digital audio mod11 / Mbed 2 deprecated fftimplement

oldexamplecode

Dependencies:   mbed

LookupTables.cpp@0:6863633bf8a4, 2017-03-24 (annotated)

Committer:
rik
Date:
Fri Mar 24 11:22:30 2017 +0000
Revision:
0:6863633bf8a4
oldexamplecode;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
rik 0:6863633bf8a4 1
rik 0:6863633bf8a4 2 #include "LookupTables.h"
rik 0:6863633bf8a4 3
rik 0:6863633bf8a4 4 ////////////////// COSINE SINE LOOKUP TABLES
rik 0:6863633bf8a4 5
rik 0:6863633bf8a4 6 // Returns the cosine value using the lut of a given value
rik 0:6863633bf8a4 7 float lut_cos(float value){
rik 0:6863633bf8a4 8 // Cosine is symmetric so convert to absolute
rik 0:6863633bf8a4 9 if (value < 0)
rik 0:6863633bf8a4 10 value = -value;
rik 0:6863633bf8a4 11
rik 0:6863633bf8a4 12 // and subtract the "offset"
rik 0:6863633bf8a4 13 //float actualvalue = (float)(value % (2*M_PI));
rik 0:6863633bf8a4 14
rik 0:6863633bf8a4 15 while (value >= 2 * (float)M_PI){
rik 0:6863633bf8a4 16 value -= 2 * (float)M_PI;
rik 0:6863633bf8a4 17 }
rik 0:6863633bf8a4 18
rik 0:6863633bf8a4 19 // Calculate the value to a discrete value (1024*0.00613592 = 2 pi)
rik 0:6863633bf8a4 20 int discreteValue = (int)(value / 0.00613592);
rik 0:6863633bf8a4 21
rik 0:6863633bf8a4 22 return cosLookupTable_f[discreteValue];
rik 0:6863633bf8a4 23 }
rik 0:6863633bf8a4 24 // Returns the sine value using the lut for a given value
rik 0:6863633bf8a4 25 float lut_sin(float value){
rik 0:6863633bf8a4 26 // Convert to cosine
rik 0:6863633bf8a4 27 value -= 0.5*(float)M_PI;
rik 0:6863633bf8a4 28 // Cosine is symmetric so convert to absolute
rik 0:6863633bf8a4 29 if (value < 0)
rik 0:6863633bf8a4 30 value = -value;
rik 0:6863633bf8a4 31
rik 0:6863633bf8a4 32 // subtract the "offset" of the original 0-2pi
rik 0:6863633bf8a4 33 //float actualvalue = (float)(value % (float)(2 * M_PI));
rik 0:6863633bf8a4 34
rik 0:6863633bf8a4 35 while (value >= (2 * (float)M_PI)){
rik 0:6863633bf8a4 36 value -= (2 * (float)M_PI);
rik 0:6863633bf8a4 37 }
rik 0:6863633bf8a4 38
rik 0:6863633bf8a4 39 // Calculate the value to a discrete value (1024*0.00613592 = 2 pi)
rik 0:6863633bf8a4 40 int discreteValue = (int)(value / 0.00613592);
rik 0:6863633bf8a4 41
rik 0:6863633bf8a4 42 return cosLookupTable_f[discreteValue];
rik 0:6863633bf8a4 43 }
rik 0:6863633bf8a4 44
rik 0:6863633bf8a4 45 // Returns the cosine value using the lut of a given value
rik 0:6863633bf8a4 46 // WARNING, FAST VERSION ONLY WORKS WITH VALUES 0 - 2 PI
rik 0:6863633bf8a4 47 float lut_cos_f(float value){
rik 0:6863633bf8a4 48 // Calculate the value to a discrete value (1024*0.00613592 = 2 pi)
rik 0:6863633bf8a4 49 int discreteValue = (int)(value / 0.00613592);
rik 0:6863633bf8a4 50
rik 0:6863633bf8a4 51 return cosLookupTable_f[discreteValue];
rik 0:6863633bf8a4 52 }
rik 0:6863633bf8a4 53
rik 0:6863633bf8a4 54 ////////////////// END COSINE SINE LOOKUP TABLES
rik 0:6863633bf8a4 55
rik 0:6863633bf8a4 56 ////////////////// HANNING LOOKUP TABLE
rik 0:6863633bf8a4 57
rik 0:6863633bf8a4 58 // Applies the hanning LUT to the supplied array of data
rik 0:6863633bf8a4 59 void applyHanningTable(float* data, int datasize){
rik 0:6863633bf8a4 60 if (datasize == 1024){ // Only works for 10 bit data arrays
rik 0:6863633bf8a4 61 for (int i = 0; i < 1024; i++){
rik 0:6863633bf8a4 62 data[i] *= hanningTable_f[i];
rik 0:6863633bf8a4 63 }
rik 0:6863633bf8a4 64 }
rik 0:6863633bf8a4 65 }
rik 0:6863633bf8a4 66
rik 0:6863633bf8a4 67 ////////////////// END HANNING LOOKUP TABLE