4 * Based on a posting to lkml by Austin Zhang <austin.zhang@intel.com>
6 * Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
7 * CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
8 * CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
9 * http://www.intel.com/products/processor/manuals/
10 * Intel(R) 64 and IA-32 Architectures Software Developer's Manual
11 * Volume 2A: Instruction Set Reference, A-M
14 bool crc32c_intel_available = false;
16 #ifdef ARCH_HAVE_SSE4_2
18 #if BITS_PER_LONG == 64
19 #define REX_PRE "0x48, "
26 static bool crc32c_probed;
28 static uint32_t crc32c_intel_le_hw_byte(uint32_t crc, unsigned char const *data,
33 ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
44 * Steps through buffer one byte at at time, calculates reflected
47 uint32_t crc32c_intel(unsigned char const *data, unsigned long length)
49 unsigned int iquotient = length / SCALE_F;
50 unsigned int iremainder = length % SCALE_F;
51 #if BITS_PER_LONG == 64
52 uint64_t *ptmp = (uint64_t *) data;
54 uint32_t *ptmp = (uint32_t *) data;
60 ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
68 crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
74 void crc32c_intel_probe(void)
77 unsigned int eax, ebx, ecx = 0, edx;
81 do_cpuid(&eax, &ebx, &ecx, &edx);
82 crc32c_intel_available = (ecx & (1 << 20)) != 0;
87 #endif /* ARCH_HAVE_SSE4_2 */