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94 lines
1.9 KiB
94 lines
1.9 KiB
#include <inttypes.h> |
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#include <string.h> |
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#include <unistd.h> |
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#include <stdlib.h> |
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#include <signal.h> |
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#include <sys/types.h> |
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#include <sys/wait.h> |
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#include "crc32c.h" |
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/* |
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* Based on a posting to lkml by Austin Zhang <austin.zhang@intel.com> |
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* |
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* Using hardware provided CRC32 instruction to accelerate the CRC32 disposal. |
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* CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE) |
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* CRC32 is a new instruction in Intel SSE4.2, the reference can be found at: |
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* http://www.intel.com/products/processor/manuals/ |
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* Intel(R) 64 and IA-32 Architectures Software Developer's Manual |
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* Volume 2A: Instruction Set Reference, A-M |
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*/ |
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int crc32c_intel_available = 0; |
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#ifdef ARCH_HAVE_SSE4_2 |
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#if BITS_PER_LONG == 64 |
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#define REX_PRE "0x48, " |
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#define SCALE_F 8 |
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#else |
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#define REX_PRE |
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#define SCALE_F 4 |
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#endif |
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static int crc32c_probed; |
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static uint32_t crc32c_intel_le_hw_byte(uint32_t crc, unsigned char const *data, |
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unsigned long length) |
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{ |
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while (length--) { |
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__asm__ __volatile__( |
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".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1" |
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:"=S"(crc) |
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:"0"(crc), "c"(*data) |
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); |
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data++; |
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} |
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return crc; |
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} |
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/* |
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* Steps through buffer one byte at at time, calculates reflected |
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* crc using table. |
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*/ |
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uint32_t crc32c_intel(unsigned char const *data, unsigned long length) |
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{ |
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unsigned int iquotient = length / SCALE_F; |
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unsigned int iremainder = length % SCALE_F; |
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#if BITS_PER_LONG == 64 |
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uint64_t *ptmp = (uint64_t *) data; |
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#else |
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uint32_t *ptmp = (uint32_t *) data; |
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#endif |
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uint32_t crc = ~0; |
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while (iquotient--) { |
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__asm__ __volatile__( |
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".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;" |
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:"=S"(crc) |
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:"0"(crc), "c"(*ptmp) |
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); |
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ptmp++; |
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} |
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if (iremainder) |
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crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp, |
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iremainder); |
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return crc; |
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} |
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void crc32c_intel_probe(void) |
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{ |
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if (!crc32c_probed) { |
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unsigned int eax, ebx, ecx = 0, edx; |
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eax = 1; |
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do_cpuid(&eax, &ebx, &ecx, &edx); |
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crc32c_intel_available = (ecx & (1 << 20)) != 0; |
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crc32c_probed = 1; |
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} |
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} |
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#endif /* ARCH_HAVE_SSE */
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