audioeffect.c

dsp 5416dsk aduio音效code

/*****************************************************************************/
/* FILENAME                                                                  */
/*   AudioEffect.c                                                           */
/*                                                                           */
/* DESCRIPTION                                                               */
/*   Audio effect illustration project based on TMS320C5416 DSK.             */
/*                                                                           */
/* VERSION                                                                   */
/*   1.01                                                                    */
/*                                                                           */
/* AUTHOR                                                                    */
/*   Bao Xiaojing                                                            */
/*                                                                           */
/* REVISION HISTORY                                                          */
/*   VER   DATE        AUTHOR          DESCRIPTION                           */
/* ------------------------------------------------------------------------  */
/*   1.01  2008.12.06  Bao Xiaojing    Update 3 audio effects.               */
/*   1.00  2002.10.30  Richard Sikora  Initial version.                      */
/*                                                                           */
/*****************************************************************************/

#include <stdio.h>    // Required for functions printf() and puts()

#include "AudioEffectcfg.h"

#include "dsk5416.h"
#include "dsk5416_pcm3002.h"

#include "bargraph.h"
#include "switches.h"
#include "stereo.h"
#include "FIR_filters_asm.h"
#include "blackman_low_pass_filter_1000Hz.h"

// Configuration setup of registers of PCM3002 Codec
DSK5416_PCM3002_Config setup = {

    0x1FF,      // Set-Up Reg 0 - Left channel DAC attenuation
    0x1FF,      // Set-Up Reg 1 - Right channel DAC attenuation
    0x0,        // Set-Up Reg 2 - Various ctl e.g. power-down modes
    0x0         // Set-Up Reg 3 - Codec data format control
};

#define DELAY_TIME 12000
#define MAX_DELAY 12001
signed int delay_array[MAX_DELAY]; // Buffer for maximum delay of 1 second

// delayed_input()
// ---------------
// Take oldest sample from the array and replace with the newest
// Uses a circular buffer because a straight buffer would be too slow.
signed int delayed_input(signed int latest_input, unsigned int delay_time)
{
    signed int return_value;
    static unsigned int index = 0; // Static to retain value between calls

    return_value = delay_array[index]; // Take oldest sample

    delay_array[index] = latest_input; // Overwrite with latest input

    if (index < (delay_time - 1))
    {
        index++;     // Not at end of buffer. Point to next element
    }
    else
    {
        index = 0;   // Go back to beginning of buffer
    }

    return(return_value);
}

// delay_array_clear()
// -------------------
// Fill delay array with zeroes to prevent noise / clicks.
void delay_array_clear(void)
{
    int i;

    for ( i = 0 ; i < MAX_DELAY ; i++)
    {
        delay_array[i] = 0; // Initialize array to all zeroes
    }
}

// For compatibility with pcm3002 read / write, these variables must
// be declared as Int16 or short int, rather than int.
Int16 left_input;
Int16 left_output;
Int16 right_input;
Int16 right_output;

// shift_channel()
// ---------------
// Attentuate one channel and amplify the other channel periodically.
void shift_channel(void)
{
	static unsigned long cnt = 1;
	static signed int dir = 1;
	unsigned int att;

	att = (unsigned int) (cnt / 20000);
	left_output = left_input >> att;
	right_output = right_input >> (5 - att);
	cnt += dir;
	if (cnt == 99999)
	{
		dir = -1;
	}
	if (cnt == 1)
	{
		dir = 1;
	}

}

// UserTask()
// ----------
// The main user task.
// Note that this task is not called by main(). It is scheduled by DSP/BIOS
void UserTask()
{
    DSK5416_PCM3002_CodecHandle hCodec;
    unsigned int flag;
    unsigned int switch_value;
    signed int mono_input;
    signed long output;

    puts("TMS320C5416 DSK: Audio effect project started\n");

    delay_array_clear();

    flag = 1;

    // Start the codec
    hCodec = DSK5416_PCM3002_openCodec(0, &setup);

    while (flag)
    {
        // Read left input channel
        while (!DSK5416_PCM3002_read16(hCodec, &left_input));

        // Output to left output channel
        while (!DSK5416_PCM3002_write16(hCodec, left_output));

        // Read right input channel
        while (!DSK5416_PCM3002_read16(hCodec, &right_input));

        // Output to right output channel
        while (!DSK5416_PCM3002_write16(hCodec, right_output));

        // Read user switches on DSK and display their meaning on Stdout.
        switch_value = switch_status_display();

        // Where required, generate mono input from left input and right input
        mono_input = stereo_to_mono ( left_input, right_input);

        // Digital Signal Processing
        if (switch_value == 15)
        {
            // Straight through stereo. No electronic crossover
            left_output = left_input ;
            right_output = right_input ;
            left_output >>= 1;
            right_output >>= 1;      // Attenuate slightly
        }
        else if (switch_value == 14)
        {
            // Crossover at 1000 Hz
            output = FIR_dual_filter_asm( &blackman_low_pass_filter_1000Hz[0],
                mono_input);
            left_output = (signed int) (output & 0xFFFF ); // Treble channel
            right_output = (signed int) (output >> 16 );   // Bass channel
        }
        else if (switch_value == 13)
        {
		   shift_channel();
        }
        else if (switch_value == 11)
        {
            // Output delayed
            right_output = mono_input + delayed_input( mono_input, DELAY_TIME);
            left_output = left_input;
            left_output >>= 1;
            right_output >>= 1;      // Attenuate slightly

        }
        else if (switch_value == 7)
        {
            flag = 0;
        }

        // Display greater of two outputs on bargraph
        bargraph ( left_output, right_output);
    }

    // Finished processing. Close the codec
    DSK5416_PCM3002_closeCodec(hCodec);

    puts("TMS320C5416 DSK: Audio effect project stopped\n");
}

// main()
void main()
{
    // Initialize the board support library
    // There is no need to initialize the DIP switches and the LEDs
    DSK5416_init();

    // All other functions are scheduled by DSP/BIOS
}

/******************************************************************************/
/* End of AudioEffect.c                                                       */
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