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winamp/Src/external_dependencies/openmpt-trunk/soundlib/ITCompression.cpp

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Initial community commit
2024-09-24 12:54:57 +00:00
/*
* ITCompression.cpp
* -----------------
* 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.
*/
#include "stdafx.h"
#include <ostream>
#include "ITCompression.h"
#include "mpt/io/base.hpp"
#include "mpt/io/io.hpp"
#include "mpt/io/io_stdstream.hpp"
#include "../common/misc_util.h"
#include "ModSample.h"
#include "SampleCopy.h"
OPENMPT_NAMESPACE_BEGIN
// Algorithm parameters for 16-Bit samples
struct IT16BitParams
{
using sample_t = int16;
static constexpr int16 lowerTab[] = {0, -1, -3, -7, -15, -31, -56, -120, -248, -504, -1016, -2040, -4088, -8184, -16376, -32760, -32768};
static constexpr int16 upperTab[] = {0, 1, 3, 7, 15, 31, 55, 119, 247, 503, 1015, 2039, 4087, 8183, 16375, 32759, 32767};
static constexpr int8 fetchA = 4;
static constexpr int8 lowerB = -8;
static constexpr int8 upperB = 7;
static constexpr int8 defWidth = 17;
static constexpr int mask = 0xFFFF;
};
// Algorithm parameters for 8-Bit samples
struct IT8BitParams
{
using sample_t = int8;
static constexpr int8 lowerTab[] = {0, -1, -3, -7, -15, -31, -60, -124, -128};
static constexpr int8 upperTab[] = {0, 1, 3, 7, 15, 31, 59, 123, 127};
static constexpr int8 fetchA = 3;
static constexpr int8 lowerB = -4;
static constexpr int8 upperB = 3;
static constexpr int8 defWidth = 9;
static constexpr int mask = 0xFF;
};
static constexpr int8 ITWidthChangeSize[] = { 4, 5, 6, 7, 8, 9, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 };
//////////////////////////////////////////////////////////////////////////////
// IT 2.14 compression
ITCompression::ITCompression(const ModSample &sample, bool it215, std::ostream *f, SmpLength maxLength)
: file(f)
, mptSample(sample)
, is215(it215)
{
if(mptSample.GetElementarySampleSize() > 1)
Compress<IT16BitParams>(mptSample.sample16(), maxLength);
else
Compress<IT8BitParams>(mptSample.sample8(), maxLength);
}
template<typename Properties>
void ITCompression::Compress(const typename Properties::sample_t *mptSampleData, SmpLength maxLength)
{
packedData.resize(bufferSize);
std::vector<typename Properties::sample_t> sampleData;
sampleData.resize(blockSize / sizeof(typename Properties::sample_t));
if(maxLength == 0 || maxLength > mptSample.nLength)
maxLength = mptSample.nLength;
for(uint8 chn = 0; chn < mptSample.GetNumChannels(); chn++)
{
SmpLength offset = 0;
SmpLength remain = maxLength;
while(remain > 0)
{
// Initialise output buffer and bit writer positions
packedLength = 2;
bitPos = 0;
remBits = 8;
byteVal = 0;
CompressBlock<Properties>(mptSampleData + chn, offset, remain, sampleData.data());
if(file) mpt::IO::WriteRaw(*file, packedData.data(), packedLength);
packedTotalLength += packedLength;
offset += baseLength;
remain -= baseLength;
}
}
packedData.resize(0);
packedData.shrink_to_fit();
}
template<typename T>
void ITCompression::CopySample(T *target, const T *source, SmpLength offset, SmpLength length, SmpLength skip)
{
T *out = target;
const T *in = source + offset * skip;
for(SmpLength i = 0, j = 0; j < length; i += skip, j++)
{
out[j] = in[i];
}
}
// Convert sample to delta values.
template<typename T>
void ITCompression::Deltafy(T *sampleData)
{
T *p = sampleData;
int oldVal = 0;
for(SmpLength i = 0; i < baseLength; i++)
{
int newVal = p[i];
p[i] = static_cast<T>(newVal - oldVal);
oldVal = newVal;
}
}
template<typename Properties>
void ITCompression::CompressBlock(const typename Properties::sample_t *data, SmpLength offset, SmpLength actualLength, typename Properties::sample_t *sampleData)
{
baseLength = std::min(actualLength, SmpLength(blockSize / sizeof(typename Properties::sample_t)));
CopySample<typename Properties::sample_t>(sampleData, data, offset, baseLength, mptSample.GetNumChannels());
Deltafy(sampleData);
if(is215)
{
Deltafy(sampleData);
}
// Initialise bit width table with initial values
bwt.assign(baseLength, Properties::defWidth);
// Recurse!
