Retro68/gcc/libgloss/mips/syscalls.c
2012-03-27 01:51:53 +02:00

46 lines
1.1 KiB
C

#include <_ansi.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "regs.S"
extern char _end[];
/* FIXME: This is not ideal, since we do a get_mem_info() call for
every sbrk() call. */
char *
sbrk (nbytes)
int nbytes;
{
static char *heap_ptr = _end;
static char *heap_start = _end;
char *base;
struct s_mem {
unsigned int size;
unsigned int icsize;
unsigned int dcsize;
} mem;
unsigned int avail = 0;
/* The sizeof (s_mem.size) must be 4 bytes. The compiler should be
able to eliminate this check */
if (sizeof (unsigned int) != 4)
return (char *)-1;
get_mem_info(&mem);
/* NOTE: The value returned from the get_mem_info call is the amount
of memory, and not the address of the (last byte + 1) */
if (((size_t)heap_ptr >= heap_start) && ((size_t)heap_ptr < (heap_start + mem.size))) {
avail = (heap_start + mem.size) - (size_t)heap_ptr;
base = heap_ptr;
} /* else will fail since "nbytes" will be greater than zeroed "avail" value */
if ((nbytes > avail) || (heap_ptr + nbytes < _end))
base = (char *)-1;
else
heap_ptr += nbytes;
return base;
}