allocos2.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 107 行

/****************************************************************************
*
*                            Open Watcom Project
*
*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
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*    provided with the Original Code and Modifications, and is also
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* Description:  WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
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****************************************************************************/


#include "variety.h"
#define INCL_DOSMEMMGR
#include <wos2.h>
#include <stdlib.h>
#include <dos.h>
#include "rtdata.h"
#include "seterrno.h"


#if defined(__386__) || defined(__PPC__)
  typedef void                  *mem_id;
#elif defined(M_I86)
  typedef unsigned short        mem_id;
  #if defined(__BIG_DATA__)
    #define MODIFIES ds es
  #else
    #define MODIFIES es
  #endif
#else
  #error platform not supported
#endif

_WCRTLINK unsigned _dos_allocmem( unsigned size, mem_id *p_mem )
// Note: size is in paragraphs of 16 bytes
{
    APIRET      error;

#if defined(__386__) || defined(__PPC__)
    /*
        Note:   _dos_allocmem() needs better documentation for 32-bit
                since mem is an offset instead a selector value.
    */
    void        *mem;

    error = DosAllocMem( &mem, size << 4, PAG_COMMIT | PAG_READ | PAG_WRITE );
#elif defined(M_I86)
    SEL         mem;
    USHORT      number_segments, remaining_bytes;

    number_segments = size >> 12;       // Number of 64k segments
    remaining_bytes = (size << 4) & 0xFFFF;     // remainder, < 64k
    error = DosAllocHuge( number_segments, remaining_bytes, &mem, 0, 0 );
#else
    #error platform not supported
#endif
    *p_mem = mem;
    if( error ) {
        __set_errno_dos( error );
        return( error );        /* allocation failed */
    }
    return( 0 );
}

#if defined(M_I86)
  extern unsigned __FreeSeg( mem_id );
  #pragma aux _dos_freemem modify [MODIFIES]
#endif
_WCRTLINK unsigned _dos_freemem( mem_id mem )
{
#if defined(__386__) || defined(__PPC__)
    APIRET      error;
    error = DosFreeMem( mem );
    if( error ) {
        __set_errno_dos( error );
        return( error );
    }
    return( 0 );
#elif defined(M_I86)
    // defined inside heap
    return( __FreeSeg( mem ) );
#else
    #error platform not supported
#endif
}