Linux内核中的bsearch二分查找函数

void *bsearch(const void *key, const void *base, size_t num, size_t size,
	int(*cmp)(const void *key, const void *elt))
{
	size_t start = 0, end = num;
	int result;
	while (start < end) {
		size_t mid = start + (end - start) / 2;
		result = cmp(key, base + mid * size);
		if (result < 0)
			end = mid;
		else if (result > 0)
			start = mid + 1;
		else
			return (void *)base + mid * size;
	}
	return NULL;
}