_p_SetInputSignals';

    { Get the standard input's signal generation, if it is a terminal. }
    function  GetInputSignals: Boolean; external
      name '_p_GetInputSignals';

    { Internal routines }

    { Returns system information if available. Fields not available will
      be set to nil. }
    procedure CStringSystemInfo (var SysName: CString; var NodeName:
      CString; var Release: CString; var Version: CString; var Machine:
      CString; var DomainName: CString); external
      name '_p_CStringSystemInfo';

    { Returns the path of the running executable *if possible*. }
    function  CStringExecutablePath (Buffer: CString): CString; external
      name '_p_CStringExecutablePath';

    { Sets ErrNo to the value of errno and returns the description
      for this error. May return nil if not supported! ErrNo may be
      Null (then only the description is returned). }
    function  CStringStrError (var ErrNo: Integer): CString; external
      name '_p_CStringStrError';

    { File routines }

    type
      TOpenMode = (fo_None, fo_Reset, fo_Rewrite, fo_Append,
      fo_SeekRead, fo_SeekWrite, fo_SeekUpdate);
      PAnyFile = ^AnyFile;

    var
      FileMode: Integer; external name '_p_FileMode'; external;

    procedure GetBinding   (protected var aFile: AnyFile; var aBinding:
      BindingType); external name '_p_Binding';
    procedure ClearBinding (var aBinding: BindingType); external
      name '_p_ClearBinding';

    { TFDD interface @@ Subject to change! Use with caution! }

    type
      TOpenProc   = procedure (var PrivateData; Mode: TOpenMode);
      TSelectFunc = function  (var PrivateData; Writing: Boolean):
      Integer;  { called before SelectHandle, must return a file handle
      }
      TSelectProc = procedure (var PrivateData; var ReadSelect,
      WriteSelect, ExceptSelect: Boolean);  { called before and after
      SelectHandle }
      TReadFunc   = function  (var PrivateData; var   Buffer; Size:
      SizeType): SizeType;
      TWriteFunc  = function  (var PrivateData; const Buffer; Size:
      SizeType): SizeType;
      TFileProc   = procedure (var PrivateData);
      TFlushProc  = TFileProc;
      TCloseProc  = TFileProc;
      TDoneProc   = TFileProc;

    procedure AssignTFDD (var f: AnyFile;
                          OpenProc   : TOpenProc;
                          SelectFunc : TSelectFunc;
                          SelectProc : TSelectProc;
                          ReadFunc   : TReadFunc;
                          WriteFunc  : TWriteFunc;
                          FlushProc  : TFlushProc;
                          CloseProc  : TCloseProc;
                          DoneProc   : TDoneProc;
                          PrivateData: Pointer); external
      name '_p_AssignTFDD';

    procedure SetTFDD    (var f: AnyFile;
                          OpenProc   : TOpenProc;
                          SelectFunc : TSelectFunc;
                          SelectProc : TSelectProc;
                          ReadFunc   : TReadFunc;
                          WriteFunc  : TWriteFunc;
                          FlushProc  : TFlushProc;
                          CloseProc  : TCloseProc;
                          DoneProc   : TDoneProc;
                          PrivateData: Pointer); external
      name '_p_SetTFDD';

    { Any parameter except f may be Null }
    procedure GetTFDD    (var f: AnyFile;
                          var OpenProc   : TOpenProc;
                          var SelectFunc : TSelectFunc;
                          var SelectProc : TSelectProc;
                          var ReadFunc   : TReadFunc;
                          var WriteFunc  : TWriteFunc;
                          var FlushProc  : TFlushProc;
                          var CloseProc  : TCloseProc;
                          var DoneProc   : TDoneProc;
                          var PrivateData: Pointer); external
      name '_p_GetTFDD';

    procedure FileMove (var f: AnyFile; NewName: CString; Overwrite:
      Boolean); attribute (iocritical); external name '_p_Mv';

    { Flags that can be ORed into FileMode. The default value of
      FileMode is FileMode_Reset_ReadWrite. The somewhat confusing
      values are meant to be compatible to BP (as far as BP supports
      them). }
    const
      { Allow writing to binary files opened with Reset }
      FileMode_Reset_ReadWrite      = 2;

      { Do not allow reading from files opened with Rewrite }
      FileMode_Rewrite_WriteOnly    = 4;

      { Do not allow reading from files opened with Extend }
      FileMode_Extend_WriteOnly     = 8;

      { Allow writing to text files opened with Reset }
      FileMode_Text_Reset_ReadWrite = $100;

    type
      TextFile = Text;

    const
      NoChange = -1;  { can be passed to ChOwn for Owner and/or Group to
      not change that value }

    procedure CloseFile (var aFile: AnyFile); external name '_p_Close';
    procedure ChMod (var aFile: AnyFile; Mode: Integer); attribute
      (iocritical); external name '_p_ChMod';
    procedure ChOwn (var aFile: AnyFile; Owner, Group: Integer);
      attribute (iocritical); external name '_p_ChOwn';

    { Checks if data are available to be read from aFile. This is
      similar to not EOF (aFile), but does not block on "files" that
      can grow, like Ttys or pipes. }
    function  CanRead      (var aFile: AnyFile): Boolean; external
      name '_p_CanRead';

    { Get the file handle. }
    function  FileHandle   (protected var aFile: AnyFile): Integer;
      external name '_p_FileHandle';

    { Lock files }
    function  FileLock   (var aFile: AnyFile; WriteLock, Block:
      Boolean): Boolean; external name '_p_FileLock';
    function  FileUnlock (var aFile: AnyFile): Boolean; external
      name '_p_FileUnlock';

    { Try to map (a part of) a file to memory. }
    function  MemoryMap (Start: Pointer; Length: SizeType; Access:
      Integer; Shared: Boolean;
                         var aFile: AnyFile; Offset: FileSizeType):
      Pointer; external name '_p_MemoryMap';

    { Unmap a previous memory mapping. }
    procedure MemoryUnMap (Start: Pointer; Length: SizeType); external
      name '_p_MemoryUnMap';

    { Mathematical routines, from math.pas }

    function Ln1Plus  (x: Real): Real; attribute (const, name
      = '_p_Ln1Plus'); external;

    { String handling routines (lower level), from string.pas }

    { TString is a string type that is used for function results and
      local variables, as long as undiscriminated strings are not
      allowed there. The default size of 2048 characters should be
      enough for file names on any system, but can be changed when
      necessary. It should be at least as big as MAXPATHLEN. }

    const
      TStringSize = 2048;
      SpaceCharacters = [' ', #9];
      NewLine = "\n";  { the separator of lines within a string }
      LineBreak = {$if defined (__OS_DOS__) and not defined
      (__CYGWIN__)}
                  "\r\n"
                  {$else}
                  "\n"
                  {$endif};  { the separator of lines within a file }

    type
      TString    = String (TStringSize);
      TStringBuf = packed array [0 .. TStringSize] of Char;
      CharSet    = set of Char;
      Str64      = String (64);

    var
      CParamCount: Integer; attribute (name = '_p_CParamCount');
      external;
      CParameters: PCStrings; attribute (name = '_p_CParameters');
      external;

    function  MemCmp      (const s1, s2; Size: SizeType): Integer;
      external name 'memcmp';
    function  MemComp     (const s1, s2; Size: SizeType): Integer;
      external name 'memcmp';
    function  MemCompCase (const s1, s2; Size: SizeType): Boolean;
      attribute (name = '_p_MemCompCase'); external;

    procedure UpCaseString    (var s: String); attribute (name
      = '_p_UpCaseString'); external;
    procedure LoCaseString    (var s: String); attribute (name
      = '_p_LoCaseString'); external;
    function  UpCaseStr       (const s: String): TString; attribute
      (name = '_p_UpCaseStr'); external;
    function  LoCaseStr       (const s: String): TString; attribute
      (name = '_p_LoCaseStr'); external;

    function  StrEqualCase    (const s1, s2: String): Boolean; attribute
      (name = '_p_StrEqualCase'); external;

    function  Pos             (const SubString, s: String): Integer;
      attribute (name = '_p_Pos'); external;
    function  LastPos         (const SubString, s: String): Integer;
      attribute (name = '_p_LastPos'); external;
    function  PosCase         (const SubString, s: String): Integer;
      attribute (name = '_p_PosCase'); external;
    function  LastPosCase     (const SubString, s: String): Integer;
      attribute (name = '_p_LastPosCase'); external;
    function  CharPos         (const Chars: CharSet; const s: String):
      Integer; attribute (name = '_p_CharPos'); external;
    function  LastCharPos     (const Chars: CharSet; const s: String):
      Integer; attribute (name = '_p_LastCharPos'); external;

    function  PosFrom         (const SubString, s: String; From:
      Integer): Integer; attribute (name = '_p_PosFrom'); external;
    function  LastPosTill     (const SubString, s: String; Till:
      Integer): Integer; attribute (name = '_p_LastPosTill'); external;
    function  PosFromCase     (const SubString, s: String; From:
      Integer): Integer; attribute (name = '_p_PosFromCase'); external;
    function  LastPosTillCase (const SubString, s: String; Till:
      Integer): Integer; attribute (name = '_p_LastPosTillCase');
      external;
    function  CharPosFrom     (const Chars: CharSet; const s: String;
      From: Integer): Integer; attribute (name = '_p_CharPosFrom');
      external;
    function  LastCharPosTill (const Chars: CharSet; const s: String;
      Till: Integer): Integer; attribute (name = '_p_LastCharPosTill');
      external;

