crc/crc32c-intel.c

   1 #include <inttypes.h>
   2 #include "crc32c.h"
   3
   4 /*
   5  * Based on a posting to lkml by Austin Zhang <austin.zhang@intel.com>
   6  *
   7  * Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
   8  * CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
   9  * CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
  10  * http://www.intel.com/products/processor/manuals/
  11  * Intel(R) 64 and IA-32 Architectures Software Developer's Manual
  12  * Volume 2A: Instruction Set Reference, A-M
  13  */
  14
  15 #ifdef ARCH_HAVE_SSE
  16
  17 #if BITS_PER_LONG == 64
  18 #define REX_PRE "0x48, "
  19 #define SCALE_F 8
  20 #else
  21 #define REX_PRE
  22 #define SCALE_F 4
  23 #endif
  24
  25 uint32_t crc32c_intel_le_hw_byte(uint32_t crc, unsigned char const *data,
  26                                  unsigned long length)
  27 {
  28         while (length--) {
  29                 __asm__ __volatile__(
  30                         ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
  31                         :"=S"(crc)
  32                         :"0"(crc), "c"(*data)
  33                 );
  34                 data++;
  35         }
  36
  37         return crc;
  38 }
  39
  40 /*
  41  * Steps through buffer one byte at at time, calculates reflected
  42  * crc using table.
  43  */
  44 uint32_t crc32c_intel(unsigned char const *data, unsigned long length)
  45 {
  46         unsigned int iquotient = length / SCALE_F;
  47         unsigned int iremainder = length % SCALE_F;
  48 #if BITS_PER_LONG == 64
  49         uint64_t *ptmp = (uint64_t *) data;
  50 #else
  51         uint32_t *ptmp = (uint32_t *) data;
  52 #endif
  53         uint32_t crc = ~0;
  54
  55         while (iquotient--) {
  56                 __asm__ __volatile__(
  57                         ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
  58                         :"=S"(crc)
  59                         :"0"(crc), "c"(*ptmp)
  60                 );
  61                 ptmp++;
  62         }
  63
  64         if (iremainder)
  65                 crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
  66                                  iremainder);
  67
  68         return crc;
  69 }
  70
  71 #endif /* ARCH_HAVE_SSE */
  72