70 lines
1.5 KiB
C
70 lines
1.5 KiB
C
/*-------------------------------------------------------------------------
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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) 1996-2024, 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 <nmmintrin.h>
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#include "port/pg_crc32c.h"
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pg_attribute_no_sanitize_alignment()
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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 unsigned char *pend = p + len;
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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 accesses here. The Intel architecture allows that,
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* and performance testing didn't show any performance gain from aligning
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* the begin address.
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*/
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#ifdef __x86_64__
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while (p + 8 <= pend)
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{
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crc = (uint32) _mm_crc32_u64(crc, *((const uint64 *) p));
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p += 8;
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}
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/* Process remaining full four bytes if any */
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if (p + 4 <= pend)
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{
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crc = _mm_crc32_u32(crc, *((const unsigned int *) p));
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p += 4;
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}
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#else
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/*
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* Process four bytes at a time. (The eight byte instruction is not
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* available on the 32-bit x86 architecture).
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*/
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while (p + 4 <= pend)
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{
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crc = _mm_crc32_u32(crc, *((const unsigned int *) p));
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p += 4;
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}
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#endif /* __x86_64__ */
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/* Process any remaining bytes one at a time. */
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while (p < pend)
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{
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crc = _mm_crc32_u8(crc, *p);
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p++;
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}
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return crc;
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}
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