    function  IsPrefix        (const Prefix, s: String): Boolean;
      attribute (name = '_p_IsPrefix'); external;
    function  IsSuffix        (const Suffix, s: String): Boolean;
      attribute (name = '_p_IsSuffix'); external;
    function  IsPrefixCase    (const Prefix, s: String): Boolean;
      attribute (name = '_p_IsPrefixCase'); external;
    function  IsSuffixCase    (const Suffix, s: String): Boolean;
      attribute (name = '_p_IsSuffixCase'); external;

    function  CStringLength      (Src: CString): SizeType; attribute
      (inline, name = '_p_CStringLength'); external;
    function  CStringEnd         (Src: CString): CString; attribute
      (inline, name = '_p_CStringEnd'); external;
    function  CStringNew         (Src: CString): CString; attribute
      (name = '_p_CStringNew'); external;
    function  CStringComp        (s1, s2: CString): Integer; attribute
      (name = '_p_CStringComp'); external;
    function  CStringCaseComp    (s1, s2: CString): Integer; attribute
      (name = '_p_CStringCaseComp'); external;
    function  CStringLComp       (s1, s2: CString; MaxLen: SizeType):
      Integer; attribute (name = '_p_CStringLComp'); external;
    function  CStringLCaseComp   (s1, s2: CString; MaxLen: SizeType):
      Integer; attribute (name = '_p_CStringLCaseComp'); external;
    function  CStringCopy        (Dest, Source: CString): CString;
      attribute (name = '_p_CStringCopy'); external;
    function  CStringCopyEnd     (Dest, Source: CString): CString;
      attribute (name = '_p_CStringCopyEnd'); external;
    function  CStringLCopy       (Dest, Source: CString; MaxLen:
      SizeType): CString; attribute (name = '_p_CStringLCopy');
      external;
    function  CStringMove        (Dest, Source: CString; Count:
      SizeType): CString; attribute (name = '_p_CStringMove'); external;
    function  CStringCat         (Dest, Source: CString): CString;
      attribute (name = '_p_CStringCat'); external;
    function  CStringLCat        (Dest, Source: CString; MaxLen:
      SizeType): CString; attribute (name = '_p_CStringLCat'); external;
    function  CStringChPos       (Src: CString; ch: Char): CString;
      attribute (inline, name = '_p_CStringChPos'); external;
    function  CStringLastChPos   (Src: CString; ch: Char): CString;
      attribute (inline, name = '_p_CStringLastChPos'); external;
    function  CStringPos         (s, SubString: CString): CString;
      attribute (name = '_p_CStringPos'); external;
    function  CStringLastPos     (s, SubString: CString): CString;
      attribute (name = '_p_CStringLastPos'); external;
    function  CStringCasePos     (s, SubString: CString): CString;
      attribute (name = '_p_CStringCasePos'); external;
    function  CStringLastCasePos (s, SubString: CString): CString;
      attribute (name = '_p_CStringLastCasePos'); external;
    function  CStringUpCase      (s: CString): CString; attribute (name
      = '_p_CStringUpCase'); external;
    function  CStringLoCase      (s: CString): CString; attribute (name
      = '_p_CStringLoCase'); external;
    function  CStringIsEmpty     (s: CString): Boolean; attribute (name
      = '_p_CStringIsEmpty'); external;
    function  NewCString         (const Source: String): CString;
      attribute (name = '_p_NewCString'); external;
    function  CStringCopyString  (Dest: CString; const Source: String):
      CString; attribute (name = '_p_CStringCopyString'); external;
    procedure CopyCString        (Source: CString; var Dest: String);
      attribute (name = '_p_CopyCString'); external;

    function  NewString       (const s: String): PString; attribute
      (name = '_p_NewString'); external;
    procedure DisposeString   (p: PString); external name '_p_Dispose';

    procedure SetString       (var s: String; Buffer: PChar; Count:
      Integer); attribute (name = '_p_SetString'); external;
    function  StringOfChar    (ch: Char; Count: Integer) = s: TString;
      attribute (name = '_p_StringOfChar'); external;

    procedure TrimLeft        (var s: String); attribute (name
      = '_p_TrimLeft'); external;
    procedure TrimRight       (var s: String); attribute (name
      = '_p_TrimRight'); external;
    procedure TrimBoth        (var s: String); attribute (name
      = '_p_TrimBoth'); external;
    function  TrimLeftStr     (const s: String): TString; attribute
      (name = '_p_TrimLeftStr'); external;
    function  TrimRightStr    (const s: String): TString; attribute
      (name = '_p_TrimRightStr'); external;
    function  TrimBothStr     (const s: String): TString; attribute
      (name = '_p_TrimBothStr'); external;
    function  LTrim           (const s: String): TString; external
      name '_p_TrimLeftStr';

    function  GetStringCapacity (const s: String): Integer; attribute
      (name = '_p_GetStringCapacity'); external;

    { A shortcut for a common use of WriteStr as a function }
    function  Integer2String (i: Integer): Str64; attribute (name
      = '_p_Integer2String'); external;

    { String handling routines (higher level), from string2.pas }

    type
      PChars0 = ^TChars0;
      TChars0 = array [0 .. MaxVarSize div SizeOf (Char) - 1] of Char;

      PChars = ^TChars;
      TChars = packed array [1 .. MaxVarSize div SizeOf (Char)] of Char;

      { Under development. Interface subject to change.
        Use with caution. }
      { When a const or var AnyString parameter is passed, internally
        these records are passed as const parameters. Value AnyString
        parameters are passed like value string parameters. }
      ConstAnyString = record
        Length: Integer;
        Chars: PChars
      end;

      { Capacity is the allocated space (used internally). Count is the
        actual number of environment strings. The CStrings array
        contains the environment strings, terminated by a nil pointer,
        which is not counted in Count. @CStrings can be passed to libc
        routines like execve which expect an environment (see
        GetCEnvironment). }
      PEnvironment = ^TEnvironment;
      TEnvironment (Capacity: Integer) = record
        Count: Integer;
        CStrings: array [1 .. Capacity + 1] of CString
      end;

    var
      Environment: PEnvironment; attribute (name = '_p_Environment');
      external;

    { Get an environment variable. If it does not exist, GetEnv returns
      the empty string, which can't be distinguished from a variable
      with an empty value, while CStringGetEnv returns nil then. Note,
      Dos doesn't know empty environment variables, but treats them as
      non-existing, and does not distinguish case in the names of
      environment variables. However, even under Dos, empty environment
      variables and variable names with different case can now be set
      and used within GPC programs. }
    function  GetEnv (const EnvVar: String): TString; attribute (name
      = '_p_GetEnv'); external;
    function  CStringGetEnv (EnvVar: CString): CString; attribute (name
      = '_p_CStringGetEnv'); external;

    { Sets an environment variable with the name given in VarName to the
      value Value. A previous value, if any, is overwritten. }
    procedure SetEnv (const VarName, Value: String); attribute (name
      = '_p_SetEnv'); external;

    { Un-sets an environment variable with the name given in VarName. }
    procedure UnSetEnv (const VarName: String); attribute (name
      = '_p_UnSetEnv'); external;

    { Returns @Environment^.CStrings, converted to PCStrings, to be
      passed to libc routines like execve which expect an environment. }
    function  GetCEnvironment: PCStrings; attribute (name
      = '_p_GetCEnvironment'); external;

    type
      FormatStringTransformType = ^function (const Format: String):
      TString;

    var
      FormatStringTransformPtr: FormatStringTransformType; attribute
      (name = '_p_FormatStringTransformPtr'); external;

    { Runtime error and signal handling routines, from error.pas }

    const
      EAssert = 381;
      EAssertString = 382;
      EOpen = 405;
      EMMap = 408;
      ERead = 413;
      EWrite = 414;
      EWriteReadOnly = 422;
      EOpenRead = 442;
      EOpenWrite = 443;
      EOpenUpdate = 444;
      EReading = 464;
      EWriting = 466;
      ECannotWriteAll = 467;
      ECannotFork = 600;
      ECannotSpawn = 601;
      EProgramNotFound = 602;
      EProgramNotExecutable = 603;
      EPipe = 604;
      EPrinterRead = 610;
      EIOCtl = 630;
      EConvertError = 875;
      ELibraryFunction = 952;
      EExitReturned = 953;

      RuntimeErrorExitValue = 42;

      DummyReturnAddress = Pointer ($deadbeef);

    var
      { Error number (after runtime error) or exit status (after Halt)
        or 0 (during program run and after succesful termination). }
      ExitCode: Integer; attribute (name = '_p_ExitCode'); external;

      { Contains the address of the code where a runtime occurred, nil
        if no runtime error occurred. }
      ErrorAddr: Pointer; attribute (name = '_p_ErrorAddr'); external;

      { Error message }
      ErrorMessageString: TString; attribute (name
      = '_p_ErrorMessageString'); external;

      { String parameter to some error messages, *not* the text of the
        error message (the latter can be obtained with
        GetErrorMessage). }
      InOutResString: PString; attribute (name = '_p_InOutResString');
      external;

      { Optional libc error string to some error messages. }
      InOutResCErrorString: PString; attribute (name
      = '_p_InOutResCErrorString'); external;

