isotp.cpp

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/**
 *
 * https://en.wikipedia.org/wiki/ISO_15765-2
 */
 
#include "pch.h"
#include "isotp.h"
 
#if HAL_USE_CAN || EFI_UNIT_TEST
 
int CanStreamerState::sendFrame(const IsoTpFrameHeader & header, const uint8_t *data, int num, can_sysinterval_t timeout) {
    int dlc = 8; // standard 8 bytes
    CanTxMessage txmsg(CanCategory::SERIAL, txFrameId, dlc, busIndex, IS_EXT_RANGE_ID(txFrameId));
 
    // fill the frame data according to the CAN-TP protocol (ISO 15765-2)
    txmsg[isoHeaderByteIndex] = (uint8_t)((header.frameType & 0xf) << 4);
    int offset, maxNumBytes;
    switch (header.frameType) {
    case ISO_TP_FRAME_SINGLE:
        offset = 1;
        maxNumBytes = minI(header.numBytes, dlc - offset);
        txmsg[isoHeaderByteIndex] |= maxNumBytes;
        break;
    case ISO_TP_FRAME_FIRST:
        txmsg[isoHeaderByteIndex] |= (header.numBytes >> 8) & 0xf;
        txmsg[isoHeaderByteIndex + 1] = (uint8_t)(header.numBytes & 0xff);
        offset = isoHeaderByteIndex + 2;
        maxNumBytes = minI(header.numBytes, dlc - offset);
        break;
    case ISO_TP_FRAME_CONSECUTIVE:
        txmsg[isoHeaderByteIndex] |= header.index & 0xf;
        offset = isoHeaderByteIndex + 1;
        // todo: is it correct?
        maxNumBytes = dlc - offset;
        break;
    case ISO_TP_FRAME_FLOW_CONTROL:
        txmsg[isoHeaderByteIndex] |= header.fcFlag & 0xf;
        txmsg[isoHeaderByteIndex + 1] = (uint8_t)(header.blockSize);
        txmsg[isoHeaderByteIndex + 2] = (uint8_t)(header.separationTime);
        offset = isoHeaderByteIndex + 3;
        maxNumBytes = 0;    // no data is sent with 'flow control' frame
        break;
    default:
        // bad frame type
        return 0;
    }
 
    int numBytes = minI(maxNumBytes, num);
    // copy the contents
    if (data != nullptr) {
        for (int i = 0; i < numBytes; i++) {
            txmsg[i + offset] = data[i];
        }
    }
 
    // send the frame!
    if (transport->transmit(&txmsg, timeout) == CAN_MSG_OK)
        return numBytes;
    return 0;
}
 
// returns the number of copied bytes
int CanStreamerState::receiveFrame(CANRxFrame *rxmsg, uint8_t *buf, int num, can_sysinterval_t timeout) {
    if (rxmsg == nullptr || rxmsg->DLC < 1)
        return 0;
    engine->pauseCANdueToSerial = true;
    int frameType = (rxmsg->data8[isoHeaderByteIndex] >> 4) & 0xf;
    int numBytesAvailable, frameIdx;
    uint8_t *srcBuf = rxmsg->data8;
    switch (frameType) {
    case ISO_TP_FRAME_SINGLE:
        numBytesAvailable = rxmsg->data8[isoHeaderByteIndex] & 0xf;
        srcBuf = rxmsg->data8 + 1;
        this->waitingForNumBytes = -1;
        break;
    case ISO_TP_FRAME_FIRST:
        this->waitingForNumBytes = ((rxmsg->data8[isoHeaderByteIndex] & 0xf) << 8) | rxmsg->data8[isoHeaderByteIndex + 1];
        this->waitingForFrameIndex = 1;
        numBytesAvailable = minI(this->waitingForNumBytes, 6 - isoHeaderByteIndex);
        srcBuf = rxmsg->data8 + 2 + isoHeaderByteIndex;
        break;
    case ISO_TP_FRAME_CONSECUTIVE:
        frameIdx = rxmsg->data8[isoHeaderByteIndex] & 0xf;
        if (this->waitingForNumBytes < 0 || this->waitingForFrameIndex != frameIdx) {
            // todo: that's an abnormal situation, and we probably should react?
            return 0;
        }
        numBytesAvailable = minI(this->waitingForNumBytes, 7 - isoHeaderByteIndex);
        srcBuf = rxmsg->data8 + 1 + isoHeaderByteIndex;
        this->waitingForFrameIndex = (this->waitingForFrameIndex + 1) & 0xf;
        break;
    case ISO_TP_FRAME_FLOW_CONTROL:
        // todo: currently we just ignore the FC frame
        return 0;
    default:
        // bad frame type
        return 0;
    }
 
/** performance optimization specific to TS over CAN tunnelling
TODO: refactor into child class if we ever choose to revive this logic
#if defined(TS_CAN_DEVICE_SHORT_PACKETS_IN_ONE_FRAME)
    if (frameType == ISO_TP_FRAME_SINGLE) {
        // restore the CRC on the whole packet
        uint32_t crc = crc32((void *) srcBuf, numBytesAvailable);
        // we need a separate buffer for crc because srcBuf may not be word-aligned for direct copy
        uint8_t crcBuffer[sizeof(uint32_t)];
        *(uint32_t *) (crcBuffer) = SWAP_UINT32(crc);
 
