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Merge pull request #243 from Schmidor/faster_ccitt

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CCITT speedup on getNextChangingElement
This commit is contained in:
Harald Kuhr 2016-05-11 11:05:40 +02:00
commit 70bb5de4de
1 changed files with 11 additions and 4 deletions
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15
imageio/imageio-tiff/src/main/java/com/twelvemonkeys/imageio/plugins/tiff/CCITTFaxDecoderStream.java
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@ -62,6 +62,8 @@ final class CCITTFaxDecoderStream extends FilterInputStream {
private int changesReferenceRowCount; private int changesReferenceRowCount;
private int changesCurrentRowCount; private int changesCurrentRowCount;
private int lastChangingElement = 0;
private boolean optionG32D = false; private boolean optionG32D = false;
@SuppressWarnings("unused") // Leading zeros for aligning EOL @SuppressWarnings("unused") // Leading zeros for aligning EOL
@ -185,7 +187,7 @@ final class CCITTFaxDecoderStream extends FilterInputStream {
case VALUE_PASSMODE: case VALUE_PASSMODE:
int pChangingElement = getNextChangingElement(index, white) + 1; int pChangingElement = getNextChangingElement(index, white) + 1;
if (pChangingElement >= changesReferenceRowCount || pChangingElement == -1) { if (pChangingElement >= changesReferenceRowCount) {
index = columns; index = columns;
} }
else { else {
@ -218,11 +220,15 @@ final class CCITTFaxDecoderStream extends FilterInputStream {
} }
} }
private int getNextChangingElement(final int a0, final boolean white) { private int getNextChangingElement(final int a0, final boolean white) throws IOException {
int start = white ? 0 : 1; int start = (lastChangingElement & 0xFFFF_FFFC) + (white ? 0 : 1);
if (a0 == 0) {
return start;
}
for (int i = start; i < changesReferenceRowCount; i += 2) { for (int i = start; i < changesReferenceRowCount; i += 2) {
if (a0 < changesReferenceRow[i] || (a0 == 0 && changesReferenceRow[i] == 0)) { if (a0 < changesReferenceRow[i]) {
lastChangingElement = i;
return i; return i;
} }
} }
@ -281,6 +287,7 @@ final class CCITTFaxDecoderStream extends FilterInputStream {
int index = 0; int index = 0;
boolean white = true; boolean white = true;
lastChangingElement = 0;
for (int i = 0; i <= changesCurrentRowCount; i++) { for (int i = 0; i <= changesCurrentRowCount; i++) {
int nextChange = columns; int nextChange = columns;