mirror of https://github.com/facebook/rocksdb.git
97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
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// Copyright (c) 2017 International Business Machines Corp.
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// All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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// This source code is also licensed under the GPLv2 license found in the
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// COPYING file in the root directory of this source tree.
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#define CRC_TABLE
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#include <inttypes.h>
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#include <stdlib.h>
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#include <strings.h>
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#include "util/crc32c_ppc_constants.h"
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#define VMX_ALIGN 16
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#define VMX_ALIGN_MASK (VMX_ALIGN - 1)
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#ifdef REFLECT
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static unsigned int crc32_align(unsigned int crc, unsigned char const *p,
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unsigned long len) {
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while (len--) crc = crc_table[(crc ^ *p++) & 0xff] ^ (crc >> 8);
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return crc;
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}
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#endif
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#ifdef HAVE_POWER8
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unsigned int __crc32_vpmsum(unsigned int crc, unsigned char const *p,
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unsigned long len);
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static uint32_t crc32_vpmsum(uint32_t crc, unsigned char const *data,
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unsigned len) {
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unsigned int prealign;
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unsigned int tail;
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#ifdef CRC_XOR
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crc ^= 0xffffffff;
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#endif
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if (len < VMX_ALIGN + VMX_ALIGN_MASK) {
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crc = crc32_align(crc, data, (unsigned long)len);
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goto out;
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}
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if ((unsigned long)data & VMX_ALIGN_MASK) {
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prealign = VMX_ALIGN - ((unsigned long)data & VMX_ALIGN_MASK);
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crc = crc32_align(crc, data, prealign);
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len -= prealign;
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data += prealign;
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}
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crc = __crc32_vpmsum(crc, data, (unsigned long)len & ~VMX_ALIGN_MASK);
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tail = len & VMX_ALIGN_MASK;
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if (tail) {
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data += len & ~VMX_ALIGN_MASK;
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crc = crc32_align(crc, data, tail);
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}
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out:
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#ifdef CRC_XOR
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crc ^= 0xffffffff;
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#endif
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return crc;
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}
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/* This wrapper function works around the fact that crc32_vpmsum
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* does not gracefully handle the case where the data pointer is NULL. There
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* may be room for performance improvement here.
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*/
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uint32_t crc32c_ppc(uint32_t crc, unsigned char const *data, unsigned len) {
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unsigned char *buf2;
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if (!data) {
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buf2 = (unsigned char *)malloc(len);
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bzero(buf2, len);
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crc = crc32_vpmsum(crc, buf2, len);
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free(buf2);
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} else {
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crc = crc32_vpmsum(crc, data, (unsigned long)len);
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}
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return crc;
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}
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#else /* HAVE_POWER8 */
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/* This symbol has to exist on non-ppc architectures (and on legacy
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* ppc systems using power7 or below) in order to compile properly
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* there, even though it won't be called.
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*/
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uint32_t crc32c_ppc(uint32_t crc, unsigned char const *data, unsigned len) {
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return 0;
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}
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#endif /* HAVE_POWER8 */
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