projects / fio.git / blame
| Commit | Line | Data |
|---|---|---|
| 419484b9 | 1 | #include "crc32c.h" |
| 3845591f JA |
2 | |
| 3 | /* | |
| 4 | * Based on a posting to lkml by Austin Zhang <austin.zhang@intel.com> | |
| 5 | * | |
| 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 | |
| 12 | */ | |
| 13 | ||
| 97211af3 | 14 | bool crc32c_intel_available = false; |
| e3aaafc4 | 15 | |
| 2f68124f | 16 | #ifdef ARCH_HAVE_SSE4_2 |
| 419484b9 | 17 | |
| 3845591f JA |
18 | #if BITS_PER_LONG == 64 |
| 19 | #define REX_PRE "0x48, " | |
| 20 | #define SCALE_F 8 | |
| 21 | #else | |
| 22 | #define REX_PRE | |
| 23 | #define SCALE_F 4 | |
| 24 | #endif | |
| 25 | ||
| 97211af3 | 26 | static bool crc32c_probed; |
| e3aaafc4 | 27 | |
| cc62ea70 JA |
28 | static uint32_t crc32c_intel_le_hw_byte(uint32_t crc, unsigned char const *data, |
| 29 | unsigned long length) | |
| 3845591f JA |
30 | { |
| 31 | while (length--) { | |
| 32 | __asm__ __volatile__( | |
| 33 | ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1" | |
| 34 | :"=S"(crc) | |
| 35 | :"0"(crc), "c"(*data) | |
| 36 | ); | |
| 37 | data++; | |
| 38 | } | |
| 39 | ||
| 40 | return crc; | |
| 41 | } | |
| 42 | ||
| 43 | /* | |
| 44 | * Steps through buffer one byte at at time, calculates reflected | |
| 45 | * crc using table. | |
| 46 | */ | |
| 47 | uint32_t crc32c_intel(unsigned char const *data, unsigned long length) | |
| 48 | { | |
| 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; | |
| 53 | #else | |
| 54 | uint32_t *ptmp = (uint32_t *) data; | |
| 55 | #endif | |
| 56 | uint32_t crc = ~0; | |
| 57 | ||
| 58 | while (iquotient--) { | |
| 59 | __asm__ __volatile__( | |
| 60 | ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;" | |
| 61 | :"=S"(crc) | |
| 62 | :"0"(crc), "c"(*ptmp) | |
| 63 | ); | |
| 64 | ptmp++; | |
| 65 | } | |
| 66 | ||
| 67 | if (iremainder) | |
| 68 | crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp, | |
| 69 | iremainder); | |
| 70 | ||
| 71 | return crc; | |
| 72 | } | |
| 419484b9 | 73 | |
| e3aaafc4 | 74 | void crc32c_intel_probe(void) |
| 5d7c5d34 | 75 | { |
| e3aaafc4 | 76 | if (!crc32c_probed) { |
| 267339ff | 77 | unsigned int eax, ebx, ecx = 0, edx; |
| 419484b9 | 78 | |
| e3aaafc4 | 79 | eax = 1; |
| e0ab5f97 | 80 | |
| e3aaafc4 JA |
81 | do_cpuid(&eax, &ebx, &ecx, &edx); |
| 82 | crc32c_intel_available = (ecx & (1 << 20)) != 0; | |
| 97211af3 | 83 | crc32c_probed = true; |
| e3aaafc4 | 84 | } |
| 5d7c5d34 JA |
85 | } |
| 86 | ||
| 09c81e13 | 87 | #endif /* ARCH_HAVE_SSE4_2 */ |