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