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OP-4 Flight/Telemetry Implement CRC in telemetry protocol
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@549 ebee16cc-31ac-478f-84a7-5cbb03baadba
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vassilis
vassilis
parent
2dc193ae5a
commit
613b17f970
@ -36,10 +36,30 @@
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#define TYPE_ACK (TYPE_VER | 0x03)
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#define HEADER_LENGTH 7 // type (1), object ID (4), instance ID (2, not used in single objects)
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#define CHECKSUM_LENGTH 2
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#define CHECKSUM_LENGTH 1
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#define MAX_PAYLOAD_LENGTH 256
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#define MAX_PACKET_LENGTH (HEADER_LENGTH+MAX_PAYLOAD_LENGTH+CHECKSUM_LENGTH)
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// CRC lookup table
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static const uint8_t crc_table[256] = {
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0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15, 0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d,
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0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65, 0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d,
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0xe0, 0xe7, 0xee, 0xe9, 0xfc, 0xfb, 0xf2, 0xf5, 0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd,
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0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85, 0xa8, 0xaf, 0xa6, 0xa1, 0xb4, 0xb3, 0xba, 0xbd,
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0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2, 0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea,
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0xb7, 0xb0, 0xb9, 0xbe, 0xab, 0xac, 0xa5, 0xa2, 0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a,
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0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32, 0x1f, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0d, 0x0a,
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0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42, 0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a,
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0x89, 0x8e, 0x87, 0x80, 0x95, 0x92, 0x9b, 0x9c, 0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4,
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0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec, 0xc1, 0xc6, 0xcf, 0xc8, 0xdd, 0xda, 0xd3, 0xd4,
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0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c, 0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44,
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0x19, 0x1e, 0x17, 0x10, 0x05, 0x02, 0x0b, 0x0c, 0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34,
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0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b, 0x76, 0x71, 0x78, 0x7f, 0x6a, 0x6d, 0x64, 0x63,
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0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b, 0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13,
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0xae, 0xa9, 0xa0, 0xa7, 0xb2, 0xb5, 0xbc, 0xbb, 0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8d, 0x84, 0x83,
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0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb, 0xe6, 0xe1, 0xe8, 0xef, 0xfa, 0xfd, 0xf4, 0xf3
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};
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// Private types
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typedef enum {STATE_SYNC, STATE_OBJID, STATE_INSTID, STATE_DATA, STATE_CS} RxState;
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@ -55,7 +75,7 @@ static uint8_t txBuffer[MAX_PACKET_LENGTH];
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static UAVTalkStats stats;
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// Private functions
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static uint16_t updateChecksum(uint16_t cs, uint8_t* data, int32_t length);
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static uint8_t updateCRC(uint8_t crc, const uint8_t* data, int32_t length);
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static int32_t objectTransaction(uint32_t objectId, uint16_t instId, uint8_t type, int32_t timeout);
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static int32_t sendObject(UAVObjHandle obj, uint16_t instId, uint8_t type);
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static int32_t sendSingleObject(UAVObjHandle obj, uint16_t instId, uint8_t type);
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@ -218,7 +238,7 @@ int32_t UAVTalkProcessInputStream(uint8_t rxbyte)
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static uint32_t objId;
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static uint16_t instId;
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static uint32_t length;
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static uint16_t cs, csRx;
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static uint8_t cs, csRx;
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static int32_t rxCount;
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static RxState state = STATE_SYNC;
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@ -228,7 +248,7 @@ int32_t UAVTalkProcessInputStream(uint8_t rxbyte)
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case STATE_SYNC:
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if ((rxbyte & TYPE_MASK) == TYPE_VER )
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{
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cs = rxbyte;
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cs = updateCRC(0, &rxbyte, 1);
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type = rxbyte;
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state = STATE_OBJID;
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rxCount = 0;
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@ -249,7 +269,7 @@ int32_t UAVTalkProcessInputStream(uint8_t rxbyte)
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else
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{
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// Update checksum
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cs = updateChecksum(cs, tmpBuffer, 4);
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cs = updateCRC(cs, tmpBuffer, 4);
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// Determine data length
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if (type == TYPE_OBJ_REQ || type == TYPE_ACK)
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{
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@ -296,7 +316,7 @@ int32_t UAVTalkProcessInputStream(uint8_t rxbyte)
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if (rxCount == 2)
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{
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instId = (tmpBuffer[1] << 8) | (tmpBuffer[0]);
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cs = updateChecksum(cs, tmpBuffer, 2);
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cs = updateCRC(cs, tmpBuffer, 2);
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rxCount = 0;
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// If there is a payload get it, otherwise receive checksum
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if (length > 0)
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@ -313,30 +333,26 @@ int32_t UAVTalkProcessInputStream(uint8_t rxbyte)
