From 3eef81bc6551a304e415f9af625ac365c96e8f11 Mon Sep 17 00:00:00 2001 From: Piotr Rzysko Date: Sat, 4 Oct 2025 21:40:52 +0200 Subject: [PATCH] Fix handling of output offset in SkippableComposition classes Previously, when outpos passed to headlessUncompress was greater than zero, the second scheme would receive an incorrect number of remaining integers to decode. --- .../SkippableComposition.java | 4 +- .../SkippableIntegratedComposition.java | 4 +- .../SkippableLongComposition.java | 4 +- .../SkippableBasicTest.java | 49 +++++++++++++++++++ .../SkippableLongBasicTest.java | 24 +++++++++ 5 files changed, 82 insertions(+), 3 deletions(-) diff --git a/src/main/java/me/lemire/integercompression/SkippableComposition.java b/src/main/java/me/lemire/integercompression/SkippableComposition.java index 7dd4736..fc3c18e 100644 --- a/src/main/java/me/lemire/integercompression/SkippableComposition.java +++ b/src/main/java/me/lemire/integercompression/SkippableComposition.java @@ -52,12 +52,14 @@ public void headlessCompress(int[] in, IntWrapper inpos, int inlength, int[] out public void headlessUncompress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos, int num) { int init = inpos.get(); + int outposInit = outpos.get(); + F1.headlessUncompress(in, inpos, inlength, out, outpos, num); if (inpos.get() == init) { inpos.increment(); } inlength -= inpos.get() - init; - num -= outpos.get(); + num -= outpos.get() - outposInit; F2.headlessUncompress(in, inpos, inlength, out, outpos, num); } diff --git a/src/main/java/me/lemire/integercompression/differential/SkippableIntegratedComposition.java b/src/main/java/me/lemire/integercompression/differential/SkippableIntegratedComposition.java index a1379ad..4786ec5 100644 --- a/src/main/java/me/lemire/integercompression/differential/SkippableIntegratedComposition.java +++ b/src/main/java/me/lemire/integercompression/differential/SkippableIntegratedComposition.java @@ -66,13 +66,15 @@ public void headlessUncompress(int[] in, IntWrapper inpos, int inlength, if (inlength == 0) return; int init = inpos.get(); + int outposInit = outpos.get(); + F1.headlessUncompress(in, inpos, inlength, out, outpos,num,initvalue); if (inpos.get() == init) { inpos.increment(); } inlength -= inpos.get() - init; - num -= outpos.get(); + num -= outpos.get() - outposInit; F2.headlessUncompress(in, inpos, inlength, out, outpos,num,initvalue); } diff --git a/src/main/java/me/lemire/longcompression/SkippableLongComposition.java b/src/main/java/me/lemire/longcompression/SkippableLongComposition.java index 0f9800e..eb03b72 100644 --- a/src/main/java/me/lemire/longcompression/SkippableLongComposition.java +++ b/src/main/java/me/lemire/longcompression/SkippableLongComposition.java @@ -53,12 +53,14 @@ public void headlessCompress(long[] in, IntWrapper inpos, int inlength, long[] o public void headlessUncompress(long[] in, IntWrapper inpos, int inlength, long[] out, IntWrapper outpos, int num) { int init = inpos.get(); + int outposInit = outpos.get(); + F1.headlessUncompress(in, inpos, inlength, out, outpos, num); if (inpos.get() == init) { inpos.increment(); } inlength -= inpos.get() - init; - num -= outpos.get(); + num -= outpos.get() - outposInit; F2.headlessUncompress(in, inpos, inlength, out, outpos, num); } diff --git a/src/test/java/me/lemire/integercompression/SkippableBasicTest.java b/src/test/java/me/lemire/integercompression/SkippableBasicTest.java index 57a07e3..881dada 100644 --- a/src/test/java/me/lemire/integercompression/SkippableBasicTest.java +++ b/src/test/java/me/lemire/integercompression/SkippableBasicTest.java @@ -15,6 +15,7 @@ import me.lemire.integercompression.differential.SkippableIntegratedIntegerCODEC; import org.junit.Test; +import static org.junit.Assert.assertArrayEquals; import static org.junit.Assert.assertTrue; /** @@ -236,4 +237,52 @@ private static void testMaxHeadlessCompressedLength(SkippableIntegerCODEC