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LibDEFLATE: Add GZip support

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This allows compressing and decompressing with data using GZip headers
and footers
This commit is contained in:
Oskari Alaranta
2026-02-20 00:00:32 +02:00
parent 632787b142
commit 7c1b403e05
4 changed files with 125 additions and 0 deletions
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27
LibDEFLATE/Compressor.cpp
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@@ -580,6 +580,8 @@ namespace LibDEFLATE
BAN::ErrorOr<BAN::Vector<uint8_t>> Compressor::compress()
{
const uint32_t data_size = m_data.size();
uint32_t checksum = 0;
switch (m_type)
{
@@ -590,6 +592,21 @@ namespace LibDEFLATE
TRY(m_stream.write_bits(0x9C, 8)); // default compression
checksum = calculate_adler32(m_data);
break;
case StreamType::GZip:
{
const time_t current_time = time(nullptr);
TRY(m_stream.write_bits(0x1F, 8)); // ID1
TRY(m_stream.write_bits(0x8B, 8)); // ID2
TRY(m_stream.write_bits(8, 8)); // CM (deflate)
TRY(m_stream.write_bits(0, 8)); // FLG
TRY(m_stream.write_bits(current_time >> 0, 8)); // MTIME
TRY(m_stream.write_bits(current_time >> 8, 8));
TRY(m_stream.write_bits(current_time >> 16, 8));
TRY(m_stream.write_bits(current_time >> 24, 8));
TRY(m_stream.write_bits(0, 8)); // XFL
TRY(m_stream.write_bits(3, 8)); // OS (Unix)
checksum = calculate_crc32(m_data);
}
}
constexpr size_t max_block_size = 16 * 1024;
@@ -612,6 +629,16 @@ namespace LibDEFLATE
TRY(m_stream.write_bits(checksum >> 8, 8));
TRY(m_stream.write_bits(checksum >> 0, 8));
break;
case StreamType::GZip:
TRY(m_stream.write_bits(checksum >> 0, 8));
TRY(m_stream.write_bits(checksum >> 8, 8));
TRY(m_stream.write_bits(checksum >> 16, 8));
TRY(m_stream.write_bits(checksum >> 24, 8));
TRY(m_stream.write_bits(data_size >> 0, 8));
TRY(m_stream.write_bits(data_size >> 8, 8));
TRY(m_stream.write_bits(data_size >> 16, 8));
TRY(m_stream.write_bits(data_size >> 24, 8));
break;
}
return m_stream.take_buffer();