sbrk.c

Newlib 嵌入式 C库 标准实现代码

#include <_ansi.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "sys/syscall.h"

int errno;

int __trap0 ();

#define TRAP0(f, p1, p2, p3) __trap0(f, (p1), (p2), (p3))

caddr_t
_sbrk (size_t incr)
{
  extern char end;		/* Defined by the linker */
  static char *heap_end;
  char *prev_heap_end;
#if 0
  char *sp = (char *)stack_ptr;
#else
  char *sp = (char *)&sp;
#endif

  if (heap_end == 0)
    {
      heap_end = &end;
    }
  prev_heap_end = heap_end;
  if (heap_end + incr > sp)
    {
      _write (1, "Heap and stack collision\n", 25);
      abort ();
    }
  heap_end += incr;
  return (caddr_t) prev_heap_end;
}