SquishRecurse<Properties>(Properties::defWidth, Properties::defWidth, Properties::defWidth, Properties::defWidth - 2, 0, baseLength, sampleData);
// Write those bits!
const typename Properties::sample_t *p = sampleData;
int8 width = Properties::defWidth;
for(size_t i = 0; i < baseLength; i++)
{
if(bwt[i] != width)
{
if(width <= 6)
{
// Mode A: 1 to 6 bits
MPT_ASSERT(width);
WriteBits(width, (1 << (width - 1)));
WriteBits(Properties::fetchA, ConvertWidth(width, bwt[i]));
} else if(width < Properties::defWidth)
{
// Mode B: 7 to 8 / 16 bits
int xv = (1 << (width - 1)) + Properties::lowerB + ConvertWidth(width, bwt[i]);
WriteBits(width, xv);
} else
{
// Mode C: 9 / 17 bits
MPT_ASSERT((bwt[i] - 1) >= 0);
WriteBits(width, (1 << (width - 1)) + bwt[i] - 1);
}
width = bwt[i];
}
WriteBits(width, static_cast<int>(p[i]) & Properties::mask);
}
// Write last byte and update block length
WriteByte(byteVal);
packedData[0] = static_cast<uint8>((packedLength - 2) & 0xFF);
packedData[1] = static_cast<uint8>((packedLength - 2) >> 8);
}
int8 ITCompression::GetWidthChangeSize(int8 w, bool is16)
{
MPT_ASSERT(w > 0 && static_cast<unsigned int>(w) <= std::size(ITWidthChangeSize));
int8 wcs = ITWidthChangeSize[w - 1];
if(w <= 6 && is16)
wcs++;
return wcs;
}
template<typename Properties>
void ITCompression::SquishRecurse(int8 sWidth, int8 lWidth, int8 rWidth, int8 width, SmpLength offset, SmpLength length, const typename Properties::sample_t *sampleData)
{
if(width + 1 < 1)
{
for(SmpLength i = offset; i < offset + length; i++)
bwt[i] = sWidth;
return;
}
MPT_ASSERT(width >= 0 && static_cast<unsigned int>(width) < std::size(Properties::lowerTab));
SmpLength i = offset;
SmpLength end = offset + length;
const typename Properties::sample_t *p = sampleData;
while(i < end)
{
if(p[i] >= Properties::lowerTab[width] && p[i] <= Properties::upperTab[width])
{
SmpLength start = i;
// Check for how long we can keep this bit width
while(i < end && p[i] >= Properties::lowerTab[width] && p[i] <= Properties::upperTab[width])
{
i++;
}
const SmpLength blockLength = i - start;
const int8 xlwidth = start == offset ? lWidth : sWidth;
const int8 xrwidth = i == end ? rWidth : sWidth;
const bool is16 = sizeof(typename Properties::sample_t) > 1;
const int8 wcsl = GetWidthChangeSize(xlwidth, is16);
const int8 wcss = GetWidthChangeSize(sWidth, is16);
const int8 wcsw = GetWidthChangeSize(width + 1, is16);
bool comparison;
if(i == baseLength)
{
SmpLength keepDown = wcsl + (width + 1) * blockLength;
SmpLength levelLeft = wcsl + sWidth * blockLength;
if(xlwidth == sWidth)
levelLeft -= wcsl;
comparison = (keepDown <= levelLeft);
} else
{
SmpLength keepDown = wcsl + (width + 1) * blockLength + wcsw;
SmpLength levelLeft = wcsl + sWidth * blockLength + wcss;
if(xlwidth == sWidth)
levelLeft -= wcsl;
if(xrwidth == sWidth)
levelLeft -= wcss;
comparison = (keepDown <= levelLeft);
}
SquishRecurse<Properties>(comparison ? (width + 1) : sWidth, xlwidth, xrwidth, width - 1, start, blockLength, sampleData);
} else
{
