compilers/linux86-0.16.17/libc/gnu_i386/heap.c

   1 /* Copyright (C) 1995-1997 Robert de Bath <rdebath@cix.compulink.co.uk>
   2  * This file is part of the Linux-8086 C library and is distributed
   3  * under the GNU Library General Public License.
   4  */
   5
   6 #include <errno.h>
   7
   8 /****************************************************************************/
   9
  10 #if defined(__GNUC__) && defined(__i386__)
  11 extern char * __brk_addr;
  12 extern char * __brk();
  13
  14 #ifdef L___brk_addr
  15 char * __brk_addr = 0;  /* This holds the current return for sbrk(0) */
  16
  17          /* "mov        %ebx,4(%esp),%ebx\n\t" "mov     $45,%eax\n\t" */
  18
  19 char *
  20 __brk(char * val)
  21 {
  22    char * retval;
  23    __asm__(
  24          "int   $0x80"
  25          : "=a" (retval)
  26          : "0" (45), "b" (val)
  27    );
  28    return retval;
  29 }
  30
  31 __brk_addr_init()
  32 {
  33    if( __brk_addr == 0 && (__brk_addr = __brk(0)) == 0 )
  34    {
  35       errno = ENOMEM;
  36       return -1;
  37    }
  38    return 0;
  39 }
  40 #endif
  41
  42 #ifdef L_sbrk
  43 char *
  44 sbrk(brk_off)
  45 int brk_off;
  46 {
  47    char * new_brk;
  48    if( __brk_addr_init() ) return (char*)-1;
  49    if( brk_off == 0 ) return __brk_addr;
  50
  51    new_brk = __brk_addr + brk_off;
  52    __brk_addr = __brk(new_brk);
  53    if( __brk_addr != new_brk )
  54    {
  55       errno = ENOMEM;
  56       return (char*)-1;
  57    }
  58    return __brk_addr - brk_off;
  59 }
  60 #endif
  61
  62 #ifdef L_brk
  63 int
  64 brk(new_brk)
  65 char * new_brk;
  66 {
  67    if( __brk_addr_init() ) return -1;
  68
  69    __brk_addr = __brk(new_brk);
  70    if( __brk_addr == new_brk ) return 0;
  71    errno = ENOMEM;
  72    return -1;
  73 }
  74 #endif
  75
  76 #endif