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// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// main entry for the decoder
//
// Authors: Vikas Arora (vikaas.arora@gmail.com)
//          Jyrki Alakuijala (jyrki@google.com)

#include <stdlib.h>

#include "./alphai.h"
#include "./vp8li.h"
#include "../dsp/dsp.h"
#include "../dsp/lossless.h"
#include "../dsp/yuv.h"
#include "../utils/huffman.h"
#include "../utils/utils.h"

#define NUM_ARGB_CACHE_ROWS          16

static const int kCodeLengthLiterals = 16;
static const int kCodeLengthRepeatCode = 16;
static const int kCodeLengthExtraBits[3] = { 2, 3, 7 };
static const int kCodeLengthRepeatOffsets[3] = { 3, 3, 11 };

// -----------------------------------------------------------------------------
//  Five Huffman codes are used at each meta code:
//  1. green + length prefix codes + color cache codes,
//  2. alpha,
//  3. red,
//  4. blue, and,
//  5. distance prefix codes.
typedef enum {
  GREEN = 0,
  RED   = 1,
  BLUE  = 2,
  ALPHA = 3,
  DIST  = 4
} HuffIndex;

static const uint16_t kAlphabetSize[HUFFMAN_CODES_PER_META_CODE] = {
  NUM_LITERAL_CODES + NUM_LENGTH_CODES,
  NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES,
  NUM_DISTANCE_CODES
};

static const uint8_t kLiteralMap[HUFFMAN_CODES_PER_META_CODE] = {
  0, 1, 1, 1, 0
};

#define NUM_CODE_LENGTH_CODES       19
static const uint8_t kCodeLengthCodeOrder[NUM_CODE_LENGTH_CODES] = {
  17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
};

#define CODE_TO_PLANE_CODES        120
static const uint8_t kCodeToPlane[CODE_TO_PLANE_CODES] = {
  0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a,
  0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a,
  0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b,
  0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03,
  0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c,
  0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e,
  0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b,
  0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f,
  0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b,
  0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41,
  0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f,
  0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70
};

// Memory needed for lookup tables of one Huffman tree group. Red, blue, alpha
// and distance alphabets are constant (256 for red, blue and alpha, 40 for
// distance) and lookup table sizes for them in worst case are 630 and 410
// respectively. Size of green alphabet depends on color cache size and is equal
// to 256 (green component values) + 24 (length prefix values)
// + color_cache_size (between 0 and 2048).
// All values computed for 8-bit first level lookup with Mark Adler's tool:
// http://www.hdfgroup.org/ftp/lib-external/zlib/zlib-1.2.5/examples/enough.c
#define FIXED_TABLE_SIZE (630 * 3 + 410)
static const int kTableSize[12] = {
  FIXED_TABLE_SIZE + 654,
  FIXED_TABLE_SIZE + 656,
  FIXED_TABLE_SIZE + 658,
  FIXED_TABLE_SIZE + 662,
  FIXED_TABLE_SIZE + 670,
  FIXED_TABLE_SIZE + 686,
  FIXED_TABLE_SIZE + 718,
  FIXED_TABLE_SIZE + 782,
  FIXED_TABLE_SIZE + 912,
  FIXED_TABLE_SIZE + 1168,
  FIXED_TABLE_SIZE + 1680,
  FIXED_TABLE_SIZE + 2704
};

static int DecodeImageStream(int xsize, int ysize,
                             int is_level0,
                             VP8LDecoder* const dec,
                             uint32_t** const decoded_data);

//------------------------------------------------------------------------------

int VP8LCheckSignature(const uint8_t* const data, size_t size) {
  return (size >= VP8L_FRAME_HEADER_SIZE &&
          data[0] == VP8L_MAGIC_BYTE &&
          (data[4] >> 5) == 0);  // version
}

static int ReadImageInfo(VP8LBitReader* const br,
                         int* const width, int* const height,
                         int* const has_alpha) {
  if (VP8LReadBits(br, 8) != VP8L_MAGIC_BYTE) return 0;
  *width = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1;
  *height = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1;
  *has_alpha = VP8LReadBits(br, 1);
  if (VP8LReadBits(br, VP8L_VERSION_BITS) != 0) return 0;
  return !br->eos_;
}

int VP8LGetInfo(const uint8_t* data, size_t data_size,
                int* const width, int* const height, int* const has_alpha) {