wtm.c

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#include "co.h"

#ifndef LELY_NO_CO_WTM

#include <lely/co/crc.h>
#include <lely/co/wtm.h>
#include <lely/util/diag.h>
#include <lely/util/endian.h>
#include <lely/util/time.h>

#include <assert.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>

#define CO_WTM_MAX_NIF 127

struct co_wtm_can {
        uint8_t st;
        uint8_t err;
        uint8_t load;
        uint16_t ec;
        uint16_t foc;
        uint16_t coc;
        struct timespec recv_time;
        struct timespec send_time;
        struct timespec send_next;
};

struct __co_wtm {
        uint8_t nif;
        uint8_t quality;
        struct co_wtm_can can[CO_WTM_MAX_NIF];
        co_wtm_diag_can_con_t *diag_can_con;
        void *diag_can_con_data;
        co_wtm_diag_wtm_con_t *diag_wtm_con;
        void *diag_wtm_con_data;
        co_wtm_diag_can_ind_t *diag_can_ind;
        void *diag_can_ind_data;
        co_wtm_diag_wtm_ind_t *diag_wtm_ind;
        void *diag_wtm_ind_data;
        co_wtm_diag_ac_ind_t *diag_ac_ind;
        void *diag_ac_data;
        co_wtm_recv_func_t *recv_func;
        void *recv_data;
        co_wtm_send_func_t *send_func;
        void *send_data;
        uint8_t recv_buf[CO_WTM_MAX_LEN];
        size_t recv_nbytes;
        uint8_t recv_nseq;
        uint8_t send_buf[CO_WTM_MAX_LEN];
        size_t send_nbytes;
        uint8_t send_nseq;
};

static int co_wtm_send_diag_can_res(co_wtm_t *wtm, uint8_t nif);

static int co_wtm_send_diag_wtm_res(co_wtm_t *wtm);

static void co_wtm_diag_ac(co_wtm_t *wtm, uint32_t ac);

static void default_wtm_diag_ac_ind(co_wtm_t *wtm, uint32_t ac, void *data);

static uint32_t co_wtm_recv_can(co_wtm_t *wtm, const void *buf, size_t nbytes);

const char *
co_wtm_ac_str(uint32_t ac)
{
        switch (ac) {
        case CO_WTM_AC_ERROR: return "General error";
        case CO_WTM_AC_TIMEOUT:
                return "Diagnostic protocol timed out limit reached";
        case CO_WTM_AC_NO_MEM: return "Out of memory";
        case CO_WTM_AC_HARDWARE: return "Access failed due to a hardware error";
        case CO_WTM_AC_DATA:
                return "Data cannot be transferred or stored to the application";
        case CO_WTM_AC_DATA_CTL:
                return "Data cannot be transferred or stored to the application because of local control";
        case CO_WTM_AC_DATA_DEV:
                return "Data cannot be transferred or stored to the application because of the present device state";
        case CO_WTM_AC_NO_DATA: return "No data available";
        case CO_WTM_AC_NO_IF: return "Requested interface not implemented";
        case CO_WTM_AC_IF_DOWN: return "Requested interface disabled";
        case CO_WTM_AC_DIAG: return "Diagnostic data generation not supported";
        case CO_WTM_AC_DIAG_CAN:
                return "Diagnostic data generation for requested CAN interface not supported";
        case CO_WTM_AC_DIAG_WTM:
                return "Diagnostic data generation for requested WTM interface not supported";
        case CO_WTM_AC_FRAME: return "General generic frame error";
        case CO_WTM_AC_PREAMBLE: return "Invalid generic frame preamble";
        case CO_WTM_AC_SEQ: return "Invalid sequence counter in generic frame";
        case CO_WTM_AC_TYPE: return "Message type not valid or unknown";
        case CO_WTM_AC_PAYLOAD: return "Payload field in generic frame invalid";
        case CO_WTM_AC_CRC: return "CRC error (Generic frame)";
        case CO_WTM_AC_CAN: return "CAN telegram essentials invalid";
        default: return "Unknown abort code";
        }
}

void *
__co_wtm_alloc(void)
{
        void *ptr = malloc(sizeof(struct __co_wtm));
        if (__unlikely(!ptr))
                set_errc(errno2c(errno));
        return ptr;
}

void
__co_wtm_free(void *ptr)
{
        free(ptr);
}

struct __co_wtm *
__co_wtm_init(struct __co_wtm *wtm)
{
        assert(wtm);

