/*****************************************************************************

 * md5.cpp: Calculate MD5 for SEI

 *****************************************************************************

 * Copyright (C) 2013-2020 MulticoreWare, Inc

 *

 * Authors: Min Chen <chenm003@163.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation;

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111, USA.

 *

 * This program is also available under a commercial proprietary license.

 * For more information, contact us at chenm003@163.com.

 *****************************************************************************/

#include "common.h"

#include "md5.h"

namespace X265_NS {

// private x265 namespace

#ifndef ARCH_BIG_ENDIAN

#define byteReverse(buf, len)   /* Nothing */

#else

static void byteReverse(uint8_t_t *buf, unsigned int nSize)

{

    int i;

    uint32_t tmp;

    for (i = 0; i < nSize; i++)

    {

        tmp = ((unsigned int)buf[3] << 8 | buf[2]) << 16 |

            ((unsigned int)buf[1] << 8 | buf[0]);

        *(uint32_t*)buf = tmp;

        buf += 4;

    }

}

#endif // ifndef ARCH_BIG_ENDIAN

void MD5Transform(uint32_t *buf, uint32_t *in);

/*

 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious

 * initialization constants.

 */

void MD5Init(MD5Context *ctx)

{

    ctx->buf[0] = 0x67452301;

    ctx->buf[1] = 0xefcdab89;

    ctx->buf[2] = 0x98badcfe;

    ctx->buf[3] = 0x10325476;

    ctx->bits[0] = 0;

    ctx->bits[1] = 0;

}

/*

 * Update context to reflect the concatenation of another buffer full

 * of bytes.

 */

void MD5Update(MD5Context *ctx, uint8_t *buf, uint32_t len)

{

    uint32_t t;

    /* Update bitcount */

    t = ctx->bits[0];

    if ((ctx->bits[0] = t + ((uint32_t)len << 3)) < t)

        ctx->bits[1]++; /* Carry from low to high */

    ctx->bits[1] += len >> 29;

    t = (t >> 3) & 0x3F;        /* Bytes already in shsInfo->data */

    /* Handle any leading odd-sized chunks */

    if (t)

    {

        uint8_t *p = (uint8_t*)ctx->in + t;

        t = 64 - t;

        if (len < t)

        {

            memcpy(p, buf, len);

            return;

        }

        memcpy(p, buf, t);

        byteReverse(ctx->in, 16);

        MD5Transform(ctx->buf, (uint32_t*)ctx->in);

        buf += t;

        len -= t;

    }

    /* Process data in 64-byte chunks */

    while (len >= 64)

    {

        memcpy(ctx->in, buf, 64);

        byteReverse(ctx->in, 16);

        MD5Transform(ctx->buf, (uint32_t*)ctx->in);

        buf += 64;

        len -= 64;

    }

    /* Handle any remaining bytes of data. */

    memcpy(ctx->in, buf, len);

}

/*

 * Final wrapup - pad to 64-byte boundary with the bit pattern

 * 1 0* (64-bit count of bits processed, MSB-first)

 */

void MD5Final(MD5Context *ctx, uint8_t *digest)

{

    uint32_t count;

    uint8_t  *p;

    /* Compute number of bytes mod 64 */

    count = (ctx->bits[0] >> 3) & 0x3F;

    /* Set the first char of padding to 0x80.  This is safe since there is

       always at least one byte free */

    p = ctx->in + count;

    *p++ = 0x80;

    /* Bytes of padding needed to make 64 bytes */

    count = 64 - 1 - count;

    /* Pad out to 56 mod 64 */

    if (count < 8)

    {

        /* Two lots of padding:  Pad the first block to 64 bytes */

        memset(p, 0, count);

        byteReverse(ctx->in, 16);

        MD5Transform(ctx->buf, (uint32_t*)ctx->in);

        /* Now fill the next block with 56 bytes */

        memset(ctx->in, 0, 56);

    }

    else

    {

        /* Pad block to 56 bytes */

        memset(p, 0, count - 8);

    }

    byteReverse(ctx->in, 14);

    /* Append length in bits and transform */

    // CHECK_ME: Always use 32-bits operator

    uint32_t *table = (uint32_t*)&ctx->in;

    table[14] = ctx->bits[0];

    table[15] = ctx->bits[1];

    MD5Transform(ctx->buf, (uint32_t*)ctx->in);

    byteReverse((uint8_t*)ctx->buf, 4);

    memcpy(digest, ctx->buf, 16);

    memset(ctx, 0, sizeof(*ctx));        /* In case it's sensitive */

}

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */

#define F1(x, y, z) (z ^ (x & (y ^ z)))

#define F2(x, y, z) F1(z, x, y)

#define F3(x, y, z) (x ^ y ^ z)

#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */

#define MD5STEP(f, w, x, y, z, data, s) \

    (w += f(x, y, z) + data,  w = w << s | w >> (32 - s),  w += x)

/*

 * The core of the MD5 algorithm, this alters an existing MD5 hash to

 * reflect the addition of 16 longwords of new data.  MD5Update blocks

 * the data and converts bytes into longwords for this routine.

 */

void MD5Transform(uint32_t *buf, uint32_t *in)

{

    register uint32_t a, b, c, d;

    a = buf[0];

    b = buf[1];

    c = buf[2];

    d = buf[3];

    MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);

    MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);

    MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);

    MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);

    MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);

    MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);

    MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);

    MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);

    MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);

    MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);

    MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);

    MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);

    MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);

    MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);

    MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);

    MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

    MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);

    MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);

    MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);

    MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);

    MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);

    MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);

    MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);

    MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);

    MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);

    MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);

    MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);

    MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);

    MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);

    MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);

    MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);

    MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

    MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);

    MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);

    MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);

    MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);

    MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);

    MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);

    MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);

    MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);

    MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);

    MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);

    MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);

    MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);

    MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);

    MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);

    MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);

    MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

    MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);

    MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);

    MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);

    MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);

    MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);

    MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);

    MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);

    MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);

    MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);

    MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);

    MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);

    MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);

    MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);

    MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);

    MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);

    MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

    buf[0] += a;

    buf[1] += b;

    buf[2] += c;

    buf[3] += d;

}

}