echo.c

Using DSP/BIOS I/O in Multichannel Systems

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#include <std.h>
#include <mem.h>
#include <log.h>
#include <sio.h>
#include <tsk.h>

#define NUM_CHANNELS	2
#define SAMPLE_BUF_LEN 	160 /* number of samples in a frame */
#define SAMPLE_BUF_SIZE (SAMPLE_BUF_LEN * sizeof(unsigned short))
#define	CHANNEL0		0
#define CHANNEL1		1
#define CHAN_0_READY	1
#define CHAN_1_READY	2

extern far LOG_Obj trace; 	   	/* application printf() log */ 
extern far LOG_Obj trace1;
extern far SIO_Obj inStream0;
extern far SIO_Obj outStream0;
extern far SIO_Obj inStream1;
extern far SIO_Obj outStream1;
extern Int IDRAM;

extern Void doLoad(int load);

void echo(void);

/* template for a single channel record in the channel database */
typedef struct dataChannel {
	SIO_Obj 	*inStream;
	SIO_Obj 	*outStream;
	Int			load;
} dataChannel;

dataChannel		audioChannel[NUM_CHANNELS];

/*
 * Performs all channel processing. gets a buffer from the input stream, performs
 * necessary processing on it (simulated by load), and puts the buffer into the
 * output stream.
 */
Bool processChannel(dataChannel *channel, Ptr *buffer)
{   
	Int 	nbytes;
            
	LOG_printf(&trace1, "sio_get uses buffer 0x%x", *buffer);
	
	if ((nbytes = SIO_get(channel->inStream, buffer)) < 0)
		return(FALSE);

	LOG_printf(&trace1, "sio_get returns buffer 0x%x", *buffer);
		
	/* processing of received buffer is done here */
	doLoad(channel->load);
	
	if ((nbytes = SIO_put(channel->outStream, buffer, nbytes)) < 0)
		return(FALSE);
		
	LOG_printf(&trace1, "sio_put returns buffer 0x%x", *buffer);
	return(TRUE);
	
}

/*
 * echo is executed in the main system task, echoTSK. It performs all channel
 * processing. SIO_select is used as a polling mechanism so that the first 
 * channel to be processed is the first one that is ready for it.
 */
void echo(void)
{
    Ptr 			buf;                       
    Uns				mask;
    SIO_Handle		inStreams[NUM_CHANNELS];
    
    /* initialize the channel database */ 
	audioChannel[CHANNEL0].inStream = &inStream0;
	audioChannel[CHANNEL0].outStream = &outStream0;
	audioChannel[CHANNEL0].load = 0;
	
	audioChannel[CHANNEL1].inStream = &inStream1;
	audioChannel[CHANNEL1].outStream = &outStream1;
	audioChannel[CHANNEL1].load = 0;
	
	/* create the buffer used to prime the input stream */
    if (SIO_staticbuf(audioChannel[CHANNEL0].inStream, &buf) == 0) {
        SYS_abort("Cannot get static buffer");
    }   
    
	/* SIO_select requires an array of the streams it checks for input; this */
	/* initializes that array */
	inStreams[0] = &inStream0;
	inStreams[1] = &inStream1;
    
    /* loop forever: check each input stream for input; only perform processing */
    /* for a channel if the channel has input ready */
	while (TRUE) {
		mask = SIO_select(inStreams, 2, SYS_FOREVER);
		
		if (mask & CHAN_0_READY) {
			LOG_printf(&trace1, "channel 0");
		
			if (!processChannel(&audioChannel[0], &buf)) {
				LOG_printf(&trace, "processing error on channel 0");
			}
		}
		
		if (mask & CHAN_1_READY) {
			LOG_printf(&trace1, "channel 1");
		
			if (!processChannel(&audioChannel[1], &buf)) {
				LOG_printf(&trace, "processing error on channel 1");
			}
		}
		
		/* other processing may go here */
	}
}

main()
{
}