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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
tree | f435a8308119effd964b339f76abb83a57c29483 /third_party/libwebrtc/rtc_base/crc32.cc | |
parent | Initial commit. (diff) | |
download | firefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz firefox-26a029d407be480d791972afb5975cf62c9360a6.zip |
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/libwebrtc/rtc_base/crc32.cc')
-rw-r--r-- | third_party/libwebrtc/rtc_base/crc32.cc | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/third_party/libwebrtc/rtc_base/crc32.cc b/third_party/libwebrtc/rtc_base/crc32.cc new file mode 100644 index 0000000000..42f86cb268 --- /dev/null +++ b/third_party/libwebrtc/rtc_base/crc32.cc @@ -0,0 +1,50 @@ +/* + * Copyright 2012 The WebRTC Project Authors. All rights reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + +#include "rtc_base/crc32.h" + +#include "rtc_base/arraysize.h" + +namespace rtc { + +// This implementation is based on the sample implementation in RFC 1952. + +// CRC32 polynomial, in reversed form. +// See RFC 1952, or http://en.wikipedia.org/wiki/Cyclic_redundancy_check +static const uint32_t kCrc32Polynomial = 0xEDB88320; + +static uint32_t* LoadCrc32Table() { + static uint32_t kCrc32Table[256]; + for (uint32_t i = 0; i < arraysize(kCrc32Table); ++i) { + uint32_t c = i; + for (size_t j = 0; j < 8; ++j) { + if (c & 1) { + c = kCrc32Polynomial ^ (c >> 1); + } else { + c >>= 1; + } + } + kCrc32Table[i] = c; + } + return kCrc32Table; +} + +uint32_t UpdateCrc32(uint32_t start, const void* buf, size_t len) { + static uint32_t* kCrc32Table = LoadCrc32Table(); + + uint32_t c = start ^ 0xFFFFFFFF; + const uint8_t* u = static_cast<const uint8_t*>(buf); + for (size_t i = 0; i < len; ++i) { + c = kCrc32Table[(c ^ u[i]) & 0xFF] ^ (c >> 8); + } + return c ^ 0xFFFFFFFF; +} + +} // namespace rtc |