shellmatta/src/shellmatta_ymodem.c

/**
 * @file    shellmatta_ymodem.c
 * @brief   ymodem functions of shellmatta
 * @author  Simon Fischer <dev@s-fischer.net>
 */

#include "shellmatta_ymodem.h"
#include "shellmatta_crc.h"
#include "shellmatta_utils.h"
#include <stddef.h>

/* current ymodem packet size */
uint16_t    yModemPacketSize = YMODEM_PACKET_SIZE;
/* packet counter - counts all correctly received packets during one transmission */
uint16_t    shellmatta_ymodem_packet_counter = 0u;
/* counts total amount of data bytes received during one transmission */
uint32_t    shellmatta_ymodem_total_bytes_received = 0u;
/* counts total amount of data bytes received during one packet */
uint16_t    shellmatta_ymodem_byte_counter = 0u;
uint8_t fileNameDelimiterPosition = 255u;
uint8_t fileSizeDelimiterPosition = 255u;
/* structure of a packet consisting of data and metadata */
shellmatta_ymodem_packet_t shellmatta_ymodem_packet;
/* holds information about which data type is currently actice: YMODEM_NONE, YMODEM_HEADER, YMODEM_BODY, YMODEM_FOOTER */
shellmatta_ymodem_datatype_t shellmatta_ymodem_current_data_type = YMODEM_NONE;
/* structure of ymodem callback functions */
shellmatta_ymodem_callbacks_t shellmatta_ymodem_callbacks;
/* flag to disable byte processing in ymodem */
bool ymodem_is_enabled = true;

/**
 * @brief                       Initialise the ymodem prior to actually receiving data
 * @param[in, out]  handle      shellmatta handle of the instance
 * @param[in]       recvBuffer  pointer to the buffer to save the received payload in
 * @param[in]       fileSize    pointer to the file size variable
 * @param[in]       packetSize  pointer to the packet size variable
 * @param[in]       callbacks   callback functions for the ymodem module
*/
void shellmatta_ymodem_init(shellmatta_handle_t handle, 
                            uint8_t* recvBuffer, 
                            uint32_t* fileSize,
                            uint16_t* packetSize,
                            shellmatta_ymodem_callbacks_t callbacks)
{
    if ((void*)0u == recvBuffer) return;
    /* init packet structure */
    shellmatta_ymodem_packet.packetNumber = 0u;
    shellmatta_ymodem_packet.reversePacketNumber = 0u;
    shellmatta_ymodem_packet.packetCrc = 0u;
    shellmatta_ymodem_packet.packetSize = packetSize;
    shellmatta_ymodem_packet.fileSize = fileSize;
    shellmatta_ymodem_packet.packetData = recvBuffer;

    /* init callbacks */
    shellmatta_ymodem_callbacks = callbacks;

    /* init ymodem state */
    shellmatta_ymodem_set_state(handle, WAIT_FOR_START);

    /* init current data type */
    shellmatta_ymodem_current_data_type = YMODEM_NONE;
}

/**
 * @brief                       change the current state of the ymodem module
 * @param[in, out]  handle      shellmatta handle of the instance
 * @param[in]       newState    the state the ymodem module should be changed to
*/
void shellmatta_ymodem_set_state(shellmatta_handle_t handle, shellmatta_ymodem_state_t newState)
{
    ((shellmatta_instance_t*)handle)->ymodemState = newState;
}

/**
 * @brief                   Returns the current state of the ymodem module
 * @param[in, out]  handle  shellmatta handle of the instance
 * @return                  the current state of the ymodem module
*/
shellmatta_ymodem_state_t shellmatta_ymodem_get_state(shellmatta_handle_t handle)
{
    return ((shellmatta_instance_t*)handle)->ymodemState;
}

/**
 * @brief                   State machine that processes bytewise input during active ymodem transmission
 * @param[in, out]  handle  shellmatta handle of the instance
 * @param[in]       byteIn  the byte to be processed
 * @note                    won't do anything if ymodem module is not initialized
*/
void shellmatta_ymodem_receive_packet(shellmatta_handle_t handle, uint8_t byteIn)
{
    static uint32_t fileSize = 0u;
    static char fileSizeStr[7u]; /* hopefully no more bytes than a million will ever be transmitted */
    shellmatta_ymodem_rcv_retcode_t recvRetCode;

