/*
    ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT 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.

    ChibiOS/RT 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, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file mac.c
 * @brief MAC Driver code.
 * @addtogroup MAC
 * @{
 */

#include <ch.h>
#include <mac.h>

/**
 * @brief Transmit descriptors counter semaphore.
 */
static Semaphore tdsem, rdsem;

/**
 * @brief MAC Driver initialization.
 */
void macInit(void) {

  mac_lld_init();
}

/**
 * @brief Initialize the standard part of a @p MACDriver structure.
 *
 * @param[in] macp pointer to the @p MACDriver object
 */
void macObjectInit(MACDriver *macp) {

  chSemInit(&macp->md_tdsem, 0);
  chSemInit(&macp->md_rdsem, 0);
#if CH_USE_EVENTS
  chEvtInit(&macp->md_rdevent);
#endif
}

/**
 * @brief MAC address setup.
 *
 * @param[in] macp pointer to the @p MACDriver object
 * @param[in] p pointer to a six bytes buffer containing the MAC address. If
 *            this parameter is set to @p NULL then a system default MAC is
 *            used.
 *
 * @note This function must be invoked only with the driver in the stopped
 *       state. If invoked on an active interface then it is ignored.
 */
void macSetAddress(MACDriver *macp, uint8_t *p) {

  mac_lld_set_address(macp, p);
}

/**
 * @brief Allocates a transmission descriptor.
 * @details One of the available transmission descriptors is locked and
 *          returned. If a descriptor is not currently available then the
 *          invoking thread is queued until one is freed.
 *
 * @param[in] macp pointer to the @p MACDriver object
 * @param[in] size size of the frame to be transmitted
 * @param[in] time the number of ticks before the operation timeouts,
 *            the following special values are allowed:
 *            - @a TIME_IMMEDIATE immediate timeout.
 *            - @a TIME_INFINITE no timeout.
 *            .
 * @return A pointer to a @p MACTransmitDescriptor structure or @p NULL if
 *         the operation timed out.
 */
MACTransmitDescriptor *macWaitTransmitDescriptor(MACDriver *macp,
                                                 size_t size,
                                                 systime_t time) {
  MACTransmitDescriptor *tdp;

  while ((time > 0) &&
         (tdp = max_lld_get_transmit_descriptor(macp, size)) == NULL) {
    chSysLock();
    systime_t now = chTimeNow();
    if (chSemWaitTimeoutS(&tdsem, time) == RDY_TIMEOUT) {
      tdp = NULL;
      break;
    }
    if (time != TIME_INFINITE)
      time -= (chTimeNow() - now);
    chSysUnlock();
  }
  return tdp;
}

/**
 * @brief Releases a transmit descriptor and starts the transmission of the
 *        enqueued data as a single frame.
 *
 * @param[in] macp pointer to the @p MACDriver object
 * @param[in] tdp the pointer to the @p MACTransmitDescriptor structure
 */
void macReleaseTransmitDescriptor(MACDriver *macp,
                                  MACTransmitDescriptor *tdp) {

  mac_lld_release_transmit_descriptor(macp, tdp);
}

/**
 * @brief Waits for a received frame.
 * @details Stops until a frame is received and buffered. If a frame is
 *          not immediately available then the invoking thread is queued
 *          until one is received.
 *
 * @param[in] macp pointer to the @p MACDriver object
 * @param[out szp size of the received frame
 * @param[in] time the number of ticks before the operation timeouts,
 *            the following special values are allowed:
 *            - @a TIME_IMMEDIATE immediate timeout.
 *            - @a TIME_INFINITE no timeout.
 *            .
 * @return A pointer to a @p MACReceiveDescriptor structure or @p NULL if
 *         the operation timed out or some transient error happened.
 */
MACReceiveDescriptor *macWaitReceiveDescriptor(MACDriver *macp,
                                               size_t *szp,
                                               systime_t time) {
  MACReceiveDescriptor *rdp;

  while ((time > 0) &&
         (rdp = max_lld_get_receive_descriptor(macp, szp)) == NULL) {
    chSysLock();
    systime_t now = chTimeNow();
    if (chSemWaitTimeoutS(&rdsem, time) == RDY_TIMEOUT) {
     rdp = NULL;
      break;
    }
    if (time != TIME_INFINITE)
      time -= (chTimeNow() - now);
    chSysUnlock();
  }
  return rdp;
}

/**
 * @brief Releases a receive descriptor.
 * @details The descriptor and its buffer is made available for more incoming
 *          frames.
 *
 * @param[in] macp pointer to the @p MACDriver object
 * @param[in] rdp the pointer to the @p MACReceiveDescriptor structure
 */
void macReleaseReceiveDescriptor(MACDriver *macp,
                                 MACReceiveDescriptor *rdp) {

  mac_lld_release_receive_descriptor(macp, rdp);
}

/** @} */