libgloss/moxie/sbrk.c

   1 /* sbrk.c -- allocate memory dynamically.
   2  *
   3  * Copyright (c) 2008 Anthony Green
   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 /* just in case, most boards have at least some memory */
  19 #ifndef RAMSIZE
  20 #  define RAMSIZE             (caddr_t)0x100000
  21 #endif
  22
  23 char *__heap_ptr = (char *)&_end;
  24
  25 /*
  26  * sbrk -- changes heap size size. Get nbytes more
  27  *         RAM. We just increment a pointer in what's
  28  *         left of memory on the board.
  29  */
  30 char *
  31 _sbrk (nbytes)
  32      int nbytes;
  33 {
  34   char *base;
  35   char *sp;
  36
  37   base = __heap_ptr;
  38   __heap_ptr += nbytes;
  39
  40   return base;
  41 /* FIXME: We really want to make sure we don't run out of RAM, but this
  42  *       isn't very portable.
  43  */
  44 #if 0
  45   if ((RAMSIZE - heap_ptr - nbytes) >= 0) {
  46     base = heap_ptr;
  47     heap_ptr += nbytes;
  48     return (base);
  49   } else {
  50     errno = ENOMEM;
  51     return ((char *)-1);
  52   }
  53 #endif
  54 }