39 lines
1.1 KiB
C++
39 lines
1.1 KiB
C++
// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <stdint.h>
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#include <stdbool.h>
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extern "C" unsigned long crc32_le(unsigned long crc_in, unsigned char const* data, unsigned int length)
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{
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uint32_t i;
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bool bit;
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uint8_t c;
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uint32_t crc = (uint32_t) crc_in;
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while (length--) {
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c = *data++;
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for (i = 0x80; i > 0; i >>= 1) {
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bit = crc & 0x80000000;
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if (c & i) {
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bit = !bit;
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}
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crc <<= 1;
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if (bit) {
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crc ^= 0x04c11db7;
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}
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}
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}
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return crc;
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}
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