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Merge pull request #1253 from ltrk2/bugfix/hashing-on-big-endian

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Make hashes identical between LE and BE platforms
This commit is contained in:
Yann Collet 2023-12-22 17:45:25 -08:00 committed by GitHub
commit 26b3b238fe
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5 changed files with 35 additions and 0 deletions
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1
.gitignore vendored
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@ -21,6 +21,7 @@ lz4
# IDE / editors files
.clang_complete
.vscode
_codelite/
_codelite_lz4/
bin/

9
build/meson/meson/meson.build
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@ -81,6 +81,15 @@ if get_option('memory-usage') > 0
compile_args += '-DLZ4_MEMORY_USAGE=@0@'.format(get_option('memory-usage'))
endif
if get_option('endianness-independent-output')
if get_option('default_library') != 'static'
error('Endianness-independent output can only be enabled in static builds')
endif
add_project_arguments('-DLZ4_STATIC_LINKING_ONLY_ENDIANNESS_INDEPENDENT_OUTPUT')
compile_args += '-DLZ4_STATIC_LINKING_ONLY_ENDIANNESS_INDEPENDENT_OUTPUT'
endif
if get_option('unstable')
add_project_arguments('-DLZ4_STATIC_LINKING_ONLY', language: 'c')
compile_args += '-DLZ4_STATIC_LINKING_ONLY'

2
build/meson/meson_options.txt
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@ -18,6 +18,8 @@ option('disable-memory-allocation', type: 'boolean', value: false,
description: 'See LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION. Static builds only')
option('distance-max', type: 'integer', min: 0, max: 65535, value: 65535,
description: 'See LZ4_DISTANCE_MAX')
option('endianness-independent-output', type: 'boolean', value: false,
description: 'See LZ4_STATIC_LINKING_ONLY_ENDIANNESS_INDEPENDENT_OUTPUT. Static builds only')
option('examples', type: 'boolean', value: false,
description: 'Enable examples')
option('fast-dec-loop', type: 'feature', value: 'auto',

6
lib/README.md
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@ -108,6 +108,12 @@ The following build macro can be selected to adjust source code behavior at comp
Remove support of dynamic memory allocation.
For more details, see description of this macro in `lib/lz4.c`.
- `LZ4_STATIC_LINKING_ONLY_ENDIANNESS_INDEPENDENT_OUTPUT` : experimental feature aimed at producing the same
compressed output on platforms of different endianness (i.e. little-endian and big-endian).
Output on little-endian platforms shall remain unchanged, while big-endian platforms will start producing
the same output as little-endian ones. This isn't expected to impact backward- and forward-compatibility
in any way.
- `LZ4_FREESTANDING` : by setting this build macro to 1,
LZ4/HC removes dependencies on the C standard library,
including allocation functions and `memmove()`, `memcpy()`, and `memset()`.

17
lib/lz4.c
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@ -434,6 +434,18 @@ static U16 LZ4_readLE16(const void* memPtr)
}
}
#ifdef LZ4_STATIC_LINKING_ONLY_ENDIANNESS_INDEPENDENT_OUTPUT
static U32 LZ4_readLE32(const void* memPtr)
{
if (LZ4_isLittleEndian()) {
return LZ4_read32(memPtr);
} else {
const BYTE* p = (const BYTE*)memPtr;
return (U32)p[0] + (p[1]<<8) + (p[2]<<16) + (p[3]<<24);
}
}
#endif
static void LZ4_writeLE16(void* memPtr, U16 value)
{
if (LZ4_isLittleEndian()) {
@ -782,7 +794,12 @@ LZ4_FORCE_INLINE U32 LZ4_hash5(U64 sequence, tableType_t const tableType)
LZ4_FORCE_INLINE U32 LZ4_hashPosition(const void* const p, tableType_t const tableType)
{
if ((sizeof(reg_t)==8) && (tableType != byU16)) return LZ4_hash5(LZ4_read_ARCH(p), tableType);
#ifdef LZ4_STATIC_LINKING_ONLY_ENDIANNESS_INDEPENDENT_OUTPUT
return LZ4_hash4(LZ4_readLE32(p), tableType);
#else
return LZ4_hash4(LZ4_read32(p), tableType);
#endif
}
LZ4_FORCE_INLINE void LZ4_clearHash(U32 h, void* tableBase, tableType_t const tableType)