/*
 * RFC 1321 compliant MD5 implementation,
 * by Christophe Devine <devine@cr0.net>;
 * this program is licensed under the GPL.
 */

/* Modified October 3, 2003, to remove testing code, and add
		include of "fceu-types.h".

		Added simple MD5 to ASCII string conversion function.
		-Xodnizel
*/

#include <string.h>
#include "fceu-types.h"
#include "md5.h"

#define GET_UINT32(n, b, i)	\
{	\
	(n) =	((uint32)(b)[(i) + 3] << 24) |	\
			((uint32)(b)[(i) + 2] << 16) |	\
			((uint32)(b)[(i) + 1] <<  8) |	\
			((uint32)(b)[(i)    ]);	\
}

#define PUT_UINT32(n, b, i)	\
{	\
	(b)[(i)    ] = (uint8)((n));	\
	(b)[(i) + 1] = (uint8)((n) >>  8);	\
	(b)[(i) + 2] = (uint8)((n) >> 16);	\
	(b)[(i) + 3] = (uint8)((n) >> 24);	\
}

void md5_starts(struct md5_context *ctx) {
	ctx->total[0] = 0;
	ctx->total[1] = 0;
	ctx->state[0] = 0x67452301;
	ctx->state[1] = 0xEFCDAB89;
	ctx->state[2] = 0x98BADCFE;
	ctx->state[3] = 0x10325476;
}

void md5_process(struct md5_context *ctx, uint8 data[64]) {
	uint32 A, B, C, D, X[16];

	GET_UINT32(X[0], data, 0);
	GET_UINT32(X[1], data, 4);
	GET_UINT32(X[2], data, 8);
	GET_UINT32(X[3], data, 12);
	GET_UINT32(X[4], data, 16);
	GET_UINT32(X[5], data, 20);
	GET_UINT32(X[6], data, 24);
	GET_UINT32(X[7], data, 28);
	GET_UINT32(X[8], data, 32);
	GET_UINT32(X[9], data, 36);
	GET_UINT32(X[10], data, 40);
	GET_UINT32(X[11], data, 44);
	GET_UINT32(X[12], data, 48);
	GET_UINT32(X[13], data, 52);
	GET_UINT32(X[14], data, 56);
	GET_UINT32(X[15], data, 60);

#define S(x, n) ((x << n) | ((x & 0xFFFFFFFF) >> (32 - n)))

#define P(a, b, c, d, k, s, t)		  \
	{					\
		a += F(b, c, d) + X[k] + t; a = S(a, s) + b;	 \
	}

	A = ctx->state[0];
	B = ctx->state[1];
	C = ctx->state[2];
	D = ctx->state[3];

#define F(x, y, z) (z ^ (x & (y ^ z)))

	P(A, B, C, D, 0, 7, 0xD76AA478);
	P(D, A, B, C, 1, 12, 0xE8C7B756);
	P(C, D, A, B, 2, 17, 0x242070DB);
	P(B, C, D, A, 3, 22, 0xC1BDCEEE);
	P(A, B, C, D, 4, 7, 0xF57C0FAF);
	P(D, A, B, C, 5, 12, 0x4787C62A);
	P(C, D, A, B, 6, 17, 0xA8304613);
	P(B, C, D, A, 7, 22, 0xFD469501);
	P(A, B, C, D, 8, 7, 0x698098D8);
	P(D, A, B, C, 9, 12, 0x8B44F7AF);
	P(C, D, A, B, 10, 17, 0xFFFF5BB1);
	P(B, C, D, A, 11, 22, 0x895CD7BE);
	P(A, B, C, D, 12, 7, 0x6B901122);
	P(D, A, B, C, 13, 12, 0xFD987193);
	P(C, D, A, B, 14, 17, 0xA679438E);
	P(B, C, D, A, 15, 22, 0x49B40821);

#undef F

#define F(x, y, z) (y ^ (z & (x ^ y)))

	P(A, B, C, D, 1, 5, 0xF61E2562);
	P(D, A, B, C, 6, 9, 0xC040B340);
	P(C, D, A, B, 11, 14, 0x265E5A51);
	P(B, C, D, A, 0, 20, 0xE9B6C7AA);
	P(A, B, C, D, 5, 5, 0xD62F105D);
	P(D, A, B, C, 10, 9, 0x02441453);
	P(C, D, A, B, 15, 14, 0xD8A1E681);
	P(B, C, D, A, 4, 20, 0xE7D3FBC8);
	P(A, B, C, D, 9, 5, 0x21E1CDE6);
	P(D, A, B, C, 14, 9, 0xC33707D6);
	P(C, D, A, B, 3, 14, 0xF4D50D87);
	P(B, C, D, A, 8, 20, 0x455A14ED);
	P(A, B, C, D, 13, 5, 0xA9E3E905);
	P(D, A, B, C, 2, 9, 0xFCEFA3F8);
	P(C, D, A, B, 7, 14, 0x676F02D9);
	P(B, C, D, A, 12, 20, 0x8D2A4C8A);

