53 lines
1.1 KiB
C
53 lines
1.1 KiB
C
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/*-------------------------------------------------------------------------
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*
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* pg_crc32c_sse42.c
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* Compute CRC-32C checksum using Intel SSE 4.2 instructions.
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*
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* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* src/port/pg_crc32c_sse42.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "c.h"
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#include "port/pg_crc32c.h"
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#include <nmmintrin.h>
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pg_crc32c
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pg_comp_crc32c_sse42(pg_crc32c crc, const void *data, size_t len)
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{
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const unsigned char *p = data;
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const uint64 *p8;
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/*
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* Process eight bytes of data at a time.
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*
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* NB: We do unaligned 8-byte accesses here. The Intel architecture
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* allows that, and performance testing didn't show any performance
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* gain from aligning the beginning address.
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*/
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p8 = (const uint64 *) p;
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while (len >= 8)
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{
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crc = (uint32) _mm_crc32_u64(crc, *p8++);
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len -= 8;
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}
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/*
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* Handle any remaining bytes one at a time.
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*/
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p = (const unsigned char *) p8;
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while (len > 0)
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{
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crc = _mm_crc32_u8(crc, *p++);
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len--;
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}
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return crc;
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}
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