| /*------------------------------------------------------------------------- |
| * |
| * pg_crc32c_sse42.c |
| * Compute CRC-32C checksum using Intel SSE 4.2 instructions. |
| * |
| * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group |
| * Portions Copyright (c) 1994, Regents of the University of California |
| * |
| * |
| * IDENTIFICATION |
| * src/port/pg_crc32c_sse42.c |
| * |
| *------------------------------------------------------------------------- |
| */ |
| #include "c.h" |
| |
| #include "port/pg_crc32c.h" |
| |
| #include <nmmintrin.h> |
| |
| pg_crc32c |
| pg_comp_crc32c_sse42(pg_crc32c crc, const void *data, size_t len) |
| { |
| const unsigned char *p = data; |
| const unsigned char *pend = p + len; |
| |
| /* |
| * Process eight bytes of data at a time. |
| * |
| * NB: We do unaligned accesses here. The Intel architecture allows that, |
| * and performance testing didn't show any performance gain from aligning |
| * the begin address. |
| */ |
| #ifdef __x86_64__ |
| while (p + 8 <= pend) |
| { |
| crc = (uint32) _mm_crc32_u64(crc, *((const uint64 *) p)); |
| p += 8; |
| } |
| |
| /* Process remaining full four bytes if any */ |
| if (p + 4 <= pend) |
| { |
| crc = _mm_crc32_u32(crc, *((const unsigned int *) p)); |
| p += 4; |
| } |
| #else |
| |
| /* |
| * Process four bytes at a time. (The eight byte instruction is not |
| * available on the 32-bit x86 architecture). |
| */ |
| while (p + 4 <= pend) |
| { |
| crc = _mm_crc32_u32(crc, *((const unsigned int *) p)); |
| p += 4; |
| } |
| #endif /* __x86_64__ */ |
| |
| /* Process any remaining bytes one at a time. */ |
| while (p < pend) |
| { |
| crc = _mm_crc32_u8(crc, *p); |
| p++; |
| } |
| |
| return crc; |
| } |