toolchain/gcc/libgloss/zpu/sbrk.c

   1 /* sbrk.c -- allocate memory dynamically.
   2  *
   3  * Copyright (c) 1995,1996 Cygnus Support
   4  *
   5  * The authors hereby grant permission to use, copy, modify, distribute,
   6  * and license this software and its documentation for any purpose, provided
   7  * that existing copyright notices are retained in all copies and that this
   8  * notice is included verbatim in any distributions. No written agreement,
   9  * license, or royalty fee is required for any of the authorized uses.
  10  * Modifications to this software may be copyrighted by their authors
  11  * and need not follow the licensing terms described here, provided that
  12  * the new terms are clearly indicated on the first page of each file where
  13  * they apply.
  14  */
  15 #include <errno.h>
  16 #include "glue.h"
  17
  18
  19 char *heap_ptr;
  20 extern char _stack[];
  21
  22 /*
  23  * sbrk -- changes heap size size. Get nbytes more
  24  *         RAM. We just increment a pointer in what's
  25  *         left of memory on the board.
  26  */
  27 char *
  28 sbrk (nbytes)
  29      int nbytes;
  30 {
  31   char        *base;
  32
  33   if (!heap_ptr)
  34     heap_ptr = (char *)&_end;
  35   base = heap_ptr;
  36
  37   if (heap_ptr+nbytes>_stack-0x4000)
  38   {
  39         return (char *)-1;
  40   }
  41
  42   heap_ptr += nbytes;
  43
  44   return base;
  45 /* FIXME: We really want to make sure we don't run out of RAM, but this
  46  *       isn't very portable.
  47  */
  48 #if 0
  49   if ((RAMSIZE - heap_ptr - nbytes) >= 0) {
  50     base = heap_ptr;
  51     heap_ptr += nbytes;
  52     return (base);
  53   } else {
  54     errno = ENOMEM;
  55     return ((char *)-1);
  56   }
  57 #endif
  58 }