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R=mark@chromium.org Review URL: https://breakpad.appspot.com/1644002 git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1320 4c0a9323-5329-0410-9bdc-e9ce6186880e
70 lines
2.6 KiB
C++
70 lines
2.6 KiB
C++
// Copyright 2014 Google Inc.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "common/linux/crc32.h"
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namespace google_breakpad {
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// This implementation is based on the sample implementation in RFC 1952.
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// CRC32 polynomial, in reversed form.
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// See RFC 1952, or http://en.wikipedia.org/wiki/Cyclic_redundancy_check
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static const uint32_t kCrc32Polynomial = 0xEDB88320;
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static uint32_t kCrc32Table[256] = { 0 };
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#define arraysize(f) (sizeof(f) / sizeof(*f))
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static void EnsureCrc32TableInited() {
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if (kCrc32Table[arraysize(kCrc32Table) - 1])
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return; // already inited
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for (uint32_t i = 0; i < arraysize(kCrc32Table); ++i) {
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uint32_t c = i;
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for (size_t j = 0; j < 8; ++j) {
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if (c & 1) {
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c = kCrc32Polynomial ^ (c >> 1);
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} else {
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c >>= 1;
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}
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}
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kCrc32Table[i] = c;
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}
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}
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uint32_t UpdateCrc32(uint32_t start, const void* buf, size_t len) {
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EnsureCrc32TableInited();
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uint32_t c = start ^ 0xFFFFFFFF;
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const uint8_t* u = static_cast<const uint8_t*>(buf);
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for (size_t i = 0; i < len; ++i) {
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c = kCrc32Table[(c ^ u[i]) & 0xFF] ^ (c >> 8);
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}
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return c ^ 0xFFFFFFFF;
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}
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} // namespace google_breakpad
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