      RTSErrorFD: Integer; attribute (name = '_p_ErrorFD'); external;
      RTSErrorFileName: PString; attribute (name = '_p_ErrorFileName');
      external;

    function  GetErrorMessage                 (n: Integer): CString;
      attribute (name = '_p_GetErrorMessage'); external;
    procedure RuntimeError                    (n: Integer); attribute
      (noreturn, name = '_p_RuntimeError'); external;
    procedure RuntimeErrorErrNo               (n: Integer); attribute
      (noreturn, name = '_p_RuntimeErrorErrNo'); external;
    procedure RuntimeErrorInteger             (n: Integer; i: MedInt);
      attribute (noreturn, name = '_p_RuntimeErrorInteger'); external;
    procedure RuntimeErrorCString             (n: Integer; s: CString);
      attribute (noreturn, name = '_p_RuntimeErrorCString'); external;
    procedure InternalError                   (n: Integer); attribute
      (noreturn, name = '_p_InternalError'); external;
    procedure InternalErrorInteger            (n: Integer; i: MedInt);
      attribute (noreturn, name = '_p_InternalErrorInteger'); external;
    procedure InternalErrorCString            (n: Integer; s: CString);
      attribute (noreturn, name = '_p_InternalErrorCString'); external;
    procedure RuntimeWarning                  (Message: CString);
      attribute (name = '_p_RuntimeWarning'); external;
    procedure RuntimeWarningInteger           (Message: CString; i:
      MedInt); attribute (name = '_p_RuntimeWarningInteger'); external;
    procedure RuntimeWarningCString           (Message: CString; s:
      CString); attribute (name = '_p_RuntimeWarningCString'); external;
    procedure DebugStatement                  (const FileName: String;
      Line: Integer); attribute (name = '_p_DebugStatement'); external;

    procedure IOError                         (n: Integer; ErrNoFlag:
      Boolean); attribute (iocritical, name = '_p_IOError'); external;
    procedure IOErrorInteger                  (n: Integer; i: MedInt;
      ErrNoFlag: Boolean); attribute (iocritical, name
      = '_p_IOErrorInteger'); external;
    procedure IOErrorCString                  (n: Integer; s: CString;
      ErrNoFlag: Boolean); attribute (iocritical, name
      = '_p_IOErrorCString'); external;
    procedure IOErrorFile                     (n: Integer; protected var
      f: AnyFile; ErrNoFlag: Boolean); attribute (iocritical, name
      = '_p_IOErrorFile'); external;

    function  GetIOErrorMessage: TString; attribute (name
      = '_p_GetIOErrorMessage'); external;
    procedure CheckInOutRes; attribute (name = '_p_CheckInOutRes');
      external;

    { Registers a procedure to be called to restore the terminal for
      another process that accesses the terminal, or back for the
      program itself. Used e.g. by the CRT unit. The procedures must
      allow for being called multiple times in any order, even at the
      end of the program (see the comment for RestoreTerminal). }
    procedure RegisterRestoreTerminal (ForAnotherProcess: Boolean;
      procedure Proc); attribute (name = '_p_RegisterRestoreTerminal');
      external;

    { Unregisters a procedure registered with RegisterRestoreTerminal.
      Returns False if the procedure had not been registered, and True
      if it had been registered and was unregistered successfully. }
    function  UnregisterRestoreTerminal (ForAnotherProcess: Boolean;
      procedure Proc): Boolean; attribute (name
      = '_p_UnregisterRestoreTerminal'); external;

    { Calls the procedures registered by RegisterRestoreTerminal. When
      restoring the terminal for another process, the procedures are
      called in the opposite order of registration. When restoring back
      for the program, they are called in the order of registration.

      RestoreTerminal (True) will also be called at the end of the
      program, before outputting any runtime error message. It can also
      be used if you want to write an error message and exit the program
      (especially when using e.g. the CRT unit). For this purpose, to
      avoid side effects, call RestoreTerminal immediately before
      writing the error message (to StdErr, not to Output!), and then
      exit the program (e.g. with Halt). }
    procedure RestoreTerminal (ForAnotherProcess: Boolean); attribute
      (name = '_p_RestoreTerminal'); external;

    procedure AtExit (procedure Proc); attribute (name = '_p_AtExit');
      external;

    function  ReturnAddr2Hex (p: Pointer): TString; attribute (name
      = '_p_ReturnAddr2Hex'); external;

    { This function is used to write error messages etc. It does not use
      the Pascal I/O system here because it is usually called at the
      very end of a program after the Pascal I/O system has been shut
      down. }
    function  WriteErrorMessage (const s: String; StdErrFlag: Boolean):
      Boolean; attribute (name = '_p_WriteErrorMessage'); external;

    procedure SetReturnAddress (Address: Pointer); attribute (name
      = '_p_SetReturnAddress'); external;
    procedure RestoreReturnAddress; attribute (name
      = '_p_RestoreReturnAddress'); external;
    function  SetTempDummyReturnAddress: Pointer; attribute (name
      = '_p_SetTempDummyReturnAddress'); external;
    procedure RestoreTempReturnAddress (Address: Pointer); attribute
      (name = '_p_RestoreTempReturnAddress'); external;

    { Returns a description for a signal }
    function  StrSignal (Signal: Integer): TString; attribute (name
      = '_p_StrSignal'); external;

    { Installs some signal handlers that cause runtime errors on certain
      signals. This procedure runs only once, and returns immediately
      when called again (so you can't use it to set the signals again if
      you changed them meanwhile). @@Does not work on all systems (since
      the handler might have too little stack space). }
    procedure InstallDefaultSignalHandlers; attribute (name
      = '_p_InstallDefaultSignalHandlers'); external;

    var
      { Signal actions }
      SignalDefault: TSignalHandler; attribute (const); external
      name '_p_SIG_DFL';
      SignalIgnore : TSignalHandler; attribute (const); external
      name '_p_SIG_IGN';
      SignalError  : TSignalHandler; attribute (const); external
      name '_p_SIG_ERR';

      { Signals. The constants are set to the signal numbers, and
        are 0 for signals not defined. }
      { POSIX signals }
      SigHUp   : Integer; attribute (const); external name '_p_SIGHUP';
      SigInt   : Integer; attribute (const); external name '_p_SIGINT';
      SigQuit  : Integer; attribute (const); external name '_p_SIGQUIT';
      SigIll   : Integer; attribute (const); external name '_p_SIGILL';
      SigAbrt  : Integer; attribute (const); external name '_p_SIGABRT';
      SigFPE   : Integer; attribute (const); external name '_p_SIGFPE';
      SigKill  : Integer; attribute (const); external name '_p_SIGKILL';
      SigSegV  : Integer; attribute (const); external name '_p_SIGSEGV';
      SigPipe  : Integer; attribute (const); external name '_p_SIGPIPE';
      SigAlrm  : Integer; attribute (const); external name '_p_SIGALRM';
      SigTerm  : Integer; attribute (const); external name '_p_SIGTERM';
      SigUsr1  : Integer; attribute (const); external name '_p_SIGUSR1';
      SigUsr2  : Integer; attribute (const); external name '_p_SIGUSR2';
      SigChld  : Integer; attribute (const); external name '_p_SIGCHLD';
      SigCont  : Integer; attribute (const); external name '_p_SIGCONT';
      SigStop  : Integer; attribute (const); external name '_p_SIGSTOP';
      SigTStp  : Integer; attribute (const); external name '_p_SIGTSTP';
      SigTTIn  : Integer; attribute (const); external name '_p_SIGTTIN';
      SigTTOu  : Integer; attribute (const); external name '_p_SIGTTOU';

      { Non-POSIX signals }
      SigTrap  : Integer; attribute (const); external name '_p_SIGTRAP';
      SigIOT   : Integer; attribute (const); external name '_p_SIGIOT';
      SigEMT   : Integer; attribute (const); external name '_p_SIGEMT';
      SigBus   : Integer; attribute (const); external name '_p_SIGBUS';
      SigSys   : Integer; attribute (const); external name '_p_SIGSYS';
      SigStkFlt: Integer; attribute (const); external
      name '_p_SIGSTKFLT';
      SigUrg   : Integer; attribute (const); external name '_p_SIGURG';
      SigIO    : Integer; attribute (const); external name '_p_SIGIO';
      SigPoll  : Integer; attribute (const); external name '_p_SIGPOLL';
      SigXCPU  : Integer; attribute (const); external name '_p_SIGXCPU';
      SigXFSz  : Integer; attribute (const); external name '_p_SIGXFSZ';
      SigVTAlrm: Integer; attribute (const); external
      name '_p_SIGVTALRM';
      SigProf  : Integer; attribute (const); external name '_p_SIGPROF';
      SigPwr   : Integer; attribute (const); external name '_p_SIGPWR';
      SigInfo  : Integer; attribute (const); external name '_p_SIGINFO';
      SigLost  : Integer; attribute (const); external name '_p_SIGLOST';
      SigWinCh : Integer; attribute (const); external
      name '_p_SIGWINCH';

      { Signal subcodes (only used on some systems, -1 if not used) }
      FPEIntegerOverflow      : Integer; attribute (const); external
      name '_p_FPE_INTOVF_TRAP';
      FPEIntegerDivisionByZero: Integer; attribute (const); external
      name '_p_FPE_INTDIV_TRAP';
      FPESubscriptRange       : Integer; attribute (const); external
      name '_p_FPE_SUBRNG_TRAP';
      FPERealOverflow         : Integer; attribute (const); external
      name '_p_FPE_FLTOVF_TRAP';
      FPERealDivisionByZero   : Integer; attribute (const); external
      name '_p_FPE_FLTDIV_TRAP';
      FPERealUnderflow        : Integer; attribute (const); external
      name '_p_FPE_FLTUND_TRAP';
      FPEDecimalOverflow      : Integer; attribute (const); external
      name '_p_FPE_DECOVF_TRAP';

    { Routines called implicitly by the compiler. }
    procedure GPC_Assert (Condition: Boolean; const Message: String);
      attribute (name = '_p_Assert'); external;
    function  ObjectTypeIs (Left, Right: PObjectType): Boolean;
      attribute (const, name = '_p_ObjectTypeIs'); external;
    procedure ObjectTypeAsError; attribute (name
      = '_p_ObjectTypeAsError'); external;
    procedure CaseNoMatchError; attribute (name
      = '_p_CaseNoMatchError'); external;
    procedure ModRangeError; attribute (name = '_p_ModRangeError');
      external;