        wtm->nif = 1;

        wtm->quality = 0xff;

        for (uint8_t nif = 1; nif <= CO_WTM_MAX_NIF; nif++) {
                struct co_wtm_can *can = &wtm->can[nif - 1];

                can->st = 0xf;
                can->err = 0xf;
                can->load = 0xff;
                can->ec = 0xffff;
                can->foc = 0xffff;
                can->coc = 0xffff;

                can->recv_time = (struct timespec){ 0, 0 };
                can->send_time = (struct timespec){ 0, 0 };
                can->send_next = (struct timespec){ 0, 0 };
        }

        wtm->diag_can_con = NULL;
        wtm->diag_can_con_data = NULL;

        wtm->diag_wtm_con = NULL;
        wtm->diag_wtm_con_data = NULL;

        wtm->diag_can_ind = NULL;
        wtm->diag_can_ind_data = NULL;

        wtm->diag_wtm_ind = NULL;
        wtm->diag_wtm_ind_data = NULL;

        wtm->diag_ac_ind = &default_wtm_diag_ac_ind;
        wtm->diag_ac_data = NULL;

        wtm->recv_func = NULL;
        wtm->recv_data = NULL;

        wtm->send_func = NULL;
        wtm->send_data = NULL;

        wtm->recv_nbytes = 0;
        wtm->recv_nseq = 0;

        wtm->send_nbytes = 0;
        wtm->send_nseq = 0;

        return wtm;
}

void
__co_wtm_fini(struct __co_wtm *wtm)
{
        (void)wtm;
}

co_wtm_t *
co_wtm_create(void)
{
        int errc = 0;

        co_wtm_t *wtm = __co_wtm_alloc();
        if (__unlikely(!wtm)) {
                errc = get_errc();
                goto error_alloc_wtm;
        }

        if (__unlikely(!__co_wtm_init(wtm))) {
                errc = get_errc();
                goto error_init_wtm;
        }

        return wtm;

error_init_wtm:
        __co_wtm_free(wtm);
error_alloc_wtm:
        set_errc(errc);
        return NULL;
}

void
co_wtm_destroy(co_wtm_t *wtm)
{
        if (wtm) {
                __co_wtm_fini(wtm);
                __co_wtm_free(wtm);
        }
}

uint8_t
co_wtm_get_nif(const co_wtm_t *wtm)
{
        assert(wtm);

        return wtm->nif;
}

int
co_wtm_set_nif(co_wtm_t *wtm, uint8_t nif)
{
        assert(wtm);

        if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }

        wtm->nif = nif;

        return 0;
}

int
co_wtm_set_diag_can(co_wtm_t *wtm, uint8_t nif, uint8_t st, uint8_t err,
                uint8_t load, uint16_t ec, uint16_t foc, uint16_t coc)
{
        assert(wtm);

        if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }
        struct co_wtm_can *can = &wtm->can[nif - 1];

        switch (st) {
        case CAN_STATE_ACTIVE: st = 0; break;
        case CAN_STATE_PASSIVE: st = 1; break;
        case CAN_STATE_BUSOFF: st = 2; break;
        case 0xf: break;
        default: set_errnum(ERRNUM_INVAL); return -1;
        }

        if (err == 0xf) {
        } else if (err & CAN_ERROR_BIT) {
                err = 1;
        } else if (err & CAN_ERROR_STUFF) {
                err = 2;
        } else if (err & CAN_ERROR_CRC) {
                err = 3;
        } else if (err & CAN_ERROR_FORM) {
                err = 4;
        } else if (err & CAN_ERROR_ACK) {
                err = 5;
        } else if (err) {
                err = 0xf;
        }

        if (__unlikely(load > 100 && load != 0xff)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }

        can->st = st;
        can->err = err;
        can->load = load;
        can->ec = ec;
        can->foc = foc;
        can->coc = coc;

        return 0;
}

int
co_wtm_set_diag_wtm(co_wtm_t *wtm, uint8_t quality)
{
        assert(wtm);

        if (__unlikely(quality > 100 && quality != 0xff)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }

        wtm->quality = quality;

        return 0;
}

void
co_wtm_get_diag_can_con(
                const co_wtm_t *wtm, co_wtm_diag_can_con_t **pcon, void **pdata)
{
        assert(wtm);

