diff options
| -rw-r--r-- | engines/parallaction/disk_ns.cpp | 65 |
1 files changed, 41 insertions, 24 deletions
diff --git a/engines/parallaction/disk_ns.cpp b/engines/parallaction/disk_ns.cpp index 4cc3fb4fe1..beb0db4f22 100644 --- a/engines/parallaction/disk_ns.cpp +++ b/engines/parallaction/disk_ns.cpp @@ -386,32 +386,50 @@ Frames* DosDisk_ns::loadFrames(const char* name) { return loadCnv(name); } -// -// slides (background images) are stored compressed by scanline in a rle fashion -// -// the uncompressed data must then be unpacked to get: -// * color data [bits 0-5] -// * mask data [bits 6-7] (z buffer) -// * path data [bit 8] (walkable areas) -// -void DosDisk_ns::unpackBackground(Common::ReadStream *stream, byte *screen, byte *mask, byte *path) { +/* + Background images are compressed using a RLE algorithm that resembles PackBits. - byte b; - uint32 i = 0; + The uncompressed data is then unpacked as following: + - color data [bits 0-5] + - mask data [bits 6-7] (z buffer) + - path data [bit 8] (walkable areas) +*/ +void DosDisk_ns::unpackBackground(Common::ReadStream *stream, byte *screen, byte *mask, byte *path) { + byte storage[127]; + uint32 storageLen = 0, len = 0; + uint32 j = 0; while (1) { - b = stream->readByte(); - - if (stream->eos()) - break; - - path[i/8] |= ((b & 0x80) >> 7) << (i & 7); - mask[i/4] |= ((b & 0x60) >> 5) << ((i & 3) << 1); - screen[i] = b & 0x1F; - i++; + // first extracts packbits variant data + do { + len = stream->readByte(); + if (stream->eos()) + return; + + if (len == 128) { + storageLen = 0; + } else if (len <= 127) { + len++; + for (uint32 i = 0; i < len; i++) { + storage[i] = stream->readByte(); + } + storageLen = len; + } else { + len = (256 - len) + 1; + byte v = stream->readByte(); + memset(storage, v, len); + storageLen = len; + } + } while (storageLen == 0); + + // then unpacks the bits to the destination buffers + for (uint32 i = 0; i < storageLen; i++, j++) { + byte b = storage[i]; + path[j/8] |= ((b & 0x80) >> 7) << (j & 7); + mask[j/4] |= ((b & 0x60) >> 5) << ((j & 3) << 1); + screen[j] = b & 0x1F; + } } - - return; } void DosDisk_ns::parseDepths(BackgroundInfo &info, Common::SeekableReadStream &stream) { @@ -465,8 +483,7 @@ void DosDisk_ns::loadBackground(BackgroundInfo& info, const char *filename) { info._path->create(info.width, info.height); info._path->bigEndian = true; - Graphics::PackBitsReadStream pbstream(*stream); - unpackBackground(&pbstream, (byte*)info.bg.pixels, info._mask->data, info._path->data); + unpackBackground(stream, (byte*)info.bg.pixels, info._mask->data, info._path->data); delete stream; } |