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author | Paul Gilbert | 2011-12-09 12:24:32 +1100 |
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committer | Paul Gilbert | 2011-12-09 12:24:32 +1100 |
commit | f169e17ecaeda0f0039dc68efc93d3ef2c1592b5 (patch) | |
tree | edfb37bf5148b53db095e07acb6d18de8f42e93c /engines | |
parent | 509cc5f4c4214d0111339a4fe211f82f89d1df56 (diff) | |
download | scummvm-rg350-f169e17ecaeda0f0039dc68efc93d3ef2c1592b5.tar.gz scummvm-rg350-f169e17ecaeda0f0039dc68efc93d3ef2c1592b5.tar.bz2 scummvm-rg350-f169e17ecaeda0f0039dc68efc93d3ef2c1592b5.zip |
LURE: Converted the vgaDecode routine to remove GOTO usage
Diffstat (limited to 'engines')
-rw-r--r-- | engines/lure/decode.cpp | 117 |
1 files changed, 67 insertions, 50 deletions
diff --git a/engines/lure/decode.cpp b/engines/lure/decode.cpp index 59390e6e91..6fa8330296 100644 --- a/engines/lure/decode.cpp +++ b/engines/lure/decode.cpp @@ -34,12 +34,18 @@ namespace Lure { /* Provides the functionality for decoding screens */ /*--------------------------------------------------------------------------*/ +/** + * Write a single byte to the output buffer + */ void PictureDecoder::writeByte(MemoryBlock *dest, byte v) { if (outputOffset == dest->size()) error("Decoded data exceeded allocated output buffer size"); dest->data()[outputOffset++] = v; } +/** + * Writes out a specified byte a given number of times to the output + */ void PictureDecoder::writeBytes(MemoryBlock *dest, byte v, uint16 numBytes) { if (outputOffset + numBytes > dest->size()) error("Decoded data exceeded allocated output buffer size"); @@ -47,6 +53,9 @@ void PictureDecoder::writeBytes(MemoryBlock *dest, byte v, uint16 numBytes) { outputOffset += numBytes; } +/** + * Gets a byte from the compressed source using the first data pointer + */ byte PictureDecoder::DSSI(bool incr) { if (dataPos > dataIn->size()) error("PictureDecoder went beyond end of source data"); @@ -57,6 +66,9 @@ byte PictureDecoder::DSSI(bool incr) { return result; } +/** + * Gets a byte from the compressed source using the second data pointer + */ byte PictureDecoder::ESBX(bool incr) { if (dataPos2 >= dataIn->size()) error("PictureDecoder went beyond end of source data"); @@ -227,56 +239,61 @@ MemoryBlock *PictureDecoder::vgaDecode(MemoryBlock *src, uint32 maxOutputSize) { CH = ESBX(); CL = 9; -Loc754: - AL = DSSI(); - writeByte(dest, AL); - BP = ((uint16) AL) << 2; - -Loc755: - decrCtr(); - if (shlCarry()) goto Loc761; - decrCtr(); - if (shlCarry()) goto Loc759; - AL = dataIn->data()[BP]; - -Loc758: - writeByte(dest, AL); - BP = ((uint16) AL) << 2; - goto Loc755; - -Loc759: - AL = (byte) (BP >> 2); - AH = DSSI(); - if (AH == 0) goto Loc768; - - writeBytes(dest, AL, AH); - goto Loc755; - -Loc761: - decrCtr(); - if (shlCarry()) goto Loc765; - decrCtr(); - - if (shlCarry()) goto Loc764; - AL = dataIn->data()[BP+1]; - goto Loc758; - -Loc764: - AL = dataIn->data()[BP+2]; - goto Loc758; - -Loc765: - decrCtr(); - if (shlCarry()) goto Loc767; - AL = dataIn->data()[BP+3]; - goto Loc758; - -Loc767: - goto Loc754; - -Loc768: - AL = DSSI(); - if (AL != 0) goto Loc755; + // Main decoding loop + bool loopFlag = true; + while (loopFlag) { + AL = DSSI(); + writeByte(dest, AL); + BP = ((uint16) AL) << 2; + + // Inner loop + for (;;) { + decrCtr(); + if (shlCarry()) { + decrCtr(); + if (shlCarry()) { + decrCtr(); + if (shlCarry()) + break; + + AL = dataIn->data()[BP + 3]; + } else { + decrCtr(); + if (shlCarry()) + AL = dataIn->data()[BP + 2]; + else + AL = dataIn->data()[BP + 1]; + } + } else { + decrCtr(); + if (shlCarry()) { + AL = (byte) (BP >> 2); + AH = DSSI(); + if (AH == 0) { + AL = DSSI(); + if (AL == 0) { + // Finally done + loopFlag = false; + break; + } else { + // Keep going + continue; + } + } else { + // Write out byte sequence + writeBytes(dest, AL, AH); + continue; + } + } else { + AL = dataIn->data()[BP]; + } + } + + // Write out the next byte + writeByte(dest, AL); + BP = ((uint16) AL) << 2; + } + } // Resize the output to be the number of outputed bytes and return it if (outputOffset < dest->size()) dest->reallocate(outputOffset); |