        if (pcon)
                *pcon = wtm->diag_can_con;
        if (pdata)
                *pdata = wtm->diag_can_con_data;
}

void
co_wtm_set_diag_can_con(co_wtm_t *wtm, co_wtm_diag_can_con_t *con, void *data)
{
        assert(wtm);

        wtm->diag_can_con = con;
        wtm->diag_can_con_data = data;
}

void
co_wtm_get_diag_wtm_con(
                const co_wtm_t *wtm, co_wtm_diag_wtm_con_t **pcon, void **pdata)
{
        assert(wtm);

        if (pcon)
                *pcon = wtm->diag_wtm_con;
        if (pdata)
                *pdata = wtm->diag_wtm_con_data;
}

void
co_wtm_set_diag_wtm_con(co_wtm_t *wtm, co_wtm_diag_wtm_con_t *con, void *data)
{
        assert(wtm);

        wtm->diag_wtm_con = con;
        wtm->diag_wtm_con_data = data;
}

void
co_wtm_get_diag_can_ind(
                const co_wtm_t *wtm, co_wtm_diag_can_ind_t **pcon, void **pdata)
{
        assert(wtm);

        if (pcon)
                *pcon = wtm->diag_can_ind;
        if (pdata)
                *pdata = wtm->diag_can_ind_data;
}

void
co_wtm_set_diag_can_ind(co_wtm_t *wtm, co_wtm_diag_can_ind_t *con, void *data)
{
        assert(wtm);

        wtm->diag_can_ind = con;
        wtm->diag_can_ind_data = data;
}

void
co_wtm_get_diag_wtm_ind(
                const co_wtm_t *wtm, co_wtm_diag_wtm_ind_t **pcon, void **pdata)
{
        assert(wtm);

        if (pcon)
                *pcon = wtm->diag_wtm_ind;
        if (pdata)
                *pdata = wtm->diag_wtm_ind_data;
}

void
co_wtm_set_diag_wtm_ind(co_wtm_t *wtm, co_wtm_diag_wtm_ind_t *con, void *data)
{
        assert(wtm);

        wtm->diag_wtm_ind = con;
        wtm->diag_wtm_ind_data = data;
}

void
co_wtm_get_diag_ac_ind(
                const co_wtm_t *wtm, co_wtm_diag_ac_ind_t **pind, void **pdata)
{
        assert(wtm);

        if (pind)
                *pind = wtm->diag_ac_ind;
        if (pdata)
                *pdata = wtm->diag_ac_data;
}

void
co_wtm_set_diag_ac_ind(co_wtm_t *wtm, co_wtm_diag_ac_ind_t *ind, void *data)
{
        assert(wtm);

        wtm->diag_ac_ind = ind ? ind : &default_wtm_diag_ac_ind;
        wtm->diag_ac_data = ind ? data : NULL;
}

void
co_wtm_recv(co_wtm_t *wtm, const void *buf, size_t nbytes)
{
        assert(wtm);
        assert(wtm->diag_ac_ind);
        assert(buf);

