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https://github.com/Barubary/dsdecmp.git
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231 lines
10 KiB
C#
231 lines
10 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Text;
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using System.IO;
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namespace DSDecmp.Formats.Nitro
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{
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/// <summary>
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/// Compressor and decompressor for the LZ-0x11 format used in many of the games for the
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/// newer Nintendo consoles and handhelds.
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/// </summary>
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public class LZ11 : NitroCFormat
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{
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public LZ11() : base(0x11) { }
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public override long Decompress(Stream instream, long inLength, Stream outstream)
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{
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#region Format definition in NDSTEK style
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/* Data header (32bit)
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Bit 0-3 Reserved
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Bit 4-7 Compressed type (must be 1 for LZ77)
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Bit 8-31 Size of decompressed data. if 0, the next 4 bytes are decompressed length
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Repeat below. Each Flag Byte followed by eight Blocks.
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Flag data (8bit)
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Bit 0-7 Type Flags for next 8 Blocks, MSB first
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Block Type 0 - Uncompressed - Copy 1 Byte from Source to Dest
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Bit 0-7 One data byte to be copied to dest
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Block Type 1 - Compressed - Copy LEN Bytes from Dest-Disp-1 to Dest
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If Reserved is 0: - Default
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Bit 0-3 Disp MSBs
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Bit 4-7 LEN - 3
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Bit 8-15 Disp LSBs
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If Reserved is 1: - Higher compression rates for files with (lots of) long repetitions
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Bit 4-7 Indicator
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If Indicator > 1:
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Bit 0-3 Disp MSBs
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Bit 4-7 LEN - 1 (same bits as Indicator)
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Bit 8-15 Disp LSBs
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If Indicator is 1: A(B CD E)(F GH)
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Bit 0-3 (LEN - 0x111) MSBs
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Bit 4-7 Indicator; unused
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Bit 8-15 (LEN- 0x111) 'middle'-SBs
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Bit 16-19 Disp MSBs
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Bit 20-23 (LEN - 0x111) LSBs
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Bit 24-31 Disp LSBs
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If Indicator is 0:
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Bit 0-3 (LEN - 0x11) MSBs
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Bit 4-7 Indicator; unused
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Bit 8-11 Disp MSBs
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Bit 12-15 (LEN - 0x11) LSBs
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Bit 16-23 Disp LSBs
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*/
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#endregion
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long readBytes = 0;
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byte type = (byte)instream.ReadByte();
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if (type != base.magicByte)
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throw new InvalidDataException("The provided stream is not a valid LZ-0x11 "
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+ "compressed stream (invalid type 0x" + type.ToString("X") + ")");
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byte[] sizeBytes = new byte[3];
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instream.Read(sizeBytes, 0, 3);
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int decompressedSize = base.Bytes2Size(sizeBytes);
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readBytes += 4;
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if (decompressedSize == 0)
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{
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sizeBytes = new byte[4];
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instream.Read(sizeBytes, 0, 4);
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decompressedSize = base.Bytes2Size(sizeBytes);
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readBytes += 4;
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}
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// the maximum 'DISP-1' is still 0xFFF.
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int bufferLength = 0x1000;
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byte[] buffer = new byte[bufferLength];
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int bufferOffset = 0;
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int currentOutSize = 0;
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int flags = 0, mask = 1;
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while (currentOutSize < decompressedSize)
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{
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// (throws when requested new flags byte is not available)
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#region Update the mask. If all flag bits have been read, get a new set.
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// the current mask is the mask used in the previous run. So if it masks the
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// last flag bit, get a new flags byte.
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if (mask == 1)
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{
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if (readBytes >= inLength)
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throw new NotEnoughDataException(currentOutSize, decompressedSize);
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flags = instream.ReadByte(); readBytes++;
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if (flags < 0)
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throw new StreamTooShortException();
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mask = 0x80;
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}
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else
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{
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mask >>= 1;
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}
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#endregion
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// bit = 1 <=> compressed.
