toolchain/gcc/newlib/libc/sys/mmixware/sbrk.c

   1 /* sbrk for MMIXware.
   2
   3    Copyright (C) 2001 Hans-Peter Nilsson
   4
   5    Permission to use, copy, modify, and distribute this software is
   6    freely granted, provided that the above copyright notice, this notice
   7    and the following disclaimer are preserved with no changes.
   8
   9    THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  10    IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  11    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  12    PURPOSE.  */
  13
  14 #include <_ansi.h>
  15 #include <sys/types.h>
  16 #include <sys/stat.h>
  17 #include "sys/syscall.h"
  18
  19 extern char *_Sbrk_high;
  20
  21 /* When the program is loaded, the first location in Pool_Segment holds
  22    the first available octabyte in the memory pool (a.k.a. the heap);
  23    somewhere after the command-line parameters.  We don't have to
  24    initialize that location, we can just use it straight up as a pointer;
  25    just point the symbol there.
  26
  27    This file will be compiled with -no-builtin-syms, so we need to define
  28    Pool_Segment and any other symbols that would be predefined in mmixal.  */
  29
  30 __asm__ (" .global _Sbrk_high\n"
  31          "_Sbrk_high    IS      Pool_Segment\n"
  32          "Pool_Segment  IS      0x40<<56");
  33
  34 caddr_t
  35 _sbrk (size_t incr)
  36 {
  37   extern char end;              /* Defined by the linker */
  38   char *prev_heap_end;
  39
  40   prev_heap_end = _Sbrk_high;
  41   _Sbrk_high += incr;
  42   return (caddr_t) prev_heap_end;
  43 }