diff --git a/flight/OpenPilot/UAVTalk/uavtalk.c b/flight/OpenPilot/UAVTalk/uavtalk.c index 0ace34da1..b7279a07a 100644 --- a/flight/OpenPilot/UAVTalk/uavtalk.c +++ b/flight/OpenPilot/UAVTalk/uavtalk.c @@ -36,10 +36,30 @@ #define TYPE_ACK (TYPE_VER | 0x03) #define HEADER_LENGTH 7 // type (1), object ID (4), instance ID (2, not used in single objects) -#define CHECKSUM_LENGTH 2 +#define CHECKSUM_LENGTH 1 #define MAX_PAYLOAD_LENGTH 256 #define MAX_PACKET_LENGTH (HEADER_LENGTH+MAX_PAYLOAD_LENGTH+CHECKSUM_LENGTH) +// CRC lookup table +static const uint8_t crc_table[256] = { + 0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15, 0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d, + 0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65, 0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d, + 0xe0, 0xe7, 0xee, 0xe9, 0xfc, 0xfb, 0xf2, 0xf5, 0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd, + 0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85, 0xa8, 0xaf, 0xa6, 0xa1, 0xb4, 0xb3, 0xba, 0xbd, + 0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2, 0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea, + 0xb7, 0xb0, 0xb9, 0xbe, 0xab, 0xac, 0xa5, 0xa2, 0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a, + 0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32, 0x1f, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0d, 0x0a, + 0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42, 0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a, + 0x89, 0x8e, 0x87, 0x80, 0x95, 0x92, 0x9b, 0x9c, 0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4, + 0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec, 0xc1, 0xc6, 0xcf, 0xc8, 0xdd, 0xda, 0xd3, 0xd4, + 0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c, 0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44, + 0x19, 0x1e, 0x17, 0x10, 0x05, 0x02, 0x0b, 0x0c, 0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34, + 0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b, 0x76, 0x71, 0x78, 0x7f, 0x6a, 0x6d, 0x64, 0x63, + 0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b, 0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13, + 0xae, 0xa9, 0xa0, 0xa7, 0xb2, 0xb5, 0xbc, 0xbb, 0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8d, 0x84, 0x83, + 0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb, 0xe6, 0xe1, 0xe8, 0xef, 0xfa, 0xfd, 0xf4, 0xf3 +}; + // Private types typedef enum {STATE_SYNC, STATE_OBJID, STATE_INSTID, STATE_DATA, STATE_CS} RxState; @@ -55,7 +75,7 @@ static uint8_t txBuffer[MAX_PACKET_LENGTH]; static UAVTalkStats stats; // Private functions -static uint16_t updateChecksum(uint16_t cs, uint8_t* data, int32_t length); +static uint8_t updateCRC(uint8_t crc, const uint8_t* data, int32_t length); static int32_t objectTransaction(uint32_t objectId, uint16_t instId, uint8_t type, int32_t timeout); static int32_t sendObject(UAVObjHandle obj, uint16_t instId, uint8_t type); static int32_t sendSingleObject(UAVObjHandle obj, uint16_t instId, uint8_t type); @@ -218,7 +238,7 @@ int32_t UAVTalkProcessInputStream(uint8_t rxbyte) static uint32_t objId; static uint16_t instId; static uint32_t length; - static uint16_t cs, csRx; + static uint8_t cs, csRx; static int32_t rxCount; static RxState state = STATE_SYNC; @@ -228,7 +248,7 @@ int32_t UAVTalkProcessInputStream(uint8_t rxbyte) case STATE_SYNC: if ((rxbyte & TYPE_MASK) == TYPE_VER ) { - cs = rxbyte; + cs = updateCRC(0, &rxbyte, 1); type = rxbyte; state = STATE_OBJID; rxCount = 0; @@ -249,7 +269,7 @@ int32_t UAVTalkProcessInputStream(uint8_t rxbyte) else { // Update checksum - cs = updateChecksum(cs, tmpBuffer, 4); + cs = updateCRC(cs, tmpBuffer, 4); // Determine data length if (type == TYPE_OBJ_REQ || type == TYPE_ACK) { @@ -296,7 +316,7 @@ int32_t UAVTalkProcessInputStream(uint8_t rxbyte) if (rxCount == 2) { instId = (tmpBuffer[1] << 8) | (tmpBuffer[0]); - cs = updateChecksum(cs, tmpBuffer, 2); + cs = updateCRC(cs, tmpBuffer, 2); rxCount = 0; // If there is a payload get it, otherwise receive checksum if (length > 0) @@ -313,30 +333,26 @@ int32_t UAVTalkProcessInputStream(uint8_t rxbyte) rxBuffer[rxCount++] = rxbyte; if (rxCount == length) { - cs = updateChecksum(cs, rxBuffer, length); + cs = updateCRC(cs, rxBuffer, length); state = STATE_CS; rxCount = 0; } break; case STATE_CS: - tmpBuffer[rxCount++] = rxbyte; - if (rxCount == 2) + csRx = rxbyte; + if (csRx == cs) { - csRx = (tmpBuffer[1] << 8) | (tmpBuffer[0]); - if (csRx == cs) - { - xSemaphoreTakeRecursive(lock, portMAX_DELAY); - receiveObject(type, obj, instId, rxBuffer, length); - ++stats.rxObjects; - stats.rxObjectBytes += length; - xSemaphoreGiveRecursive(lock); - } - else - { - ++stats.rxErrors; - } - state = STATE_SYNC; + xSemaphoreTakeRecursive(lock, portMAX_DELAY); + receiveObject(type, obj, instId, rxBuffer, length); + ++stats.rxObjects; + stats.rxObjectBytes += length; + xSemaphoreGiveRecursive(lock); } + else + { + ++stats.rxErrors; + } + state = STATE_SYNC; break; default: state = STATE_SYNC; @@ -502,7 +518,6 @@ static int32_t sendSingleObject(UAVObjHandle obj, uint16_t instId, uint8_t type) { int32_t length; int32_t dataOffset; - uint16_t cs = 0; uint32_t objId; // Setup type and object id fields @@ -551,10 +566,7 @@ static int32_t sendSingleObject(UAVObjHandle obj, uint16_t instId, uint8_t type) } // Calculate checksum - cs = 0; - cs = updateChecksum(cs, txBuffer, dataOffset+length); - txBuffer[dataOffset+length] = (uint8_t)(cs & 0xFF); - txBuffer[dataOffset+length+1] = (uint8_t)((cs >> 8) & 0xFF); + txBuffer[dataOffset+length] = updateCRC(0, txBuffer, dataOffset+length); // Send buffer if (outStream!=NULL) (*outStream)(txBuffer, dataOffset+length+CHECKSUM_LENGTH); @@ -569,25 +581,35 @@ static int32_t sendSingleObject(UAVObjHandle obj, uint16_t instId, uint8_t type) } /** - * Update checksum. - * TODO: Replace with CRC-16 - * \param[in] data Data buffer to update checksum on - * \param[in] length Length of buffer - * \return Updated checksum + * Update the crc value with new data. + * + * Generated by pycrc v0.7.5, http://www.tty1.net/pycrc/ + * using the configuration: + * Width = 8 + * Poly = 0x07 + * XorIn = 0x00 + * ReflectIn = False + * XorOut = 0x00 + * ReflectOut = False + * Algorithm = table-driven + * + * \param crc The current crc value. + * \param data Pointer to a buffer of \a data_len bytes. + * \param length Number of bytes in the \a data buffer. + * \return The updated crc value. */ -static uint16_t updateChecksum(uint16_t cs, uint8_t* data, int32_t length) +static uint8_t updateCRC(uint8_t crc, const uint8_t* data, int32_t length) { - int32_t n; - for (n = 0; n < length; ++n) - { - cs += (uint16_t)data[n]; + uint32_t tbl_idx; + + while (length--) { + tbl_idx = ((crc >> 0) ^ *data) & 0xff; + crc = (crc_table[tbl_idx] ^ (crc << 8)) & 0xff; + data++; } - return cs; + return crc; } - - -