License, Windows and Compatibility Upgrade (redux) #19
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vkrasnov
reviewed
Feb 25, 2020
configure
Outdated
| cat > $test.c << EOF | ||
| #include <immintrin.h> | ||
| void foo(void) { | ||
| _mm_clmulepi64_si128(_mm_set1_epi16(1), _mm_set1_epi16(2), 0); | ||
| #include <wmmintrin.h> |
vkrasnov
reviewed
Feb 25, 2020
crc32.c
Outdated
| #ifndef _MSC_VER | ||
| #include <cpuid.h> | ||
| #endif | ||
| //#include <stdio.h> |
vkrasnov
reviewed
Feb 25, 2020
crc32.c
Outdated
| #endif | ||
| if ((ecx & crc_bit_PCLMUL) != 0) | ||
| cpu_has_pclmul = 1; | ||
| //printf("leaf=%d, eax=0x%x, ebx=0x%x, ecx=0x%x, edx=0x%x, cpu_has_pclmul %d\n", leaf, eax, ebx, ecx, edx, cpu_has_pclmul); |
vkrasnov
reviewed
Feb 25, 2020
| #ifndef SKIP_CPUID_CHECK | ||
| if (!has_pclmul()) | ||
| return crc32_generic(crc, buf, len); | ||
| #endif |
There was a problem hiding this comment.
Not aligned with the #ifndef above it
vkrasnov
reviewed
Feb 25, 2020
deflate.c
Outdated
| @@ -545,7 +545,7 @@ int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain) | |||
| * upper bound of about 14% expansion does not seem onerous for output buffer | |||
| * allocation. | |||
| */ | |||
| uint64_t ZEXPORT deflateBound(strm, sourceLen) | |||
| uLong ZEXPORT deflateBound(strm, sourceLen) | |||
|
@vkrasnov thanks for your careful review. I believe my latest commit includes all your suggestions. |
kornelski
approved these changes
Feb 25, 2020
|
@neurolabusc thank you very much for the contribution! |
Merged
fhanau
pushed a commit
to fhanau/zlib
that referenced
this pull request
Feb 27, 2023
Add a "compression context" to CompressionStream and DecompressionStream to make the tracking of the internal state explicit.
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This pull request responds to feedback to an earlier pull request.
It adds 3 benefits:
I would be excited to see this pull request included, as it can be called from the pigz make. This dramatically accelerates pigz, with the SIMD CRC directly accelerating the serial stage that is most impacted by Amdahl's law.
The first time the CRC is called it set the atomic int cpu_has_pclmul, which reports whether or not the clmul instructions are available. This ensures the program does not crash if compiled on a modern computer and executed on an old computer. I appreciate different people have different views on this, which I summarize below. I do not have a preference, the pull request I am providing is robust (tested on Ubuntu 14.04 as well as recent versions) and simple. The CRC SIMD code and CPUID is only tested for x86-64, but again this extends the current repository. Future developments my consider alternatives:
Other comments
For most cases (where files are large) testing the CPU for CLMUL support on has negligible performance impact. One can conceive of use cases where an statically compiled executable is called many times to compress tiny files. If one is confident the resulting executable is going to be only run on modern (Westmere or later) CPUs, one can compile with the DSKIP_CPUID_CHECK compiler directive to skip this check for cmake the command is "cmake -DSKIP_CPUID_CHECK=ON ..".