// lab4b.c
// Uses PN generation, IIR filtering, and autocorrelation
// code by Matt Kleffner -9/2004
// Based on swi_process.c by Educational DSP

#include "dsk5510_dual3006cfg.h"
#include "dsk5510.h"
#include "swi_process.h"
#include "dsplib.h"

#include "lab4b.h"              /* Define N here in header file */

/* function defined in pn.c */
void rand_fillbuffer(void);

/* IIR values and buffers (declared in c_fft_given_iirc.asm) */
#define IIR_order 4
extern int scale;
extern int coef[IIR_order];
extern int state[IIR_order];

/* Pointer to state buffer location */
int iirptr;
extern unsigned int *iseed;            /* seed for rand_fillbuffer() and randbit() */

/* function defined in iirfilt.c */
void iirfilt(void);

/* function defined in autocorr.c */
void autocorr(void);

/* Function defined by c_fft_given_iirc.asm */
//void bit_rev_fft(void);

/* FFT data buffers (declared in c_fft_given_iirc.asm) */
extern int bit_rev_data[N*2];   /* Data output for bit-reverse function */
extern int fft_data[N*2];       /* In-place FFT input & Output array */

/* Our input/output buffers */
int autocorr_in[N];
int autocorr_out[N];

// all data processing should be done in SWI_ProcessBuffer

void SWI_ProcessBuffer()
{
	static unsigned int mbox_value = 0;
	short *psrc, *pdest;
	unsigned int i;

	mbox_value |= SWI_getmbox();

	// buffers are only processed when both transmit and receive are ready
	if((mbox_value & DMA_RECEIVE_DONE) && (mbox_value & DMA_TRANSMIT_DONE)) {
 		mbox_value = 0;

		// get buffer pointers
		psrc = receive_buffer[receive_buffer_to_process_index];
		pdest = transmit_buffer[transmit_buffer_to_fill_index];
		
		    /* First, transfer inputs and outputs */

	    for (i = 0; i < N; i++) 
	    {
    	    pdest[4*i] = autocorr_in[i];
        	pdest[4*i+1] = bit_rev_data[i*2] << 8;
		
        /* Some statements useful in debugging */
        /* pdest[4*i] = psrc[4*i+2]; */
        /* Be sure to comment out PN-sequence generation */
        /* when using the next two lines */
        //autocorr_in[i] = psrc[4i+2];
		
	    }
    	
    	/* Last, set the DC coefficient to -1 for a trigger pulse */
    	pdest[0] = -32768;

		/* Generate PN input */
    	rand_fillbuffer();
		
    	/* Filter input */
    	iirfilt();

    	/* Calculate autocorrelation */
    	autocorr();
	
	 	/* Transfer autocorr output to FFT input buffer */
    	for (i = 0; i < N; i++) {
        	fft_data[i*2] = autocorr_out[i];
        	fft_data[i*2+1] = 0;
    	}
 
		
		// Bit-reverse and compute FFT 
		cfft((DATA *)fft_data,N, SCALE);
		cbrev((DATA *)fft_data,(DATA *)bit_rev_data,N);
		
		
		 /* Done, wait for next time around! */
		receive_buffer_processed = 1; // flag receive buffer as processed
		transmit_buffer_filled = 1; // flag output buffer as full
	}
}