Age Owner TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * pg_crc32c_sse42_choose.c
4 : * Choose between Intel SSE 4.2 and software CRC-32C implementation.
5 : *
6 : * On first call, checks if the CPU we're running on supports Intel SSE
7 : * 4.2. If it does, use the special SSE instructions for CRC-32C
8 : * computation. Otherwise, fall back to the pure software implementation
9 : * (slicing-by-8).
10 : *
11 : * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
12 : * Portions Copyright (c) 1994, Regents of the University of California
13 : *
14 : *
15 : * IDENTIFICATION
16 : * src/port/pg_crc32c_sse42_choose.c
17 : *
18 : *-------------------------------------------------------------------------
19 : */
20 :
21 : #include "c.h"
22 :
23 : #ifdef HAVE__GET_CPUID
24 : #include <cpuid.h>
25 : #endif
26 :
27 : #ifdef HAVE__CPUID
28 : #include <intrin.h>
29 : #endif
30 :
31 : #include "port/pg_crc32c.h"
32 :
33 : static bool
2917 heikki.linnakangas 34 CBC 1419 : pg_crc32c_sse42_available(void)
35 : {
36 1419 : unsigned int exx[4] = {0, 0, 0, 0};
37 :
38 : #if defined(HAVE__GET_CPUID)
39 1419 : __get_cpuid(1, &exx[0], &exx[1], &exx[2], &exx[3]);
40 : #elif defined(HAVE__CPUID)
41 : __cpuid(exx, 1);
42 : #else
43 : #error cpuid instruction not available
44 : #endif
45 :
2878 bruce 46 1419 : return (exx[2] & (1 << 20)) != 0; /* SSE 4.2 */
47 : }
48 :
49 : /*
50 : * This gets called on the first call. It replaces the function pointer
51 : * so that subsequent calls are routed directly to the chosen implementation.
52 : */
53 : static pg_crc32c
2917 heikki.linnakangas 54 1419 : pg_comp_crc32c_choose(pg_crc32c crc, const void *data, size_t len)
55 : {
56 1419 : if (pg_crc32c_sse42_available())
57 1419 : pg_comp_crc32c = pg_comp_crc32c_sse42;
58 : else
2917 heikki.linnakangas 59 UBC 0 : pg_comp_crc32c = pg_comp_crc32c_sb8;
60 :
2917 heikki.linnakangas 61 CBC 1419 : return pg_comp_crc32c(crc, data, len);
62 : }
63 :
64 : pg_crc32c (*pg_comp_crc32c) (pg_crc32c crc, const void *data, size_t len) = pg_comp_crc32c_choose;
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