GY-63_MS5611/libraries/CRC/CRC32.cpp
2021-04-07 13:31:22 +02:00

105 lines
1.7 KiB
C++

//
// FILE: CRC32.cpp
// AUTHOR: Rob Tillaart
// PURPOSE: Arduino class for CRC32;
// URL: https://github.com/RobTillaart/CRC
#include "CRC32.h"
CRC32::CRC32()
{
reset();
}
void CRC32::reset()
{
_polynome = CRC32_DEFAULT_POLYNOME;
_startMask = 0;
_endMask = 0;
_crc = 0;
_reverseIn = false;
_reverseOut = false;
_started = false;
_count = 0;
}
void CRC32::restart()
{
_started = true;
_crc = _startMask;
_count = 0;
}
void CRC32::add(uint8_t value)
{
_count++;
_update(value);
}
void CRC32::add(uint8_t * array, uint32_t length)
{
_count += length;
while (length--)
{
yield();
_update(*array++);
}
}
uint32_t CRC32::getCRC()
{
uint32_t rv = _crc;
if (_reverseOut) rv = _reverse(rv);
rv ^=_endMask;
return rv;
}
void CRC32::_update(uint8_t value)
{
if (!_started) restart();
if (_reverseIn) value = _reverse8(value);
_crc ^= ((uint32_t)value) << 24;;
for (uint8_t i = 8; i; i--)
{
if (_crc & (1UL << 31))
{
_crc <<= 1;
_crc ^= _polynome;
}
else
{
_crc <<= 1;
}
}
}
uint32_t CRC32::_reverse(uint32_t in)
{
uint32_t x = in;
x = (((x & 0xAAAAAAAA) >> 1) | ((x & 0x55555555) << 1));
x = (((x & 0xCCCCCCCC) >> 2) | ((x & 0x33333333) << 2));
x = (((x & 0xF0F0F0F0) >> 4) | ((x & 0x0F0F0F0F) << 4));
x = (((x & 0xFF00FF00) >> 8) | ((x & 0x00FF00FF) << 8));
x = (x >> 16) | (x << 16);
return x;
}
uint8_t CRC32::_reverse8(uint8_t in)
{
uint8_t x = in;
x = (((x & 0xAA) >> 1) | ((x & 0x55) << 1));
x = (((x & 0xCC) >> 2) | ((x & 0x33) << 2));
x = ((x >> 4) | (x << 4));
return x;
}
// -- END OF FILE --