/*
 * GeeXboX Valhalla: tiny media scanner API.
 *
 * This implementation of SHA comes from FFmpeg/libavutil. The part related
 * to SHA-1 is removed. Only SHA-224 and SHA-256 are supported here.
 *
 * Copyright (C) 2007 Michael Niedermayer <michaelni@gmx.at>
 * Copyright (C) 2009 Konstantin Shishkov
 * based on public domain SHA-1 code by Steve Reid <steve@edmweb.com>
 * and on BSD-licensed SHA-2 code by Aaron D. Gifford
 *
 * This file is part of libvalhalla.
 *
 * libvalhalla 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.
 *
 * libvalhalla 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 libvalhalla; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <libavutil/avutil.h>

#include "sha.h"

/* hash context */
struct vh_sha_s {
  uint8_t  digest_len; /* digest length in 32-bit words */
  uint64_t count;      /* number of bytes in buffer */
  uint8_t  buffer[64]; /* 512-bit of input values used in hash updating */
  uint32_t state[8];   /* current hash value */
  /* function used to update hash for 512-bit input block */
  void     (*transform) (uint32_t *state, const uint8_t buffer[64]);
};

const int vh_sha_size = sizeof (vh_sha_t);


static inline uint32_t
bswap_32 (uint32_t x)
{
  x = ((x << 8) & 0xFF00FF00) | ((x >> 8) & 0x00FF00FF);
  x = (x >> 16) | (x << 16);
  return x;
}

static inline uint64_t
bswap_64 (uint64_t x)
{
  union {
    uint64_t ll;
    uint32_t l[2];
  } w, r;

  w.ll = x;
  r.l[0] = bswap_32 (w.l[1]);
  r.l[1] = bswap_32 (w.l[0]);
  return r.ll;
}

#ifdef HAVE_BIGENDIAN
#define be2me_32(x) (x)
#define be2me_64(x) (x)
#else
#define be2me_32(x) bswap_32(x)
#define be2me_64(x) bswap_64(x)
#endif /* !HAVE_BIGENDIAN */

static const uint32_t K256[64] = {
  0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
  0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
  0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
  0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
  0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
  0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
  0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
  0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
  0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
  0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
  0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
  0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
  0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
  0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
  0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
  0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
};

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

#define Ch(x,y,z)   (((x) & ((y) ^ (z))) ^ (z))
#define Maj(x,y,z)  ((((x) | (y)) & (z)) | ((x) & (y)))

#define Sigma0_256(x)   (rol ((x), 30) ^ rol ((x), 19) ^ rol ((x), 10))
#define Sigma1_256(x)   (rol ((x), 26) ^ rol ((x), 21) ^ rol ((x),  7))
#define sigma0_256(x)   (rol ((x), 25) ^ rol ((x), 14) ^ ((x) >> 3))
#define sigma1_256(x)   (rol ((x), 15) ^ rol ((x), 13) ^ ((x) >> 10))

#define blk0(i) (block[i] = be2me_32(((const uint32_t *) buffer)[i]))
#define blk(i)  (block[i] = block[i - 16] + sigma0_256 (block[i - 15]) + \
                            sigma1_256 (block[i - 2]) + block[i - 7])

#define ROUND256(a,b,c,d,e,f,g,h)                             \
  T1 += (h) + Sigma1_256 (e) + Ch ((e), (f), (g)) + K256[i];  \
  (d) += T1;                                                  \
  (h) = T1 + Sigma0_256 (a) + Maj ((a), (b), (c));            \
  i++

#define ROUND256_0_TO_15(a,b,c,d,e,f,g,h)   \
  T1 = blk0 (i);                            \
  ROUND256 (a,b,c,d,e,f,g,h)