#undef F

#define F(x, y, z) (x ^ y ^ z)

	P(A, B, C, D, 5, 4, 0xFFFA3942);
	P(D, A, B, C, 8, 11, 0x8771F681);
	P(C, D, A, B, 11, 16, 0x6D9D6122);
	P(B, C, D, A, 14, 23, 0xFDE5380C);
	P(A, B, C, D, 1, 4, 0xA4BEEA44);
	P(D, A, B, C, 4, 11, 0x4BDECFA9);
	P(C, D, A, B, 7, 16, 0xF6BB4B60);
	P(B, C, D, A, 10, 23, 0xBEBFBC70);
	P(A, B, C, D, 13, 4, 0x289B7EC6);
	P(D, A, B, C, 0, 11, 0xEAA127FA);
	P(C, D, A, B, 3, 16, 0xD4EF3085);
	P(B, C, D, A, 6, 23, 0x04881D05);
	P(A, B, C, D, 9, 4, 0xD9D4D039);
	P(D, A, B, C, 12, 11, 0xE6DB99E5);
	P(C, D, A, B, 15, 16, 0x1FA27CF8);
	P(B, C, D, A, 2, 23, 0xC4AC5665);

#undef F

#define F(x, y, z) (y ^ (x | ~z))

	P(A, B, C, D, 0, 6, 0xF4292244);
	P(D, A, B, C, 7, 10, 0x432AFF97);
	P(C, D, A, B, 14, 15, 0xAB9423A7);
	P(B, C, D, A, 5, 21, 0xFC93A039);
	P(A, B, C, D, 12, 6, 0x655B59C3);
	P(D, A, B, C, 3, 10, 0x8F0CCC92);
	P(C, D, A, B, 10, 15, 0xFFEFF47D);
	P(B, C, D, A, 1, 21, 0x85845DD1);
	P(A, B, C, D, 8, 6, 0x6FA87E4F);
	P(D, A, B, C, 15, 10, 0xFE2CE6E0);
	P(C, D, A, B, 6, 15, 0xA3014314);
	P(B, C, D, A, 13, 21, 0x4E0811A1);
	P(A, B, C, D, 4, 6, 0xF7537E82);
	P(D, A, B, C, 11, 10, 0xBD3AF235);
	P(C, D, A, B, 2, 15, 0x2AD7D2BB);
	P(B, C, D, A, 9, 21, 0xEB86D391);

#undef F

	ctx->state[0] += A;
	ctx->state[1] += B;
	ctx->state[2] += C;
	ctx->state[3] += D;
}

void md5_update(struct md5_context *ctx, uint8 *input, uint32 length) {
	uint32 left, fill;

	if (!length) return;

	left = (ctx->total[0] >> 3) & 0x3F;
	fill = 64 - left;

	ctx->total[0] += length << 3;
	ctx->total[1] += length >> 29;

	ctx->total[0] &= 0xFFFFFFFF;
	ctx->total[1] += ctx->total[0] < (length << 3);

	if (left && length >= fill) {
		memcpy((void*)(ctx->buffer + left), (void*)input, fill);
		md5_process(ctx, ctx->buffer);
		length -= fill;
		input += fill;
		left = 0;
	}

	while (length >= 64) {
		md5_process(ctx, input);
		length -= 64;
		input += 64;
	}

	if (length) {
		memcpy((void*)(ctx->buffer + left), (void*)input, length);
	}
}

static uint8 md5_padding[64] =
{
	0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

void md5_finish(struct md5_context *ctx, uint8 digest[16]) {
	uint32 last, padn;
	uint8 msglen[8];

	PUT_UINT32(ctx->total[0], msglen, 0);
	PUT_UINT32(ctx->total[1], msglen, 4);

	last = (ctx->total[0] >> 3) & 0x3F;
	padn = (last < 56) ? (56 - last) : (120 - last);

	md5_update(ctx, md5_padding, padn);
	md5_update(ctx, msglen, 8);

	PUT_UINT32(ctx->state[0], digest, 0);
	PUT_UINT32(ctx->state[1], digest, 4);
	PUT_UINT32(ctx->state[2], digest, 8);
	PUT_UINT32(ctx->state[3], digest, 12);
}


/* Uses a static buffer, so beware of how it's used. */
char *md5_asciistr(uint8 digest[16]) {
	static char str[33];
	static char trans[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
	int x;

	for (x = 0; x < 16; x++) {
		str[x * 2] = trans[digest[x] >> 4];
		str[x * 2 + 1] = trans[digest[x] & 0x0F];
	}
	return(str);
}