pg_crc32c_armv8.c

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/*-------------------------------------------------------------------------
 *
 * pg_crc32c_armv8.c
 *    Compute CRC-32C checksum using ARMv8 CRC Extension instructions
 *
 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/port/pg_crc32c_armv8.c
 *
 *-------------------------------------------------------------------------
 */
#include "c.h"
 
#include <arm_acle.h>
 
#include "port/pg_crc32c.h"
 
pg_crc32c
pg_comp_crc32c_armv8(pg_crc32c crc, const void *data, size_t len)
{
    const unsigned char *p = data;
    const unsigned char *pend = p + len;
 
    /*
     * ARMv8 doesn't require alignment, but aligned memory access is
     * significantly faster. Process leading bytes so that the loop below
     * starts with a pointer aligned to eight bytes.
     */
    if (!PointerIsAligned(p, uint16) &&
        p + 1 <= pend)
    {
        crc = __crc32cb(crc, *p);
        p += 1;
    }
    if (!PointerIsAligned(p, uint32) &&
        p + 2 <= pend)
    {
        crc = __crc32ch(crc, *(uint16 *) p);
        p += 2;
    }
    if (!PointerIsAligned(p, uint64) &&
        p + 4 <= pend)
    {
        crc = __crc32cw(crc, *(uint32 *) p);
        p += 4;
    }
 
    /* Process eight bytes at a time, as far as we can. */
    while (p + 8 <= pend)
    {
        crc = __crc32cd(crc, *(uint64 *) p);
        p += 8;
    }
 
    /* Process remaining 0-7 bytes. */
    if (p + 4 <= pend)
    {
        crc = __crc32cw(crc, *(uint32 *) p);
        p += 4;
    }
    if (p + 2 <= pend)
    {
        crc = __crc32ch(crc, *(uint16 *) p);
        p += 2;
    }
    if (p < pend)
    {
        crc = __crc32cb(crc, *p);
    }
 
    return crc;
}