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-rw-r--r--common/huffman.cpp71
-rw-r--r--common/huffman.h118
-rw-r--r--common/module.mk1
3 files changed, 94 insertions, 96 deletions
diff --git a/common/huffman.cpp b/common/huffman.cpp
deleted file mode 100644
index 3268ddf251..0000000000
--- a/common/huffman.cpp
+++ /dev/null
@@ -1,71 +0,0 @@
-/* ScummVM - Graphic Adventure Engine
- *
- * ScummVM is the legal property of its developers, whose names
- * are too numerous to list here. Please refer to the COPYRIGHT
- * file distributed with this source distribution.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- */
-
-// Based on eos' Huffman code
-
-#include "common/huffman.h"
-#include "common/util.h"
-#include "common/textconsole.h"
-#include "common/bitstream.h"
-
-namespace Common {
-
-Huffman::Symbol::Symbol(uint32 c, uint32 s) : code(c), symbol(s) {
-}
-
-
-Huffman::Huffman(uint8 maxLength, uint32 codeCount, const uint32 *codes, const uint8 *lengths, const uint32 *symbols) {
- assert(codeCount > 0);
-
- assert(codes);
- assert(lengths);
-
- if (maxLength == 0)
- for (uint32 i = 0; i < codeCount; i++)
- maxLength = MAX(maxLength, lengths[i]);
-
- assert(maxLength <= 32);
-
- _codes.resize(maxLength);
- _symbols.resize(codeCount);
-
- for (uint32 i = 0; i < codeCount; i++) {
- // The symbol. If none were specified, just assume it's identical to the code index
- uint32 symbol = symbols ? symbols[i] : i;
-
- // Put the code and symbol into the correct list
- _codes[lengths[i] - 1].push_back(Symbol(codes[i], symbol));
-
- // And put the pointer to the symbol/code struct into the symbol list.
- _symbols[i] = &_codes[lengths[i] - 1].back();
- }
-}
-
-Huffman::~Huffman() {
-}
-
-void Huffman::setSymbols(const uint32 *symbols) {
- for (uint32 i = 0; i < _symbols.size(); i++)
- _symbols[i]->symbol = symbols ? *symbols++ : i;
-}
-
-} // End of namespace Common
diff --git a/common/huffman.h b/common/huffman.h
index b4de5ab483..052c7bf825 100644
--- a/common/huffman.h
+++ b/common/huffman.h
@@ -20,7 +20,7 @@
*
*/
-// Based on eos' Huffman code
+// Based on xoreos' Huffman code
#ifndef COMMON_HUFFMAN_H
#define COMMON_HUFFMAN_H
@@ -31,12 +31,22 @@
namespace Common {
+inline uint32 REVERSEBITS(uint32 x) {
+ x = (((x & ~0x55555555) >> 1) | ((x & 0x55555555) << 1));
+ x = (((x & ~0x33333333) >> 2) | ((x & 0x33333333) << 2));
+ x = (((x & ~0x0F0F0F0F) >> 4) | ((x & 0x0F0F0F0F) << 4));
+ x = (((x & ~0x00FF00FF) >> 8) | ((x & 0x00FF00FF) << 8));
+
+ return((x >> 16) | (x << 16));
+}
+
/**
* Huffman bitstream decoding
*
* Used in engines:
* - scumm
*/
+template<class BITSTREAM>
class Huffman {
public:
/** Construct a Huffman decoder.
@@ -48,47 +58,107 @@ public:
* @param symbols The symbols. If 0, assume they are identical to the code indices.
