mirror of https://git.tukaani.org/xz.git
118 lines
3.6 KiB
C
118 lines
3.6 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file crc32_arm64.h
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/// \brief CRC32 calculation with ARM64 optimization
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//
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// Authors: Chenxi Mao
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// Jia Tan
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// Hans Jansen
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//
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///////////////////////////////////////////////////////////////////////////////
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#ifndef LZMA_CRC32_ARM64_H
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#define LZMA_CRC32_ARM64_H
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// MSVC always has the CRC intrinsics available when building for ARM64
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// there is no need to include any header files.
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#ifndef _MSC_VER
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# include <arm_acle.h>
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#endif
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#if defined(CRC32_GENERIC) && defined(CRC32_ARCH_OPTIMIZED)
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# if defined(HAVE_GETAUXVAL) || defined(HAVE_ELF_AUX_INFO)
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# include <sys/auxv.h>
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# elif defined(_WIN32)
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# include <processthreadsapi.h>
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# elif defined(__APPLE__) && defined(HAVE_SYSCTLBYNAME)
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# include <sys/sysctl.h>
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# endif
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#endif
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// Some EDG-based compilers support ARM64 and define __GNUC__
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// (such as Nvidia's nvcc), but do not support function attributes.
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//
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// NOTE: Build systems check for this too, keep them in sync with this.
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#if (defined(__GNUC__) || defined(__clang__)) && !defined(__EDG__)
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# define crc_attr_target \
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__attribute__((__target__("+crc")))
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#else
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# define crc_attr_target
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#endif
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crc_attr_target
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static uint32_t
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crc32_arch_optimized(const uint8_t *buf, size_t size, uint32_t crc)
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{
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crc = ~crc;
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// Align the input buffer because this was shown to be
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// significantly faster than unaligned accesses.
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const size_t align_amount = my_min(size, (8 - (uintptr_t)buf) & 7);
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for (const uint8_t *limit = buf + align_amount; buf < limit; ++buf)
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crc = __crc32b(crc, *buf);
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size -= align_amount;
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// Process 8 bytes at a time. The end point is determined by
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// ignoring the least significant three bits of size to ensure
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// we do not process past the bounds of the buffer. This guarantees
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// that limit is a multiple of 8 and is strictly less than size.
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for (const uint8_t *limit = buf + (size & ~((size_t)7));
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buf < limit; buf += 8)
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crc = __crc32d(crc, aligned_read64le(buf));
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// Process the remaining bytes that are not 8 byte aligned.
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for (const uint8_t *limit = buf + (size & 7); buf < limit; ++buf)
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crc = __crc32b(crc, *buf);
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return ~crc;
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}
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#if defined(CRC32_GENERIC) && defined(CRC32_ARCH_OPTIMIZED)
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static inline bool
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is_arch_extension_supported(void)
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{
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#if defined(HAVE_GETAUXVAL)
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return (getauxval(AT_HWCAP) & HWCAP_CRC32) != 0;
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#elif defined(HAVE_ELF_AUX_INFO)
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unsigned long feature_flags;
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elf_aux_info(AT_HWCAP, &feature_flags, sizeof(feature_flags));
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return feature_flags & HWCAP_CRC32 != 0;
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#elif defined(_WIN32)
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return IsProcessorFeaturePresent(
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PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE);
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#elif defined(__APPLE__) && defined(HAVE_SYSCTLBYNAME)
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int has_crc32 = 0;
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size_t size = sizeof(has_crc32);
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// The sysctlbyname() function requires a string identifier for the
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// CPU feature it tests. The Apple documentation lists the string
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// "hw.optional.armv8_crc32", which can be found here:
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// (https://developer.apple.com/documentation/kernel/1387446-sysctlbyname/determining_instruction_set_characteristics#3915619)
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int err = sysctlbyname("hw.optional.armv8_crc32", &has_crc32,
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&size, NULL, 0);
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return !err && has_crc32;
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#else
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// If a runtime detection method cannot be found, then this must
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// be a compile time error. The checks in crc_common.h should ensure
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// a runtime detection method is always found if this function is
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// built. It would be possible to just return false here, but this
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// is inefficient for binary size and runtime since only the generic
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// method could ever be used.
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# error Runtime detection method unavailable.
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#endif
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}
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#endif
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#endif // LZMA_CRC32_ARM64_H
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