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 *
sbrk(nbytes)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 }
46