1 files changed, 21 insertions, 33 deletions

diff --git a/lab5/RTDSP/intio.c b/lab5/RTDSP/intio.c
index 6c90633..124fc03 100644
--- a/lab5/RTDSP/intio.c
+++ b/lab5/RTDSP/intio.c
@@ -36,19 +36,16 @@
 
 // Some functions to help with writing/reading the audio ports when using interrupts.
 #include <helper_functions_ISR.h>
+#include "Matlab/filter_coeff.txt"
 // Some functions to help with configuring hardware
 #include "helper_functions_polling.h"
 
 
 // PI defined here for use in your code
 #define PI 3.141592653589793
-#include "Matlab/filter_coeff_ell_a.txt"
-#include "Matlab/filter_coeff_ell_b.txt"
-
-int N = sizeof(a)/sizeof(a[0]);
-short* x;
-double* y;
-
+#define N 249
+double buffer[N]= {0};
+unsigned ptr = N-1;
 
 /******************************* Global declarations ********************************/
 
@@ -82,24 +79,14 @@ void ISR_AIC(void);
 short circ_fir(void);
 /********************************** Main routine ************************************/
 void main(){
-    int i;
-    x = (short*)calloc(N, sizeof(short));
-	y = (double*)calloc(N, sizeof(double));
     // initialize board and the audio port
     init_hardware();
 
     /* initialize hardware interrupts */
     init_HWI();
-	
-	/* Initialises array to 0 */
-	for (i = 0; i < N; ++i) {
-		y[i] = 0.0;
-		x[i] = 0;
-	}
 
     /* loop indefinitely, waiting for interrupts */
     while(1) {};
-    
 }
 
 /********************************** init_hardware() **********************************/
@@ -139,22 +126,23 @@ void init_HWI()
 /******************** INTERRUPT SERVICE ROUTINE ***********************/
 void ISR_AIC()
 {
-	int i;
-	
-	//Shift the values
-	for (i = N-1; i > 0; --i) {
-		x[i] = x[i-1];
-		y[i] = y[i-1];
+	buffer[ptr] = (double) mono_read_16Bit();
+	mono_write_16Bit((short)circ_fir());
+	if (ptr == 0)
+		ptr = N;
+	ptr--;
+}
+
+// Perform linear convolution
+short circ_fir()
+{
+	double y = 0;
+	int i = 0;
+	for(; i+ptr < N; i++) {
+		y += buffer[i+ptr] * b[N-i-1];
 	}
-	
-	x[0] = mono_read_16Bit();
-	y[0] = 0.0;
-	
-	for (i = 0; i < N; ++i) {
-		y[0] += b[i] * x[i];
-		if (i != 0)
-			y[0] -= a[i] * y[i];	
+	for(; i < N; i++) {
+		y += buffer[i+ptr-N] * b[N-i-1];
 	}
-	
-	mono_write_16Bit((short)y[0]);
+	return y;
 }