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if ((flags & mask) > 0)
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{
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// (throws when not enough bytes are available)
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#region Get length and displacement('disp') values from next 2, 3 or 4 bytes
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// read the first byte first, which also signals the size of the compressed block
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if (readBytes >= inLength)
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throw new NotEnoughDataException(currentOutSize, decompressedSize);
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int byte1 = instream.ReadByte(); readBytes++;
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if (byte1 < 0)
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throw new StreamTooShortException();
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int length = byte1 >> 4;
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int disp = -1;
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if (length == 0)
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{
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#region case 0; (0B C)(D EF) + (0x11)(0x1) = (LEN)(DISP)
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// case 0:
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// data = AB CD EF (with A=0)
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// LEN = ABC + 0x11 == BC + 0x11
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// DISP = DEF + 1
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// we need two more bytes available
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if (readBytes + 1 >= inLength)
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throw new NotEnoughDataException(currentOutSize, decompressedSize);
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int byte2 = instream.ReadByte(); readBytes++;
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int byte3 = instream.ReadByte(); readBytes++;
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if (byte3 < 0)
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throw new StreamTooShortException();
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length = (((byte1 & 0x0F) << 4) | (byte2 >> 4)) + 0x11;
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disp = (((byte2 & 0x0F) << 8) | byte3) + 0x1;
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#endregion
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}
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else if (length == 1)
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{
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#region case 1: 1(B CD E)(F GH) + (0x111)(0x1) = (LEN)(DISP)
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// case 1:
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// data = AB CD EF GH (with A=1)
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// LEN = BCDE + 0x111
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// DISP = FGH + 1
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// we need three more bytes available
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if (readBytes + 2 >= inLength)
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throw new NotEnoughDataException(currentOutSize, decompressedSize);
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int byte2 = instream.ReadByte(); readBytes++;
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int byte3 = instream.ReadByte(); readBytes++;
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int byte4 = instream.ReadByte(); readBytes++;
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if (byte4 < 0)
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throw new StreamTooShortException();
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length = (((byte1 & 0x0F) << 12) | (byte2 << 4) | (byte3 >> 4)) + 0x111;
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disp = (((byte3 & 0x0F) << 8) | byte4) + 0x1;
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#endregion
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}
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else
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{
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#region case > 1: (A)(B CD) + (0x1)(0x1) = (LEN)(DISP)
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// case other:
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// data = AB CD
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// LEN = A + 1
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// DISP = BCD + 1
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// we need only one more byte available
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if (readBytes >= inLength)
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throw new NotEnoughDataException(currentOutSize, decompressedSize);
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int byte2 = instream.ReadByte(); readBytes++;
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if (byte2 < 0)
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throw new StreamTooShortException();
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length = ((byte1 & 0xF0) >> 4) + 0x1;
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disp = (((byte1 & 0x0F) << 8) | byte2) + 0x1;
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#endregion
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}
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if (disp > currentOutSize)
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throw new InvalidDataException("Cannot go back more than already written. "
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+ "DISP = " + disp + ", #written bytes = 0x" + currentOutSize.ToString("X")
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+ " before 0x" + instream.Position.ToString("X") + " with indicator 0x"
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+ (byte1 >> 4).ToString("X"));
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#endregion
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int bufIdx = bufferOffset + bufferLength - disp;
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for (int i = 0; i < length; i++)
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{
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byte next = buffer[bufIdx % bufferLength];
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bufIdx++;
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outstream.WriteByte(next);
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buffer[bufferOffset] = next;
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bufferOffset = (bufferOffset + 1) % bufferLength;
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}
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currentOutSize += length;
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}
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else
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{
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if (readBytes >= inLength)
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throw new NotEnoughDataException(currentOutSize, decompressedSize);
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int next = instream.ReadByte(); readBytes++;
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if (next < 0)
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throw new StreamTooShortException();
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outstream.WriteByte((byte)next); currentOutSize++;
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buffer[bufferOffset] = (byte)next;
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bufferOffset = (bufferOffset + 1) % bufferLength;
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}
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}
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if (readBytes < inLength)
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{
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// the input may be 4-byte aligned.
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if ((readBytes ^ (readBytes & 3)) + 4 < inLength)
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throw new TooMuchInputException(readBytes, inLength);
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}
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return decompressedSize;
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}
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public override int Compress(Stream instream, long inLength, Stream outstream)
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{
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throw new NotImplementedException();
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}
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}
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}
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