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#ifdef USING_SIM_SPECS
// Gdb simulator requires that sbrk be implemented without a syscall.
extern char _end[]; /* _end is set in the linker command file */
char *heap_ptr;
/*
* sbrk -- changes heap size size. Get nbytes more
* RAM. We just increment a pointer in what's
* left of memory on the board.
*/
char *
_sbrk (nbytes)
int nbytes;
{
char *base;
if (!heap_ptr)
heap_ptr = (char *)&_end;
base = heap_ptr;
heap_ptr += nbytes;
return base;
}
#else
// QEMU uses a syscall.
#include <machine/syscall.h>
#include <sys/types.h>
#include "internal_syscall.h"
/* Increase program data space. As malloc and related functions depend
on this, it is useful to have a working implementation. The following
is suggested by the newlib docs and suffices for a standalone
system. */
void *
_sbrk(ptrdiff_t incr)
{
static unsigned long heap_end;
if (heap_end == 0)
{
long brk = __internal_syscall (SYS_brk, 1, 0, 0, 0, 0, 0, 0);
if (brk == -1)
return (void *)__syscall_error (-ENOMEM);
heap_end = brk;
}
if (__internal_syscall (SYS_brk, 1, heap_end + incr, 0, 0, 0, 0, 0) != heap_end + incr)
return (void *)__syscall_error (-ENOMEM);
heap_end += incr;
return (void *)(heap_end - incr);
}
#endif
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