1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72
|
#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 */
|