        for (const char *bp = buf; nbytes;) {
                uint32_t ac = 0;
                // Search for the preamble (see section 5.2 in CiA 315 version
                // 1.0.0).
                size_t size = 1;
                if (wtm->recv_nbytes < size) {
                        wtm->recv_buf[wtm->recv_nbytes] = *bp;
                        wtm->recv_nbytes++;
                        bp++;
                        nbytes--;
                }
                if (__unlikely(wtm->recv_buf[0] != 0x55)) {
                        ac = CO_WTM_AC_PREAMBLE;
                        goto error;
                }
                // Copy the rest of the header (plus the CRC checksum if there
                // is no payload).
                size += 5;
                if (wtm->recv_nbytes < size) {
                        size_t n = MIN(nbytes, size - wtm->recv_nbytes);
                        memcpy(wtm->recv_buf + wtm->recv_nbytes, bp, n);
                        wtm->recv_nbytes += n;
                        bp += n;
                        nbytes -= n;
                        if (wtm->recv_nbytes < size)
                                continue;
                }
                // Copy the payload (plus the CRC checksum).
                uint8_t len = wtm->recv_buf[1];
                size += len;
                if (wtm->recv_nbytes < size) {
                        size_t n = MIN(nbytes, size - wtm->recv_nbytes);
                        memcpy(wtm->recv_buf + wtm->recv_nbytes, bp, n);
                        wtm->recv_nbytes += n;
                        bp += n;
                        nbytes -= n;
                        if (wtm->recv_nbytes < size)
                                continue;
                }
                // Check the CRC checksum (see section 5.7 in CiA 315 version
                // 1.0.0).
                uint16_t crc = co_crc(0xffff, wtm->recv_buf, 4 + len);
                if (__unlikely(crc != ldle_u16(wtm->recv_buf + 4 + len))) {
                        ac = CO_WTM_AC_CRC;
                        goto error;
                }
                // Check the sequence counter (see section 5.4 in CiA 315
                // version 1.0.0).
                uint8_t seq = wtm->recv_buf[2];
                if (__unlikely(seq != wtm->recv_nseq))
                        // Generate an error, but do not abort processing the
                        // message.
                        co_wtm_diag_ac(wtm, CO_WTM_AC_SEQ);
                wtm->recv_nseq = seq + 1;
                // Process message payload based on its type (see Table 2 in CiA
                // 315 version 1.0.0).
                uint8_t type = wtm->recv_buf[3];
                uint8_t nif;
                switch (type) {
                // CAN messages forwarding (see section 6 in CiA 315 version
                // 1.0.0).
                case 0x00:
                        // Process the CAN frames.
                        // clang-format off
                        if (__unlikely((ac = co_wtm_recv_can(wtm,
                                        wtm->recv_buf + 4, len)) != 0))
                                // clang-format on
                                goto error;
                        break;
                // Keep-alive (see section 7.3 in CiA 315 version 1.0.0).
                case 0x10:
                        if (__unlikely(len < 1)) {
                                ac = CO_WTM_AC_PAYLOAD;
                                goto error;
                        }
                        // Obtain the WTM interface indicator.
                        nif = wtm->recv_buf[4];
                        if (__unlikely(nif <= 0x80)) {
                                ac = CO_WTM_AC_PAYLOAD;
                                goto error;
                        }
                        // Ignore keep-alive messages for other WTM interfaces.
                        if (__unlikely(nif != 0x80 + wtm->nif))
                                break;
                        // TODO: handle keep-alive message.
                        break;
                // Timer-overrun (see section 7.4 in CiA 315 version 1.0.0).
                case 0x11:
                        if (__unlikely(len < 1)) {
                                ac = CO_WTM_AC_PAYLOAD;
                                goto error;
                        }
                        // Obtain the CAN interface indicator.
                        nif = wtm->recv_buf[4];
                        if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                                ac = CO_WTM_AC_PAYLOAD;
                                goto error;
                        }
                        // Add 6553.5 ms to the CAN interface timer.
                        timespec_add_usec(
                                        &wtm->can[nif - 1].recv_time, 6553500);
                        break;
                // Communication quality request.
                case 0x12:
                        if (__unlikely(len < 1)) {
                                ac = CO_WTM_AC_PAYLOAD;
                                goto error;
                        }
                        // Obtain the interface indicator.
                        nif = wtm->recv_buf[4];
                        if (nif <= 0x80) {
                                if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                                        co_wtm_send_diag_ac(
                                                        wtm, CO_WTM_AC_NO_IF);
                                        break;
                                }
                                // Send the communication quality response.
                                co_wtm_send_diag_can_res(wtm, nif);
                        } else {
                                // Only accept communication quality requests
                                // for this WTM interface.
                                if (__unlikely(nif != 0x80 + wtm->nif)) {
                                        co_wtm_send_diag_ac(
                                                        wtm, CO_WTM_AC_NO_IF);
