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pg_crc32c_sse42.c
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1 /*-------------------------------------------------------------------------
2  *
3  * pg_crc32c_sse42.c
4  * Compute CRC-32C checksum using Intel SSE 4.2 instructions.
5  *
6  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  *
10  * IDENTIFICATION
11  * src/port/pg_crc32c_sse42.c
12  *
13  *-------------------------------------------------------------------------
14  */
15 #include "c.h"
16 
17 #include <nmmintrin.h>
18 
19 #include "port/pg_crc32c.h"
20 
23 pg_comp_crc32c_sse42(pg_crc32c crc, const void *data, size_t len)
24 {
25  const unsigned char *p = data;
26  const unsigned char *pend = p + len;
27 
28  /*
29  * Process eight bytes of data at a time.
30  *
31  * NB: We do unaligned accesses here. The Intel architecture allows that,
32  * and performance testing didn't show any performance gain from aligning
33  * the begin address.
34  */
35 #ifdef __x86_64__
36  while (p + 8 <= pend)
37  {
38  crc = (uint32) _mm_crc32_u64(crc, *((const uint64 *) p));
39  p += 8;
40  }
41 
42  /* Process remaining full four bytes if any */
43  if (p + 4 <= pend)
44  {
45  crc = _mm_crc32_u32(crc, *((const unsigned int *) p));
46  p += 4;
47  }
48 #else
49 
50  /*
51  * Process four bytes at a time. (The eight byte instruction is not
52  * available on the 32-bit x86 architecture).
53  */
54  while (p + 4 <= pend)
55  {
56  crc = _mm_crc32_u32(crc, *((const unsigned int *) p));
57  p += 4;
58  }
59 #endif /* __x86_64__ */
60 
61  /* Process any remaining bytes one at a time. */
62  while (p < pend)
63  {
64  crc = _mm_crc32_u8(crc, *p);
65  p++;
66  }
67 
68  return crc;
69 }
uint32 pg_crc32c
Definition: pg_crc32c.h:38
pg_attribute_no_sanitize_alignment()
unsigned int uint32
Definition: c.h:441