/* Copyright 2013 Google Inc. All Rights Reserved.

   Distributed under MIT license.

   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT

*/

/* Utilities for building Huffman decoding tables. */

#ifndef BROTLI_DEC_HUFFMAN_H_

#define BROTLI_DEC_HUFFMAN_H_

#include <brotli/types.h>

#include "../common/platform.h"

#if defined(__cplusplus) || defined(c_plusplus)

extern "C" {

#endif

#define BROTLI_HUFFMAN_MAX_CODE_LENGTH 15

/* BROTLI_NUM_BLOCK_LEN_SYMBOLS == 26 */

#define BROTLI_HUFFMAN_MAX_SIZE_26 396

/* BROTLI_MAX_BLOCK_TYPE_SYMBOLS == 258 */

#define BROTLI_HUFFMAN_MAX_SIZE_258 632

/* BROTLI_MAX_CONTEXT_MAP_SYMBOLS == 272 */

#define BROTLI_HUFFMAN_MAX_SIZE_272 646

#define BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH 5

#if ((defined(BROTLI_TARGET_ARMV7) || defined(BROTLI_TARGET_ARMV8_32)) && \

  BROTLI_GNUC_HAS_ATTRIBUTE(aligned, 2, 7, 0))

#define BROTLI_HUFFMAN_CODE_FAST_LOAD

#endif

#if !defined(BROTLI_HUFFMAN_CODE_FAST_LOAD)

/* Do not create this struct directly - use the ConstructHuffmanCode

 * constructor below! */

typedef struct {

  uint8_t bits;    /* number of bits used for this symbol */

  uint16_t value;  /* symbol value or table offset */

} HuffmanCode;

static BROTLI_INLINE HuffmanCode ConstructHuffmanCode(const uint8_t bits,

    const uint16_t value) {

  HuffmanCode h;

  h.bits = bits;

  h.value = value;

  return h;

}

Unexecuted instantiation: decode.c:ConstructHuffmanCode

Unexecuted instantiation: state.c:ConstructHuffmanCode

Unexecuted instantiation: huffman.c:ConstructHuffmanCode

/* Please use the following macros to optimize HuffmanCode accesses in hot

 * paths.

 *

 * For example, assuming |table| contains a HuffmanCode pointer:

 *

 *   BROTLI_HC_MARK_TABLE_FOR_FAST_LOAD(table);

 *   BROTLI_HC_ADJUST_TABLE_INDEX(table, index_into_table);

 *   *bits = BROTLI_HC_GET_BITS(table);

 *   *value = BROTLI_HC_GET_VALUE(table);

 *   BROTLI_HC_ADJUST_TABLE_INDEX(table, offset);

 *   *bits2 = BROTLI_HC_GET_BITS(table);

 *   *value2 = BROTLI_HC_GET_VALUE(table);

 *

 */

#define BROTLI_HC_MARK_TABLE_FOR_FAST_LOAD(H)

#define BROTLI_HC_ADJUST_TABLE_INDEX(H, V) H += (V)

/* These must be given a HuffmanCode pointer! */

#define BROTLI_HC_FAST_LOAD_BITS(H) (H->bits)

#define BROTLI_HC_FAST_LOAD_VALUE(H) (H->value)

#else /* BROTLI_HUFFMAN_CODE_FAST_LOAD */

typedef BROTLI_ALIGNED(4) uint32_t HuffmanCode;

static BROTLI_INLINE HuffmanCode ConstructHuffmanCode(const uint8_t bits,

    const uint16_t value) {

  return (HuffmanCode) ((value & 0xFFFF) << 16) | (bits & 0xFF);

}

#define BROTLI_HC_MARK_TABLE_FOR_FAST_LOAD(H) uint32_t __fastload_##H = (*H)

#define BROTLI_HC_ADJUST_TABLE_INDEX(H, V) H += (V); __fastload_##H = (*H)

/* These must be given a HuffmanCode pointer! */

#define BROTLI_HC_FAST_LOAD_BITS(H) ((__fastload_##H) & 0xFF)

#define BROTLI_HC_FAST_LOAD_VALUE(H) ((__fastload_##H) >> 16)

#endif /* BROTLI_HUFFMAN_CODE_FAST_LOAD */

/* Builds Huffman lookup table assuming code lengths are in symbol order. */

BROTLI_INTERNAL void BrotliBuildCodeLengthsHuffmanTable(HuffmanCode* root_table,

    const uint8_t* const code_lengths, uint16_t* count);

/* Builds Huffman lookup table assuming code lengths are in symbol order.

   Returns size of resulting table. */

BROTLI_INTERNAL uint32_t BrotliBuildHuffmanTable(HuffmanCode* root_table,

    int root_bits, const uint16_t* const symbol_lists, uint16_t* count);

/* Builds a simple Huffman table. The |num_symbols| parameter is to be

   interpreted as follows: 0 means 1 symbol, 1 means 2 symbols,

   2 means 3 symbols, 3 means 4 symbols with lengths [2, 2, 2, 2],

   4 means 4 symbols with lengths [1, 2, 3, 3]. */

BROTLI_INTERNAL uint32_t BrotliBuildSimpleHuffmanTable(HuffmanCode* table,

    int root_bits, uint16_t* symbols, uint32_t num_symbols);

/* Contains a collection of Huffman trees with the same alphabet size. */

/* alphabet_size_limit is needed due to simple codes, since

   log2(alphabet_size_max) could be greater than log2(alphabet_size_limit). */

typedef struct {

  HuffmanCode** htrees;

  HuffmanCode* codes;

  uint16_t alphabet_size_max;

  uint16_t alphabet_size_limit;

  uint16_t num_htrees;

} HuffmanTreeGroup;

#if defined(__cplusplus) || defined(c_plusplus)

}  /* extern "C" */

#endif

#endif  /* BROTLI_DEC_HUFFMAN_H_ */