sbrk.c
2.71 KB
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/*
* Copyright (c) 2017, Cobham Gaisler AB
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdint.h>
#include <stdlib.h>
#include "bcc/bcc_param.h"
/* Default heap limits from linker script. */
extern uint8_t __heap_min;
static const ptrdiff_t DEFAULT_STACK_SIZE = 8 * 1024;
/* End of currently allocated heap. */
static uint8_t *__sbrk_heap_end;
/*
* Stack pointer at application entry. This value can be read to calculate
* __bcc_heap_max.
*/
extern uint8_t *const __bcc_sp_at_entry;
void *_sbrk(ptrdiff_t incr)
{
uint8_t *prev_sbrk_heap_end;
/* Initialization step */
if (NULL == __bcc_heap_min) {
/*
* User did not specified heap lower limit: get value from
* linker script.
*/
__bcc_heap_min = &__heap_min;
}
if (NULL == __bcc_heap_max) {
/*
* User did not specify heap upper limit: calculate value from stack pointer
* at entry.
*/
__bcc_heap_max = __bcc_sp_at_entry - DEFAULT_STACK_SIZE;
}
if (NULL == __sbrk_heap_end) {
__sbrk_heap_end = __bcc_heap_min;
}
prev_sbrk_heap_end = __sbrk_heap_end;
if (__sbrk_heap_end + incr < __bcc_heap_max) {
__sbrk_heap_end += incr;
return (void *) prev_sbrk_heap_end;
} else {
return (void *) -1;
}
}