    /* skip byte processing if ymodem is not enabled */
    if (!ymodem_is_enabled)
    {
        return;
    }

    recvRetCode = shellmatta_ymodem_receive_byte(handle, byteIn);
    switch (shellmatta_ymodem_get_state(handle))
    {
    case INACTIVE:
        /* cant do anything if ymodem module was not correctly initialized */
        return;
    case WAIT_FOR_START:
        /* wait for start symbol of a packet */
        switch (shellmatta_ymodem_current_data_type)
        {
        case YMODEM_NONE: /* go here if the header packet is to be expected */
            if (recvRetCode == SOH_RECEIVED || recvRetCode == STX_RECEIVED)
            {
                /* reset packet counter */
                shellmatta_ymodem_packet_counter = 0u;
                shellmatta_ymodem_byte_counter = 0u;
                shellmatta_ymodem_set_state(handle, RECEIVE_PACKET);
                shellmatta_ymodem_current_data_type = YMODEM_HEADER;
            }
            break;
        
        case YMODEM_HEADER: /* go here if the first body packet is to be expected */
            if (recvRetCode == STX_RECEIVED || SOH_RECEIVED)
            {
                shellmatta_ymodem_byte_counter = 0u;
                shellmatta_ymodem_set_state(handle, RECEIVE_PACKET);
                shellmatta_ymodem_current_data_type = YMODEM_BODY;
            }
            break;

        case YMODEM_BODY: /* go here if the data transmission loop is active */
            if (recvRetCode == SOH_RECEIVED || recvRetCode == STX_RECEIVED)
            {
                shellmatta_ymodem_byte_counter = 0u;
                /* stay in body when SOH was received */
                shellmatta_ymodem_set_state(handle, RECEIVE_PACKET);
                shellmatta_ymodem_current_data_type = YMODEM_BODY;
            }
            else /* go here if the end of transmission symbol is received */
            if (recvRetCode == EOT_RECEIVED)
            {
                shellmatta_ymodem_byte_counter = 0u;
                /* answer with ACK */
                shellmatta_ymodem_ack(handle);
                /* then send 0x43 symbol */
                shellmatta_ymodem_control(handle, YMODEM_CRC);
                /* go to footer when EOT was received */
                shellmatta_ymodem_current_data_type = YMODEM_FOOTER;
                /* then wait for SOH */
            }
            break;
        case YMODEM_FOOTER: /* go here if the end of transmission packet is to be expected */
            /* it _may_ be, that EOT is sent multiple times, repeat previous procedure */
            if (recvRetCode == EOT_RECEIVED)
            {
                /* answer with ACK */
                shellmatta_ymodem_ack(handle);
                /* then send 0x43 symbol */
                shellmatta_ymodem_control(handle, YMODEM_CRC);
            }
            if (recvRetCode == SOH_RECEIVED)
            {
                /* reset packet counter */
                shellmatta_ymodem_packet_counter = 0u;
                /* reset byte counter to avoid error by one caused by previously received EOT symbol */
                shellmatta_ymodem_byte_counter = 0u;
                shellmatta_ymodem_set_state(handle, RECEIVE_PACKET);
            }
            break;

