mac_tx.c

Zigbee2006入门（源代码+文档讲解+系统推荐）

/**************************************************************************************************
    Filename:
    Revised:        $Date: 2007-03-26 16:18:09 -0700 (Mon, 26 Mar 2007) $
    Revision:       $Revision: 13860 $

    Description:

    Describe the purpose and contents of the file.

    Copyright (c) 2006 by Texas Instruments, Inc.
    All Rights Reserved.  Permission to use, reproduce, copy, prepare
    derivative works, modify, distribute, perform, display or sell this
    software and/or its documentation for any purpose is prohibited
    without the express written consent of Texas Instruments, Inc.
**************************************************************************************************/



/* ------------------------------------------------------------------------------------------------
 *                                          Includes
 * ------------------------------------------------------------------------------------------------
 */

/* hal */
#include "hal_types.h"
#include "hal_defs.h"
#include "hal_mcu.h"
#include "hal_mac_cfg.h"

/* high-level */
#include "mac_spec.h"
#include "mac_pib.h"

/* exported low-level */
#include "mac_low_level.h"

/* low-level specific */
#include "mac_tx.h"
#include "mac_backoff_timer.h"
#include "mac_rx.h"
#include "mac_rx_onoff.h"
#include "mac_radio.h"
#include "mac_sleep.h"

/* target specific */
#include "mac_radio_defs.h"

/* debug */
#include "mac_assert.h"


/* ------------------------------------------------------------------------------------------------
 *                                            Defines
 * ------------------------------------------------------------------------------------------------
 */
#define MFR_LEN                   MAC_FCS_FIELD_LEN
#define PREPENDED_BYTE_LEN        1


/* ------------------------------------------------------------------------------------------------
 *                                         Global Constants
 * ------------------------------------------------------------------------------------------------
 */

/*
 *  This is the time, in backoffs, required to set up a slotted transmit.
 *  It is exported to high level so that code can schedule enough time
 *  for slotted transmits.
 *
 *  A default is provided if a value is not specified.  If the default
 *  is not appropriate, a #define should be added within hal_mac_cfg.h.
 */
#ifndef HAL_MAC_TX_SLOTTED_DELAY
#define HAL_MAC_TX_SLOTTED_DELAY    3
#endif
uint8 const macTxSlottedDelay = HAL_MAC_TX_SLOTTED_DELAY;


/* ------------------------------------------------------------------------------------------------
 *                                         Global Variables
 * ------------------------------------------------------------------------------------------------
 */
uint8 macTxActive;
uint8 macTxType;
uint8 macTxBe;
uint8 macTxCsmaBackoffDelay;


/* ------------------------------------------------------------------------------------------------
 *                                         Local Variables
 * ------------------------------------------------------------------------------------------------
 */
static uint8 nb;
static uint8 txSeqn;
static uint8 txAckReq;
static uint8 txRetransmitFlag;


/* ------------------------------------------------------------------------------------------------
 *                                         Local Prototypes
 * ------------------------------------------------------------------------------------------------
 */
static void txCsmaPrep(void);
static void txGo(void);
static void txCsmaGo(void);
static void txComplete(uint8 status);


/**************************************************************************************************
 * @fn          macTxInit
 *
 * @brief       Initialize variables for tx module.
 *
 * @param       none
 *
 * @return      none
 **************************************************************************************************
 */
void macTxInit(void)
{
  macTxActive      = MAC_TX_ACTIVE_NO_ACTIVITY;
  txRetransmitFlag = 0;
}


/**************************************************************************************************
 * @fn          macTxHaltCleanup
 *
 * @brief       -
 *
 * @param       none
 *
 * @return      none
 **************************************************************************************************
 */
void macTxHaltCleanup(void)
{
  MAC_RADIO_TX_RESET();
  macTxInit();
}


/**************************************************************************************************
 * @fn          macTxFrame
 *
 * @brief       Transmit the frame pointed to by pMacDataTx with the specified type.
 *              NOTE! It is not legal to call this function from interrupt context.
 *
 * @param       txType - type of transmit
 *
 * @return      none
 **************************************************************************************************
 */
void macTxFrame(uint8 txType)
{
  MAC_ASSERT(!macTxActive);            /* transmit on top of transmit */

  /* mark transmit as active */
  macTxActive = MAC_TX_ACTIVE_INITIALIZE;

  /*
   *  The MAC will not enter sleep mode if there is an active transmit.  However, if macSleep() is
   *  ever called from interrupt context, it possible to enter sleep state after a transmit is
   *  intiated but before macTxActive is set.  To recover from this, the transmit must be aborted
   *  and proper notificiation given to high-level.
   */
  if (macSleepState != MAC_SLEEP_STATE_AWAKE)
  {
    /* notify high-level that transmit had to be aborted */
    txComplete(MAC_TX_ABORTED);