    { Time and date routines, from time.pas }

    const
      InvalidYear = -MaxInt;

    var
      { DayOfWeekName is a constant and therefore does not respect the
        locale. Therefore, it's recommended to use FormatTime instead. }
      DayOfWeekName: array [0 .. 6] of String [9]; attribute (const,
      name = '_p_DayOfWeekName'); external;

      { MonthName is a constant and therefore does not respect the
        locale. Therefore, it's recommended to use FormatTime instead. }
      MonthName: array [1 .. 12] of String [9]; attribute (const, name
      = '_p_MonthName'); external;

    function  GetDayOfWeek (Day, Month, Year: Integer): Integer;
      attribute (name = '_p_GetDayOfWeek'); external;
    function  GetDayOfYear (Day, Month, Year: Integer): Integer;
      attribute (name = '_p_GetDayOfYear'); external;
    function  GetSundayWeekOfYear (Day, Month, Year: Integer): Integer;
      attribute (name = '_p_GetSundayWeekOfYear'); external;
    function  GetMondayWeekOfYear (Day, Month, Year: Integer): Integer;
      attribute (name = '_p_GetMondayWeekOfYear'); external;
    procedure GetISOWeekOfYear (Day, Month, Year: Integer; var ISOWeek,
      ISOWeekYear: Integer); attribute (name = '_p_GetISOWeekOfYear');
      external;
    procedure UnixTimeToTimeStamp (UnixTime: UnixTimeType; var
      aTimeStamp: TimeStamp); attribute (name
      = '_p_UnixTimeToTimeStamp'); external;
    function  TimeStampToUnixTime (protected var aTimeStamp: TimeStamp):
      UnixTimeType; attribute (name = '_p_TimeStampToUnixTime');
      external;
    function  GetMicroSecondTime: MicroSecondTimeType; attribute (name
      = '_p_GetMicroSecondTime'); external;

    { Is the year a leap year? }
    function  IsLeapYear (Year: Integer): Boolean; attribute (name
      = '_p_IsLeapYear'); external;

    { Returns the length of the month, taking leap years into account. }
    function  MonthLength (Month, Year: Integer): Integer; attribute
      (name = '_p_MonthLength'); external;

    { Formats a TimeStamp value according to a Format string. The format
      string can contain date/time items consisting of %, followed by
      the specifiers listed below. All characters outside of these items
      are copied to the result unmodified. The specifiers correspond to
      those of the C function strftime(), including POSIX.2 and glibc
      extensions and some more extensions. The extensions are also
      available on systems whose strftime() doesn't support them.

      The following modifiers may appear after the %:

      _  The item is left padded with spaces to the given or default
           width.

      -  The item is not padded at all.

      0  The item is left padded with zeros to the given or default
           width.

      /  The item is right trimmed if it is longer than the given
           width.

      ^  The item is converted to upper case.

      ~  The item is converted to lower case.

      After zero or more of these flags, an optional width may be
      specified for padding and trimming. It must be given as a decimal
      number (not starting with 0 since 0 has a meaning of its own,
      see above).

      Afterwards, the following optional modifiers may follow. Their
      meaning is locale-dependent, and many systems and locales just
      ignore them.

      E  Use the locale's alternate representation for date and time.
           In a Japanese locale, for example, %Ex might yield a date
           format based on the Japanese Emperors' reigns.

      O  Use the locale's alternate numeric symbols for numbers. This
           modifier applies only to numeric format specifiers.

      Finally, exactly one of the following specifiers must appear. The
      padding rules listed here are the defaults that can be overriden
      with the modifiers listed above.

      a  The abbreviated weekday name according to the current locale.

      A  The full weekday name according to the current locale.

      b  The abbreviated month name according to the current locale.

      B  The full month name according to the current locale.

      c  The preferred date and time representation for the current
           locale.

      C  The century of the year. This is equivalent to the greatest
           integer not greater than the year divided by 100.

      d  The day of the month as a decimal number (01 .. 31).

      D  The date using the format %m/%d/%y. NOTE: Don't use this
           format if it can be avoided. Things like this caused Y2K
           bugs!

      e  The day of the month like with %d, but padded with blanks
           ( 1 .. 31).

      F  The date using the format %Y-%m-%d. This is the form
           specified in the ISO 8601 standard and is the preferred form
           for all uses.

      g  The year corresponding to the ISO week number, but without
           the century (00 .. 99). This has the same format and
           value as y, except that if the ISO week number (see V)
           belongs to the previous or next year, that year is used
           instead. NOTE: Don't use this format if it can be avoided.
           Things like this caused Y2K bugs!

      G  The year corresponding to the ISO week number. This has the
           same format and value as Y, except that if the ISO week
           number (see V) belongs to the previous or next year, that
           year is used instead.

      h  The abbreviated month name according to the current locale.
           This is the same as b.

      H  The hour as a decimal number, using a 24-hour clock
           (00 .. 23).

      I  The hour as a decimal number, using a 12-hour clock
           (01 .. 12).

      j  The day of the year as a decimal number (001 .. 366).

      k  The hour as a decimal number, using a 24-hour clock like H,
           but padded with blanks ( 0 .. 23).

      l  The hour as a decimal number, using a 12-hour clock like I,
           but padded with blanks ( 1 .. 12).

      m  The month as a decimal number (01 .. 12).

      M  The minute as a decimal number (00 .. 59).

      n  A single newline character.

      p  Either AM or PM, according to the given time value; or
           the corresponding strings for the current locale. Noon is
           treated as PM and midnight as AM.

      P  Either am or pm, according to the given time value; or
           the corresponding strings for the current locale, printed in
           lowercase characters. Noon is treated as pm and midnight as
           am.

      Q  The fractional part of the second. This format has special
           effects on the modifiers. The width, if given, determines the
           number of digits to output. Therefore, no actual clipping or
           trimming is done. However, if padding with spaces is
           specified, any trailing (i.e., right!) zeros are converted to
           spaces, and if "no padding" is specified, they are removed.
           The default is "padding with zeros", i.e. trailing zeros are
           left unchanged. The digits are cut when necessary without
           rounding (otherwise, the value would not be consistent with
           the seconds given by S and s). Note that GPC's TimeStamp
           currently provides for microsecond resolution, so there are
           at most 6 valid digits (which is also the default width), any
           further digits will be 0 (but if TimeStamp will ever change,
           this format will be adjusted). However, the actual resolution
           provided by the operating system via GetTimeStamp etc. may be
           far lower (e.g., ~1/18s under Dos).

      r  The complete time using the AM/PM format of the current
           locale.

      R  The hour and minute in decimal numbers using the format
           %H:%M.

      s  Unix time, i.e. the number of seconds since the epoch, i.e.,
           since 1970-01-01 00:00:00 UTC. Leap seconds are not counted
           unless leap second support is available.

      S  The seconds as a decimal number (00 .. 60).

      t  A single tab character.

      T  The time using decimal numbers using the format %H:%M:%S.

      u  The day of the week as a decimal number (1 .. 7), Monday
           being 1.

      U  The week number of the current year as a decimal number
           (00 .. 53), starting with the first Sunday as the first
           day of the first week. Days preceding the first Sunday in the
           year are considered to be in week 00.

      V  The ISO 8601:1988 week number as a decimal number
           (01 .. 53). ISO weeks start with Monday and end with
           Sunday. Week 01 of a year is the first week which has the
           majority of its days in that year; this is equivalent to the
           week containing the year's first Thursday, and it is also
           equivalent to the week containing January 4. Week 01 of a
           year can contain days from the previous year. The week before
           week 01 of a year is the last week (52 or 53) of the
           previous year even if it contains days from the new year.

      w  The day of the week as a decimal number (0 .. 6), Sunday
           being 0.

      W  The week number of the current year as a decimal number
           (00 .. 53), starting with the first Monday as the first
           day of the first week. All days preceding the first Monday in
           the year are considered to be in week 00.

      x  The preferred date representation for the current locale, but
           without the time.

      X  The preferred time representation for the current locale, but
           with no date.

      y  The year without a century as a decimal number
           (00 .. 99). This is equivalent to the year modulo 100.
           NOTE: Don't use this format if it can be avoided. Things like
           this caused Y2K bugs!

      Y  The year as a decimal number, using the Gregorian calendar.
           Years before the year 1 are numbered 0, -1, and so on.

      z  RFC 822/ISO 8601:1988 style numeric time zone (e.g., -0600
           or +0100), or nothing if no time zone is determinable.

      Z  The time zone abbreviation (empty if the time zone can't be
           determined).