        default:
            break;
        }
        break;
    case RECEIVE_PACKET:
        /* receiving data */
        if (recvRetCode == DATA_RECEIVED)
        {
            switch (shellmatta_ymodem_current_data_type)
            {
            case YMODEM_HEADER:
                switch (shellmatta_ymodem_byte_counter)
                {
                /* first two bytes are packet number and reverse packet number */
                case 0:
                    shellmatta_ymodem_packet.packetNumber = byteIn;
                    break;
                case 1:
                    shellmatta_ymodem_packet.reversePacketNumber = byteIn;
                    break;
                default:
                    break;
                }
                /* after packet numbers, data field begins */
                if ((shellmatta_ymodem_byte_counter >= YMODEM_HEADER_DATA_OFFSET) && 
                    (shellmatta_ymodem_byte_counter < YMODEM_HEADER_CRC_POSITION))
                {
                    shellmatta_ymodem_packet.packetData[shellmatta_ymodem_byte_counter - YMODEM_HEADER_DATA_OFFSET] = byteIn;
                    /* check for filename */
                    if (shellmatta_ymodem_byte_counter < fileNameDelimiterPosition)
                    {
                        /* find NULL-Terminator in filename */
                        if (byteIn == YMODEM_NULL)
                        {
                            fileNameDelimiterPosition = shellmatta_ymodem_byte_counter + 1;
                        }
                    }
                    /* after filename the filesize begins */
                    else
                    if (shellmatta_ymodem_byte_counter >= fileNameDelimiterPosition && 
                        (shellmatta_ymodem_byte_counter < fileSizeDelimiterPosition))
                    {
                        /* find space as delimiter after filesize */
                        if (byteIn == YMODEM_SPACE)
                        {
                            fileSizeDelimiterPosition = shellmatta_ymodem_byte_counter;
                            /* convert file size string to actual number */
                            fileSize = utils_shellAsciiToUInt32(fileSizeStr, fileSizeDelimiterPosition - fileNameDelimiterPosition);
                            *shellmatta_ymodem_packet.fileSize = fileSize;
                        }
                        /* save characters in string otherwise */
                        else
                        {
                            fileSizeStr[shellmatta_ymodem_byte_counter - fileNameDelimiterPosition] = byteIn;
                        }
                    }
                    else
                    {
                        /* some meta data from sender, possibly file date */
                        /* not needed for now */
                    }
                }
                /* after data field, crc begins */
                if (shellmatta_ymodem_byte_counter >= YMODEM_HEADER_CRC_POSITION)
                {
                    if (shellmatta_ymodem_byte_counter == YMODEM_HEADER_CRC_POSITION)
                    {
                        /* upper byte */
                        shellmatta_ymodem_packet.packetCrc = byteIn << 8u;
                    }
                    if (shellmatta_ymodem_byte_counter == YMODEM_HEADER_CRC_POSITION + 1)
                    {
                        /* lower byte */
                        shellmatta_ymodem_packet.packetCrc |= byteIn;
                        /* change ymodem state to check packet */
                        shellmatta_ymodem_check_packet(handle);
                    }
                }
                shellmatta_ymodem_byte_counter++;
                break;

            case YMODEM_BODY:
                switch (shellmatta_ymodem_byte_counter)
                {
                case 0:
                    shellmatta_ymodem_packet.packetNumber = byteIn;
                    break;
                case 1:
                    shellmatta_ymodem_packet.reversePacketNumber = byteIn;
                    break;
                default:
                    break;
                }

                /* after data field, crc begins */
                if (shellmatta_ymodem_byte_counter >= yModemPacketSize + YMODEM_HEADER_DATA_OFFSET)
                {
                    if (shellmatta_ymodem_byte_counter == yModemPacketSize + YMODEM_HEADER_DATA_OFFSET)
                    {
                        /* upper byte */
                        shellmatta_ymodem_packet.packetCrc = byteIn << 8u;
                    }
                    if (shellmatta_ymodem_byte_counter == yModemPacketSize + YMODEM_HEADER_DATA_OFFSET + 1)
                    {
                        /* lower byte */
                        shellmatta_ymodem_packet.packetCrc |= byteIn;
                        /* change ymodem state to check packet */
                        shellmatta_ymodem_check_packet(handle);
                    }
                }
                else
                if ((shellmatta_ymodem_byte_counter > 1) && 
                    (shellmatta_ymodem_byte_counter < (yModemPacketSize + YMODEM_HEADER_DATA_OFFSET)))
                {
                    shellmatta_ymodem_packet.packetData[shellmatta_ymodem_byte_counter - YMODEM_HEADER_DATA_OFFSET] = byteIn;
                }
                shellmatta_ymodem_byte_counter++;
                break;

            case YMODEM_FOOTER:
                /* reset packet counter */
                shellmatta_ymodem_packet_counter = 0;

                switch (shellmatta_ymodem_byte_counter)
                {
                case 0:
                    shellmatta_ymodem_packet.packetNumber = byteIn;
                    break;
                case 1:
                    shellmatta_ymodem_packet.reversePacketNumber = byteIn;
                    break;
                default:
                    break;
                }

                /* after data field, crc begins */
                if (shellmatta_ymodem_byte_counter >= yModemPacketSize + YMODEM_HEADER_DATA_OFFSET)
                {
                    if (shellmatta_ymodem_byte_counter == yModemPacketSize + YMODEM_HEADER_DATA_OFFSET)
                    {
                        /* upper byte */
                        shellmatta_ymodem_packet.packetCrc = byteIn << 8u;
                    }
                    if (shellmatta_ymodem_byte_counter == yModemPacketSize + YMODEM_HEADER_DATA_OFFSET + 1)
                    {
                        /* lower byte */
                        shellmatta_ymodem_packet.packetCrc |= byteIn;
                        /* change ymodem state to check packet */
                        shellmatta_ymodem_check_packet(handle);
                    }
                }
                else
                if ((shellmatta_ymodem_byte_counter > 1) && 
                    (shellmatta_ymodem_byte_counter < (yModemPacketSize + YMODEM_HEADER_DATA_OFFSET)))
                {
                    /* save data */
                    shellmatta_ymodem_packet.packetData[shellmatta_ymodem_byte_counter - YMODEM_HEADER_DATA_OFFSET] = byteIn;
                }
                shellmatta_ymodem_byte_counter++;
                break;
            