    /* exit from transmit logic */
    return;
  }
  
  /* save transmit type */
  macTxType = txType;

  /*-------------------------------------------------------------------------------
   *  Prepare for transmit.
   */
  if (macTxType == MAC_TX_TYPE_SLOTTED)
  {
    MAC_RADIO_TX_PREP_SLOTTED();
  }
  else
  {
    MAC_ASSERT((macTxType == MAC_TX_TYPE_SLOTTED_CSMA) || (macTxType == MAC_TX_TYPE_UNSLOTTED_CSMA));

    nb = 0;
    macTxBe = (pMacDataTx->internal.txOptions & MAC_TXOPTION_ALT_BE) ? macPib.altBe : macPib.minBe;

    if ((macTxType == MAC_TX_TYPE_SLOTTED_CSMA) && (macPib.battLifeExt))
    {
      macTxBe = MIN(2, macTxBe);
    }

    txCsmaPrep();
  }

  /*-------------------------------------------------------------------------------
   *  Load transmit FIFO unless this is a retransmit.  No need to write
   *  the FIFO again in that case.
   */
  if (!txRetransmitFlag)
  {
    uint8 * p;
    uint8   lenMhrMsdu;

    MAC_ASSERT(pMacDataTx != NULL); /* must have data to transmit */

    /* save needed parameters */
    txAckReq = MAC_ACK_REQUEST(pMacDataTx->msdu.p);
    txSeqn   = MAC_SEQ_NUMBER(pMacDataTx->msdu.p);

    /* set length of frame (note: use of term msdu is a misnomer, here it's actually mhr + msdu) */
    lenMhrMsdu = pMacDataTx->msdu.len;

    /* calling code guarantees an unused prepended byte  */
    p = pMacDataTx->msdu.p - PREPENDED_BYTE_LEN;

    /* first byte of buffer is length of MPDU */
    *p = lenMhrMsdu + MFR_LEN;

    /*
     *  Flush the TX FIFO.  This is necessary in case the previous transmit was never
     *  actually sent (e.g. CSMA failed without strobing TXON).  If bytes are written to
     *  the FIFO but not transmitted, they remain in the FIFO to be transmitted whenever
     *  a strobe of TXON does happen.
     */
    MAC_RADIO_FLUSH_TX_FIFO();

    /* write bytes to FIFO, prepended byte is included, MFR is not (it's generated by hardware) */
    MAC_RADIO_WRITE_TX_FIFO(p, PREPENDED_BYTE_LEN + lenMhrMsdu);
  }

  /*-------------------------------------------------------------------------------
   *  If not receiving, start the transmit.  If receive is active
   *  queue up the transmit.
   *
   *  Critical sections around the state change prevents any sort of race condition
   *  with  macTxStartQueuedFrame().  This guarantees function txGo() will only be
   *  called once.
   */
  {
    halIntState_t  s;

    HAL_ENTER_CRITICAL_SECTION(s);
    if (!macRxActive && !macRxOutgoingAckFlag)
    {
      macTxActive = MAC_TX_ACTIVE_GO;
      HAL_EXIT_CRITICAL_SECTION(s);
      txGo();
    }
    else
    {
      macTxActive = MAC_TX_ACTIVE_QUEUED;
      HAL_EXIT_CRITICAL_SECTION(s);
    }
  }
}


/*=================================================================================================
 * @fn          txCsmaPrep
 *
 * @brief       Prepare/initialize for a CSMA transmit.
 *
 * @param       none
 *
 * @return      none
 *=================================================================================================
 */
static void txCsmaPrep(void)
{
  macTxCsmaBackoffDelay = macRadioRandomByte() & ((1 << macTxBe) - 1);

  if (macTxType == MAC_TX_TYPE_SLOTTED_CSMA)
  {
    MAC_RADIO_TX_PREP_CSMA_SLOTTED();
  }
  else
  {
    MAC_RADIO_TX_PREP_CSMA_UNSLOTTED();
  }
}


/*=================================================================================================
 * @fn          txGo
 *
 * @brief       Start a transmit going.
 *
 * @param       none
 *
 * @return      none
 *=================================================================================================
 */
static void txGo(void)
{
  /*
   *  If execution has reached this point, any transmitted ACK has long since completed.  It is
   *  possible though that there is still a pending callback.  If so, it is irrelevant and needs to
   *  be canceled at this point.
   */
  MAC_RADIO_CANCEL_ACK_TX_DONE_CALLBACK();

  /* based on type of transmit, call the correct "go" functionality */
  if (macTxType == MAC_TX_TYPE_SLOTTED)
  {
    MAC_RADIO_TX_GO_SLOTTED();
  }
  else
  {
    txCsmaGo();
  }
}


/*=================================================================================================
 * @fn          txCsmaGo
 *
 * @brief       Start a CSMA transmit going.
 *
 * @param       none
 *