codec, } } } + + @Test + public void testUncompressOutputOffset_SkippableComposition() { + for (int offset : new int[] {0, 1, 6}) { + SkippableComposition codec = new SkippableComposition(new BinaryPacking(), new VariableByte()); + + int[] input = { 2, 3, 4, 5 }; + int[] compressed = new int[codec.maxHeadlessCompressedLength(new IntWrapper(0), input.length)]; + int[] uncompressed = new int[offset + input.length]; + + IntWrapper inputOffset = new IntWrapper(0); + IntWrapper compressedOffset = new IntWrapper(0); + + codec.headlessCompress(input, inputOffset, input.length, compressed, compressedOffset); + + int compressedLength = compressedOffset.get(); + IntWrapper uncompressedOffset = new IntWrapper(offset); + compressedOffset = new IntWrapper(0); + codec.headlessUncompress(compressed, compressedOffset, compressedLength, uncompressed, uncompressedOffset, input.length); + + assertArrayEquals(input, Arrays.copyOfRange(uncompressed, offset, offset + input.length)); + } + } + + @Test + public void testUncompressOutputOffset_SkippableIntegratedComposition() { + for (int offset : new int[] {0, 1, 6}) { + SkippableIntegratedComposition codec = new SkippableIntegratedComposition(new IntegratedBinaryPacking(), new IntegratedVariableByte()); + + int[] input = { 2, 3, 4, 5 }; + int[] compressed = new int[codec.maxHeadlessCompressedLength(new IntWrapper(0), input.length)]; + int[] uncompressed = new int[offset + input.length]; + + IntWrapper inputOffset = new IntWrapper(0); + IntWrapper compressedOffset = new IntWrapper(0); + IntWrapper initValue = new IntWrapper(0); + + codec.headlessCompress(input, inputOffset, input.length, compressed, compressedOffset, initValue); + + int compressedLength = compressedOffset.get(); + IntWrapper uncompressedOffset = new IntWrapper(offset); + compressedOffset = new IntWrapper(0); + initValue = new IntWrapper(0); + codec.headlessUncompress(compressed, compressedOffset, compressedLength, uncompressed, uncompressedOffset, input.length, initValue); + + assertArrayEquals(input, Arrays.copyOfRange(uncompressed, offset, offset + input.length)); + } + } } diff --git a/src/test/java/me/lemire/longcompression/SkippableLongBasicTest.java b/src/test/java/me/lemire/longcompression/SkippableLongBasicTest.java index 4309e9d..c4b7e01 100644 --- a/src/test/java/me/lemire/longcompression/SkippableLongBasicTest.java +++ b/src/test/java/me/lemire/longcompression/SkippableLongBasicTest.java @@ -15,6 +15,7 @@ import me.lemire.integercompression.TestUtils; import me.lemire.integercompression.VariableByte; +import static org.junit.Assert.assertArrayEquals; import static org.junit.Assert.assertTrue; /** @@ -167,4 +168,27 @@ private static void testMaxHeadlessCompressedLength(SkippableLongCODEC codec, in assertTrue(maxOutputLength <= outPos.get() + 1); // +1 because SkippableLongComposition always adds one extra integer for the potential header } } + + @Test + public void testUncompressOutputOffset_SkippableLongComposition() { + for (int offset : new int[] {0, 1, 6}) { + SkippableLongComposition codec = new SkippableLongComposition(new LongBinaryPacking(), new LongVariableByte()); + + long[] input = { 2, 3, 4, 5 }; + long[] compressed = new long[codec.maxHeadlessCompressedLength(new IntWrapper(0), input.length)]; + long[] uncompressed = new long[offset + input.length]; + + IntWrapper inputOffset = new IntWrapper(0); + IntWrapper compressedOffset = new IntWrapper(0); + + codec.headlessCompress(input, inputOffset, input.length, compressed, compressedOffset); + + int compressedLength = compressedOffset.get(); + IntWrapper uncompressedOffset = new IntWrapper(offset); + compressedOffset = new IntWrapper(0); + codec.headlessUncompress(compressed, compressedOffset, compressedLength, uncompressed, uncompressedOffset, input.length); + + assertArrayEquals(input, Arrays.copyOfRange(uncompressed, offset, offset + input.length)); + } + } }