ceph/src/common/crc32c_ppc.c

   1 /* Copyright (C) 2017 International Business Machines Corp.
   2  * All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8  */
   9 #define CRC_TABLE
  10 #include "acconfig.h"
  11 #include "include/int_types.h"
  12 #include "crc32c_ppc_constants.h"
  13
  14 #include <stdlib.h>
  15 #include <strings.h>
  16
  17 #define VMX_ALIGN       16
  18 #define VMX_ALIGN_MASK  (VMX_ALIGN-1)
  19
  20 #ifdef REFLECT
  21 static unsigned int crc32_align(unsigned int crc, unsigned char const *p,
  22                                 unsigned long len)
  23 {
  24   while (len--)
  25     crc = crc_table[(crc ^ *p++) & 0xff] ^ (crc >> 8);
  26   return crc;
  27 }
  28 #else
  29 static unsigned int crc32_align(unsigned int crc, unsigned char const *p,
  30                                 unsigned long len)
  31 {
  32   while (len--)
  33     crc = crc_table[((crc >> 24) ^ *p++) & 0xff] ^ (crc << 8);
  34   return crc;
  35 }
  36 #endif
  37
  38
  39 #ifdef HAVE_POWER8
  40 unsigned int __crc32_vpmsum(unsigned int crc, unsigned char const *p,
  41                             unsigned long len);
  42
  43 static uint32_t crc32_vpmsum(uint32_t crc, unsigned char const *data,
  44                              unsigned len)
  45 {
  46   unsigned int prealign;
  47   unsigned int tail;
  48
  49 #ifdef CRC_XOR
  50   crc ^= 0xffffffff;
  51 #endif
  52
  53   if (len < VMX_ALIGN + VMX_ALIGN_MASK) {
  54     crc = crc32_align(crc, data, (unsigned long)len);
  55     goto out;
  56   }
  57
  58   if ((unsigned long)data & VMX_ALIGN_MASK) {
  59     prealign = VMX_ALIGN - ((unsigned long)data & VMX_ALIGN_MASK);
  60     crc = crc32_align(crc, data, prealign);
  61     len -= prealign;
  62     data += prealign;
  63   }
  64
  65   crc = __crc32_vpmsum(crc, data, (unsigned long)len & ~VMX_ALIGN_MASK);
  66
  67   tail = len & VMX_ALIGN_MASK;
  68   if (tail) {
  69     data += len & ~VMX_ALIGN_MASK;
  70     crc = crc32_align(crc, data, tail);
  71   }
  72
  73 out:
  74 #ifdef CRC_XOR
  75   crc ^= 0xffffffff;
  76 #endif
  77
  78   return crc;
  79 }
  80
  81 /* This wrapper function works around the fact that crc32_vpmsum
  82  * does not gracefully handle the case where the data pointer is NULL.  There
  83  * may be room for performance improvement here.
  84  */
  85 uint32_t ceph_crc32c_ppc(uint32_t crc, unsigned char const *data, unsigned len)
  86 {
  87   unsigned char *buf2;
  88
  89   if (!data) {
  90     buf2 = malloc(len);
  91     bzero(buf2, len);
  92     crc = crc32_vpmsum(crc, buf2, len);
  93     free(buf2);
  94   } else {
  95     crc = crc32_vpmsum(crc, data, (unsigned long)len);
  96   }
  97   return crc;
  98 }
  99
 100 #else /* HAVE_POWER8 */
 101
 102 /* This symbol has to exist on non-ppc architectures (and on legacy
 103  * ppc systems using power7 or below) in order to compile properly
 104  * there, even though it won't be called.
 105  */
 106 uint32_t ceph_crc32c_ppc(uint32_t crc, unsigned char const *data, unsigned len)
 107 {
 108   return 0;
 109 }
 110
 111 #endif /* HAVE_POWER8 */