            default:
                break;
            }
        }
        break;

    default:
        break;
    }
}

/**
 * @brief                   Gives a return code depending on symbol received at different states of the ymodem module
 * @param[in, out]  handle  shellmatta handle of the instance
 * @param[in]       byteIn  currently processed input byte
*/
shellmatta_ymodem_rcv_retcode_t shellmatta_ymodem_receive_byte(shellmatta_handle_t handle, uint8_t byteIn)
{
    shellmatta_ymodem_rcv_retcode_t ret;
    if (WAIT_FOR_START == shellmatta_ymodem_get_state(handle))
    {
        switch (byteIn)
        {
        case YMODEM_SOH:
            /* start of header -> default packet size */
            yModemPacketSize = YMODEM_PACKET_SIZE;
            ret = SOH_RECEIVED;
            break;
        
        case YMODEM_STX:
            /* start of header -> extended packet size */
            yModemPacketSize = YMODEM_PACKET_SIZE_1K;
            ret = STX_RECEIVED;
            break;

        case YMODEM_EOT:
            /* end of transmission -> data transmission complete */
            ret = EOT_RECEIVED;
            break;
        
        case YMODEM_CA:
            /* cancel transmssion -> reset state machine */
            ret = CA_RECEIVED;
            break;

        default:
            /* no other data should be received in this state */
            ret = ERROR;
            break;
        }
        /* give packet size back to upper layer */
        *shellmatta_ymodem_packet.packetSize = yModemPacketSize;
    }
    else
    if (RECEIVE_PACKET == shellmatta_ymodem_get_state(handle))
    {
        ret = DATA_RECEIVED;
    }
    return ret;
}

/**
 * @brief                   Checks packet data for validity and sends ACK or NAK accordingly
 * @param[in, out]  handle  shellmatta handle of the instance
 * @note                    Only to be called after full packet is received
 * @note                    Will call yModemRecvPacketCallback when packet is received correctly
 * @note                    Will call ymodemTransmissionCompleteCallback when transmission is completed
*/
void shellmatta_ymodem_check_packet(shellmatta_handle_t handle)
{
    uint16_t computedCrc = 0u;
    if (shellmatta_ymodem_packet.packetNumber != (0xFF - shellmatta_ymodem_packet.reversePacketNumber))
    {
        shellmatta_ymodem_nak(handle);
        return;
    }
    /* compare to internal packet counter */
    if (shellmatta_ymodem_packet.packetNumber != ((uint8_t)shellmatta_ymodem_packet_counter)) /* uint8_t cast to cause overflow */
    {
        shellmatta_ymodem_nak(handle);
        return;
    }
    /* compare packet crc only after other checks succeeded */
    computedCrc = crc16Calc((const char*)shellmatta_ymodem_packet.packetData, yModemPacketSize);
    //! uncomment to ignore crc check for debug purposes
    if (shellmatta_ymodem_packet.packetCrc != computedCrc)
    {
        shellmatta_ymodem_nak(handle);
        return;
    }
    /* if previous checks passed, packet is acknowledged */
    (void) computedCrc;
    shellmatta_ymodem_total_bytes_received += shellmatta_ymodem_byte_counter;
    shellmatta_ymodem_byte_counter = 0u;
    shellmatta_ymodem_ack(handle);
    if (shellmatta_ymodem_current_data_type == YMODEM_HEADER)
    {
        /* send additional CRC symbol if the packet was a header packet */
        shellmatta_ymodem_control(handle, YMODEM_CRC);
    }

