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sys/newlib: enable multiple heaps in _sbrk_r

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Some MCUs have non-continuous memory regions.
To support those, iterate over all available memory regions
and allocate the first region that fits.
This commit is contained in:
Benjamin Valentin 2019-12-12 00:27:19 +01:00 committed by Benjamin Valentin
parent 0d9d496618
commit 2ed0dd7405
1 changed files with 81 additions and 7 deletions
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88
sys/newlib_syscalls_default/syscalls.c
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@ -56,12 +56,79 @@
#include "xtimer.h"
#endif
#ifndef NUM_HEAPS
#define NUM_HEAPS 1
#endif
/**
* @brief manage the heap
*/
extern char _sheap; /* start of the heap */
extern char _eheap; /* end of the heap */
char *heap_top = &_sheap + 4;
/**
* @brief Additional heap sections that may be defined in the linkerscript.
*
* The compiler should not generate references to those symbols if
* they are not used, so only provide them if additional memory sections
* that can be used as heap are available.
* @{
*/
extern char _sheap1;
extern char _eheap1;
extern char _sheap2;
extern char _eheap2;
extern char _sheap3;
extern char _eheap3;
/* @} */
struct heap {
char* start;
char* end;
};
static char *heap_top[NUM_HEAPS] = {
&_sheap,
#if NUM_HEAPS > 1
&_sheap1,
#endif
#if NUM_HEAPS > 2
&_sheap2,
#endif
#if NUM_HEAPS > 3
&_sheap3,
#endif
#if NUM_HEAPS > 4
#error "Unsupported NUM_HEAPS value, edit newlib_syscalls_default/syscalls.c to add more heaps."
#endif
};
static const struct heap heaps[NUM_HEAPS] = {
{
.start = &_sheap,
.end = &_eheap
},
#if NUM_HEAPS > 1
{
.start = &_sheap1,
.end = &_eheap1
},
#endif
#if NUM_HEAPS > 2
{
.start = &_sheap2,
.end = &_eheap2
},
#endif
#if NUM_HEAPS > 3
{
.start = &_sheap3,
.end = &_eheap3
},
#endif
};
/* MIPS newlib crt implements _init,_fini and _exit and manages the heap */
#ifndef __mips__
@ -108,15 +175,22 @@ void _exit(int n)
*/
void *_sbrk_r(struct _reent *r, ptrdiff_t incr)
{
void *res = (void*)UINTPTR_MAX;
unsigned int state = irq_disable();
void *res = heap_top;
if ((heap_top + incr > &_eheap) || (heap_top + incr < &_sheap)) {
r->_errno = ENOMEM;
res = (void *)-1;
for (unsigned i = 0; i < NUM_HEAPS; ++i) {
if ((heap_top[i] + incr > heaps[i].end) ||
(heap_top[i] + incr < heaps[i].start)) {
continue;
}
res = heap_top[i];
heap_top[i] += incr;
break;
}
else {
heap_top += incr;
if (res == (void*)UINTPTR_MAX) {
r->_errno = ENOMEM;
}
irq_restore(state);