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Move RF CRC16-DNP to bits.cpp

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This commit is contained in:
Nanosonde 2020-11-10 10:31:35 +01:00
parent 08cc2fff11
commit 108927cd15
4 changed files with 28 additions and 28 deletions
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21
src/knx/bits.cpp
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@ -135,3 +135,24 @@ uint16_t crc16Ccitt(uint8_t* input, uint16_t length)
}
return result & 0xffff;
}
uint16_t crc16Dnp(uint8_t* input, uint16_t length)
{
// CRC-16-DNP
// generator polynomial = 2^16 + 2^13 + 2^12 + 2^11 + 2^10 + 2^8 + 2^6 + 2^5 + 2^2 + 2^0
uint32_t pn = 0x13d65; // 1 0011 1101 0110 0101
// for much data, using a lookup table would be a way faster CRC calculation
uint32_t crc = 0;
for (uint32_t i = 0; i < length; i++) {
uint8_t bite = input[i] & 0xff;
for (uint8_t b = 8; b --> 0;) {
bool bit = ((bite >> b) & 1) == 1;
bool one = (crc >> 15 & 1) == 1;
crc <<= 1;
if (one ^ bit)
crc ^= pn;
}
}
return (~crc) & 0xffff;
}

1
src/knx/bits.h
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@ -94,3 +94,4 @@ void sixBytesFromUInt64(uint64_t num, uint8_t* toByteArray);
uint64_t sixBytesToUInt64(uint8_t* data);
uint16_t crc16Ccitt(uint8_t* input, uint16_t length);
uint16_t crc16Dnp(uint8_t* input, uint16_t length);

33
src/knx/rf_data_link_layer.cpp
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@ -85,27 +85,6 @@ RfDataLinkLayer::RfDataLinkLayer(DeviceObject& devObj, RfMediumObject& rfMediumO
{
}
uint16_t RfDataLinkLayer::calcCrcRF(uint8_t* buffer, uint32_t offset, uint32_t len)
{
// CRC-16-DNP
// generator polynomial = 2^16 + 2^13 + 2^12 + 2^11 + 2^10 + 2^8 + 2^6 + 2^5 + 2^2 + 2^0
uint32_t pn = 0x13d65; // 1 0011 1101 0110 0101
// for much data, using a lookup table would be a way faster CRC calculation
uint32_t crc = 0;
for (uint32_t i = offset; i < offset + len; i++) {
uint8_t bite = buffer[i] & 0xff;
for (uint8_t b = 8; b --> 0;) {
bool bit = ((bite >> b) & 1) == 1;
bool one = (crc >> 15 & 1) == 1;
crc <<= 1;
if (one ^ bit)
crc ^= pn;
}
}
return (~crc) & 0xffff;
}
void RfDataLinkLayer::frameBytesReceived(uint8_t* rfPacketBuf, uint16_t length)
{
// RF data link layer frame format
@ -128,7 +107,7 @@ void RfDataLinkLayer::frameBytesReceived(uint8_t* rfPacketBuf, uint16_t length)
// The first block basically contains the RF-info field and the KNX SN/Domain address.
if ((rfPacketBuf[1] == 0x44) &&
(rfPacketBuf[2] == 0xFF) &&
(calcCrcRF(rfPacketBuf, 0, 10) == block1Crc))
(crc16Dnp(rfPacketBuf, 10) == block1Crc))
{
// bytes left from the remaining block(s)
uint16_t bytesLeft = length - 12;
@ -151,7 +130,7 @@ void RfDataLinkLayer::frameBytesReceived(uint8_t* rfPacketBuf, uint16_t length)
{
// Get CRC16 from end of the block
blockCrc = pRfPacketBuf[16] << 8 | pRfPacketBuf[17];
if (calcCrcRF(pRfPacketBuf, 0, 16) == blockCrc)
if (crc16Dnp(pRfPacketBuf, 16) == blockCrc)
{
// Copy only the payload without the checksums
memcpy(pBuffer, pRfPacketBuf, 16);
@ -169,7 +148,7 @@ void RfDataLinkLayer::frameBytesReceived(uint8_t* rfPacketBuf, uint16_t length)
// Now process the last block
blockCrc = pRfPacketBuf[bytesLeft - 2] << 8 | pRfPacketBuf[bytesLeft - 1];
crcOk = crcOk && (calcCrcRF(&pRfPacketBuf[0], 0, bytesLeft -2) == blockCrc);
crcOk = crcOk && (crc16Dnp(&pRfPacketBuf[0], bytesLeft -2) == blockCrc);
// If all checksums were ok, then...
if (crcOk)
@ -290,7 +269,7 @@ void RfDataLinkLayer::fillRfFrame(CemiFrame& frame, uint8_t* data)
// Generate CRC16-DNP over the first block of data
pushByteArray(frame.rfSerialOrDoA(), 6, &data[4]);
crc = calcCrcRF(&data[0], 0, 10);
crc = crc16Dnp(&data[0], 10);
pushWord(crc, &data[10]);
// Put the complete KNX telegram into a temporary buffer
@ -304,7 +283,7 @@ void RfDataLinkLayer::fillRfFrame(CemiFrame& frame, uint8_t* data)
while (bytesLeft > 16)
{
memcpy(pData, pBuffer, 16);
crc = calcCrcRF(pData, 0, 16);
crc = crc16Dnp(pData, 16);
pushWord(crc, &pData[16]);
pBuffer += 16;
@ -315,7 +294,7 @@ void RfDataLinkLayer::fillRfFrame(CemiFrame& frame, uint8_t* data)
// Copy remaining bytes of last block. Could be less than 16 bytes
memcpy(pData, pBuffer, bytesLeft);
// And add last CRC
crc = calcCrcRF(pData, 0, bytesLeft);
crc = crc16Dnp(pData, bytesLeft);
pushWord(crc, &pData[bytesLeft]);
}

1
src/knx/rf_data_link_layer.h
View File

@ -62,7 +62,6 @@ class RfDataLinkLayer : public DataLinkLayer
void loadNextTxFrame(uint8_t** sendBuffer, uint16_t* sendBufferLength);
bool sendFrame(CemiFrame& frame);
void frameBytesReceived(uint8_t* buffer, uint16_t length);
uint16_t calcCrcRF(uint8_t* buffer, uint32_t offset, uint32_t len);
};
#endif