/*------------------------------------------------------------------------- * * pg_crc32c_sse42.c * Compute CRC-32C checksum using Intel SSE 4.2 instructions. * * Portions Copyright (c) 1996-2023, 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 #include "port/pg_crc32c.h" pg_attribute_no_sanitize_alignment() 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; }