      %  (i.e., an item %%) A literal % character. }
    function  FormatTime (const Time: TimeStamp; const Format: String):
      TString; attribute (name = '_p_FormatTime'); external;

    { Pseudo random number generator, from random.pas }

    type
      RandomSeedType = Cardinal attribute (Size = 32);
      RandomizeType  = ^procedure;
      SeedRandomType = ^procedure (Seed: RandomSeedType);
      RandRealType   = ^function: LongestReal;
      RandIntType    = ^function (MaxValue: LongestCard): LongestCard;

    var
      RandomizePtr : RandomizeType; attribute (name
      = '_p_RandomizePtr'); external;
      SeedRandomPtr: SeedRandomType; attribute (name
      = '_p_SeedRandomPtr'); external;
      RandRealPtr  : RandRealType; attribute (name = '_p_RandRealPtr');
      external;
      RandIntPtr   : RandIntType; attribute (name = '_p_RandIntPtr');
      external;

    procedure SeedRandom (Seed: RandomSeedType); attribute (name
      = '_p_SeedRandom'); external;

    { File name routines, from filename.pas }

    { Define constants for different systems:

      OSDosFlag:         flag to indicate whether the target system is
                         Dos

      QuotingCharacter:  the character used to quote wild cards and
                         other special characters (#0 if not available)

      PathSeparator:     the separator of multiple paths, e.g. in the
                         PATH environment variable

      DirSeparator:      the separator of the directories within a full
                         file name

      DirSeparators:     a set of all possible directory and drive name
                         separators

      ExtSeparator:      the separator of a file name extension

      DirRoot:           the name of the root directory

      DirSelf:           the name of a directory in itself

      DirParent:         the name of the parent directory

      MaskNoStdDir:      a file name mask that matches all names except
                         the standard directories DirSelf and DirParent

      NullDeviceName:    the full file name of the null device

      TtyDeviceName:     the full file name of the current Tty

      ConsoleDeviceName: the full file name of the system console. On
                         Dos systems, this is the same as the Tty, but
                         on systems that allow remote login, this is a
                         different thing and may reach a completely
                         different user than the one running the
                         program, so use it with care.

      EnvVarCharsFirst:  the characters accepted at the beginning of the
                         name of an environment variable without quoting

      EnvVarChars:       the characters accepted in the name of an
                         environment variable without quoting

      PathEnvVar:        the name of the environment variable which
                         (usually) contains the executable search path

      ShellEnvVar:       the name of the environment variable which
                         (usually) contains the path of the shell
                         executable (see GetShellPath)

      ShellExecCommand:  the option to the (default) shell to execute
                         the command specified in the following argument
                         (see GetShellPath)

      ConfigFileMask:    a mask for the option file name as returned by
                         ConfigFileName

      FileNamesCaseSensitive:
                         flag to indicate whether file names are case
                         sensitive }

    const
      UnixShellEnvVar        = 'SHELL';
      UnixShellExecCommand   = '-c';

    {$ifdef __OS_DOS__}

    const
      OSDosFlag              = True;
      QuotingCharacter       = #0;
      PathSeparator          = {$ifdef __CYGWIN__} ':' {$else} ';'
      {$endif};
      DirSeparator           = '\';
      DirSeparators          = [':', '\', '/'];
      ExtSeparator           = '.';
      DirRoot                = '\';
      DirSelf                = '.';
      DirParent              = '..';
      MaskNoStdDir           = '{*,.[^.]*,..?*}';
      NullDeviceName         = 'nul';
      TtyDeviceName          = 'con';
      ConsoleDeviceName      = 'con';
      EnvVarCharsFirst       = ['A' .. 'Z', 'a' .. 'z', '_'];
      EnvVarChars            = EnvVarCharsFirst + ['0' .. '9'];
      PathEnvVar             = 'PATH';
      ShellEnvVar            = 'COMSPEC';
      ShellExecCommand       = '/c';
      ConfigFileMask         = '*.cfg';
      FileNamesCaseSensitive = False;

    {$else}

    const
      OSDosFlag              = False;
      QuotingCharacter       = '\';
      PathSeparator          = ':';
      DirSeparator           = '/';
      DirSeparators          = ['/'];
      ExtSeparator           = '.';
      DirRoot                = '/';
      DirSelf                = '.';
      DirParent              = '..';
      MaskNoStdDir           = '{*,.[^.]*,..?*}';
      NullDeviceName         = '/dev/null';
      TtyDeviceName          = '/dev/tty';
      ConsoleDeviceName      = '/dev/console';
      EnvVarCharsFirst       = ['A' .. 'Z', 'a' .. 'z', '_'];
      EnvVarChars            = EnvVarCharsFirst + ['0' .. '9'];
      PathEnvVar             = 'PATH';
      ShellEnvVar            = UnixShellEnvVar;
      ShellExecCommand       = UnixShellExecCommand;
      ConfigFileMask         = '.*';
      FileNamesCaseSensitive = True;

    {$endif}

    const
      WildCardChars = ['*', '?', '[', ']'];
      FileNameSpecialChars = (WildCardChars + SpaceCharacters +
      ['{', '}', '$', QuotingCharacter]) - DirSeparators;

    type
      DirPtr = Pointer;

    { Convert ch to lower case if FileNamesCaseSensitive is False, leave
      it unchanged otherwise. }
    function  FileNameLoCase (ch: Char): Char; attribute (name
      = '_p_FileNameLoCase'); external;

    { Change a file name to use the OS dependent directory separator }
    function  Slash2OSDirSeparator (const s: String): TString; attribute
      (name = '_p_Slash2OSDirSeparator'); external;

    { Change a file name to use '/' as directory separator }
    function  OSDirSeparator2Slash (const s: String): TString; attribute
      (name = '_p_OSDirSeparator2Slash'); external;

    { Like Slash2OSDirSeparator for CStrings. *Note*: overwrites the
      CString }
    function  Slash2OSDirSeparator_CString (s: CString): CString;
      attribute (name = '_p_Slash2OSDirSeparator_CString'); external;

    { Like OSDirSeparator2Slash for CStrings. *Note*: overwrites the
      CString }
    function  OSDirSeparator2Slash_CString (s: CString): CString;
      attribute (name = '_p_OSDirSeparator2Slash_CString'); external;

    { Add a DirSeparator to the end of s, if there is not already one
      and s denotes an existing directory }
    function  AddDirSeparator (const s: String): TString; attribute
      (name = '_p_AddDirSeparator'); external;

    { Like AddDirSeparator, but also if the directory does not exist }
    function  ForceAddDirSeparator (const s: String): TString; attribute
      (name = '_p_ForceAddDirSeparator'); external;

    { Remove all trailing DirSeparators from s, if there are any, as
      long as removing them doesn't change the meaning (i.e., they don't
      denote the root directory. }
    function  RemoveDirSeparator (const s: String): TString; attribute
      (name = '_p_RemoveDirSeparator'); external;

    { Returns the current directory using OS dependent directory
      separators }
    function  GetCurrentDirectory: TString; attribute (name
      = '_p_GetCurrentDirectory'); external;

    { Returns a directory suitable for storing temporary files using OS
      dependent directory separators. If found, the result always ends
      in DirSeparator. If no suitable directory is found, an empty
      string is returned. }
    function  GetTempDirectory: TString; attribute (name
      = '_p_GetTempDirectory'); external;

    { Returns a non-existing file name in the directory given. If the
      directory doesn't exist or the Directory name is empty, an I/O
      error is raised, and GetTempFileNameInDirectory returns the empty
      string. }
    function  GetTempFileNameInDirectory (const Directory: String):
      TString; attribute (iocritical, name
      = '_p_GetTempFileNameInDirectory'); external;

    { Returns a non-existing file name in GetTempDirectory. If no temp
      directory is found, i.e. GetTempDirectory returns the empty
      string, an I/O error is raised, and GetTempFileName returns the
      empty string as well. }
    function  GetTempFileName: TString; attribute (iocritical, name
      = '_p_GetTempFileName'); external;

    { The same as GetTempFileName, but returns a CString allocated from
      the heap. }
    function  GetTempFileName_CString: CString; attribute (iocritical,
      name = '_p_GetTempFileName_CString'); external;

    { Get the external name of a file }
    function  FileName (protected var f: AnyFile): TString; attribute
      (name = '_p_FileName'); external;

    { Returns True if the given file name is an existing plain file }
    function  FileExists      (const aFileName: String): Boolean;
      attribute (name = '_p_FileExists'); external;

    { Returns True if the given file name is an existing directory }
    function  DirectoryExists (const aFileName: String): Boolean;
      attribute (name = '_p_DirectoryExists'); external;

    { Returns True if the given file name is an existing file, directory
      or special file (device, pipe, socket, etc.) }
    function  PathExists      (const aFileName: String): Boolean;
      attribute (name = '_p_PathExists'); external;

    { If a file of the given name exists in one of the directories given
      in DirList (separated by PathSeparator), returns the full path,
      otherwise returns an empty string. If aFileName already contains
      an element of DirSeparators, returns Slash2OSDirSeparator
      (aFileName) if it exists. }
    function  FSearch (const aFileName, DirList: String): TString;
      attribute (name = '_p_FSearch'); external;

    { Like FSearch, but only find executable files. Under Dos, if not
      found, the function tries appending '.com', '.exe', '.bat' and
      .cmd (the last one only if $COMSPEC points to a cmd.exe), so
      you don't have to specify these extensions in aFileName (and with
      respect to portability, it might be preferable not to do so). }
    function  FSearchExecutable (const aFileName, DirList: String):
      TString; attribute (name = '_p_FSearchExecutable'); external;

    { Replaces all occurrences of $FOO and ~ in s by the value of
      the environment variables FOO or HOME, respectively. If a variable
      is not defined, the function returns False, and s contains the
      name of the undefined variable (or the empty string if the
      variable name is invalid, i.e., doesn't start with a character
      from EnvVarCharsFirst). Otherwise, if all variables are found, s
      contains the replaced string, and True is returned. }
    function  ExpandEnvironment (var s: String): Boolean; attribute
      (name = '_p_ExpandEnvironment'); external;

    { Expands the given path name to a full path name. Relative paths
      are expanded using the current directory, and occurrences of
      DirSelf and DirParent are resolved. Under Dos, the result is
      converted to lower case and a trailing ExtSeparator (except in a
      trailing DirSelf or DirParent) is removed, like Dos does. If the
      directory, i.e. the path without the file name, is invalid, the
      empty string is returned. }
    function  FExpand       (const Path: String): TString; attribute
      (name = '_p_FExpand'); external;

