1 files changed, 31 insertions, 0 deletions
diff --git a/sine_lookup.c b/sine_lookup.c
new file mode 100644
index 0000000..1d12f76
--- /dev/null
+++ b/sine_lookup.c
@@ -0,0 +1,31 @@
+
+#include <stdio.h>
+
+
+unsigned char sine_lookup[] = {127, 139, 151, 163, 175, 186, 197, 207, 216,  
+    225, 232, 239, 244, 248, 251, 253, 254, 253, 251, 248, 244, 239, 232, 225,
+    216, 207, 197, 186, 175, 163, 151, 139, 126, 114, 102, 90, 78, 67, 56, 46,
+    37, 28, 21, 14, 9, 5, 2, 0, 0, 0, 2, 5, 9, 14, 21, 28, 37, 46, 56, 67, 78,
+    90, 102, 114}; 
+
+unsigned char sin_8bit(int counter, int period);
+
+unsigned char sin_8bit(int counter, int period) {
+    int high, low;
+    float t = (counter % period) / (float)period;
+    float weight = (63*t) - (int)(63*t);
+    low = sine_lookup[(int)(63*t)];
+    if (63*t >= 62)
+        high = sine_lookup[0];
+    else
+        high = sine_lookup[1+(int)(63*t)];
+    //printf("\tl=%d h=%d w=%f\n", low, high, weight);    
+    return (int)(high * weight + low * (1.0 - weight));
+}   
+
+void main() {
+    int i;
+    for(i=0; i<800;i++){
+        printf("%d\t%d\n", i, sin_8bit(i, 800));
+    }
+}