#define ROUND256_16_TO_63(a,b,c,d,e,f,g,h)  \
  T1 = blk (i);                             \
  ROUND256 (a,b,c,d,e,f,g,h)

static void
sha256_transform (uint32_t *state, const uint8_t buffer[64])
{
  unsigned int i, a, b, c, d, e, f, g, h;
  uint32_t block[64];
  uint32_t T1, av_unused (T2);

  a = state[0];
  b = state[1];
  c = state[2];
  d = state[3];
  e = state[4];
  f = state[5];
  g = state[6];
  h = state[7];
#ifdef CONFIG_SMALL
  for (i = 0; i < 64; i++)
  {
    if (i < 16)
      T1 = blk0 (i);
    else
      T1 = blk (i);
    T1 += h + Sigma1_256 (e) + Ch (e, f, g) + K256[i];
    T2 = Sigma0_256 (a) + Maj (a, b, c);
    h = g;
    g = f;
    f = e;
    e = d + T1;
    d = c;
    c = b;
    b = a;
    a = T1 + T2;
  }
#else
  for (i = 0; i < 16;)
  {
    ROUND256_0_TO_15 (a, b, c, d, e, f, g, h);
    ROUND256_0_TO_15 (h, a, b, c, d, e, f, g);
    ROUND256_0_TO_15 (g, h, a, b, c, d, e, f);
    ROUND256_0_TO_15 (f, g, h, a, b, c, d, e);
    ROUND256_0_TO_15 (e, f, g, h, a, b, c, d);
    ROUND256_0_TO_15 (d, e, f, g, h, a, b, c);
    ROUND256_0_TO_15 (c, d, e, f, g, h, a, b);
    ROUND256_0_TO_15 (b, c, d, e, f, g, h, a);
  }

  for (; i < 64;)
  {
    ROUND256_16_TO_63 (a, b, c, d, e, f, g, h);
    ROUND256_16_TO_63 (h, a, b, c, d, e, f, g);
    ROUND256_16_TO_63 (g, h, a, b, c, d, e, f);
    ROUND256_16_TO_63 (f, g, h, a, b, c, d, e);
    ROUND256_16_TO_63 (e, f, g, h, a, b, c, d);
    ROUND256_16_TO_63 (d, e, f, g, h, a, b, c);
    ROUND256_16_TO_63 (c, d, e, f, g, h, a, b);
    ROUND256_16_TO_63 (b, c, d, e, f, g, h, a);
  }
#endif /* !CONFIG_SMALL */
  state[0] += a;
  state[1] += b;
  state[2] += c;
  state[3] += d;
  state[4] += e;
  state[5] += f;
  state[6] += g;
  state[7] += h;
}

int
vh_sha_init (vh_sha_t *ctx, int bits)
{
  ctx->digest_len = bits >> 5;

  switch (bits)
  {
  case 224: /* SHA-224 */
    ctx->state[0] = 0xC1059ED8;
    ctx->state[1] = 0x367CD507;
    ctx->state[2] = 0x3070DD17;
    ctx->state[3] = 0xF70E5939;
    ctx->state[4] = 0xFFC00B31;
    ctx->state[5] = 0x68581511;
    ctx->state[6] = 0x64F98FA7;
    ctx->state[7] = 0xBEFA4FA4;
    ctx->transform = sha256_transform;
    break;

  case 256: /* SHA-256 */
    ctx->state[0] = 0x6A09E667;
    ctx->state[1] = 0xBB67AE85;
    ctx->state[2] = 0x3C6EF372;
    ctx->state[3] = 0xA54FF53A;
    ctx->state[4] = 0x510E527F;
    ctx->state[5] = 0x9B05688C;
    ctx->state[6] = 0x1F83D9AB;
    ctx->state[7] = 0x5BE0CD19;
    ctx->transform = sha256_transform;
    break;

  default:
    return -1;
  }

  ctx->count = 0;
  return 0;
}

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

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

void
vh_sha_final (vh_sha_t *ctx, uint8_t *digest)
{
  int i;
  uint64_t finalcount = be2me_64 (ctx->count << 3);

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