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/* sbrk.c -- allocate space on heap on OpenRISC 1000.
*
* Copyright (c) 2014 Authors
*
* Contributor Stefan Wallentowitz <stefan.wallentowitz@tum.de>
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice is included verbatim in any distributions. No written agreement,
* license, or royalty fee is required for any of the authorized uses.
* Modifications to this software may be copyrighted by their authors
* and need not follow the licensing terms described here, provided that
* the new terms are clearly indicated on the first page of each file where
* they apply.
*/
#include <reent.h>
#include "include/or1k-support.h"
extern uint32_t end; /* Set by linker. */
uint32_t _or1k_heap_start = &end;
uint32_t _or1k_heap_end;
void *
_sbrk_r (struct _reent * reent, ptrdiff_t incr)
{
uint32_t prev_heap_end;
// This needs to be atomic
// Disable interrupts on this core
uint32_t sr_iee = or1k_interrupts_disable();
uint32_t sr_tee = or1k_timer_disable();
// Initialize heap end to end if not initialized before
or1k_sync_cas((void*) &_or1k_heap_end, 0, (uint32_t) _or1k_heap_start);
do {
// Read previous heap end
prev_heap_end = _or1k_heap_end;
// and try to set it to the new value as long as it has changed
} while (or1k_sync_cas((void*) &_or1k_heap_end,
(uint32_t) prev_heap_end,
(uint32_t) (prev_heap_end + incr)) != (uint32_t) prev_heap_end);
// Restore interrupts on this core
or1k_timer_restore(sr_tee);
or1k_interrupts_restore(sr_iee);
return (void*) prev_heap_end;
}
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