    { Like FExpand, but unquotes the directory before expanding it, and
      quotes WildCardChars again afterwards. Does not check if the
      directory is valid (because it may contain wild card characters).
      Symlinks are expanded only in the directory part, not the file
      name. }
    function  FExpandQuoted (const Path: String): TString; attribute
      (name = '_p_FExpandQuoted'); external;

    { FExpands Path, and then removes the current directory from it, if
      it is a prefix of it. If OnlyCurDir is set, the current directory
      will be removed only if Path denotes a file in, not below, it. }
    function  RelativePath (const Path: String; OnlyCurDir, Quoted:
      Boolean): TString; attribute (name = '_p_RelativePath'); external;

    { Is aFileName a UNC filename? (Always returns False on non-Dos
      systems.) }
    function  IsUNC (const aFileName: String): Boolean; attribute (name
      = '_p_IsUNC'); external;

    { Splits a file name into directory, name and extension. Each of
      Dir, BaseName and Ext may be Null. }
    procedure FSplit (const Path: String; var Dir, BaseName, Ext:
      String); attribute (name = '_p_FSplit'); external;

    { Functions that extract one or two of the parts from FSplit.
      DirFromPath returns DirSelf + DirSeparator if the path contains no
      directory. }
    function  DirFromPath     (const Path: String): TString; attribute
      (name = '_p_DirFromPath'); external;
    function  NameFromPath    (const Path: String): TString; attribute
      (name = '_p_NameFromPath'); external;
    function  ExtFromPath     (const Path: String): TString; attribute
      (name = '_p_ExtFromPath'); external;
    function  NameExtFromPath (const Path: String): TString; attribute
      (name = '_p_NameExtFromPath'); external;

    { Start reading a directory. If successful, a pointer is returned
      that can be used for subsequent calls to ReadDir and finally
      CloseDir. On failure, an I/O error is raised and (in case it is
      ignored) nil is returned. }
    function  OpenDir  (const DirName: String): DirPtr; attribute
      (iocritical, name = '_p_OpenDir'); external;

    { Reads one entry from the directory Dir, and returns the file name.
      On errors or end of directory, the empty string is returned. }
    function  ReadDir  (Dir: DirPtr): TString; attribute (name
      = '_p_ReadDir'); external;

    { Closes a directory opened with OpenDir. }
    procedure CloseDir (Dir: DirPtr); attribute (name = '_p_CloseDir');
      external;

    { Returns the first position of a non-quoted character of CharSet in
      s, or 0 if no such character exists. }
    function  FindNonQuotedChar (Chars: CharSet; const s: String; From:
      Integer): Integer; attribute (name = '_p_FindNonQuotedChar');
      external;

    { Returns the first occurence of SubString in s that is not quoted
      at the beginning, or 0 if no such occurence exists. }
    function  FindNonQuotedStr (const SubString, s: String; From:
      Integer): Integer; attribute (name = '_p_FindNonQuotedStr');
      external;

    { Does a string contain non-quoted wildcard characters? }
    function  HasWildCards (const s: String): Boolean; attribute (name
      = '_p_HasWildCards'); external;

    { Does a string contain non-quoted wildcard characters, braces or
      spaces? }
    function  HasWildCardsOrBraces (const s: String): Boolean; attribute
      (name = '_p_HasWildCardsOrBraces'); external;

    { Insert QuotingCharacter into s before any special characters }
    function  QuoteFileName (const s: String; const SpecialCharacters:
      CharSet): TString; attribute (name = '_p_QuoteFileName');
      external;

    { Remove QuotingCharacter from s }
    function  UnQuoteFileName (const s: String): TString; attribute
      (name = '_p_UnQuoteFileName'); external;

    { Splits s at non-quoted spaces and expands non-quoted braces like
      bash does. The result and its entries should be disposed after
      usage, e.g. with DisposePPStrings. }
    function  BraceExpand (const s: String): PPStrings; attribute (name
      = '_p_BraceExpand'); external;

    { Dispose of a PPStrings array as well as the strings it contains.
      If you want to keep the strings (by assigning them to other string
      pointers), you should instead free the PPStrings array with
      Dispose. }
    procedure DisposePPStrings (Strings: PPStrings); attribute (name
      = '_p_DisposePPStrings'); external;

    { Tests if a file name matches a shell wildcard pattern (?, *, []) }
    function  FileNameMatch (const Pattern, FileName: String): Boolean;
      attribute (name = '_p_FileNameMatch'); external;

    { FileNameMatch with BraceExpand }
    function  MultiFileNameMatch (const Pattern, FileName: String):
      Boolean; attribute (name = '_p_MultiFileNameMatch'); external;

    { File name globbing }
    { GlobInit is implied by Glob and MultiGlob, not by GlobOn and
      MultiGlobOn. GlobOn and MultiGlobOn must be called after GlobInit,
      Glob or MultiGlob. MultiGlob and MultiGlobOn do brace expansion,
      Glob and GlobOn do not. GlobFree frees the memory allocated by the
      globbing functions and invalidates the results in Buf. It should
      be called after globbing. }
    procedure GlobInit    (var Buf: GlobBuffer); attribute (name
      = '_p_GlobInit'); external;
    procedure Glob        (var Buf: GlobBuffer; const Pattern: String);
      attribute (name = '_p_Glob'); external;
    procedure GlobOn      (var Buf: GlobBuffer; const Pattern: String);
      attribute (name = '_p_GlobOn'); external;
    procedure MultiGlob   (var Buf: GlobBuffer; const Pattern: String);
      attribute (name = '_p_MultiGlob'); external;
    procedure MultiGlobOn (var Buf: GlobBuffer; const Pattern: String);
      attribute (name = '_p_MultiGlobOn'); external;
    procedure GlobFree    (var Buf: GlobBuffer); attribute (name
      = '_p_GlobFree'); external;

    type
      TPasswordEntry = record
        UserName, RealName, Password, HomeDirectory, Shell: PString;
        UID, GID: Integer
      end;

      PPasswordEntries = ^TPasswordEntries;
      TPasswordEntries (Count: Integer) = array [1 .. Count] of
      TPasswordEntry;

    { Finds a password entry by user name. Returns True if found, False
      otherwise. }
    function  GetPasswordEntryByName (const UserName: String; var Entry:
      TPasswordEntry): Boolean; attribute (name
      = '_p_GetPasswordEntryByName'); external;

    { Finds a password entry by UID. Returns True if found, False
      otherwise. }
    function  GetPasswordEntryByUID  (UID: Integer; var Entry:
      TPasswordEntry): Boolean; attribute (name
      = '_p_GetPasswordEntryByUID'); external;

    { Returns all password entries, or nil if none found. }
    function  GetPasswordEntries: PPasswordEntries; attribute (name
      = '_p_GetPasswordEntries'); external;

    { Dispose of a TPasswordEntry. }
    procedure DisposePasswordEntry (Entry: TPasswordEntry); attribute
      (name = '_p_DisposePasswordEntry'); external;

    { Dispose of a PPasswordEntries. }
    procedure DisposePasswordEntries (Entries: PPasswordEntries);
      attribute (name = '_p_DisposePasswordEntries'); external;

    { Returns the mount point (Unix) or drive (Dos) which is part of the
      given path. If the path does not contain any (i.e., is a relative
      path), an empty string is returned. Therefore, if you want to get
      the mount point or drive in any case, apply FExpand or
      RealPath to the argument. }
    function  GetMountPoint (const Path: String): TString; attribute
      (name = '_p_GetMountPoint'); external;

    type
      TSystemInfo = record
        OSName,
        OSRelease,
        OSVersion,
        MachineType,
        HostName,
        DomainName: TString
      end;

    { Returns system information if available. Fields not available will
      be empty. }
    function  SystemInfo: TSystemInfo; attribute (name
      = '_p_SystemInfo'); external;

    { Returns the path to the shell (as the result) and the option that
      makes it execute the command specified in the following argument
      (in Option). Usually these are the environment value of
      ShellEnvVar, and ShellExecCommand, but on Dos systems, the
      function will first try UnixShellEnvVar, and UnixShellExecCommand
      because ShellEnvVar will usually point to command.com, but
      UnixShellEnvVar can point to bash which is usually a better choice
      when present. If UnixShellEnvVar is not set, or the shell given
      does not exist, it will use ShellEnvVar, and ShellExecCommand.
      Option may be Null (in case you want to invoke the shell
      interactively). }
    function  GetShellPath (var Option: String): TString; attribute
      (name = '_p_GetShellPath'); external;

    { Returns the path of the running executable. *Note*: On most
      systems, this is *not* guaranteed to be the full path, but often
      just the same as ParamStr (0) which usually is the name given on
      the command line. Only on some systems with special support, it
      returns the full path when ParamStr (0) doesn't. }
    function  ExecutablePath: TString; attribute (name
      = '_p_ExecutablePath'); external;

    { Returns a file name suitable for a global (system-wide) or local
      (user-specific) configuration file, depending on the Global
      parameter. The function does not guarantee that the file name
      returned exists or is readable or writable.

      In the following table, the base name <base> is given with the
      BaseName parameter. If it is empty, the base name is the name of
      the running program (as returned by ExecutablePath, without
      directory and extension. <prefix> (Unix only) stands for the
      value of the Prefix parameter (usual values include '', '/usr' and
      '/usr/local'). <dir> (Dos only) stands for the directory where
      the running program resides. $foo stands for the value of the
      environment variable foo.

