/*
   mkvmerge -- utility for splicing together matroska files
   from component media subtypes

   Distributed under the GPL
   see the file COPYING for details
   or visit http://www.gnu.org/copyleft/gpl.html

   checksum calculations

   Written by Moritz Bunkus <moritz@bunkus.org>.

   The code dealing with muliple CRC variations was taken from the ffmpeg
     project, files "libavutil/crc.h" and "libavutil/crc.c".
*/

#include "common/common_pch.h"

#include "common/bswap.h"
#include "common/checksums.h"
#include "common/endian.h"

#define BASE 65521
#define A0 check += *buffer++; sum2 += check;
#define A1 A0 A0
#define A2 A1 A1
#define A3 A2 A2
#define A4 A3 A3
#define A5 A4 A4
#define A6 A5 A5

uint32_t
calc_adler32(const unsigned char *buffer,
             int size) {
  int k          = size;
  uint32_t check = 1;
  uint32_t sum2  = (check >> 16) & 0xffffL;
  check         &= 0xffffL;
  while (k >= 64) {
    A6;
    k -= 64;
  }

  if (k)
    do {
      A0;
    } while (--k);

  check %= BASE;
  check |= (sum2 % BASE) << 16;

  return check;
}

/*
   The following code was taken from the ffmpeg project, files
   "libavutil/crc.h" and "libavutil/crc.c".

   Its license here is the GPL.
 */

static struct {
  uint8_t  le;
  uint8_t  bits;
  uint32_t poly;
} s_crc_table_params[CRC_MAX] = {
  { 0,  8,       0x07 },
  { 0, 16,     0x8005 },
  { 0, 16,     0x1021 },
  { 0, 32, 0x04C11DB7 },
  { 1, 32, 0xEDB88320 },
};
static uint32_t s_crc_table[CRC_MAX][257];
#ifdef COMP_MSC
#pragma warning(disable:4146)	//unary minus operator applied to unsigned type, result still unsigned
#endif

int
crc_init(uint32_t *ctx,
         int le,
         int bits,
         uint32_t poly,
         unsigned int ctx_size) {
  int i, j;
  uint32_t c;

  if ((bits < 8) || (bits > 32) || (poly >= (1LL<<bits)))
    return -1;

  if ((ctx_size != sizeof(uint32_t) * 257) && (ctx_size != sizeof(uint32_t) * 1024))
    return -1;

  for (i = 0; i < 256; i++) {
    if (le) {
      for (c = i, j = 0; j < 8; j++)
        c = (c >> 1) ^ (poly & (-(c & 1)));
      ctx[i] = c;

    } else {
      for (c = i << 24, j = 0; j < 8; j++)
        c = (c << 1) ^ ((poly << (32 - bits)) & (((int32_t)c) >> 31));
      ctx[i] = bswap_32(c);
    }
  }

  ctx[256] = 1;

  if(ctx_size >= sizeof(uint32_t) * 1024)
    for (i = 0; i < 256; i++)
      for(j=0; j<3; j++)
        ctx[256 * (j + 1) + i] = (ctx[256 * j + i] >> 8) ^ ctx[ctx[256 * j + i] & 0xff];

  return 0;
}

const uint32_t *
crc_get_table(crc_type_e crc_id){
  if (!s_crc_table[crc_id][256])
    if (crc_init(s_crc_table[crc_id], s_crc_table_params[crc_id].le, s_crc_table_params[crc_id].bits, s_crc_table_params[crc_id].poly, sizeof(s_crc_table[crc_id])) < 0)
      return nullptr;

  return s_crc_table[crc_id];
}

uint32_t
crc_calc(const uint32_t *ctx,
         uint32_t crc,
         const unsigned char *buffer,
         size_t length) {
  const uint8_t *end = buffer + length;

  if (!ctx[256])
    while (buffer < (end - 3)){
      crc    ^= get_uint32_le(buffer);
      crc     =   ctx[3 * 256 + ( crc        & 0xff)]
                ^ ctx[2 * 256 + ((crc >>  8) & 0xff)]
                ^ ctx[1 * 256 + ((crc >> 16) & 0xff)]
                ^ ctx[0 * 256 + ((crc >> 24)       )];
      buffer += 4;
    }

  while(buffer < end)
    crc = ctx[((uint8_t)crc) ^ *buffer++] ^ (crc >> 8);

  return crc;
}

static const uint32_t crc_mpeg2_table[256] = {
  0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
  0x1a864db2, 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
  0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd, 0x4c11db70, 0x48d0c6c7,
  0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
  0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3,
  0x709f7b7a, 0x745e66cd, 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
  0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58, 0xbaea46ef,
  0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
  0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c, 0xc3f706fb,
  0xceb42022, 0xca753d95, 0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
  0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0,
  0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
  0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4,
  0x0808d07d, 0x0cc9cdca, 0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
  0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08,
  0x571d7dd1, 0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
  0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc,
  0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
  0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a, 0xe0b41de7, 0xe4750050,
  0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
  0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34,
  0xdc3abded, 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
  0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb, 0x4f040d56, 0x4bc510e1,
  0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
  0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5,
  0x3f9b762c, 0x3b5a6b9b, 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
  0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e, 0xf5ee4bb9,
  0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
  0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a, 0xc0e2d0dd,
  0xcda1f604, 0xc960ebb3, 0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
  0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71,
  0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
  0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2,
  0x470cdd2b, 0x43cdc09c, 0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
  0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24, 0x119b4be9, 0x155a565e,
  0x18197087, 0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
  0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a,
  0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
  0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c, 0xe3a1cbc1, 0xe760d676,
  0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
  0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662,
  0x933eb0bb, 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
  0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
};

uint32_t
crc_calc_mpeg2(unsigned char *data,
               int len) {
  uint32_t crc = 0xffffffff;

  for (auto i = 0; i < len; i++)
    crc = (crc << 8) ^ crc_mpeg2_table[((crc >> 24) ^ *data++) & 0xff];

  return crc;
}