        // now set the packet size
        *(uint16_t *) shortCrcPacketStagingArea = SWAP_UINT16(numBytesAvailable);
        // copy the data
        if (numBytesAvailable > 0)
            memcpy(shortCrcPacketStagingArea + sizeof(uint16_t), srcBuf, numBytesAvailable);
        // copy the crc to the end
        memcpy(shortCrcPacketStagingArea + sizeof(uint16_t) + numBytesAvailable, crcBuffer, sizeof(crcBuffer));
 
        // use the reconstructed tmp buffer as a source buffer
        srcBuf = shortCrcPacketStagingArea;
        // we added the 16-bit size & 32-bit crc bytes
        numBytesAvailable += sizeof(uint16_t) + sizeof(crcBuffer);
    }
#endif *//* TS_CAN_DEVICE_SHORT_PACKETS_IN_ONE_FRAME */
 
    int numBytesToCopy = minI(num, numBytesAvailable);
    if (buf != nullptr) {
        memcpy(buf, srcBuf, numBytesToCopy);
    }
    srcBuf += numBytesToCopy;
    waitingForNumBytes -= numBytesAvailable;
    numBytesAvailable -= numBytesToCopy;
    // if there are some more bytes left, we save them for the next time
    for (int i = 0; i < numBytesAvailable; i++) {
        rxFifoBuf.put(srcBuf[i]);
    }
 
    // according to the specs, we need to acknowledge the received multi-frame start frame
    if (frameType == ISO_TP_FRAME_FIRST) {
        IsoTpFrameHeader header;
        header.frameType = ISO_TP_FRAME_FLOW_CONTROL;
        header.fcFlag = 0;          // = "continue to send"
        header.blockSize = 0;       // = the remaining "frames" to be sent without flow control or delay
        header.separationTime = 0;  // = wait 0 milliseconds, send immediately
        sendFrame(header, nullptr, 0, timeout);
    }
 
    return numBytesToCopy;
}
 
int CanStreamerState::sendDataTimeout(const uint8_t *txbuf, int numBytes, can_sysinterval_t timeout) {
    int offset = 0;
 
    if (engineConfiguration->verboseIsoTp) {
        PRINT("*** INFO: sendDataTimeout %d" PRINT_EOL, numBytes);
    }
 
    if (numBytes < 1)
        return 0;
 
    // 1 frame
    if (numBytes <= 7) {
        IsoTpFrameHeader header;
        header.frameType = ISO_TP_FRAME_SINGLE;
        header.numBytes = numBytes;
        return sendFrame(header, txbuf, numBytes, timeout);
    }
 
    // multiple frames
 
    // send the first header frame (FF)
    IsoTpFrameHeader header;
    header.frameType = ISO_TP_FRAME_FIRST;
    header.numBytes = numBytes;
    int numSent = sendFrame(header, txbuf + offset, numBytes, timeout);
    offset += numSent;
    numBytes -= numSent;
    int totalNumSent = numSent;
 
    // get a flow control (FC) frame
#if !EFI_UNIT_TEST // todo: add FC to unit-tests?
    CANRxFrame rxmsg;
    for (int numFcReceived = 0; ; numFcReceived++) {
        if (transport->receive(&rxmsg, timeout) != CAN_MSG_OK) {
#ifdef SERIAL_CAN_DEBUG
            PRINT("*** ERROR: CAN Flow Control frame not received" PRINT_EOL);
#endif /* SERIAL_CAN_DEBUG */
            //warning(ObdCode::CUSTOM_ERR_CAN_COMMUNICATION, "CAN Flow Control frame not received");
            return 0;
        }
        receiveFrame(&rxmsg, nullptr, 0, timeout);
        int flowStatus = rxmsg.data8[0] & 0xf;
        // if something is not ok
        if (flowStatus != CAN_FLOW_STATUS_OK) {
            // if the receiver is not ready yet and asks to wait for the next FC frame (give it 3 attempts)
            if (flowStatus == CAN_FLOW_STATUS_WAIT_MORE && numFcReceived < 3) {
                continue;
            }
#ifdef SERIAL_CAN_DEBUG
            efiPrintf("*** ERROR: CAN Flow Control mode not supported");
#endif /* SERIAL_CAN_DEBUG */
            //warning(ObdCode::CUSTOM_ERR_CAN_COMMUNICATION, "CAN Flow Control mode not supported");
            return 0;
        }
        int blockSize = rxmsg.data8[1];
        int minSeparationTime = rxmsg.data8[2];
        if (blockSize != 0 || minSeparationTime != 0) {
            // todo: process other Flow Control fields (see ISO 15765-2)
#ifdef SERIAL_CAN_DEBUG
            efiPrintf("*** ERROR: CAN Flow Control fields not supported");
#endif /* SERIAL_CAN_DEBUG */
            //warning(ObdCode::CUSTOM_ERR_CAN_COMMUNICATION, "CAN Flow Control fields not supported");
        }
        break;
    }
#endif /* EFI_UNIT_TEST */
 
