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On demand buffer allocation on PCHG decompression

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This commit is contained in:
Mirco Miranda
2025-10-23 09:12:22 +02:00
committed by Albert Astals Cid
parent d6d67c7b8b
commit abfda2ce69
1 changed files with 4 additions and 9 deletions
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13
src/imageformats/chunks.cpp
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@@ -2795,10 +2795,6 @@ static QByteArray pchgFastDecomp(const QByteArray& input, int treeSize, int orig
return {}; return {};
} }
QByteArray out;
out.resize(originalSize);
char* outPtr = out.data();
// Emulate a3 pointer to words: // Emulate a3 pointer to words:
// a2 points to the *last word* => word index (0..treeWords-1) // a2 points to the *last word* => word index (0..treeWords-1)
auto resetA3 = [&]() { auto resetA3 = [&]() {
@@ -2823,10 +2819,9 @@ static QByteArray pchgFastDecomp(const QByteArray& input, int treeSize, int orig
return true; return true;
}; };
int produced = 0;
// Main decode loop: produce exactly originalSize bytes // Main decode loop: produce exactly originalSize bytes
while (produced < originalSize) { QByteArray out;
while (out.size() < qsizetype(originalSize)) {
if (bits == 0) { if (bits == 0) {
if (!refill()) { if (!refill()) {
// Not enough bits to complete output // Not enough bits to complete output
@@ -2862,7 +2857,7 @@ static QByteArray pchgFastDecomp(const QByteArray& input, int treeSize, int orig
a3_word = next; a3_word = next;
} else { } else {
// Leaf: emit low 8 bits, reset a3 // Leaf: emit low 8 bits, reset a3
outPtr[produced++] = static_cast<char>(w & 0xFF); out.append(static_cast<char>(w & 0xFF));
a3_word = resetA3(); a3_word = resetA3();
} }
} else { } else {
@@ -2882,7 +2877,7 @@ static QByteArray pchgFastDecomp(const QByteArray& input, int treeSize, int orig
// Non-negative: check bit #8; if set -> leaf // Non-negative: check bit #8; if set -> leaf
if ((w & 0x0100) != 0) { if ((w & 0x0100) != 0) {
outPtr[produced++] = static_cast<char>(w & 0xFF); out.append(static_cast<char>(w & 0xFF));
a3_word = resetA3(); a3_word = resetA3();
} else { } else {
// Not a leaf: continue scanning // Not a leaf: continue scanning