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/*-
* Public Domain 2014-2019 MongoDB, Inc.
* Public Domain 2008-2014 WiredTiger, Inc.
*
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include <wiredtiger_config.h>
#include <inttypes.h>
#include <stddef.h>
#if defined(__linux__) && !defined(HAVE_NO_CRC32_HARDWARE)
#include <asm/hwcap.h>
#include <sys/auxv.h>
#ifndef __GNUC__
#define __asm__ asm
#endif
#define CRC32CX(crc,value) \
__asm__("crc32cx %w[c], %w[c], %x[v]" : [c]"+r"(*&crc) : [v]"r"(+value))
#define CRC32CW(crc,value) \
__asm__("crc32cw %w[c], %w[c], %w[v]" : [c]"+r"(*&crc) : [v]"r"(+value))
#define CRC32CH(crc,value) \
__asm__("crc32ch %w[c], %w[c], %w[v]" : [c]"+r"(*&crc) : [v]"r"(+value))
#define CRC32CB(crc,value) \
__asm__("crc32cb %w[c], %w[c], %w[v]" : [c]"+r"(*&crc) : [v]"r"(+value))
/*
* __wt_checksum_hw --
* Return a checksum for a chunk of memory, computed in hardware
* using 8 byte steps.
*/
static uint32_t
__wt_checksum_hw(const void *chunk, size_t len)
{
uint32_t crc;
size_t nqwords;
const uint8_t *p;
const uint64_t *p64;
crc = 0xffffffff;
/* Checksum one byte at a time to the first 4B boundary. */
for (p = chunk;
((uintptr_t)p & (sizeof(uint32_t) - 1)) != 0 &&
len > 0; ++p, --len) {
CRC32CB(crc, *p);
}
p64 = (const uint64_t *)p;
/* Checksum in 8B chunks. */
for (nqwords = len / sizeof(uint64_t); nqwords; nqwords--) {
CRC32CX(crc, *p64);
p64++;
}
/* Checksum trailing bytes one byte at a time. */
p = (const uint8_t *)p64;
for (len &= 0x7; len > 0; ++p, len--) {
CRC32CB(crc, *p);
}
return (~crc);
}
#endif
extern uint32_t __wt_checksum_sw(const void *chunk, size_t len);
#if defined(__GNUC__)
extern uint32_t (*wiredtiger_crc32c_func(void))(const void *, size_t)
__attribute__((visibility("default")));
#else
extern uint32_t (*wiredtiger_crc32c_func(void))(const void *, size_t);
#endif
/*
* wiredtiger_crc32c_func --
* WiredTiger: detect CRC hardware and return the checksum function.
*/
uint32_t (*wiredtiger_crc32c_func(void))(const void *, size_t)
{
#if defined(__linux__) && !defined(HAVE_NO_CRC32_HARDWARE)
unsigned long caps = getauxval(AT_HWCAP);
if (caps & HWCAP_CRC32)
return (__wt_checksum_hw);
return (__wt_checksum_sw);
#else
return (__wt_checksum_sw);
#endif
}
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