    // send the rest of the data
    int idx = 1;
    while (numBytes > 0) {
        int len = minI(numBytes, 7);
        // send the consecutive frames
        header.frameType = ISO_TP_FRAME_CONSECUTIVE;
        header.index = ((idx++) & 0x0f);
        header.numBytes = len;
        numSent = sendFrame(header, txbuf + offset, len, timeout);
        if (numSent < 1)
            break;
        totalNumSent += numSent;
        offset += numSent;
        numBytes -= numSent;
    }
    return totalNumSent;
}
 
int CanStreamerState::getDataFromFifo(uint8_t *rxbuf, size_t &numBytes) {
    if (rxFifoBuf.isEmpty())
        return 0;
    int numReadFromFifo = minI(numBytes, rxFifoBuf.getCount());
    // move bytes from the FIFO buffer
    int i;
    for (i = 0; !rxFifoBuf.isEmpty() && i < numReadFromFifo; i++) {
        rxbuf[i] = rxFifoBuf.get();
        numBytes--;
    }
    return i;
}
 
can_msg_t CanStreamerState::streamAddToTxTimeout(size_t *np, const uint8_t *txbuf, can_sysinterval_t timeout) {
    int numBytes = *np;
    int offset = 0;
 
    if (engineConfiguration->verboseIsoTp) {
        PRINT("*** INFO: streamAddToTxTimeout adding %d, in buffer %d" PRINT_EOL, numBytes, txFifoBuf.getCount());
    }
 
    // we send here only if the TX FIFO buffer is getting overflowed
    while (numBytes >= txFifoBuf.getSize() - txFifoBuf.getCount()) {
        int numBytesToAdd = txFifoBuf.getSize() - txFifoBuf.getCount();
        txFifoBuf.put(txbuf + offset, numBytesToAdd);
        int numSent = sendDataTimeout((const uint8_t *)txFifoBuf.getElements(), txFifoBuf.getCount(), timeout);
 
        if (engineConfiguration->verboseIsoTp) {
            PRINT("*** INFO: streamAddToTxTimeout numBytesToAdd %d / numSent %d / numBytes %d" PRINT_EOL, numBytesToAdd, numSent, numBytes);
        }
 
        if (numSent < 1)
            break;
        txFifoBuf.clear();
        offset += numBytesToAdd;
        numBytes -= numBytesToAdd;
    }
 
    if (engineConfiguration->verboseIsoTp) {
        PRINT("*** INFO: streamAddToTxTimeout remaining goes to buffer %d" PRINT_EOL, numBytes);
    }
 
    // now we put the rest on hold
    txFifoBuf.put(txbuf + offset, numBytes);
 
 
    if (engineConfiguration->verboseIsoTp) {
        PRINT("*** INFO: in buffer %d" PRINT_EOL, txFifoBuf.getCount());
    }
 
    return CAN_MSG_OK;
}
 
can_msg_t CanStreamerState::streamFlushTx(can_sysinterval_t timeout) {
    int numSent = sendDataTimeout((const uint8_t *)txFifoBuf.getElements(), txFifoBuf.getCount(), timeout);
    if (numSent != txFifoBuf.getCount()) {
        //warning(ObdCode::CUSTOM_ERR_CAN_COMMUNICATION, "CAN sendDataTimeout() problems");
    }
    txFifoBuf.clear();
 
    return CAN_MSG_OK;
}
 
can_msg_t CanStreamerState::streamReceiveTimeout(size_t *np, uint8_t *rxbuf, can_sysinterval_t timeout) {
    size_t availableBufferSpace = *np;
 
    // first, fill the data from the stored buffer (saved from the previous CAN frame)
    int receivedSoFar = getDataFromFifo(rxbuf, availableBufferSpace);
 
    // if even more data is needed, then we receive more CAN frames
    while (availableBufferSpace > 0) {
        CANRxFrame rxmsg;
        if (transport->receive(&rxmsg, timeout) == CAN_MSG_OK) {
            int numReceived = receiveFrame(&rxmsg, rxbuf + receivedSoFar, availableBufferSpace, timeout);
 
            if (numReceived < 1)
                break;
            availableBufferSpace -= numReceived;
            receivedSoFar += numReceived;
        } else {
            break;
        }
    }
    *np -= availableBufferSpace;
 
#ifdef SERIAL_CAN_DEBUG
    efiPrintf("* ret: %d %d (%d)", i, *np, availableBufferSpace);
    for (int j = 0; j < receivedSoFar; j++) {
        efiPrintf("* [%d]: %02x", j, rxbuf[j]);
    }
#endif /* SERIAL_CAN_DEBUG */
 
    return CAN_MSG_OK;
}
 
#endif // HAL_USE_CAN || EFI_UNIT_TEST