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Diffstat (limited to 'engines/prince/decompress.cpp')
-rw-r--r-- | engines/prince/decompress.cpp | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/engines/prince/decompress.cpp b/engines/prince/decompress.cpp new file mode 100644 index 0000000000..7fba179541 --- /dev/null +++ b/engines/prince/decompress.cpp @@ -0,0 +1,171 @@ +/* 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. + * + */ + +// John_Doe's implementation + +#include "prince/decompress.h" + +namespace Prince { + +static const uint16 table1[] = { + 0x8000, 0x0002, + 0x4000, 0x0004, + 0x2000, 0x0008, + 0x1000, 0x0010, + 0x0800, 0x0020, + 0x0400, 0x0040, + 0x0200, 0x0080, + 0x0100, 0x0100, + 0x0080, 0x0200, + 0x0040, 0x0400 +}; + +static const uint32 table2[] = { + 0x0000F000, + 0x0020FC00, + 0x00A0FF00, + 0x02A0FF80, + 0x06A0FFC0, + 0x0EA0FFE0, + 0x1EA0FFF0, + 0x3EA0FFF8 +}; + +static const uint16 table3[] = { + 0x8000, 0x0000, + 0x4000, 0x0002, + 0x2000, 0x0006, + 0x1000, 0x000E, + 0x0800, 0x001E, + 0x0400, 0x003E, + 0x0200, 0x007E, + 0x0100, 0x00FE, + 0x0080, 0x01FE, + 0x0040, 0x03FE, + 0x0020, 0x07FE, + 0x0010, 0x0FFE, + 0x0008, 0x1FFE, + 0x0004, 0x3FFE, + 0x0002, 0x7FFE, + 0x0001, 0xFFFE +}; + +void Decompressor::decompress(byte *source, byte *dest, uint32 destSize) { + byte *destEnd = dest + destSize; + int more; + _src = source; + _dst = dest; + _bitBuffer = 0x80; + while (_dst < destEnd) { + uint32 ebp; + uint16 offset, length; + if (getBit()) { + if (getBit()) { + if (getBit()) { + if (getBit()) { + if (getBit()) { + if (getBit()) { + uint32 tableIndex = 0; + while (getBit()) + tableIndex++; + length = table3[tableIndex * 2 + 0]; + do { + more = !(length & 0x8000); + length = (length << 1) | getBit(); + } while (more); + length += table3[tableIndex * 2 + 1]; + length++; + memcpy(_dst, _src, length); + _src += length; + _dst += length; + } + *_dst++ = *_src++; + } + *_dst++ = *_src++; + } + *_dst++ = *_src++; + } + *_dst++ = *_src++; + } + *_dst++ = *_src++; + } + if (!getBit()) { + if (getBit()) { + uint32 tableIndex = getBit(); + tableIndex = (tableIndex << 1) | getBit(); + tableIndex = (tableIndex << 1) | getBit(); + ebp = table2[tableIndex]; + length = 1; + } else { + ebp = 0x0000FF00; + length = 0; + } + } else { + uint32 tableIndex = 0; + while (getBit()) + tableIndex++; + length = table1[tableIndex * 2 + 0]; + do { + more = !(length & 0x8000); + length = (length << 1) | getBit(); + } while (more); + length += table1[tableIndex * 2 + 1]; + tableIndex = getBit(); + tableIndex = (tableIndex << 1) | getBit(); + tableIndex = (tableIndex << 1) | getBit(); + ebp = table2[tableIndex]; + } + offset = ebp & 0xFFFF; + do { + if (_bitBuffer == 0x80) { + if (offset >= 0xFF00) { + offset = (offset << 8) | *_src++; + } + } + more = offset & 0x8000; + offset = (offset << 1) | getBit(); + } while (more); + offset += (ebp >> 16); + length += 2; + while (length--) { + if (_dst >= destEnd) { + return; + } + *_dst = *(_dst - offset); + _dst++; + } + } +} + +int Decompressor::getBit() { + int bit = (_bitBuffer & 0x80) >> 7; + _bitBuffer <<= 1; + if (_bitBuffer == 0) { + _bitBuffer = *_src++; + bit = (_bitBuffer & 0x80) >> 7; + _bitBuffer <<= 1; + _bitBuffer |= 1; + } + return bit; +} + +} // End of namespace Prince |