bwt[i] = sWidth;
i++;
}
}
}
int8 ITCompression::ConvertWidth(int8 curWidth, int8 newWidth)
{
curWidth--;
newWidth--;
MPT_ASSERT(newWidth != curWidth);
if(newWidth > curWidth)
newWidth--;
return newWidth;
}
void ITCompression::WriteBits(int8 width, int v)
{
while(width > remBits)
{
byteVal |= (v << bitPos);
width -= remBits;
v >>= remBits;
bitPos = 0;
remBits = 8;
WriteByte(byteVal);
byteVal = 0;
}
if(width > 0)
{
byteVal |= (v & ((1 << width) - 1)) << bitPos;
remBits -= width;
bitPos += width;
}
}
void ITCompression::WriteByte(uint8 v)
{
if(packedLength < bufferSize)
{
packedData[packedLength++] = v;
} else
{
// How could this happen, anyway?
MPT_ASSERT_NOTREACHED();
}
}
//////////////////////////////////////////////////////////////////////////////
// IT 2.14 decompression
ITDecompression::ITDecompression(FileReader &file, ModSample &sample, bool it215)
: mptSample(sample)
, is215(it215)
{
for(uint8 chn = 0; chn < mptSample.GetNumChannels(); chn++)
{
writtenSamples = writePos = 0;
while(writtenSamples < sample.nLength && file.CanRead(sizeof(uint16)))
{
uint16 compressedSize = file.ReadUint16LE();
if(!compressedSize)
continue; // Malformed sample?
bitFile = file.ReadChunk(compressedSize);
// Initialise bit reader
mem1 = mem2 = 0;
try
{
if(mptSample.GetElementarySampleSize() > 1)
Uncompress<IT16BitParams>(mptSample.sample16() + chn);
else
Uncompress<IT8BitParams>(mptSample.sample8() + chn);
} catch(const BitReader::eof &)
{
// Data is not sufficient to decode the block
//AddToLog(LogWarning, "Truncated IT sample block");
}
}
}
}
template<typename Properties>
void ITDecompression::Uncompress(typename Properties::sample_t *target)
{
curLength = std::min(mptSample.nLength - writtenSamples, SmpLength(ITCompression::blockSize / sizeof(typename Properties::sample_t)));
int width = Properties::defWidth;
while(curLength > 0)
{
if(width > Properties::defWidth)
{
// Error!
return;
}
int v = bitFile.ReadBits(width);
const int topBit = (1 << (width - 1));
if(width <= 6)
{
// Mode A: 1 to 6 bits
if(v == topBit)
ChangeWidth(width, bitFile.ReadBits(Properties::fetchA));
else
Write<Properties>(v, topBit, target);
} else if(width < Properties::defWidth)
{
// Mode B: 7 to 8 / 16 bits
if(v >= topBit + Properties::lowerB && v <= topBit + Properties::upperB)
ChangeWidth(width, v - (topBit + Properties::lowerB));
else
Write<Properties>(v, topBit, target);
} else
{
// Mode C: 9 / 17 bits
if(v & topBit)
width = (v & ~topBit) + 1;
else
Write<Properties>((v & ~topBit), 0, target);
}
}
}
void ITDecompression::ChangeWidth(int &curWidth, int width)
{
width++;
if(width >= curWidth)
width++;
curWidth = width;
}
template<typename Properties>
void ITDecompression::Write(int v, int topBit, typename Properties::sample_t *target)
{
if(v & topBit)
v -= (topBit << 1);
mem1 += v;
mem2 += mem1;
target[writePos] = static_cast<typename Properties::sample_t>(static_cast<int>(is215 ? mem2 : mem1));
writtenSamples++;
writePos += mptSample.GetNumChannels();
curLength--;
}
OPENMPT_NAMESPACE_END