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rxBuffer[rxCount++] = rxbyte;
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if (rxCount == length)
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{
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cs = updateChecksum(cs, rxBuffer, length);
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cs = updateCRC(cs, rxBuffer, length);
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state = STATE_CS;
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rxCount = 0;
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}
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break;
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case STATE_CS:
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tmpBuffer[rxCount++] = rxbyte;
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if (rxCount == 2)
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csRx = rxbyte;
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if (csRx == cs)
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{
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csRx = (tmpBuffer[1] << 8) | (tmpBuffer[0]);
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if (csRx == cs)
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{
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xSemaphoreTakeRecursive(lock, portMAX_DELAY);
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receiveObject(type, obj, instId, rxBuffer, length);
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++stats.rxObjects;
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stats.rxObjectBytes += length;
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xSemaphoreGiveRecursive(lock);
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}
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else
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{
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++stats.rxErrors;
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}
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state = STATE_SYNC;
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xSemaphoreTakeRecursive(lock, portMAX_DELAY);
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receiveObject(type, obj, instId, rxBuffer, length);
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++stats.rxObjects;
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stats.rxObjectBytes += length;
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xSemaphoreGiveRecursive(lock);
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}
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else
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{
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++stats.rxErrors;
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}
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state = STATE_SYNC;
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break;
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default:
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state = STATE_SYNC;
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@ -502,7 +518,6 @@ static int32_t sendSingleObject(UAVObjHandle obj, uint16_t instId, uint8_t type)
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{
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int32_t length;
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int32_t dataOffset;
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uint16_t cs = 0;
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uint32_t objId;
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// Setup type and object id fields
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@ -551,10 +566,7 @@ static int32_t sendSingleObject(UAVObjHandle obj, uint16_t instId, uint8_t type)
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}
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// Calculate checksum
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cs = 0;
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cs = updateChecksum(cs, txBuffer, dataOffset+length);
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txBuffer[dataOffset+length] = (uint8_t)(cs & 0xFF);
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txBuffer[dataOffset+length+1] = (uint8_t)((cs >> 8) & 0xFF);
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txBuffer[dataOffset+length] = updateCRC(0, txBuffer, dataOffset+length);
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// Send buffer
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if (outStream!=NULL) (*outStream)(txBuffer, dataOffset+length+CHECKSUM_LENGTH);
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@ -569,25 +581,35 @@ static int32_t sendSingleObject(UAVObjHandle obj, uint16_t instId, uint8_t type)
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}
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/**
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* Update checksum.
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* TODO: Replace with CRC-16
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* \param[in] data Data buffer to update checksum on
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* \param[in] length Length of buffer
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* \return Updated checksum
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* Update the crc value with new data.
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*
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* Generated by pycrc v0.7.5, http://www.tty1.net/pycrc/
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* using the configuration:
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* Width = 8
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* Poly = 0x07
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* XorIn = 0x00
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* ReflectIn = False
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* XorOut = 0x00
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* ReflectOut = False
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* Algorithm = table-driven
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*
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* \param crc The current crc value.
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* \param data Pointer to a buffer of \a data_len bytes.
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* \param length Number of bytes in the \a data buffer.
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* \return The updated crc value.
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*/
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static uint16_t updateChecksum(uint16_t cs, uint8_t* data, int32_t length)
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static uint8_t updateCRC(uint8_t crc, const uint8_t* data, int32_t length)
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{
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int32_t n;
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for (n = 0; n < length; ++n)
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{
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cs += (uint16_t)data[n];
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uint32_t tbl_idx;
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while (length--) {
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tbl_idx = ((crc >> 0) ^ *data) & 0xff;
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crc = (crc_table[tbl_idx] ^ (crc << 8)) & 0xff;
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data++;
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}
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return cs;
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return crc;
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}
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