memzero.c

来自「Hermit-at-1.1.3,一款bootloader」· C语言 代码 · 共 46 行

#include "memzero.h"

/* optimized C memzero for the ARM */
void memzero(void *s, unsigned n)
{
	union { void *vp; unsigned long *ulp; unsigned char *ucp; } u;
	int i;

	u.vp = s;

	for (i = n >> 5; i > 0; i--) {
		*u.ulp++ = 0;
		*u.ulp++ = 0;
		*u.ulp++ = 0;
		*u.ulp++ = 0;
		*u.ulp++ = 0;
		*u.ulp++ = 0;
		*u.ulp++ = 0;
		*u.ulp++ = 0;
	}

	if (n & 1 << 4) {
		*u.ulp++ = 0;
		*u.ulp++ = 0;
		*u.ulp++ = 0;
		*u.ulp++ = 0;
	}

	if (n & 1 << 3) {
		*u.ulp++ = 0;
		*u.ulp++ = 0;
	}

	if (n & 1 << 2)
		*u.ulp++ = 0;

	if (n & 1 << 1) {
		*u.ucp++ = 0;
		*u.ucp++ = 0;
	}

	if (n & 1)
		*u.ucp++ = 0;
}