Initial community commit

Src/external_dependencies/openmpt-trunk/soundlib/ITCompression.h

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+/*
+ * ITCompression.h
+ * ---------------
+ * Purpose: Code for IT sample compression and decompression.
+ * Notes  : The original Python compression code was written by GreaseMonkey and has been released into the public domain.
+ * Authors: OpenMPT Devs
+ *          Ben "GreaseMonkey" Russell
+ * The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
+ */
+
+#pragma once
+
+#include "openmpt/all/BuildSettings.hpp"
+
+#include <vector>
+#include <iosfwd>
+#include "Snd_defs.h"
+#include "BitReader.h"
+
+
+OPENMPT_NAMESPACE_BEGIN
+
+struct ModSample;
+
+class ITCompression
+{
+public:
+	ITCompression(const ModSample &sample, bool it215, std::ostream *f, SmpLength maxLength = 0);
+	size_t GetCompressedSize() const { return packedTotalLength; }
+
+	static constexpr size_t bufferSize = 2 + 0xFFFF;  // Our output buffer can't be longer than this.
+	static constexpr size_t blockSize = 0x8000;       // Block size (in bytes) in which samples are being processed
+
+protected:
+	std::vector<int8> bwt;           // Bit width table for each sampling point
+	std::vector<uint8> packedData;   // Compressed data for current sample block
+	std::ostream *file = nullptr;    // File to which compressed data will be written (can be nullptr if you only want to find out the sample size)
+	std::vector<int8> sampleData8;   // Pre-processed sample data for currently compressed sample block
+	std::vector<int16> sampleData16; // Pre-processed sample data for currently compressed sample block
+	const ModSample &mptSample;      // Sample that is being processed
+	size_t packedLength = 0;         // Size of currently compressed sample block
+	size_t packedTotalLength = 0;    // Size of all compressed data so far
+	SmpLength baseLength = 0;        // Length of the currently compressed sample block (in samples)
+
+	// Bit writer
+	int8 bitPos = 0;    // Current bit position in this byte
+	int8 remBits = 0;   // Remaining bits in this byte
+	uint8 byteVal = 0;  // Current byte value to be written
+
+	const bool is215;  // Use IT2.15 compression (double deltas)
+
+	template<typename Properties>
+	void Compress(const typename Properties::sample_t *mptSampleData, SmpLength maxLength);
+
+	template<typename T>
+	static void CopySample(T *target, const T *source, SmpLength offset, SmpLength length, SmpLength skip);
+
+	template<typename T>
+	void Deltafy(T *sampleData);
+
+	template<typename Properties>
+	void CompressBlock(const typename Properties::sample_t *data, SmpLength offset, SmpLength actualLength, typename Properties::sample_t *sampleData);
+
+	static int8 GetWidthChangeSize(int8 w, bool is16);
+
+	template<typename Properties>
+	void SquishRecurse(int8 sWidth, int8 lWidth, int8 rWidth, int8 width, SmpLength offset, SmpLength length, const typename Properties::sample_t *sampleData);
+
+	static int8 ConvertWidth(int8 curWidth, int8 newWidth);
+	void WriteBits(int8 width, int v);
+
+	void WriteByte(uint8 v);
+};
+
+
+class ITDecompression
+{
+public:
+	ITDecompression(FileReader &file, ModSample &sample, bool it215);
+
+protected:
+	BitReader bitFile;
+	ModSample &mptSample;  // Sample that is being processed
+
+	SmpLength writtenSamples = 0;     // Number of samples so far written on this channel
+	SmpLength writePos = 0;           // Absolut write position in sample (for stereo samples)
+	SmpLength curLength = 0;          // Length of currently processed block
+	unsigned int mem1 = 0, mem2 = 0;  // Integrator memory
+	
+	const bool is215;  // Use IT2.15 compression (double deltas)
+
+	template<typename Properties>
+	void Uncompress(typename Properties::sample_t *target);
+	static void ChangeWidth(int &curWidth, int width);
+
+	template<typename Properties>
+	void Write(int v, int topbit, typename Properties::sample_t *target);
+};
+
+
+OPENMPT_NAMESPACE_END