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-rw-r--r--engines/lure/decode.cpp117
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);