allocmem.gml

来自「开放源码的编译器open watcom 1.6.0版的源代码」· GML 代码 · 共 71 行

.func _dos_allocmem
#include <&doshdr>
#if defined(__NT__) || \
  ( defined(__OS2__) && \
        (defined(__386__) || defined(__PPC__)) )
unsigned _dos_allocmem( unsigned size,
                        void *         *segment);
#else
unsigned _dos_allocmem( unsigned size,
                        unsigned short *segment);
#endif
.ixfunc2 '&DosFunc' &func
.ixfunc2 '&Trig' &func
.ixfunc2 '&Hyper' &func
.funcend
.desc begin
The &func function uses system call 0x48 to allocate
.arg size
paragraphs directly from DOS.
The size of a paragraph is 16 bytes.
The allocated memory is always paragraph aligned.
The segment descriptor for the allocated memory is returned in the
word pointed to by
.arg segment.
If the allocation request fails, the maximum number of paragraphs that
can be allocated is returned in this word instead.
.np
For 32-bit DOS applications, it is recommended that the corresponding
DPMI services be used.
.desc end
.return begin
The &func function returns zero if successful.
Otherwise, it returns an OS error code and sets
.kw errno
accordingly.
.return end
.see begin
.seelist _dos_allocmem alloca calloc _dos_freemem _dos_setblock halloc malloc
.see end
.exmp begin
#include <stdio.h>
#include <&doshdr>
.exmp break
void main()
  {
#if defined(__NT__) || \
  ( defined(__OS2__) && \
        (defined(__386__) || defined(__PPC__)) )
    void *segment;
#else
    unsigned short segment;
#endif
.exmp break
    /* Try to allocate 100 paragraphs, then free them */
    if( _dos_allocmem( 100, &segment ) != 0 ) {
      printf( "_dos_allocmem failed\n" );
      printf( "Only %u paragraphs available\n",
               segment );
    } else {
      printf( "_dos_allocmem succeeded\n" );
      if( _dos_freemem( segment ) != 0 ) {
        printf( "_dos_freemem failed\n" );
      } else {
        printf( "_dos_freemem succeeded\n" );
      }
    }
  }
.exmp end
.class DOS
.system