                                        break;
                                }
                                // Send the communication quality response.
                                co_wtm_send_diag_wtm_res(wtm);
                        }
                        break;
                // Communication quality response.
                case 0x13:
                        if (__unlikely(len < 2)) {
                                ac = CO_WTM_AC_PAYLOAD;
                                goto error;
                        }
                        // Obtain the interface indicator.
                        nif = wtm->recv_buf[4];
                        if (__unlikely(!nif || nif == 0x80)) {
                                ac = CO_WTM_AC_PAYLOAD;
                                goto error;
                        }
                        if (nif < 0x80) {
                                if (__unlikely(len < 9)) {
                                        ac = CO_WTM_AC_PAYLOAD;
                                        goto error;
                                }
                                if (!wtm->diag_can_con)
                                        continue;
                                uint8_t st = 0xf;
                                switch ((wtm->recv_buf[5] >> 4) & 0xf) {
                                case 0: st = CAN_STATE_ACTIVE; break;
                                case 1: st = CAN_STATE_PASSIVE; break;
                                case 2: st = CAN_STATE_BUSOFF; break;
                                }
                                uint8_t err = 0xf;
                                switch (wtm->recv_buf[5] & 0xf) {
                                case 1: err = CAN_ERROR_BIT; break;
                                case 2: err = CAN_ERROR_STUFF; break;
                                case 3: err = CAN_ERROR_CRC; break;
                                case 4: err = CAN_ERROR_FORM; break;
                                case 5: err = CAN_ERROR_ACK; break;
                                }
                                uint8_t load = wtm->recv_buf[6];
                                uint16_t ec = ldle_u16(wtm->recv_buf + 7);
                                uint16_t foc = ldle_u16(wtm->recv_buf + 9);
                                uint16_t coc = ldle_u16(wtm->recv_buf + 11);
                                wtm->diag_can_con(wtm, nif, st, err, load, ec,
                                                foc, coc,
                                                wtm->diag_can_con_data);
                        } else {
                                if (!wtm->diag_wtm_con)
                                        continue;
                                uint8_t quality = wtm->recv_buf[5];
                                wtm->diag_wtm_con(wtm, nif - 0x80, quality,
                                                wtm->diag_wtm_con_data);
                        }
                        break;
                // Communication quality reset.
                case 0x14:
                        if (__unlikely(len < 1)) {
                                ac = CO_WTM_AC_PAYLOAD;
                                goto error;
                        }
                        // Obtain the interface indicator.
                        nif = wtm->recv_buf[4];
                        if (nif <= 0x80) {
                                if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                                        co_wtm_send_diag_ac(
                                                        wtm, CO_WTM_AC_NO_IF);
                                        break;
                                }
                                struct co_wtm_can *can = &wtm->can[nif - 1];
                                can->st = 0xf;
                                can->err = 0xf;
                                can->load = 0xff;
                                can->ec = 0xffff;
                                can->foc = 0xffff;
                                can->coc = 0xffff;
                                if (wtm->diag_can_ind)
                                        wtm->diag_can_ind(wtm, nif,
                                                        wtm->diag_can_ind_data);
                        } else {
                                // Only accept communication quality reset
                                // messages for this WTM interface.
                                if (__unlikely(nif != 0x80 + wtm->nif)) {
                                        co_wtm_send_diag_ac(
                                                        wtm, CO_WTM_AC_NO_IF);
                                        break;
                                }
                                wtm->quality = 0xff;
                                if (wtm->diag_wtm_ind)
                                        wtm->diag_wtm_ind(wtm,
                                                        wtm->diag_wtm_ind_data);
                        }
                        break;
                // Diagnostic abort message.
                case 0x15:
                        if (__unlikely(len < 5)) {
                                ac = CO_WTM_AC_PAYLOAD;
                                goto error;
                        }
                        // Obtain the WTM interface indicator.
                        nif = wtm->recv_buf[4];
                        if (__unlikely(nif <= 0x80)) {
                                ac = CO_WTM_AC_PAYLOAD;
                                goto error;
                        }
                        // Ignore diagnostic abort messages for other WTM
                        // interfaces.
                        if (__unlikely(nif != 0x80 + wtm->nif))
                                break;
                        ac = ldle_u32(wtm->recv_buf + 5);
                        break;
                default: ac = CO_WTM_AC_TYPE; goto error;
                }
        error:
                if (__unlikely(ac))
                        co_wtm_diag_ac(wtm, ac);
                // Empty the buffer for the next message.
                wtm->recv_nbytes = 0;
        }
}

