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/* $Id$ */
/*
* sbrk.c
*
* Author: Till Straumann <strauman@slac.stanford.edu>, 2002
*
* Hack around the 32bit powerpc 32M problem:
*
* GCC by default uses relative branches which can not jump
* farther than 32M. Hence all program text is confined to
* a single 32M segment.
* This hack gives the RTEMS malloc region all memory below
* 32M at startup. Only when this region is exhausted will sbrk
* add more memory. Loading modules may fail at that point, hence
* the user is expected to load all modules at startup _prior_
* to malloc()ing lots of memory...
*
* NOTE: it would probably be better to have a separate region
* for module code.
*/
#include <rtems.h>
#include <signal.h>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>
static uint32_t remaining_start=0;
static uint32_t remaining_size=0;
#define LIMIT_32M 0x02000000
uint32_t
_bsp_sbrk_init(uint32_t heap_start, uint32_t *heap_size_p)
{
uint32_t rval=0;
remaining_start = heap_start;
remaining_size =* heap_size_p;
if (remaining_start < LIMIT_32M &&
remaining_start + remaining_size > LIMIT_32M) {
/* clip at LIMIT_32M */
rval = remaining_start + remaining_size - LIMIT_32M;
*heap_size_p = LIMIT_32M - remaining_start;
}
return rval;
}
void * sbrk(ptrdiff_t incr)
{
void *rval=(void*)-1;
if (incr <= remaining_size) {
remaining_size-=incr;
rval = (void*)remaining_start;
remaining_start += incr;
} else {
errno = ENOMEM;
}
return rval;
}
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