/*
 * Copyright (C) 2007 Michael Niedermayer <michaelni@gmx.at>
 * based on public domain SHA-1 code by Steve Reid <steve@edmweb.com>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "common.h"
#include "bswap.h"
#include "sha1.h"

typedef struct AVSHA1 {
    uint64_t count;
    uint8_t buffer[64];
    uint32_t state[5];
} AVSHA1;

const int av_sha1_size = sizeof(AVSHA1);

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

/* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
#define blk0(i) (block[i] = be2me_32(((const uint32_t*)buffer)[i]))
#define blk(i)  (block[i] = rol(block[i-3] ^ block[i-8] ^ block[i-14] ^ block[i-16], 1))

#define R0(v,w,x,y,z,i) z += ((w&(x^y))^y)     + blk0(i) + 0x5A827999 + rol(v, 5); w = rol(w, 30);
#define R1(v,w,x,y,z,i) z += ((w&(x^y))^y)     + blk (i) + 0x5A827999 + rol(v, 5); w = rol(w, 30);
#define R2(v,w,x,y,z,i) z += ( w^x     ^y)     + blk (i) + 0x6ED9EBA1 + rol(v, 5); w = rol(w, 30);
#define R3(v,w,x,y,z,i) z += (((w|x)&y)|(w&x)) + blk (i) + 0x8F1BBCDC + rol(v, 5); w = rol(w, 30);
#define R4(v,w,x,y,z,i) z += ( w^x     ^y)     + blk (i) + 0xCA62C1D6 + rol(v, 5); w = rol(w, 30);

/* Hash a single 512-bit block. This is the core of the algorithm. */

static void transform(uint32_t state[5], const uint8_t buffer[64])
{
    uint32_t block[80];
    unsigned int i, a, b, c, d, e;

    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];
    e = state[4];
#if CONFIG_SMALL
    for (i = 0; i < 80; i++) {
        int t;
        if (i < 16)
            t = be2me_32(((uint32_t*)buffer)[i]);
        else
            t = rol(block[i-3] ^ block[i-8] ^ block[i-14] ^ block[i-16], 1);
        block[i] = t;
        t += e + rol(a, 5);
        if (i < 40) {
            if (i < 20)
                t += ((b&(c^d))^d)     + 0x5A827999;
            else
                t += ( b^c     ^d)     + 0x6ED9EBA1;
        } else {
            if (i < 60)
                t += (((b|c)&d)|(b&c)) + 0x8F1BBCDC;
            else
                t += ( b^c     ^d)     + 0xCA62C1D6;
        }
        e = d;
        d = c;
        c = rol(b, 30);
        b = a;
        a = t;
    }
#else
    for (i = 0; i < 15; i += 5) {
        R0(a, b, c, d, e, 0 + i);
        R0(e, a, b, c, d, 1 + i);
        R0(d, e, a, b, c, 2 + i);
        R0(c, d, e, a, b, 3 + i);
        R0(b, c, d, e, a, 4 + i);
    }
    R0(a, b, c, d, e, 15);
    R1(e, a, b, c, d, 16);
    R1(d, e, a, b, c, 17);
    R1(c, d, e, a, b, 18);
    R1(b, c, d, e, a, 19);
    for (i = 20; i < 40; i += 5) {
        R2(a, b, c, d, e, 0 + i);
        R2(e, a, b, c, d, 1 + i);
        R2(d, e, a, b, c, 2 + i);
        R2(c, d, e, a, b, 3 + i);
        R2(b, c, d, e, a, 4 + i);
    }
    for (; i < 60; i += 5) {
        R3(a, b, c, d, e, 0 + i);
        R3(e, a, b, c, d, 1 + i);
        R3(d, e, a, b, c, 2 + i);
        R3(c, d, e, a, b, 3 + i);
        R3(b, c, d, e, a, 4 + i);
    }
    for (; i < 80; i += 5) {
        R4(a, b, c, d, e, 0 + i);
        R4(e, a, b, c, d, 1 + i);
        R4(d, e, a, b, c, 2 + i);
        R4(c, d, e, a, b, 3 + i);
        R4(b, c, d, e, a, 4 + i);
    }
#endif
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
    state[4] += e;
}

void av_sha1_init(AVSHA1* ctx)
{
    ctx->state[0] = 0x67452301;
    ctx->state[1] = 0xEFCDAB89;
    ctx->state[2] = 0x98BADCFE;
    ctx->state[3] = 0x10325476;
    ctx->state[4] = 0xC3D2E1F0;
    ctx->count    = 0;
}

void av_sha1_update(AVSHA1* ctx, const uint8_t* data, unsigned int len)
{
    unsigned int i, j;

    j = ctx->count & 63;
    ctx->count += len;
#if CONFIG_SMALL
    for (i = 0; i < len; i++) {
        ctx->buffer[j++] = data[i];
        if (64 == j) {
            transform(ctx->state, ctx->buffer);
            j = 0;
        }
    }
#else
    if ((j + len) > 63) {
        memcpy(&ctx->buffer[j], data, (i = 64 - j));
        transform(ctx->state, ctx->buffer);
        for (; i + 63 < len; i += 64)
            transform(ctx->state, &data[i]);
        j = 0;
    } else
        i = 0;
    memcpy(&ctx->buffer[j], &data[i], len - i);
#endif
}

void av_sha1_final(AVSHA1* ctx, uint8_t digest[20])
{
    int i;
    uint64_t finalcount = be2me_64(ctx->count << 3);

    av_sha1_update(ctx, "\200", 1);
    while ((ctx->count & 63) != 56)
        av_sha1_update(ctx, "", 1);
    av_sha1_update(ctx, (uint8_t *)&finalcount, 8); /* Should cause a transform() */
    for (i = 0; i < 5; i++)
        ((uint32_t*)digest)[i] = be2me_32(ctx->state[i]);
}

#ifdef TEST
#include <stdio.h>
#undef printf

int main(void)
{
    int i, k;
    AVSHA1 ctx;
    unsigned char digest[20];

    for (k = 0; k < 3; k++) {
        av_sha1_init(&ctx);
        if (k == 0)
            av_sha1_update(&ctx, "abc", 3);
        else if (k == 1)
            av_sha1_update(&ctx, "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", 56);
        else
            for (i = 0; i < 1000 * 1000; i++)
                av_sha1_update(&ctx, "a", 1);
        av_sha1_final(&ctx, digest);
        for (i = 0; i < 20; i++)
            printf("%02X", digest[i]);
        putchar('\n');
    }
    //test vectors (from FIPS PUB 180-1)
    printf("A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D\n"
           "84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1\n"
           "34AA973C D4C4DAA4 F61EEB2B DBAD2731 6534016F\n");

    return 0;
}
#endif