FftTest.h

00001 /**
00002  *  @file       FftTest.h
00003  *  @brief      Header file for FftTest.cpp
00004  *  @date       2015.02.24
00005  *  @version    1.0.2
00006  */
00007 #ifndef _INC_FftTest
00008 #define _INC_FftTest
00009 
00010 // #define _LARGE_RAM   /* Uncomment if using large RAM. */
00011 /* Hann window array and bit reversal array can  */
00012 /* be generated dynamically instead of constant. */
00013 
00014 #include "mbed.h"
00015 
00016 /* Constant */
00017 #define PI              (3.141592)
00018 #define SQRT_2F         (1.41421356f)
00019 #define DATA_LENGTH     (256)
00020 
00021 /**  FFT test
00022  */
00023 class FftTest
00024 {
00025 
00026 public:
00027     FftTest();
00028     ~FftTest();
00029     void apply_window(float in_data[], float out_data[]);
00030     void calc_fft(float in_data[], float out_re_data[], float out_im_data[]);
00031     void calc_power(float re_data[], float im_data[], float pow_data[], int32_t dat_len);
00032     void calc_amplitude(float pow_data[], float amp_data[], int32_t dat_len);
00033     void norm_amplitude(float amp_data[], int32_t dat_len);
00034 
00035 private:
00036     /* Menber variables */
00037     int32_t _dat_len;
00038     int32_t _digit_len;
00039 #ifdef _LARGE_RAM
00040     float* _window_array;
00041     int32_t* _br_idx_array;
00042 #else
00043     static const float _window_array[DATA_LENGTH];  /* Hann window array */
00044     static const int _br_idx_array[DATA_LENGTH];    /* Bit reversal index array */
00045 #endif  /* LARGE_RAM */
00046 
00047     /* Member functions */
00048     void init();
00049     int32_t get_digit_len(int32_t val);
00050     void set_hann_window();
00051     void set_bit_reversal();
00052 };
00053 #endif  /* INC_FftTest */