void
co_wtm_get_recv_func(
                const co_wtm_t *wtm, co_wtm_recv_func_t **pfunc, void **pdata)
{
        assert(wtm);

        if (pfunc)
                *pfunc = wtm->recv_func;
        if (pdata)
                *pdata = wtm->recv_data;
}

void
co_wtm_set_recv_func(co_wtm_t *wtm, co_wtm_recv_func_t *func, void *data)
{
        assert(wtm);

        wtm->recv_func = func;
        wtm->recv_data = data;
}

int
co_wtm_get_time(const co_wtm_t *wtm, uint8_t nif, struct timespec *tp)
{
        assert(wtm);

        if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }

        if (tp)
                *tp = wtm->can[nif - 1].send_next;

        return 0;
}

int
co_wtm_set_time(co_wtm_t *wtm, uint8_t nif, const struct timespec *tp)
{
        assert(wtm);
        assert(tp);

        if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }
        struct co_wtm_can *can = &wtm->can[nif - 1];

        // Since the time stamp is relative, store the absolute time on the
        // first invocation.
        if (!can->send_time.tv_sec && !can->send_time.tv_nsec)
                can->send_time = *tp;
        // Update the time stamp for the next CAN frame.
        can->send_next = *tp;

        // If the difference between the current (reference) and next time is
        // larger than 6553.5 ms, send a timer-overrun message.
        while (timespec_diff_usec(&can->send_next, &can->send_time) > 6553500) {
                if (__unlikely(co_wtm_flush(wtm) == -1))
                        return -1;
                wtm->send_buf[3] = 0x11;
                wtm->send_buf[4] = nif;
                wtm->send_nbytes = 5;
                // Update the current (reference) time.
                timespec_add_usec(&can->send_time, 6553500);
        }

        return 0;
}

int
co_wtm_send(co_wtm_t *wtm, uint8_t nif, const struct can_msg *msg)
{
        assert(wtm);
        assert(msg);

        if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }
        struct co_wtm_can *can = &wtm->can[nif - 1];

#ifndef LELY_NO_CANFD
        // CAN FD frames are not supported.
        if (__unlikely(msg->flags & CAN_FLAG_EDL)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }
#endif

        if (__unlikely(msg->len > CAN_MAX_LEN)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }

        // Compute the length of the CAN frame.
        size_t len = 1 + (nif != 1) + ((msg->flags & CAN_FLAG_IDE) ? 4 : 2)
                        + msg->len + 2;
        // Flush the buffer if necessary.
        if ((wtm->send_nbytes > 3 && wtm->send_buf[3] != 0x00)
                        || wtm->send_nbytes + len + 2 > CO_WTM_MAX_LEN) {
                if (__unlikely(co_wtm_flush(wtm) == -1))
                        return -1;
        }
        wtm->send_buf[3] = 0x00;
        wtm->send_nbytes = MAX(wtm->send_nbytes, 4);
        uint8_t *bp = wtm->send_buf + wtm->send_nbytes;
        size_t nbytes = wtm->send_nbytes;

        // Write the data length code.
        uint8_t dlc = msg->len | 0x40;
        if (msg->flags & CAN_FLAG_RTR)
                dlc |= 0x10;
        if (msg->flags & CAN_FLAG_IDE)
                dlc |= 0x20;
        if (nif != 1)
                dlc |= 0x80;
        *bp = dlc;
        bp++;
        nbytes++;
        // Write the interface indicator.
        if (nif != 1) {
                *bp = nif;
                bp++;
                nbytes++;
        }
        // Write the CAN identifier.
        if (msg->flags & CAN_FLAG_IDE) {
                stle_u32(bp, msg->id & CAN_MASK_EID);
                bp += 4;
                nbytes += 4;
        } else {
                stle_u16(bp, msg->id & CAN_MASK_BID);
                bp += 2;
                nbytes += 2;
        }
        // Copy the frame payload.
        memcpy(bp, msg->data, msg->len);
        bp += msg->len;
        nbytes += msg->len;
        // Write the time stamp.
        int64_t usec = timespec_diff_usec(&can->send_next, &can->send_time);
        stle_u16(bp, (uint16_t)(usec / 100));
        nbytes += 2;

        assert(nbytes + 2 <= CO_WTM_MAX_LEN);
        wtm->send_nbytes = nbytes;

        return 0;
}

int
co_wtm_send_alive(co_wtm_t *wtm)
{
        assert(wtm);
        assert(wtm->nif && wtm->nif <= CO_WTM_MAX_NIF);

        if (__unlikely(co_wtm_flush(wtm) == -1))
                return -1;
        wtm->send_buf[3] = 0x10;
        wtm->send_buf[4] = 0x80 + wtm->nif;
        wtm->send_nbytes = 5;
        return co_wtm_flush(wtm);
}

int
co_wtm_send_diag_can_req(co_wtm_t *wtm, uint8_t nif)
{
        assert(wtm);

        if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }

        if (__unlikely(co_wtm_flush(wtm) == -1))
                return -1;
        wtm->send_buf[3] = 0x12;
        wtm->send_buf[4] = nif;
        wtm->send_nbytes = 5;
        return co_wtm_flush(wtm);
}

