libgloss/mips/syscalls.c

   1 #include <_ansi.h>
   2 #include <sys/types.h>
   3 #include <sys/stat.h>
   4
   5 #include "regs.S"
   6
   7 extern char _end[];
   8
   9 /* FIXME: This is not ideal, since we do a get_mem_info() call for
  10    every sbrk() call. */
  11 char *
  12 sbrk (nbytes)
  13      int nbytes;
  14 {
  15   static char *heap_ptr = _end;
  16   static char *heap_start = _end;
  17   char        *base;
  18   struct s_mem {
  19     unsigned int size;
  20     unsigned int icsize;
  21     unsigned int dcsize;
  22   } mem;
  23   unsigned int avail = 0;
  24
  25   /* The sizeof (s_mem.size) must be 4 bytes.  The compiler should be
  26      able to eliminate this check */
  27   if (sizeof (unsigned int) != 4)
  28     return (char *)-1;
  29
  30   get_mem_info(&mem);
  31   /* NOTE: The value returned from the get_mem_info call is the amount
  32      of memory, and not the address of the (last byte + 1) */
  33
  34   if (((size_t)heap_ptr >= heap_start) && ((size_t)heap_ptr < (heap_start + mem.size))) {
  35     avail = (heap_start + mem.size) - (size_t)heap_ptr;
  36     base = heap_ptr;
  37   } /* else will fail since "nbytes" will be greater than zeroed "avail" value */
  38
  39   if ((nbytes > avail) || (heap_ptr + nbytes < _end))
  40    base = (char *)-1;
  41   else
  42    heap_ptr += nbytes;
  43
  44   return base;
  45 }