Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * pg_crc32c_sse42.c
       4             :  *    Compute CRC-32C checksum using Intel SSE 4.2 instructions.
       5             :  *
       6             :  * Portions Copyright (c) 1996-2017, 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 "port/pg_crc32c.h"
      18             : 
      19             : #include <nmmintrin.h>
      20             : 
      21             : pg_crc32c
      22     6320495 : pg_comp_crc32c_sse42(pg_crc32c crc, const void *data, size_t len)
      23             : {
      24     6320495 :     const unsigned char *p = data;
      25     6320495 :     const unsigned char *pend = p + len;
      26             : 
      27             :     /*
      28             :      * Process eight bytes of data at a time.
      29             :      *
      30             :      * NB: We do unaligned accesses here. The Intel architecture allows that,
      31             :      * and performance testing didn't show any performance gain from aligning
      32             :      * the begin address.
      33             :      */
      34             : #ifdef __x86_64__
      35             :     while (p + 8 <= pend)
      36             :     {
      37             :         crc = (uint32) _mm_crc32_u64(crc, *((const uint64 *) p));
      38             :         p += 8;
      39             :     }
      40             : 
      41             :     /* Process remaining full four bytes if any */
      42             :     if (p + 4 <= pend)
      43             :     {
      44             :         crc = _mm_crc32_u32(crc, *((const unsigned int *) p));
      45             :         p += 4;
      46             :     }
      47             : #else
      48             : 
      49             :     /*
      50             :      * Process four bytes at a time. (The eight byte instruction is not
      51             :      * available on the 32-bit x86 architecture).
      52             :      */
      53    54752882 :     while (p + 4 <= pend)
      54             :     {
      55    84223784 :         crc = _mm_crc32_u32(crc, *((const unsigned int *) p));
      56    42111892 :         p += 4;
      57             :     }
      58             : #endif                          /* __x86_64__ */
      59             : 
      60             :     /* Process any remaining bytes one at a time. */
      61    19606382 :     while (p < pend)
      62             :     {
      63    13930784 :         crc = _mm_crc32_u8(crc, *p);
      64     6965392 :         p++;
      65             :     }
      66             : 
      67     6320495 :     return crc;
      68             : }