int
co_wtm_send_diag_wtm_req(co_wtm_t *wtm, uint8_t nif)
{
        assert(wtm);

        if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }

        if (__unlikely(co_wtm_flush(wtm) == -1))
                return -1;
        wtm->send_buf[3] = 0x12;
        wtm->send_buf[4] = 0x80 + nif;
        wtm->send_nbytes = 5;
        return co_wtm_flush(wtm);
}

int
co_wtm_send_diag_can_rst(co_wtm_t *wtm, uint8_t nif)
{
        assert(wtm);

        if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }

        if (__unlikely(co_wtm_flush(wtm) == -1))
                return -1;
        wtm->send_buf[3] = 0x14;
        wtm->send_buf[4] = nif;
        wtm->send_nbytes = 5;
        return co_wtm_flush(wtm);
}

int
co_wtm_send_diag_wtm_rst(co_wtm_t *wtm, uint8_t nif)
{
        assert(wtm);

        if (__unlikely(!nif || nif > CO_WTM_MAX_NIF)) {
                set_errnum(ERRNUM_INVAL);
                return -1;
        }

        if (__unlikely(co_wtm_flush(wtm) == -1))
                return -1;
        wtm->send_buf[3] = 0x14;
        wtm->send_buf[4] = 0x80 + nif;
        wtm->send_nbytes = 5;
        return co_wtm_flush(wtm);
}

int
co_wtm_send_diag_ac(co_wtm_t *wtm, uint32_t ac)
{
        assert(wtm);
        assert(wtm->nif && wtm->nif <= CO_WTM_MAX_NIF);

        if (__unlikely(co_wtm_flush(wtm) == -1))
                return -1;
        wtm->send_buf[3] = 0x15;
        wtm->send_buf[4] = 0x80 + wtm->nif;
        stle_u32(wtm->send_buf + 5, ac);
        wtm->send_nbytes = 9;
        return co_wtm_flush(wtm);
}

int
co_wtm_flush(co_wtm_t *wtm)
{
        assert(wtm);

        // Do not flush if there is no header.
        if (wtm->send_nbytes < 4)
                return 0;
        uint8_t len = (uint8_t)(wtm->send_nbytes - 4);
        wtm->send_nbytes = 0;

        // Fill in the header fields.
        wtm->send_buf[0] = 0x55;
        wtm->send_buf[1] = len;
        wtm->send_buf[2] = wtm->send_nseq++;
        // Compute the CRC checksum.
        uint16_t crc = co_crc(0xffff, wtm->send_buf, 4 + len);
        stle_u16(wtm->send_buf + 4 + len, crc);

        // Invoke the user-specified callback function to send the generic
        // frame.
        if (__unlikely(!wtm->send_func)) {
                set_errnum(ERRNUM_NOSYS);
                return -1;
        }
        return wtm->send_func(wtm, wtm->send_buf, 4 + len + 2, wtm->send_data)
                        ? -1
                        : 0;
}

void
co_wtm_get_send_func(
                const co_wtm_t *wtm, co_wtm_send_func_t **pfunc, void **pdata)
{
        assert(wtm);

        if (pfunc)
                *pfunc = wtm->send_func;
        if (pdata)
                *pdata = wtm->send_data;
}

void
co_wtm_set_send_func(co_wtm_t *wtm, co_wtm_send_func_t *func, void *data)
{
        assert(wtm);

        wtm->send_func = func;
        wtm->send_data = data;
}

static int
co_wtm_send_diag_can_res(co_wtm_t *wtm, uint8_t nif)
{
        assert(wtm);
        assert(nif && nif <= CO_WTM_MAX_NIF);
        struct co_wtm_can *can = &wtm->can[nif - 1];

        if (__unlikely(co_wtm_flush(wtm) == -1))
                return -1;
        wtm->send_buf[3] = 0x13;
        wtm->send_buf[4] = nif;
        wtm->send_buf[5] = ((can->st & 0xf) << 4) | (can->err & 0xf);
        wtm->send_buf[6] = can->load;
        stle_u16(wtm->send_buf + 7, can->ec);
        stle_u16(wtm->send_buf + 9, can->foc);
        stle_u16(wtm->send_buf + 11, can->coc);
        wtm->send_nbytes = 13;
        return co_wtm_flush(wtm);
}

