src/port/pg_crc32c_armv8.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * pg_crc32c_armv8.c
   4  *        Compute CRC-32C checksum using ARMv8 CRC Extension 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_armv8.c
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "c.h"
  16
  17 #include <arm_acle.h>
  18
  19 #include "port/pg_crc32c.h"
  20
  21 pg_crc32c
  22 pg_comp_crc32c_armv8(pg_crc32c crc, const void *data, size_t len)
  23 {
  24         const unsigned char *p = data;
  25         const unsigned char *pend = p + len;
  26
  27         /*
  28          * ARMv8 doesn't require alignment, but aligned memory access is
  29          * significantly faster. Process leading bytes so that the loop below
  30          * starts with a pointer aligned to eight bytes.
  31          */
  32         if (!PointerIsAligned(p, uint16) &&
  33                 p + 1 <= pend)
  34         {
  35                 crc = __crc32cb(crc, *p);
  36                 p += 1;
  37         }
  38         if (!PointerIsAligned(p, uint32) &&
  39                 p + 2 <= pend)
  40         {
  41                 crc = __crc32ch(crc, *(uint16 *) p);
  42                 p += 2;
  43         }
  44         if (!PointerIsAligned(p, uint64) &&
  45                 p + 4 <= pend)
  46         {
  47                 crc = __crc32cw(crc, *(uint32 *) p);
  48                 p += 4;
  49         }
  50
  51         /* Process eight bytes at a time, as far as we can. */
  52         while (p + 8 <= pend)
  53         {
  54                 crc = __crc32cd(crc, *(uint64 *) p);
  55                 p += 8;
  56         }
  57
  58         /* Process remaining 0-7 bytes. */
  59         if (p + 4 <= pend)
  60         {
  61                 crc = __crc32cw(crc, *(uint32 *) p);
  62                 p += 4;
  63         }
  64         if (p + 2 <= pend)
  65         {
  66                 crc = __crc32ch(crc, *(uint16 *) p);
  67                 p += 2;
  68         }
  69         if (p < pend)
  70         {
  71                 crc = __crc32cb(crc, *p);
  72         }
  73
  74         return crc;
  75 }