C6655 EDMA 触发方式Chained-triggered实现

/**
 *  \brief    Start EDMA transfer on the specified channel.
 *
 *  There are multiple ways to trigger an EDMA3 transfer. The triggering mode
 *  option allows choosing from the available triggering modes: Event,
 *  Manual or QDMA.
 *  
 *  In event triggered, a peripheral or an externally generated event triggers
 *  the transfer. This API clears the Event and Event Miss Register and then
 *  enables the DMA channel by writing to the EESR.
 *  
 *  In manual triggered mode, CPU manually triggers a transfer by writing a 1
 *  in the Event Set Register ESR. This API writes to the ESR to start the 
 *  transfer.
 *  
 *  In QDMA triggered mode, a QDMA transfer is triggered when a CPU (or other
 *  EDMA3 programmer) writes to the trigger word of the QDMA channel PaRAM set
 *  (auto-triggered) or when the EDMA3CC performs a link update on a PaRAM set
 *  that has been mapped to a QDMA channel (link triggered). This API enables
 *  the QDMA channel by writing to the QEESR register.
 *
 *  \param  baseAdd         Memory address of the EDMA instance used.\n
 *
 *  \param  chNum           Channel being used to enable transfer.\n
 *
 *  \param  trigMode        Mode of triggering start of transfer (Manual,
 *                          QDMA or Event).\n
 *
 *  trigMode can have values:
 *        EDMA3_TRIG_MODE_MANUAL\n
 *        EDMA3_TRIG_MODE_QDMA\n
 *        EDMA3_TRIG_MODE_EVENT\n
 *
 *  \return  retVal         TRUE or FALSE depending on the param passed.\n
 *
 */
unsigned int EDMA3EnableTransfer(unsigned int baseAdd, 
                                 unsigned int chNum, 
                                 unsigned int trigMode)
{
    unsigned int retVal = FALSE;
    switch (trigMode)
    {
        case EDMA3_TRIG_MODE_MANUAL :
            if (chNum < SOC_EDMA3_NUM_DMACH)
            {
                EDMA3SetEvt(baseAdd, chNum);
                retVal = TRUE;
            }
           break;
    
        case EDMA3_TRIG_MODE_QDMA :
            if (chNum < SOC_EDMA3_NUM_QDMACH)
            {
                EDMA3EnableQdmaEvt(baseAdd, chNum);
                retVal = TRUE;
            }
        break;
    
        case EDMA3_TRIG_MODE_EVENT :
            if (chNum < SOC_EDMA3_NUM_DMACH)
            {
                /*clear SECR & EMCR to clean any previous NULL request    */
                EDMA3ClrMissEvt(baseAdd, chNum);

                /* Set EESR to enable event                               */
                EDMA3EnableDmaEvt(baseAdd, chNum);
                retVal = TRUE;
            }
        break;
    
        default :
            retVal = FALSE;
        break;
    }
    return retVal;
}