              Global                    Local
      Unix:   <prefix>/etc/<base>.conf  $HOME/.<base>

      DJGPP:  $DJDIR\etc\<base>.ini     $HOME\<base>.cfg
              <dir>\<base>.ini          <dir>\<base>.cfg

      Other   $HOME\<base>.ini          $HOME\<base>.cfg
        Dos:  <dir>\<base>.ini          <dir>\<base>.cfg

      As you see, there are two possibilities under Dos. If the first
      file exists, it is returned. Otherwise, if the second file exists,
      that is returned. If none of them exists (but the program might
      want to create a file), if the environment variable (DJDIR or
      HOME, respectively) is set, the first file name is returned,
      otherwise the second one. This rather complicated scheme should
      give the most reasonable results for systems with or without DJGPP
      installed, and with or without already existing config files. Note
      that DJDIR is always set on systems with DJGPP installed, while
      HOME is not. However, it is easy for users to set it if they want
      their config files in a certain directory rather than with the
      executables. }
    function  ConfigFileName (const Prefix, BaseName: String; Global:
      Boolean): TString; attribute (name = '_p_ConfigFileName');
      external;

    { Returns a directory name suitable for global, machine-independent
      data. The function garantees that the name returned ends with a
      DirSeparator, but does not guarantee that it exists or is
      readable or writable.

      Note: If the prefix is empty, it is assumed to be '/usr'. (If you
      really want /share, you could pass '/' as the prefix, but that's
      very uncommon.)

      Unix:   <prefix>/share/<base>/

      DJGPP:  $DJDIR\share\<base>\
              <dir>\

      Other   $HOME\<base>\
        Dos:  <dir>\

      About the symbols used above, and the two possibilities under Dos,
      see the comments for ConfigFileName. }
    function  DataDirectoryName (const Prefix, BaseName: String):
      TString; attribute (name = '_p_DataDirectoryName'); external;

    { Executes a command line. Reports execution errors via the IOResult
      mechanism and returns the exit status of the executed program.
      Execute calls RestoreTerminal with the argument True before and
      False after executing the process, ExecuteNoTerminal does not. }
    function  Execute (const CmdLine: String): Integer; attribute
      (iocritical, name = '_p_Execute'); external;
    function  ExecuteNoTerminal (const CmdLine: String): Integer;
      attribute (iocritical, name = '_p_ExecuteNoTerminal'); external;

    { File handling routines, from files.pas }

    type
      Natural = 1 .. MaxInt;
      IOSelectEvents = (SelectReadOrEOF, SelectRead, SelectEOF,
      SelectWrite, SelectException, SelectAlways);

    const
      IOSelectEventMin = { @@ Low (IOSelectEvents); } SelectReadOrEOF;
      IOSelectEventMax = Pred (SelectAlways);

    type
      IOSelectType = record
        f: PAnyFile;
        Wanted: set of IOSelectEvents;
        Occurred: set of IOSelectEventMin .. IOSelectEventMax
      end;

    { Waits for one of several events to happen. Returns when one or
      more of the wanted events for one of the files occur. If they have
      already occurred before calling the function, it returns
      immediately. MicroSeconds can specify a timeout. If it is 0, the
      function will return immediately, whether or not an event has
      occurred. If it is negative, the function will wait forever until
      an event occurs. The Events parameter can be Null, in which case
      the function only waits for the timeout. If any of the file
      pointers (f) in Events are nil or the files pointed to are closed,
      they are simply ignored for convenience.

      It returns the index of one of the files for which any event has
      occurred. If events have occurred for several files, is it
      undefined which of these file's index is returned. If no event
      occurs until the timeout, 0 is returned. If an error occurs or the
      target system does not have a select() system call and Events is
      not Null, a negative value is returned. In the Occurred field of
      the elements of Events, events that have occurred are set. The
      state of events not wanted is undefined.

      The possible events are:
      SelectReadOrEOF: the file is at EOF or data can be read now.
      SelectRead:      data can be read now.
      SelectEOF:       the file is at EOF.
      SelectWrite:     data can be written now.
      SelectException: an exception occurred on the file.
      SelectAlways:    if this is set, *all* requested events will be
                       checked for this file in any case. Otherwise,
                       checks may be skipped if already another event
                       for this or another file was found.

      Notes:
      Checking for EOF requires some reading ahead internally (just like
      the EOF function) which can be avoided by setting SelectReadOrEOF
      instead of SelectRead and SelectEOF. If this is followed by, e.g.,
      a BlockRead with 4 parameters, the last parameter will be 0 if and
      only the file is at EOF, and otherwise, data will be read directly
      from the file without reading ahead and buffering.

      SelectAlways should be set for files for which events are
      considered to be of higher priority than others. Otherwise, if one
      is interested in just any event, not setting SelectAlways may be a
      little faster. }
    function  IOSelect (var Events: array [m .. n: Natural] of
      IOSelectType; MicroSeconds: MicroSecondTimeType): Integer;
      attribute (name = '_p_IOSelect'); external;

    { A simpler interface to SelectIO for the most common use. Waits for
      SelectReadOrEOF on all files and returns an index. }
    function  IOSelectRead (const Files: array [m .. n: Natural] of
      PAnyFile; MicroSeconds: MicroSecondTimeType): Integer; attribute
      (name = '_p_IOSelectRead'); external;

    { Bind a filename to an external file }
    procedure AssignFile   (var t: AnyFile; const FileName: String);
      attribute (name = '_p_Assign'); external;
    procedure AssignBinary (var t: Text; const FileName: String);
      attribute (name = '_p_AssignBinary'); external;
    procedure AssignHandle (var t: AnyFile; Handle: Integer; CloseFlag:
      Boolean); attribute (name = '_p_AssignHandle'); external;

    { BP compatible seeking routines }
    function  Internal_SeekEOF  (var f: Text): Boolean; attribute (name
      = '_p_SeekEOF'); external;
    function  Internal_SeekEOLn (var f: Text): Boolean; attribute (name
      = '_p_SeekEOLn'); external;

    { Under development }
    procedure AnyStringTFDD_Reset (var f: AnyFile; var Buf:
      ConstAnyString); attribute (name = '_p_AnyStringTFDD_Reset');
      external;
    { @@ procedure AnyStringTFDD_Rewrite (var f: AnyFile; var Buf:
      VarAnyString); attribute (name = '_p_AnyStringTFDD_Rewrite'); }
    procedure StringTFDD_Reset (var f: AnyFile; var Buf: ConstAnyString;
      const s: String); attribute (name = '_p_StringTFDD_Reset');
      external;
    { @@ procedure StringTFDD_Rewrite (var f: AnyFile; var Buf:
      VarAnyString; var s: String); attribute (name
      = '_p_StringTFDD_Rewrite'); }

    { Returns True is a terminal device is open on the file f, False if
      f is not open or not connected to a terminal. }
    function  IsTerminal (protected var f: AnyFile): Boolean; attribute
      (name = '_p_IsTerminal'); external;

    { Returns the file name of the terminal device that is open on the
      file f. Returns the empty string if (and only if) f is not open or
      not connected to a terminal. }
    function  GetTerminalName (protected var f: AnyFile): TString;
      attribute (name = '_p_GetTerminalName'); external;

    { Command line option parsing, from getopt.pas }

    const
      EndOfOptions      = #255;
      NoOption          = #1;
      UnknownOption     = '?';
      LongOption        = #0;
      UnknownLongOption = '?';

    var
      FirstNonOption        : Integer; attribute (name
      = '_p_FirstNonOption'); external;
      HasOptionArgument     : Boolean; attribute (name
      = '_p_HasOptionArgument'); external;
      OptionArgument        : TString; attribute (name
      = '_p_OptionArgument'); external;
      UnknownOptionCharacter: Char; attribute (name
      = '_p_UnknownOptionCharacter'); external;
      GetOptErrorFlag       : Boolean; attribute (name
      = '_p_GetOptErrorFlag'); external;

    { Parses command line arguments for options and returns the next
      one.

      If a command line argument starts with -, and is not exactly -
      or --, then it is an option element. The characters of this
      element (aside from the initial -) are option characters. If
      GetOpt is called repeatedly, it returns successively each of the
      option characters from each of the option elements.

      If GetOpt finds another option character, it returns that
      character, updating FirstNonOption and internal variables so
      that the next call to GetOpt can resume the scan with the
      following option character or command line argument.

      If there are no more option characters, GetOpt returns
      EndOfOptions. Then FirstNonOption is the index of the first
      command line argument that is not an option. (The command line
      arguments have been permuted so that those that are not options
      now come last.)

      OptString must be of the form [+|-]abcd:e:f:g::h::i::.

      a, b, c are options without arguments
      d, e, f are options with required arguments
      g, h, i are options with optional arguments

      Arguments are text following the option character in the same
      command line argument, or the text of the following command line
      argument. They are returned in OptionArgument. If an option has no
      argument, OptionArgument is empty. The variable HasOptionArgument
      tells whether an option has an argument. This is mostly useful for
      options with optional arguments, if one wants to distinguish an
      empty argument from no argument.

      If the first character of OptString is +, GetOpt stops at the
      first non-option argument.

      If it is -, GetOpt treats non-option arguments as options and
      return NoOption for them.

      Otherwise, GetOpt permutes arguments and handles all options,
      leaving all non-options at the end. However, if the environment
      variable POSIXLY_CORRECT is set, the default behaviour is to stop
      at the first non-option argument, as with +.

      The special argument -- forces an end of option-scanning
      regardless of the first character of OptString. In the case of
      -, only -- can cause GetOpt to return EndOfOptions with
      FirstNonOption <= ParamCount.

