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Tighten GCC 2-region _sbrk #11572

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Oct 3, 2019
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Tighten GCC 2-region _sbrk #11572

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13 changes: 6 additions & 7 deletions platform/source/mbed_retarget.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1268,27 +1268,26 @@ extern "C" WEAK void __cxa_pure_virtual(void)
extern uint32_t __mbed_sbrk_start;
extern uint32_t __mbed_krbs_start;
/* Additional RAM memory used for heap - please note this
* address should be lower address then the previous default address
* address must be lower address then the previous default address
*/
extern uint32_t __mbed_sbrk_start_0;
extern uint32_t __mbed_krbs_start_0;

extern "C" WEAK caddr_t _sbrk(int incr)
{
static uint32_t heap = (uint32_t) &__mbed_sbrk_start_0;
static bool once = true;
uint32_t prev_heap = heap;
uint32_t new_heap = heap + incr;

/**
* If the new address is outside the first region, start allocating from the second region.
* Jump to second region is done just once, and `static bool once` is used to keep track of that.
* If we exceed the first region, start allocating from the second region.
*/
if (once && (new_heap > (uint32_t) &__mbed_krbs_start_0)) {
once = false;
if (prev_heap <= (uint32_t) &__mbed_krbs_start_0 && new_heap > (uint32_t) &__mbed_krbs_start_0) {
prev_heap = (uint32_t) &__mbed_sbrk_start;
new_heap = prev_heap + incr;
} else if (new_heap > (uint32_t) &__mbed_krbs_start) {
}

if (new_heap > (uint32_t) &__mbed_krbs_start) {
/**
* If the new address is outside the second region, return out-of-memory.
*/
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