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https://github.com/aaronsgiles/JPEGView.git
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92bdb55672
These are the sources for the final official release of JPEGView for the Mac, back in 1994.
1 line
2.6 KiB
C
1 line
2.6 KiB
C
/*********************************************************/
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/* This source code copyright (c) 1991-2001, Aaron Giles */
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/* See the Read Me file for licensing information. */
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/* Contact email: mac@aarongiles.com */
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/*********************************************************/
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// void DecodeRow(GIFDataPtr theData)
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ushort *parent = (ushort *)theData->tree;
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uchar *code = (uchar *)(parent + 4096);
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short i, j, currentCode, oldCode;
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if (!theData->dest) {
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theData->charSize = *theData->src++;
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gCodeSize = theData->charSize + 1;
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gStack = theData->stack;
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gBytesLeft = gBitsInBuffer = gBitBuffer = 0;
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gTreeSize = (1 << theData->charSize);
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gClearCode = gTreeSize++;
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gEndCode = gTreeSize++;
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gInput = theData->src;
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theData->theReturn = true;
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return;
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}
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for (i = 0; i < theData->width; i++) {
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if (gStack != theData->stack) {
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*theData->dest++ = *(--gStack);
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continue;
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}
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while (gCodeSize > gBitsInBuffer) {
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if (!gBytesLeft) {
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gBytesLeft = *gInput++;
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if (!gBytesLeft) {
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theData->theReturn = true;
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return;
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}
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}
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gBytesLeft--;
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gBitBuffer |= (ulong)*gInput++ << gBitsInBuffer;
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gBitsInBuffer += 8;
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}
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currentCode = gBitBuffer & ((1 << gCodeSize) - 1);
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gBitBuffer >>= gCodeSize;
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gBitsInBuffer -= gCodeSize;
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if (currentCode == gEndCode) {
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theData->theReturn = true;
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return;
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} else if (currentCode == gClearCode) {
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gCodeSize = theData->charSize + 1;
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gTreeSize = gEndCode + 1;
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do {
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while (gCodeSize > gBitsInBuffer) {
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if (!gBytesLeft) {
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gBytesLeft = *gInput++;
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if (!gBytesLeft) {
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theData->theReturn = true;
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return;
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}
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}
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gBytesLeft--;
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gBitBuffer |= (ulong)*gInput++ << gBitsInBuffer;
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gBitsInBuffer += 8;
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}
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currentCode = gBitBuffer & ((1 << gCodeSize) - 1);
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gBitBuffer >>= gCodeSize;
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gBitsInBuffer -= gCodeSize;
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} while (currentCode == gClearCode);
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*theData->dest++ = gFirstCode = gLastCode = currentCode;
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continue;
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}
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oldCode = currentCode;
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if (currentCode > gTreeSize) {
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theData->end = nil;
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break;
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} else if (currentCode == gTreeSize) {
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*gStack++ = gFirstCode;
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currentCode = gLastCode;
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}
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for (j = currentCode; j >= gClearCode; j = parent[j]) *gStack++ = code[j];
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*theData->dest++ = gFirstCode = j;
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if (gTreeSize != 4096) {
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code[gTreeSize] = gFirstCode;
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parent[gTreeSize] = gLastCode;
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if ((++gTreeSize >= (1 << gCodeSize)) && (gCodeSize != 12)) gCodeSize++;
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}
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gLastCode = oldCode;
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}
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theData->theReturn = false;
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if (gInput > theData->end) theData->end = nil;
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