      If an option character is seen that is not listed in OptString,
      UnknownOption is returned. The unrecognized option character is
      stored in UnknownOptionCharacter. Unless GetOptErrorFlag is set to
      False, an error message is printed to StdErr automatically. }
    function  GetOpt (const OptString: String): Char; attribute (name
      = '_p_GetOpt'); external;

    type
      OptArgType = (NoArgument, RequiredArgument, OptionalArgument);

      OptionType = record
        OptionName: CString;
        Argument  : OptArgType;
        Flag      : ^Char;  { if nil, v is returned. Otherwise, Flag^ is
      ... }
        v         : Char    { ... set to v, and LongOption is returned }
      end;

    { Recognize short options, described by OptString as above, and long
      options, described by LongOptions.

      Long-named options begin with -- instead of -. Their names may
      be abbreviated as long as the abbreviation is unique or is an
      exact match for some defined option. If they have an argument, it
      follows the option name in the same argument, separated from the
      option name by a =, or else the in next argument. When GetOpt
      finds a long-named option, it returns LongOption if that option's
      Flag field is non-nil, and the value of the option's v field
      if the Flag field is nil.

      LongIndex, if not Null, returns the index in LongOptions of the
      long-named option found. It is only valid when a long-named option
      has been found by the most recent call.

      If LongOnly is set, - as well as -- can indicate a long
      option. If an option that starts with - (not --) doesn't match
      a long option, but does match a short option, it is parsed as a
      short option instead. If an argument has the form -f, where f is
      a valid short option, don't consider it an abbreviated form of a
      long option that starts with f. Otherwise there would be no way
      to give the -f short option. On the other hand, if there's a
      long option fubar and the argument is -fu, do consider that an
      abbreviation of the long option, just like --fu, and not -f
      with argument u. This distinction seems to be the most useful
      approach.

      As an additional feature (not present in the C counterpart), if
      the last character of OptString is - (after a possible starting
      + or - character), or OptString is empty, all long options
      with a nil Flag field will automatically be recognized as short
      options with the character given by the v field. This means, in
      the common (and recommended) case that all short options have long
      equivalents, you can simply pass an empty OptString (or pass +-
      or -- as OptString if you want this behaviour, see the comment
      for GetOpt), and you will only have to maintain the LongOptions
      array when you add or change options. }
    function  GetOptLong (const OptString: String; const LongOptions:
      array [m .. n: Integer] of OptionType { can be Null };
                          var LongIndex: Integer { can be Null };
      LongOnly: Boolean): Char; attribute (name = '_p_GetOptLong');
      external;

    { Reset GetOpt's state and make the next GetOpt or GetOptLong start
      (again) with the StartArgument'th argument (may be 1). This is
      useful for special purposes only. It is *necessary* to do this
      after altering the contents of CParamCount/CParameters (which is
      not usually done, either). }
    procedure ResetGetOpt (StartArgument: Integer); attribute (name
      = '_p_ResetGetOpt'); external;

    { Set operations, from sets.pas }

    { All set operations are built-in identifiers and not declared in
      gpc.pas. }

    { Heap management routines, from heap.pas }

    { GPC implements both Mark/Release and Dispose. Both can be mixed
      freely in the same program. Dispose should be preferred, since
      it's faster. }

    { C heap management routines. NOTE: if Release is used anywhere in
      the program, CFreeMem and CReAllocMem may not be used for pointers
      that were not allocated with CGetMem. }
    function  CGetMem     (Size: SizeType): Pointer; external
      name 'malloc';
    procedure CFreeMem    (aPointer: Pointer); external name 'free';
    function  CReAllocMem (aPointer: Pointer; NewSize: SizeType):
      Pointer; external name 'realloc';

    type
      GetMemType     = ^function (Size: SizeType): Pointer;
      FreeMemType    = ^procedure (aPointer: Pointer);
      ReAllocMemType = ^function (aPointer: Pointer; NewSize: SizeType):
      Pointer;

    { These variables can be set to user-defined routines for memory
      allocation/deallocation. GetMemPtr may return nil when
      insufficient memory is available. GetMem/New will produce a
      runtime error then. }
    var
      GetMemPtr    : GetMemType; attribute (name = '_p_GetMemPtr');
      external;
      FreeMemPtr   : FreeMemType; attribute (name = '_p_FreeMemPtr');
      external;
      ReAllocMemPtr: ReAllocMemType; attribute (name
      = '_p_ReAllocMemPtr'); external;

      { Address of the lowest byte of heap used }
      HeapLow: PtrCard; attribute (name = '_p_HeapLow'); external;

      { Address of the highest byte of heap used }
      HeapHigh: PtrCard; attribute (name = '_p_HeapHigh'); external;

      { If set to true, Dispose etc. will raise a runtime error if
        given an invalid pointer. }
      HeapChecking: Boolean; attribute (name = '_p_HeapChecking');
      external;

    const
      UndocumentedReturnNil = Pointer (-1);

    { Calls the procedure Proc for each block that would be released
      with Release (aMark). aMark must have been marked with Mark. For
      an example of its usage, see the HeapMon unit. }
    procedure ForEachMarkedBlock (aMark: Pointer; procedure Proc
      (aPointer: Pointer; aSize: SizeType; aCaller: Pointer)); attribute
      (name = '_p_ForEachMarkedBlock'); external;

    procedure ReAllocMem (var aPointer: Pointer; NewSize: SizeType);
      attribute (name = '_p_ReAllocMem'); external;

    { Memory transfer procedures, from move.pas }

    { The move operations are built-in identifiers and not declared in
      gpc.pas. }

    { Routines to handle endianness, from endian.pas }

    { Boolean constants about endianness and alignment }

    const
      BitsBigEndian  = {$ifdef __BITS_LITTLE_ENDIAN__}
                       False
                       {$elif defined (__BITS_BIG_ENDIAN__)}
                       True
                       {$else}
                       {$error Bit endianness is not defined!}
                       {$endif};

      BytesBigEndian = {$ifdef __BYTES_LITTLE_ENDIAN__}
                       False
                       {$elif defined (__BYTES_BIG_ENDIAN__)}
                       True
                       {$else}
                       {$error Byte endianness is not defined!}
                       {$endif};

      WordsBigEndian = {$ifdef __WORDS_LITTLE_ENDIAN__}
                       False
                       {$elif defined (__WORDS_BIG_ENDIAN__)}
                       True
                       {$else}
                       {$error Word endianness is not defined!}
                       {$endif};

      NeedAlignment  = {$ifdef __NEED_ALIGNMENT__}
                       True
                       {$elif defined (__NEED_NO_ALIGNMENT__)}
                       False
                       {$else}
                       {$error Alignment is not defined!}
                       {$endif};

    { Convert single variables from or to little or big endian format.
      This only works for a single variable or a plain array of a simple
      type. For more complicated structures, this has to be done for
      each component separately! Currently, ConvertFromFooEndian and
      ConvertToFooEndian are the same, but this might not be the case on
      middle-endian machines. Therefore, we provide different names. }
    procedure ReverseBytes            (var Buf; ElementSize, Count:
      SizeType); attribute (name = '_p_ReverseBytes'); external;
    procedure ConvertFromLittleEndian (var Buf; ElementSize, Count:
      SizeType); attribute (name = '_p_ConvertLittleEndian'); external;
    procedure ConvertFromBigEndian    (var Buf; ElementSize, Count:
      SizeType); attribute (name = '_p_ConvertBigEndian'); external;
    procedure ConvertToLittleEndian   (var Buf; ElementSize, Count:
      SizeType); external name '_p_ConvertLittleEndian';
    procedure ConvertToBigEndian      (var Buf; ElementSize, Count:
      SizeType); external name '_p_ConvertBigEndian';

    { Read a block from a file and convert it from little or
      big endian format. This only works for a single variable or a
      plain array of a simple type, note the comment for
      ConvertFromLittleEndian and ConvertFromBigEndian. }
    procedure BlockReadLittleEndian   (var aFile: File; var   Buf;
      ElementSize, Count: SizeType); attribute (iocritical, name
      = '_p_BlockRead_LittleEndian'); external;
    procedure BlockReadBigEndian      (var aFile: File; var   Buf;
      ElementSize, Count: SizeType); attribute (iocritical, name
      = '_p_BlockRead_BigEndian'); external;

    { Write a block variable to a file and convert it to little or big
      endian format before. This only works for a single variable or a
      plain array of a simple type. Apart from this, note the comment
      for ConvertToLittleEndian and ConvertToBigEndian. }
    procedure BlockWriteLittleEndian  (var aFile: File; const Buf;
      ElementSize, Count: SizeType); attribute (iocritical, name
      = '_p_BlockWrite_LittleEndian'); external;
    procedure BlockWriteBigEndian     (var aFile: File; const Buf;
      ElementSize, Count: SizeType); attribute (iocritical, name
      = '_p_BlockWrite_BigEndian'); external;

    { Read and write strings from/to binary files, where the length is
      stored in the given endianness and with a fixed size (64 bits),
      and therefore is independent of the system. }
    procedure ReadStringLittleEndian  (var f: File; var s: String);
      attribute (iocritical, name = '_p_ReadStringLittleEndian');
      external;
    procedure ReadStringBigEndian     (var f: File; var s: String);
      attribute (iocritical, name = '_p_ReadStringBigEndian'); external;
    procedure WriteStringLittleEndian (var f: File; const s: String);
      attribute (iocritical, name = '_p_WriteStringLittleEndian');
      external;
    procedure WriteStringBigEndian    (var f: File; const s: String);
      attribute (iocritical, name = '_p_WriteStringBigEndian');
      external;

    { Initialization, from init.pas }

    var
      InitProc: ^procedure; attribute (name = '_p_InitProc'); external;