/*
* sbrk.c
*
* Authorship
* ----------
* This software was created by
* Till Straumann <strauman@slac.stanford.edu>, 2002,
* Stanford Linear Accelerator Center, Stanford University.
*
* Acknowledgement of sponsorship
* ------------------------------
* This software was produced by
* the Stanford Linear Accelerator Center, Stanford University,
* under Contract DE-AC03-76SFO0515 with the Department of Energy.
*
* Government disclaimer of liability
* ----------------------------------
* Neither the United States nor the United States Department of Energy,
* nor any of their employees, makes any warranty, express or implied, or
* assumes any legal liability or responsibility for the accuracy,
* completeness, or usefulness of any data, apparatus, product, or process
* disclosed, or represents that its use would not infringe privately owned
* rights.
*
* Stanford disclaimer of liability
* --------------------------------
* Stanford University makes no representations or warranties, express or
* implied, nor assumes any liability for the use of this software.
*
* Stanford disclaimer of copyright
* --------------------------------
* Stanford University, owner of the copyright, hereby disclaims its
* copyright and all other rights in this software. Hence, anyone may
* freely use it for any purpose without restriction.
*
* Maintenance of notices
* ----------------------
* In the interest of clarity regarding the origin and status of this
* SLAC software, this and all the preceding Stanford University notices
* are to remain affixed to any copy or derivative of this software made
* or distributed by the recipient and are to be affixed to any copy of
* software made or distributed by the recipient that contains a copy or
* derivative of this software.
*
* ------------------ SLAC Software Notices, Set 4 OTT.002a, 2004 FEB 03
*/
/*
* 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 <errno.h>
#include <unistd.h>
#include <bsp/bootcard.h>
#define INVALID_REMAINING_START ((uintptr_t) -1)
static uintptr_t remaining_start = INVALID_REMAINING_START;
static uintptr_t remaining_size = 0;
/* App. may provide a value by defining the BSP_sbrk_policy
* variable.
*
* (-1) -> give all memory to the heap at initialization time
* > 0 -> value used as sbrk amount; initially give 32M
* 0 -> limit memory effectively to 32M.
*
*/
extern uintptr_t BSP_sbrk_policy[] __attribute__((weak));
#define LIMIT_32M 0x02000000
ptrdiff_t bsp_sbrk_init(Heap_Area *area, uintptr_t min_size)
{
uintptr_t rval = 0;
uintptr_t policy;
uintptr_t remaining_end;
remaining_start = (uintptr_t) area->begin;
remaining_size = area->size;
remaining_end = remaining_start + remaining_size;
if (remaining_start < LIMIT_32M &&
remaining_end > LIMIT_32M &&
min_size <= LIMIT_32M - remaining_start) {
/* clip at LIMIT_32M */
rval = remaining_end - LIMIT_32M;
area->size = LIMIT_32M - remaining_start;
remaining_start = LIMIT_32M;
remaining_size = rval;
}
policy = (0 == BSP_sbrk_policy[0] ? (uintptr_t)(-1) : BSP_sbrk_policy[0]);
switch ( policy ) {
case (uintptr_t)(-1):
area->size += rval;
remaining_start = (uintptr_t) area->begin + area->size;
remaining_size = 0;
break;
case 0:
remaining_size = 0;
break;
default:
if ( rval > policy )
rval = policy;
break;
}
return (ptrdiff_t) (rval <= PTRDIFF_MAX ? rval : rval / 2);
}
/*
* This is just so the sbrk test can force its magic. All normal applications
* should just use the default implementation in this file.
*/
void *sbrk(ptrdiff_t incr) __attribute__ (( weak, alias("bsp_sbrk") ));
static void *bsp_sbrk(ptrdiff_t incr)
{
void *rval=(void*)-1;
if ( remaining_start != INVALID_REMAINING_START && incr <= remaining_size) {
remaining_size-=incr;
rval = (void *) remaining_start;
remaining_start += incr;
} else {
errno = ENOMEM;
}
#ifdef DEBUG
printk("************* SBRK 0x%08x (ret 0x%08x) **********\n", incr, rval);
#endif
return rval;
}
