}
void SetLogFilename(char *fn) {
- logfilename = fn;
+ logfilename = fn;
}
void iceIIR_Butterworth(int *data, const size_t len){
int i,j;
int * output = (int* ) malloc(sizeof(int) * len);
+ if ( !output ) return;
+
+ // clear mem
memset(output, 0x00, len);
- float fc = 0.1125f; // center frequency
- size_t adjustedLen = len;
+ size_t adjustedLen = len;
+ float fc = 0.1125f; // center frequency
+
// create very simple low-pass filter to remove images (2nd-order Butterworth)
float complex iir_buf[3] = {0,0,0};
float b[3] = {0.003621681514929, 0.007243363029857, 0.003621681514929};
float complex x_prime = 1.0f; // save sample for estimating frequency
float complex x;
- for (i=0; i<adjustedLen; ++i) {
+ for (i = 0; i < adjustedLen; ++i) {
sample = data[i];
float freq = cargf(x*conjf(x_prime));
x_prime = x; // retain this sample for next iteration
- output[i] =(freq > 0)? 10 : -10;
+ output[i] =(freq > 0) ? 127 : -127;
}
// show data
+ //memcpy(data, output, adjustedLen);
for (j=0; j<adjustedLen; ++j)
data[j] = output[j];
-
+
free(output);
}
+void iceSimple_Filter(int *data, const size_t len, uint8_t k){
+// ref: http://www.edn.com/design/systems-design/4320010/A-simple-software-lowpass-filter-suits-embedded-system-applications
+// parameter K
+#define FILTER_SHIFT 4
+
+ int32_t filter_reg = 0;
+ int16_t input, output;
+ int8_t shift = (k <=8 ) ? k : FILTER_SHIFT;
+
+ for (int i = 0; i < len; ++i){
+
+ input = data[i];
+ // Update filter with current sample
+ filter_reg = filter_reg - (filter_reg >> shift) + input;
+
+ // Scale output for unity gain
+ output = filter_reg >> shift;
+ data[i] = output;
+ }
+}
+
float complex cexpf (float complex Z)
{
float complex Res;