static int
co_wtm_send_diag_wtm_res(co_wtm_t *wtm)
{
        assert(wtm);

        if (__unlikely(co_wtm_flush(wtm) == -1))
                return -1;
        wtm->send_buf[3] = 0x13;
        wtm->send_buf[4] = 0x80 + wtm->nif;
        wtm->send_buf[5] = wtm->quality;
        wtm->send_nbytes = 6;
        return co_wtm_flush(wtm);
}

static void
co_wtm_diag_ac(co_wtm_t *wtm, uint32_t ac)
{
        assert(wtm);
        assert(wtm->diag_ac_ind);

        wtm->diag_ac_ind(wtm, ac, wtm->diag_ac_data);
}

static void
default_wtm_diag_ac_ind(co_wtm_t *wtm, uint32_t ac, void *data)
{
        (void)wtm;
        (void)data;

        diag(DIAG_WARNING, 0, "received WTM abort code %08" PRIX32 ": %s", ac,
                        co_wtm_ac_str(ac));
}

static uint32_t
co_wtm_recv_can(co_wtm_t *wtm, const void *buf, size_t nbytes)
{
        assert(wtm);
        assert(buf);
        assert(nbytes);

        uint32_t ac = 0;
        for (const char *bp = buf; nbytes;) {
                struct can_msg msg = CAN_MSG_INIT;
                // Obtain the data length code.
                uint8_t dlc = *bp;
                bp++;
                nbytes--;
                msg.len = dlc & 0x0f;
                if (__unlikely(msg.len > CAN_MAX_LEN)) {
                        ac = CO_WTM_AC_CAN;
                        goto error;
                }
                if (dlc & 0x10)
                        msg.flags |= CAN_FLAG_RTR;
                // Obtain the CAN interface indicator.
                uint8_t nif = 1;
                if (dlc & 0x80) {
                        if (__unlikely(nbytes < 1)) {
                                ac = CO_WTM_AC_CAN;
                                goto error;
                        }
                        nif = *bp;
                        bp++;
                        nbytes--;
                }
                // Obtain the CAN identifier.
                if (dlc & 0x20) {
                        if (__unlikely(nbytes < 4)) {
                                ac = CO_WTM_AC_CAN;
                                goto error;
                        }
                        msg.id = ldle_u32(bp) & CAN_MASK_EID;
                        bp += 4;
                        nbytes -= 4;
                        msg.flags |= CAN_FLAG_IDE;
                } else {
                        if (__unlikely(nbytes < 2)) {
                                ac = CO_WTM_AC_CAN;
                                goto error;
                        }
                        msg.id = ldle_u16(bp) & CAN_MASK_BID;
                        bp += 2;
                        nbytes -= 2;
                }
                // Obtain the frame payload.
                if (__unlikely(nbytes < msg.len)) {
                        ac = CO_WTM_AC_CAN;
                        goto error;
                }
                memcpy(msg.data, bp, msg.len);
                bp += msg.len;
                nbytes -= msg.len;
                // Obtain the time stamp.
                uint16_t ts = 0;
                if (dlc & 0x40) {
                        if (__unlikely(nbytes < 2)) {
                                ac = CO_WTM_AC_CAN;
                                goto error;
                        }
                        ts = ldle_u16(bp);
                        bp += 2;
                        nbytes -= 2;
                }
                // Ignore CAN frames with an invalid interface indicator.
                if (__unlikely(!nif || nif > CO_WTM_MAX_NIF))
                        continue;
                // Update the CAN interface timer.
                struct timespec *tp = NULL;
                if (dlc & 0x40) {
                        tp = &wtm->can[nif - 1].recv_time;
                        timespec_add_usec(tp, ts * 100);
                }
                // Invoke the user-specified callback function.
                if (wtm->recv_func) {
                        int errc = get_errc();
                        // clang-format off
                        if (__unlikely(wtm->recv_func(wtm, nif, tp, &msg,
                                        wtm->recv_data))) {
                                // clang-format on
                                // Convert the error number to a WTM abort code.
                                if (!ac) {
                                        ac = get_errnum() == ERRNUM_NOMEM
                                                        ? CO_WTM_AC_NO_MEM
                                                        : CO_WTM_AC_ERROR;
                                }
                                set_errc(errc);
                        }
                }
        }

error:
        return ac;
}

#endif // !LELY_NO_CO_WTM