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LibCompress: Remove PackBitsDecoder

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This is no longer used.
This commit is contained in:
Tim Ledbetter 2026-06-12 13:14:40 +01:00 committed by Andreas Kling
parent 3cddcc8461
commit b8ff139f9c
5 changed files with 0 additions and 100 deletions
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1
Libraries/LibCompress/CMakeLists.txt
View file

@ -2,7 +2,6 @@ set(SOURCES
Deflate.cpp
GenericZlib.cpp
Gzip.cpp
PackBitsDecoder.cpp
Zlib.cpp
)

46
Libraries/LibCompress/PackBitsDecoder.cpp
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@ -1,46 +0,0 @@
/*
* Copyright (c) 2023, Lucas Chollet <lucas.chollet@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "PackBitsDecoder.h"
#include <AK/MemoryStream.h>
#include <AK/NonnullOwnPtr.h>
namespace Compress::PackBits {
ErrorOr<ByteBuffer> decode_all(ReadonlyBytes bytes, Optional<u64> expected_output_size, CompatibilityMode mode)
{
// This implementation uses unsigned values for the selector, as described in the PDF spec.
// Note that this remains compatible with other implementations based on signed numbers.
auto memory_stream = make<FixedMemoryStream>(bytes);
ByteBuffer decoded_bytes;
if (expected_output_size.has_value())
TRY(decoded_bytes.try_ensure_capacity(*expected_output_size));
while (memory_stream->remaining() > 0 && decoded_bytes.size() < expected_output_size.value_or(NumericLimits<u64>::max())) {
auto const length = TRY(memory_stream->read_value<u8>());
if (length < 128) {
for (u8 i = 0; i <= length; ++i)
TRY(decoded_bytes.try_append(TRY(memory_stream->read_value<u8>())));
} else if (length > 128) {
auto const next_byte = TRY(memory_stream->read_value<u8>());
for (u8 i = 0; i < 257 - length; ++i)
TRY(decoded_bytes.try_append(next_byte));
} else {
VERIFY(length == 128);
if (mode == CompatibilityMode::PDF)
break;
}
}
return decoded_bytes;
}
}

27
Libraries/LibCompress/PackBitsDecoder.h
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@ -1,27 +0,0 @@
/*
* Copyright (c) 2023, Lucas Chollet <lucas.chollet@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/ByteBuffer.h>
#include <AK/Optional.h>
namespace Compress::PackBits {
// This implements the PackBits compression scheme, aka run-length compression
// It is fairly simple and described here: https://web.archive.org/web/20080705155158/http://developer.apple.com/technotes/tn/tn1023.html
// But also in section:
// - 7.4.5 RunLengthDecode Filter of the PDF specification
// - Section 9: PackBits Compression of the TIFF specification
enum class CompatibilityMode {
Original, // 128 is defined as no-op
PDF, // 128 is defined as end of stream
};
ErrorOr<ByteBuffer> decode_all(ReadonlyBytes bytes, Optional<u64> expected_output_size = {}, CompatibilityMode mode = CompatibilityMode::Original);
}

1
Tests/LibCompress/CMakeLists.txt
View file

@ -2,7 +2,6 @@ set(TEST_SOURCES
TestDeflate.cpp
TestGzip.cpp
TestLzw.cpp
TestPackBits.cpp
TestZlib.cpp
)

25
Tests/LibCompress/TestPackBits.cpp
View file

@ -1,25 +0,0 @@
/*
* Copyright (c) 2023, Lucas Chollet <lucas.chollet@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibTest/TestCase.h>
#include <AK/Array.h>
#include <LibCompress/PackBitsDecoder.h>
TEST_CASE(pack_bits)
{
Array<u8, 15> const compressed {
0xFE, 0xAA, 0x02, 0x80, 0x00, 0x2A, 0xFD, 0xAA, 0x03, 0x80, 0x00, 0x2A, 0x22, 0xF7, 0xAA
};
Array<u8, 24> const raw {
0xAA, 0xAA, 0xAA, 0x80, 0x00, 0x2A, 0xAA, 0xAA, 0xAA, 0xAA, 0x80, 0x00,
0x2A, 0x22, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA
};
auto unpacked = TRY_OR_FAIL(Compress::PackBits::decode_all(compressed));
EXPECT_EQ(unpacked.bytes(), raw);
}