*/
Huffman(uint8 maxLength, uint32 codeCount, const uint32 *codes, const uint8 *lengths, const uint32 *symbols = nullptr);
- ~Huffman();
-
- /** Modify the codes' symbols. */
- void setSymbols(const uint32 *symbols = nullptr);
/** Return the next symbol in the bitstream. */
- template<class BITSTREAM>
- uint32 getSymbol(BITSTREAM &bits) const {
- uint32 code = 0;
-
- for (uint32 i = 0; i < _codes.size(); i++) {
- bits.addBit(code, i);
-
- for (CodeList::const_iterator cCode = _codes[i].begin(); cCode != _codes[i].end(); ++cCode)
- if (code == cCode->code)
- return cCode->symbol;
- }
-
- error("Unknown Huffman code");
- return 0;
- }
+ uint32 getSymbol(BITSTREAM &bits) const;
private:
struct Symbol {
uint32 code;
uint32 symbol;
- Symbol(uint32 c, uint32 s);
+ Symbol(uint32 c, uint32 s) : code(c), symbol(s) {}
};
typedef List<Symbol> CodeList;
typedef Array<CodeList> CodeLists;
- typedef Array<Symbol *> SymbolList;
/** Lists of codes and their symbols, sorted by code length. */
CodeLists _codes;
- /** Sorted list of pointers to the symbols. */
- SymbolList _symbols;
+ /** Prefix lookup table used to speed up the decoding of short codes. */
+ struct PrefixEntry {
+ uint32 symbol;
+ uint8 length;
+
+ PrefixEntry() : length(0xFF) {}
+ };
+
+ static const uint8 _prefixTableBits = 8;
+ PrefixEntry _prefixTable[1 << _prefixTableBits];
};
+template <class BITSTREAM>
+Huffman<BITSTREAM>::Huffman(uint8 maxLength, uint32 codeCount, const uint32 *codes, const uint8 *lengths, const uint32 *symbols) {
+ assert(codeCount > 0);
+
+ assert(codes);
+ assert(lengths);
+
+ if (maxLength == 0)
+ for (uint32 i = 0; i < codeCount; i++)
+ maxLength = MAX(maxLength, lengths[i]);
+
+ assert(maxLength <= 32);
+
+ // Codes that don't fit in the prefix table are stored in the _codes array
+ _codes.resize(MAX(maxLength - _prefixTableBits, 0));
+
+ for (uint i = 0; i < codeCount; i++) {
+ uint8 length = lengths[i];
+
+ // The symbol. If none were specified, just assume it's identical to the code index
+ uint32 symbol = symbols ? symbols[i] : i;
+
+ if (length <= _prefixTableBits) {
+ // Short codes go in the prefix lookup table. Set all the entries in the table
+ // with an index starting with the code to the symbol value.
+ uint32 startIndex;
+ if (BITSTREAM::isMSB2LSB()) {
+ startIndex = codes[i] << (_prefixTableBits - length);
+ } else {
+ startIndex = REVERSEBITS(codes[i]) >> (32 - _prefixTableBits);
+ }
+
+ uint32 endIndex = startIndex | ((1 << (_prefixTableBits - length)) - 1);
+
+ for (uint32 j = startIndex; j <= endIndex; j++) {
+ uint32 index = BITSTREAM::isMSB2LSB() ? j : REVERSEBITS(j) >> (32 - _prefixTableBits);
+ _prefixTable[index].symbol = symbol;
+ _prefixTable[index].length = length;
+ }
+ } else {
+ // Put the code and symbol into the correct list for the length
+ _codes[lengths[i] - 1 - _prefixTableBits].push_back(Symbol(codes[i], symbol));
+ }
+ }
+}
+
+template <class BITSTREAM>
+uint32 Huffman<BITSTREAM>::getSymbol(BITSTREAM &bits) const {
+ uint32 code = bits.peekBits(_prefixTableBits);
+
+ uint8 length = _prefixTable[code].length;
+
+ if (length != 0xFF) {
+ bits.skip(length);
+ return _prefixTable[code].symbol;
+ } else {
+ bits.skip(_prefixTableBits);
+
+ for (uint32 i = 0; i < _codes.size(); i++) {
+ bits.addBit(code, i + _prefixTableBits);
+
+ for (typename CodeList::const_iterator cCode = _codes[i].begin(); cCode != _codes[i].end(); ++cCode)
+ if (code == cCode->code)
+ return cCode->symbol;
+ }
+ }
+
+ error("Unknown Huffman code");
+ return 0;
+}
+
} // End of namespace Common
#endif // COMMON_HUFFMAN_H
diff --git a/common/module.mk b/common/module.mk
index 6742fef3e8..f456604ebb 100644
--- a/common/module.mk
+++ b/common/module.mk
@@ -49,7 +49,6 @@ MODULE_OBJS += \
cosinetables.o \
dct.o \
fft.o \
- huffman.o \
rdft.o \
sinetables.o
generated by cgit v1.2.3 (git 2.25.1) at 2025-02-21 09:00:39 +0000