Logo Search packages:      
Sourcecode: fio version File versions

crc32c-intel.c

#include <inttypes.h>
#include "crc32c.h"

/*
 * Based on a posting to lkml by Austin Zhang <austin.zhang@intel.com>
 *
 * Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
 * CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
 * CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
 * http://www.intel.com/products/processor/manuals/
 * Intel(R) 64 and IA-32 Architectures Software Developer's Manual
 * Volume 2A: Instruction Set Reference, A-M
 */

#ifdef ARCH_HAVE_SSE

#if BITS_PER_LONG == 64
#define REX_PRE "0x48, "
#define SCALE_F 8
#else
#define REX_PRE
#define SCALE_F 4
#endif

uint32_t crc32c_intel_le_hw_byte(uint32_t crc, unsigned char const *data,
                         unsigned long length)
{
      while (length--) {
            __asm__ __volatile__(
                  ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
                  :"=S"(crc)
                  :"0"(crc), "c"(*data)
            );
            data++;
      }

      return crc;
}

/*
 * Steps through buffer one byte at at time, calculates reflected 
 * crc using table.
 */
uint32_t crc32c_intel(unsigned char const *data, unsigned long length)
{
      unsigned int iquotient = length / SCALE_F;
      unsigned int iremainder = length % SCALE_F;
#if BITS_PER_LONG == 64
      uint64_t *ptmp = (uint64_t *) data;
#else
      uint32_t *ptmp = (uint32_t *) data;
#endif
      uint32_t crc = ~0;

      while (iquotient--) {
            __asm__ __volatile__(
                  ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
                  :"=S"(crc)
                  :"0"(crc), "c"(*ptmp)
            );
            ptmp++;
      }

      if (iremainder)
            crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
                         iremainder);

      return crc;
}

#endif /* ARCH_HAVE_SSE */


Generated by  Doxygen 1.6.0   Back to index