    /* callback handling */
    switch (shellmatta_ymodem_current_data_type)
    {
    case YMODEM_NONE:
        /* shouldn't happen */
        break;
    
    case YMODEM_HEADER:
        /* nothing to do after receiving the header packet */
        break;

    case YMODEM_BODY:
        /* call the ymodem receive packet callback */
        if (NULL != shellmatta_ymodem_callbacks.yModemRecvPacketCallback)
        {
            shellmatta_ymodem_callbacks.yModemRecvPacketCallback();
        }
        break;

    case YMODEM_FOOTER:
        /* call the ymodem transmission complete callback */
        if (NULL != shellmatta_ymodem_callbacks.ymodemTransmissionCompleteCallback)
        {
            shellmatta_ymodem_callbacks.ymodemTransmissionCompleteCallback();
        }
        break;
    default:
        break;
    }
}

/**
 * @brief                   Acknowledge handling. Will send ACK and set ymodem state back to WAIT_FOR_START
 * @param[in, out]  handle  shellmatta handle of the instance
*/
void shellmatta_ymodem_ack(shellmatta_handle_t handle)
{
    shellmatta_ymodem_control(handle, YMODEM_ACK);
    shellmatta_ymodem_packet_counter++;
    shellmatta_ymodem_set_state(handle, WAIT_FOR_START);
}

/**
 * @brief                   Not-Acknowledge handling. Will send NAK and set ymodem state back to WAIT_FOR_START
 * @param[in, out]  handle  shellmatta handle of the instance
*/
void shellmatta_ymodem_nak(shellmatta_handle_t handle)
{
    shellmatta_ymodem_set_state(handle, WAIT_FOR_START);
    /* set back current data type to prevent false forward stepping */
    switch (shellmatta_ymodem_current_data_type)
    {
    case YMODEM_NONE:
        /* no handling needed */
        break;
    
    case YMODEM_HEADER:
        shellmatta_ymodem_control(handle, YMODEM_NAK);
        break;

    case YMODEM_BODY:
        /* YMODEM_BODY stays in YMODEM_BODY */
        shellmatta_ymodem_control(handle, YMODEM_NAK);
        shellmatta_ymodem_current_data_type = YMODEM_BODY;
        break;

    case YMODEM_FOOTER:
        /* YMODEM_FOOTER as well */
        shellmatta_ymodem_current_data_type = YMODEM_FOOTER;
        break;

    default:
        break;
    }
}

/**
 * @brief               forwards the given character to write-function without formatting
 * @param[in]   handle  shellmatta handle of the instance
 * @param[in]   c       character to be sent
*/
void shellmatta_ymodem_control(shellmatta_handle_t handle, const char c)
{
    ((shellmatta_instance_t*)handle)->write(&c, 1);
}

/**
 * @brief                       reset function for the ymodem module
 * @param[in, out]  handle      shellmatta handle of the instance
 * @param[in]       doCancel    flag to execute the cancel-callback
*/
void shellmatta_ymodem_reset(shellmatta_handle_t handle, bool doCancel)
{
    /* call cancel callback function */
    if (doCancel)
    {
        /* send cancel symbol */
        shellmatta_ymodem_control(handle, YMODEM_CA);
        if (NULL != shellmatta_ymodem_callbacks.yModemCancelCallback)
        {
            shellmatta_ymodem_callbacks.yModemCancelCallback();
        }
    }
    /* reset global variables */
    shellmatta_ymodem_byte_counter = 0u;
    shellmatta_ymodem_packet_counter = 0u;
    shellmatta_ymodem_total_bytes_received = 0u;
    fileNameDelimiterPosition = 255u;
    fileSizeDelimiterPosition = 255u;

    /* reset all ymodem_packet data */
    shellmatta_ymodem_packet.packetNumber = 0u;
    shellmatta_ymodem_packet.reversePacketNumber = 0u;
    shellmatta_ymodem_packet.packetCrc = 0u;
    shellmatta_ymodem_packet.packetSize = 0u;
    shellmatta_ymodem_packet.fileSize = 0u;
    shellmatta_ymodem_packet.packetData = 0u;

    /* set ymodem to inactive */
    shellmatta_ymodem_set_state(handle, INACTIVE);

    shellmatta_ymodem_current_data_type = YMODEM_NONE;

#ifdef SHELLMATTA_TRANSPORT
    /* re-enable transport layer */
    ((shellmatta_instance_t*)handle)->transportEnabled = true;
#endif
}

shellmatta_ymodem_datatype_t shellmatta_ymodem_get_current_datatype(void)
{
    return shellmatta_ymodem_current_data_type;
}

void shellmatta_ymodem_enable(void)
{
    ymodem_is_enabled = true;
}

void shellmatta_ymodem_disable(void)
{
    ymodem_is_enabled = false;
}