Using mcasp example for the LCDK 6748

Hello,

I am using the mcasp example provided in the starter ware for the LCDK 6748. I have the example running properly and am passing audio from my computer into the board. Before the input audio gets sent out by the LCDK 6748 to the output, in this case a speaker I want to edit the data, aka do some simple filtering. My partner and I have been going through the main loop and as we are not expert programmers are having a difficult time tracking down the exact location of the data to work with it before sending it to the output. We know that this has to be done in main which is included below. Can anybody provide some guidance on how to do this? Any help would be greatly appreciated.

Eric

** The main function. Application starts here.
*/
int main(void)
{
    unsigned short parToSend;
    unsigned short parToLink;

    /* Set up pin mux for I2C module 0 */
    I2CPinMuxSetup(0);
    McASPPinMuxSetup();

    /* Power up the McASP module */
    PSCModuleControl(SOC_PSC_1_REGS, HW_PSC_MCASP0, PSC_POWERDOMAIN_ALWAYS_ON,
       PSC_MDCTL_NEXT_ENABLE);

    /* Power up EDMA3CC_0 and EDMA3TC_0 */
    PSCModuleControl(SOC_PSC_0_REGS, HW_PSC_CC0, PSC_POWERDOMAIN_ALWAYS_ON,
       PSC_MDCTL_NEXT_ENABLE);
    PSCModuleControl(SOC_PSC_0_REGS, HW_PSC_TC0, PSC_POWERDOMAIN_ALWAYS_ON,
       PSC_MDCTL_NEXT_ENABLE);

#ifdef _TMS320C6X
    // Initialize the DSP interrupt controller
    IntDSPINTCInit();
#else
    /* Initialize the ARM Interrupt Controller.*/
    IntAINTCInit();
#endif

    /* Initialize the I2C 0 interface for the codec AIC31 */
    I2CCodecIfInit(SOC_I2C_0_REGS, INT_CHANNEL_I2C, I2C_SLAVE_CODEC_AIC31);

    EDMA3Init(SOC_EDMA30CC_0_REGS, 0);
    EDMA3IntSetup();

    McASPErrorIntSetup();
 
#ifdef _TMS320C6X
    IntGlobalEnable();
#else
    /* Enable the interrupts generation at global level */
    IntMasterIRQEnable();
    IntGlobalEnable();
    IntIRQEnable();
#endif

    /*
    ** Request EDMA channels. Channel 0 is used for reception and
    ** Channel 1 is used for transmission
    */
    EDMA3RequestChannel(SOC_EDMA30CC_0_REGS, EDMA3_CHANNEL_TYPE_DMA,
                        EDMA3_CHA_MCASP0_TX, EDMA3_CHA_MCASP0_TX, 0);
    EDMA3RequestChannel(SOC_EDMA30CC_0_REGS, EDMA3_CHANNEL_TYPE_DMA,
                        EDMA3_CHA_MCASP0_RX, EDMA3_CHA_MCASP0_RX, 0);

    /* Initialize the DMA parameters */
    I2SDMAParamInit();

    /* Configure the Codec for I2S mode */
    AIC31I2SConfigure();

    /* Configure the McASP for I2S */
    McASPI2SConfigure();
 
    /* Activate the audio transmission and reception */
    I2SDataTxRxActivate();
  
    /*
    ** Looop forever. if a new buffer is received, the lastFullRxBuf will be
    ** updated in the rx completion ISR. if it is not the lastSentTxBuf,
    ** buffer is to be sent. This has to be mapped to proper paRAM set.
    */
    while(1)
    {
        if(lastFullRxBuf != lastSentTxBuf)
        { 
            /*
            ** Start the transmission from the link paramset. The param set
            ** 1 will be linked to param set at PAR_TX_START. So do not
            ** update paRAM set1.
            */
            parToSend =  PAR_TX_START + (parOffTxToSend % NUM_PAR);
            parOffTxToSend = (parOffTxToSend + 1) % NUM_PAR;
            parToLink  = PAR_TX_START + parOffTxToSend;
 
            lastSentTxBuf = (lastSentTxBuf + 1) % NUM_BUF;

            /* Copy the buffer */
            memcpy((void *)txBufPtr[lastSentTxBuf],
                   (void *)rxBufPtr[lastFullRxBuf],
                   AUDIO_BUF_SIZE);

            /*
            ** Send the buffer by setting the DMA params accordingly.
            ** Here the buffer to send and number of samples are passed as
            ** parameters. This is important, if only transmit section
            ** is to be used.
            */
            BufferTxDMAActivate(lastSentTxBuf, NUM_SAMPLES_PER_AUDIO_BUF,
                                (unsigned short)parToSend,
                                (unsigned short)parToLink);
        }
    }
}