checksum.c

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/*-------------------------------------------------------------------------
 *
 * checksum.c
 *    Checksum implementation for data pages.
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/storage/page/checksum.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "port/pg_cpu.h"
#include "storage/checksum.h"
/*
 * The actual code is in storage/checksum_impl.h.  This is done so that
 * external programs can incorporate the checksum code by #include'ing
 * that file from the exported Postgres headers.  (Compare our legacy
 * CRC code in pg_crc.h.)
 * The PG_CHECKSUM_INTERNAL symbol allows core to use hardware-specific
 * coding without affecting external programs.
 */
#define PG_CHECKSUM_INTERNAL
#include "storage/checksum_impl.h"  /* IWYU pragma: keep */
 
 
static uint32
pg_checksum_block_fallback(const PGChecksummablePage *page)
{
#include "storage/checksum_block_internal.h"
}
 
/*
 * AVX2-optimized block checksum algorithm.
 */
#ifdef USE_AVX2_WITH_RUNTIME_CHECK
pg_attribute_target("avx2")
static uint32
pg_checksum_block_avx2(const PGChecksummablePage *page)
{
#include "storage/checksum_block_internal.h"
}
#endif                          /* USE_AVX2_WITH_RUNTIME_CHECK */
 
/*
 * Choose the best available checksum implementation.
 */
static uint32
pg_checksum_choose(const PGChecksummablePage *page)
{
    pg_checksum_block = pg_checksum_block_fallback;
 
#ifdef USE_AVX2_WITH_RUNTIME_CHECK
    if (x86_feature_available(PG_AVX2))
        pg_checksum_block = pg_checksum_block_avx2;
#endif
 
    return pg_checksum_block(page);
}
 
static uint32 (*pg_checksum_block) (const PGChecksummablePage *page) = pg_checksum_choose;