11 * Based on a posting to lkml by Austin Zhang <austin.zhang@intel.com>
13 * Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
14 * CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
15 * CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
16 * http://www.intel.com/products/processor/manuals/
17 * Intel(R) 64 and IA-32 Architectures Software Developer's Manual
18 * Volume 2A: Instruction Set Reference, A-M
21 #ifdef ARCH_HAVE_SSE4_2
23 #if BITS_PER_LONG == 64
24 #define REX_PRE "0x48, "
31 static uint32_t crc32c_intel_le_hw_byte(uint32_t crc, unsigned char const *data,
36 ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
47 * Steps through buffer one byte at at time, calculates reflected
50 uint32_t crc32c_intel(unsigned char const *data, unsigned long length)
52 unsigned int iquotient = length / SCALE_F;
53 unsigned int iremainder = length % SCALE_F;
54 #if BITS_PER_LONG == 64
55 uint64_t *ptmp = (uint64_t *) data;
57 uint32_t *ptmp = (uint32_t *) data;
63 ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
71 crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
77 static void do_cpuid(unsigned int *eax, unsigned int *ebx, unsigned int *ecx,
88 : "=r" (*eax), "=r" (*ebx), "=r" (*ecx), "=r" (*edx)
90 : "eax", "ebx", "ecx", "edx");
93 int crc32c_intel_works(void)
95 unsigned int eax, ebx, ecx, edx;
99 do_cpuid(&eax, &ebx, &ecx, &edx);
100 return (ecx & (1 << 20)) != 0;
103 #endif /* ARCH_HAVE_SSE */