#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>

#include "mod311.h"

struct hash311 {
	uint32_t x, c;
};

void
key311(struct hash311 *h)
{

	h->x = arc4random_uniform(M31);
	h->c = arc4random_uniform(M31);
}

uint32_t
hash311(struct hash311 *h, const void *buf, size_t len)
{
	const uint32_t x = h->x;
	const uint8_t *p = buf;
	uint32_t y = 0;

	while (len --> 0)
		y = mul311(x, add311(y, 0x100 | *p++));

	return reduce311(add311(y, h->c));
}