/* public domain md5 implementation based on rfc1321 and libtomcrypt */
#include <stdint.h>
#include <string.h>

#include "../md5.h"

static uint32_t rol(uint32_t n, int k) { return (n << k) | (n >> (32-k)); }
#define F(x,y,z) (z ^ (x & (y ^ z)))
#define G(x,y,z) (y ^ (z & (y ^ x)))
#define H(x,y,z) (x ^ y ^ z)
#define I(x,y,z) (y ^ (x | ~z))
#define FF(a,b,c,d,w,s,t) a += F(b,c,d) + w + t; a = rol(a,s) + b
#define GG(a,b,c,d,w,s,t) a += G(b,c,d) + w + t; a = rol(a,s) + b
#define HH(a,b,c,d,w,s,t) a += H(b,c,d) + w + t; a = rol(a,s) + b
#define II(a,b,c,d,w,s,t) a += I(b,c,d) + w + t; a = rol(a,s) + b

static const uint32_t tab[64] = {
	0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, 0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
	0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be, 0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
	0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa, 0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
	0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed, 0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
	0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c, 0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
	0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05, 0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
	0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039, 0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
	0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1, 0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
};

static void
processblock(struct md5 *s, const uint8_t *buf)
{
	uint32_t i, W[16], a, b, c, d;

	for (i = 0; i < 16; i++) {
		W[i] = buf[4*i];
		W[i] |= (uint32_t)buf[4*i+1]<<8;
		W[i] |= (uint32_t)buf[4*i+2]<<16;
		W[i] |= (uint32_t)buf[4*i+3]<<24;
	}

	a = s->h[0];
	b = s->h[1];
	c = s->h[2];
	d = s->h[3];

	i = 0;
	while (i < 16) {
		FF(a,b,c,d, W[i],  7, tab[i]); i++;
		FF(d,a,b,c, W[i], 12, tab[i]); i++;
		FF(c,d,a,b, W[i], 17, tab[i]); i++;
		FF(b,c,d,a, W[i], 22, tab[i]); i++;
	}
	while (i < 32) {
		GG(a,b,c,d, W[(5*i+1)%16],  5, tab[i]); i++;
		GG(d,a,b,c, W[(5*i+1)%16],  9, tab[i]); i++;
		GG(c,d,a,b, W[(5*i+1)%16], 14, tab[i]); i++;
		GG(b,c,d,a, W[(5*i+1)%16], 20, tab[i]); i++;
	}
	while (i < 48) {
		HH(a,b,c,d, W[(3*i+5)%16],  4, tab[i]); i++;
		HH(d,a,b,c, W[(3*i+5)%16], 11, tab[i]); i++;
		HH(c,d,a,b, W[(3*i+5)%16], 16, tab[i]); i++;
		HH(b,c,d,a, W[(3*i+5)%16], 23, tab[i]); i++;
	}
	while (i < 64) {
		II(a,b,c,d, W[7*i%16],  6, tab[i]); i++;
		II(d,a,b,c, W[7*i%16], 10, tab[i]); i++;
		II(c,d,a,b, W[7*i%16], 15, tab[i]); i++;
		II(b,c,d,a, W[7*i%16], 21, tab[i]); i++;
	}

	s->h[0] += a;
	s->h[1] += b;
	s->h[2] += c;
	s->h[3] += d;
}

static void
pad(struct md5 *s)
{
	unsigned r = s->len % 64;

	s->buf[r++] = 0x80;
	if (r > 56) {
		memset(s->buf + r, 0, 64 - r);
		r = 0;
		processblock(s, s->buf);
	}
	memset(s->buf + r, 0, 56 - r);
	s->len *= 8;
	s->buf[56] = s->len;
	s->buf[57] = s->len >> 8;
	s->buf[58] = s->len >> 16;
	s->buf[59] = s->len >> 24;
	s->buf[60] = s->len >> 32;
	s->buf[61] = s->len >> 40;
	s->buf[62] = s->len >> 48;
	s->buf[63] = s->len >> 56;
	processblock(s, s->buf);
}

void
md5_init(void *ctx)
{
	struct md5 *s = ctx;
	s->len = 0;
	s->h[0] = 0x67452301;
	s->h[1] = 0xefcdab89;
	s->h[2] = 0x98badcfe;
	s->h[3] = 0x10325476;
}

void
md5_sum(void *ctx, uint8_t md[MD5_DIGEST_LENGTH])
{
	struct md5 *s = ctx;
	int i;

	pad(s);
	for (i = 0; i < 4; i++) {
		md[4*i] = s->h[i];
		md[4*i+1] = s->h[i] >> 8;
		md[4*i+2] = s->h[i] >> 16;
		md[4*i+3] = s->h[i] >> 24;
	}
}

void
md5_update(void *ctx, const void *m, unsigned long len)
{
	struct md5 *s = ctx;
	const uint8_t *p = m;
	unsigned r = s->len % 64;

	s->len += len;
	if (r) {
		if (len < 64 - r) {
			memcpy(s->buf + r, p, len);
			return;
		}
		memcpy(s->buf + r, p, 64 - r);
		len -= 64 - r;
		p += 64 - r;
		processblock(s, s->buf);
	}
	for (; len >= 64; len -= 64, p += 64)
		processblock(s, p);
	memcpy(s->buf, p, len);
}