sbrk.c

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/************************************************************************//**
 * \file sbrk.c
 * \brief provides _sbrk
 * \author marc dot pignat at hevs dot ch
 *
 * When not using FreeRTOS, this function is used by newlib for dynamic memory
 * allocation (malloc, free, ...).
 *
 * The heap space is provided by the linker script
 *
 * \see _heap_start
 * \see _heap_end
 ***************************************************************************/

#include "heivs/config.h"
#if !USE_FREERTOS

#include <errno.h>
#include <stddef.h>
#include "heivs/bsp.h"


static char const *heap_used_end = NULL;
static const uint32_t failed_is_fatal = USE_FATAL_MALLOC_FAILED;

/**
 * \brief Implementation of the sbrk systemcall for standalone software
 *
 * This system call is used when there is no more space for malloc.
 *
 * \see http://linux.die.net/man/2/sbrk
 * \ingroup unistd_h
 */
void *_sbrk (int incr)
{
    /**
     * Definitions provided by the linker
     */
    extern char _heap_start;
    extern char _heap_end;
    const char *end = &_heap_start;
    const char *heap_end = &_heap_end;

    const char *old_end;

    /**
     * First time run? init
     */
    if (heap_used_end == NULL)
    {
        heap_used_end = end;
    }

    /* Verify there is enough place */
    if (heap_used_end + incr > heap_end)
    {
      errno = ENOMEM;
      if (failed_is_fatal)
      {
          bsp_fatal(ERROR_OUT_OF_MEMORY);
      }

      return (void *) -1;
    }

    /* Remember last heap_used_end */
    old_end = heap_used_end;

    heap_used_end += incr;

    return (void *)old_end;
}
#endif