From 6bf0a5cb5034a7e684dcc3500e841785237ce2dd Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 19:32:43 +0200 Subject: Adding upstream version 1:115.7.0. Signed-off-by: Daniel Baumann --- media/libwebp/src/utils/huffman_utils.h | 111 ++++++++++++++++++++++++++++++++ 1 file changed, 111 insertions(+) create mode 100644 media/libwebp/src/utils/huffman_utils.h (limited to 'media/libwebp/src/utils/huffman_utils.h') diff --git a/media/libwebp/src/utils/huffman_utils.h b/media/libwebp/src/utils/huffman_utils.h new file mode 100644 index 0000000000..98415c5328 --- /dev/null +++ b/media/libwebp/src/utils/huffman_utils.h @@ -0,0 +1,111 @@ +// Copyright 2012 Google Inc. All Rights Reserved. +// +// Use of this source code is governed by a BSD-style license +// that can be found in the COPYING file in the root of the source +// tree. An additional intellectual property rights grant can be found +// in the file PATENTS. All contributing project authors may +// be found in the AUTHORS file in the root of the source tree. +// ----------------------------------------------------------------------------- +// +// Utilities for building and looking up Huffman trees. +// +// Author: Urvang Joshi (urvang@google.com) + +#ifndef WEBP_UTILS_HUFFMAN_UTILS_H_ +#define WEBP_UTILS_HUFFMAN_UTILS_H_ + +#include +#include "src/webp/format_constants.h" +#include "src/webp/types.h" + +#ifdef __cplusplus +extern "C" { +#endif + +#define HUFFMAN_TABLE_BITS 8 +#define HUFFMAN_TABLE_MASK ((1 << HUFFMAN_TABLE_BITS) - 1) + +#define LENGTHS_TABLE_BITS 7 +#define LENGTHS_TABLE_MASK ((1 << LENGTHS_TABLE_BITS) - 1) + + +// Huffman lookup table entry +typedef struct { + uint8_t bits; // number of bits used for this symbol + uint16_t value; // symbol value or table offset +} HuffmanCode; + +// long version for holding 32b values +typedef struct { + int bits; // number of bits used for this symbol, + // or an impossible value if not a literal code. + uint32_t value; // 32b packed ARGB value if literal, + // or non-literal symbol otherwise +} HuffmanCode32; + +// Contiguous memory segment of HuffmanCodes. +typedef struct HuffmanTablesSegment { + HuffmanCode* start; + // Pointer to where we are writing into the segment. Starts at 'start' and + // cannot go beyond 'start' + 'size'. + HuffmanCode* curr_table; + // Pointer to the next segment in the chain. + struct HuffmanTablesSegment* next; + int size; +} HuffmanTablesSegment; + +// Chained memory segments of HuffmanCodes. +typedef struct HuffmanTables { + HuffmanTablesSegment root; + // Currently processed segment. At first, this is 'root'. + HuffmanTablesSegment* curr_segment; +} HuffmanTables; + +// Allocates a HuffmanTables with 'size' contiguous HuffmanCodes. Returns 0 on +// memory allocation error, 1 otherwise. +int VP8LHuffmanTablesAllocate(int size, HuffmanTables* huffman_tables); +void VP8LHuffmanTablesDeallocate(HuffmanTables* const huffman_tables); + +#define HUFFMAN_PACKED_BITS 6 +#define HUFFMAN_PACKED_TABLE_SIZE (1u << HUFFMAN_PACKED_BITS) + +// Huffman table group. +// Includes special handling for the following cases: +// - is_trivial_literal: one common literal base for RED/BLUE/ALPHA (not GREEN) +// - is_trivial_code: only 1 code (no bit is read from bitstream) +// - use_packed_table: few enough literal symbols, so all the bit codes +// can fit into a small look-up table packed_table[] +// The common literal base, if applicable, is stored in 'literal_arb'. +typedef struct HTreeGroup HTreeGroup; +struct HTreeGroup { + HuffmanCode* htrees[HUFFMAN_CODES_PER_META_CODE]; + int is_trivial_literal; // True, if huffman trees for Red, Blue & Alpha + // Symbols are trivial (have a single code). + uint32_t literal_arb; // If is_trivial_literal is true, this is the + // ARGB value of the pixel, with Green channel + // being set to zero. + int is_trivial_code; // true if is_trivial_literal with only one code + int use_packed_table; // use packed table below for short literal code + // table mapping input bits to a packed values, or escape case to literal code + HuffmanCode32 packed_table[HUFFMAN_PACKED_TABLE_SIZE]; +}; + +// Creates the instance of HTreeGroup with specified number of tree-groups. +HTreeGroup* VP8LHtreeGroupsNew(int num_htree_groups); + +// Releases the memory allocated for HTreeGroup. +void VP8LHtreeGroupsFree(HTreeGroup* const htree_groups); + +// Builds Huffman lookup table assuming code lengths are in symbol order. +// The 'code_lengths' is pre-allocated temporary memory buffer used for creating +// the huffman table. +// Returns built table size or 0 in case of error (invalid tree or +// memory error). +int VP8LBuildHuffmanTable(HuffmanTables* const root_table, int root_bits, + const int code_lengths[], int code_lengths_size); + +#ifdef __cplusplus +} // extern "C" +#endif + +#endif // WEBP_UTILS_HUFFMAN_UTILS_H_ -- cgit v1.2.3