LibrePilot/flight/pios/common/pios_com_msg.c

/**
 ******************************************************************************
 * @addtogroup PIOS PIOS Core hardware abstraction layer
 * @{
 * @addtogroup PIOS_COM COM MSG layer functions
 * @brief Hardware communication layer
 * @{
 *
 * @file       pios_com_msg.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @brief      COM MSG layer functions
 * @see        The GNU Public License (GPL) Version 3
 *
 *****************************************************************************/
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include "pios.h"

#ifdef PIOS_INCLUDE_COM_MSG

#include "pios_com.h"

#define PIOS_COM_MSG_MAX_LEN 63

struct pios_com_msg_dev {
    uint32_t lower_id;
    const struct pios_com_driver *driver;

    uint8_t  rx_msg_buffer[PIOS_COM_MSG_MAX_LEN];
    volatile bool rx_msg_full;

    uint8_t  tx_msg_buffer[PIOS_COM_MSG_MAX_LEN];
    volatile bool tx_msg_full;
};

static struct pios_com_msg_dev com_msg_dev;

static uint16_t PIOS_COM_MSG_TxOutCallback(uint32_t context, uint8_t *buf, uint16_t buf_len, uint16_t *headroom, bool *need_yield);
static uint16_t PIOS_COM_MSG_RxInCallback(uint32_t context, uint8_t *buf, uint16_t buf_len, uint16_t *headroom, bool *need_yield);

int32_t PIOS_COM_MSG_Init(uint32_t *com_id, const struct pios_com_driver *driver, uint32_t lower_id)
{
    PIOS_Assert(com_id);
    PIOS_Assert(driver);

    PIOS_Assert(driver->bind_tx_cb);
    PIOS_Assert(driver->bind_rx_cb);

    struct pios_com_msg_dev *com_dev = &com_msg_dev;

    com_dev->driver      = driver;
    com_dev->lower_id    = lower_id;

    com_dev->rx_msg_full = false;
    (com_dev->driver->bind_rx_cb)(lower_id, PIOS_COM_MSG_RxInCallback, (uint32_t)com_dev);
    (com_dev->driver->rx_start)(com_dev->lower_id, sizeof(com_dev->rx_msg_buffer));

    com_dev->tx_msg_full = false;
    (com_dev->driver->bind_tx_cb)(lower_id, PIOS_COM_MSG_TxOutCallback, (uint32_t)com_dev);

    *com_id = (uint32_t)com_dev;
    return 0;
}

static uint16_t PIOS_COM_MSG_TxOutCallback(uint32_t context, uint8_t *buf, uint16_t buf_len, uint16_t *headroom, __attribute__((unused)) bool *need_yield)
{
    struct pios_com_msg_dev *com_dev = (struct pios_com_msg_dev *)context;

    PIOS_Assert(buf);
    PIOS_Assert(buf_len);

    uint16_t bytes_from_fifo = 0;

    if (com_dev->tx_msg_full && (buf_len >= sizeof(com_dev->tx_msg_buffer))) {
        /* Room for an entire message, send it */
        memcpy(buf, com_dev->tx_msg_buffer, sizeof(com_dev->tx_msg_buffer));
        bytes_from_fifo = sizeof(com_dev->tx_msg_buffer);
        com_dev->tx_msg_full = false;
    }

    if (headroom) {
        if (com_dev->tx_msg_full) {
            *headroom = sizeof(com_dev->tx_msg_buffer);
        } else {
            *headroom = 0;
        }
    }

    return bytes_from_fifo;
}

static uint16_t PIOS_COM_MSG_RxInCallback(uint32_t context, uint8_t *buf, uint16_t buf_len, uint16_t *headroom, __attribute__((unused)) bool *need_yield)
{
    struct pios_com_msg_dev *com_dev = (struct pios_com_msg_dev *)context;

    uint16_t bytes_into_fifo = 0;

    if (!com_dev->rx_msg_full && (buf_len >= sizeof(com_dev->rx_msg_buffer))) {
        memcpy(com_dev->rx_msg_buffer, buf, sizeof(com_dev->rx_msg_buffer));
        bytes_into_fifo = sizeof(com_dev->rx_msg_buffer);
        com_dev->rx_msg_full = true;
    }

    if (headroom) {
        if (!com_dev->rx_msg_full) {
            *headroom = sizeof(com_dev->rx_msg_buffer);
        } else {
            *headroom = 0;
        }
    }

    return bytes_into_fifo;
}

int32_t PIOS_COM_MSG_Send(uint32_t com_id, const uint8_t *msg, uint16_t msg_len)
{
    PIOS_Assert(msg);
    PIOS_Assert(msg_len);

    struct pios_com_msg_dev *com_dev = (struct pios_com_msg_dev *)com_id;

    PIOS_Assert(msg_len == sizeof(com_dev->tx_msg_buffer));

    /* Wait forever for room in the tx buffer */
    while (com_dev->tx_msg_full) {
        /* Kick the transmitter while we wait */
        if (com_dev->driver->tx_start) {
            (com_dev->driver->tx_start)(com_dev->lower_id, sizeof(com_dev->tx_msg_buffer));
        }
    }

    memcpy((void *)com_dev->tx_msg_buffer, msg, msg_len);
    com_dev->tx_msg_full = true;

    /* Kick the transmitter now that we've queued our message */
    if (com_dev->driver->tx_start) {
        (com_dev->driver->tx_start)(com_dev->lower_id, sizeof(com_dev->tx_msg_buffer));
    }

    return 0;
}

uint16_t PIOS_COM_MSG_Receive(uint32_t com_id, uint8_t *msg, uint16_t msg_len)
{
    PIOS_Assert(msg);
    PIOS_Assert(msg_len);

    struct pios_com_msg_dev *com_dev = (struct pios_com_msg_dev *)com_id;

    PIOS_Assert(msg_len == sizeof(com_dev->rx_msg_buffer));

    if (!com_dev->rx_msg_full) {
        /* There's room in our buffer, kick the receiver */
        (com_dev->driver->rx_start)(com_dev->lower_id, sizeof(com_dev->rx_msg_buffer));
    } else {
        memcpy(msg, com_dev->rx_msg_buffer, msg_len);
        com_dev->rx_msg_full = false;

        return msg_len;
    }

    return 0;
}

/**
 * Change the port speed without re-initializing
 * \param[in] port COM port
 * \param[in] baud Requested baud rate
 * \return -1 if port not available
 * \return 0 on success
 */
int32_t PIOS_COM_MSG_ChangeBaud(uint32_t com_id, uint32_t baud)
{
    struct pios_com_msg_dev *com_dev = (struct pios_com_msg_dev *)com_id;

    if (!com_dev) {
        /* Undefined COM port for this board (see pios_board.c) */
        return -1;
    }

    /* Invoke the driver function if it exists */
    if (com_dev->driver->set_baud) {
        com_dev->driver->set_baud(com_dev->lower_id, baud);
    }

    return 0;
}

#endif /* PIOS_INCLUDE_COM_MSG */

/**
 * @}
 * @}
 */