Takehisa Oneta
自分用に書き換えてしまったので forkします
Fork of
UIT_FFT_Real
by 
不韋 呂
Diff: fftReal.cpp
- Revision:
- 1:148bf3a521a0
- Parent:
- 0:982a9acf3a07
--- a/fftReal.cpp Fri Dec 19 12:10:34 2014 +0000
+++ b/fftReal.cpp Thu Oct 15 16:19:44 2015 +0000
@@ -3,75 +3,116 @@
// This class can execute FFT and IFFT
// Copyright (c) 2014 MIKAMI, Naoki, 2014/12/19
//------------------------------------------------------------------------------
+// for LPPC1114FN28(Cortex-M0) modified by Takehisa Oneta(ohneta) 4th Aug.2015
#include "fftReal.hpp"
+#include "mbed.h"
+#include "SoundWS2812B-FFT.h"
-namespace Mikami
+#ifdef _DEBUG_UART_
+extern Serial pc;
+#endif
+
+// Constructor
+FftReal::FftReal(int16_t n) : N_FFT_(n), N_INV_(1.0f / n)
{
- // Constructor
- FftReal::FftReal(int16_t n)
- : N_FFT_(n), N_INV_(1.0f/n)
- {
- // __clz(): Count leading zeros
- uint32_t shifted = n << (__clz(n)+1);
- if (shifted != 0)
- {
- fprintf(stderr, "\r\nNot power of 2, in FftReal class.");
- fprintf(stderr, "\r\nForce to exit the program.");
- exit(EXIT_FAILURE); // Terminate program
- }
+ // __clz(): Count leading zeros
+ uint32_t shifted = n << (__clz(n) + 1);
+ if (shifted != 0) {
+#ifdef _DEBUG_UART_
+ pc.printf("\r\nNot power of 2, in FftReal class.");
+ pc.printf("\r\nForce to exit the program.");
+#endif
+ exit(EXIT_FAILURE); // Terminate program
+ }
- wTable_ = new Complex[n/2];
- bTable_ = new uint16_t[n];
- u_ = new Complex[n];
-
- // calculation of twiddle factor
- Complex arg = Complex(0, -6.283185f/N_FFT_);
- for (int k=0; k<N_FFT_/2; k++)
- wTable_[k] = exp(arg*(float)k);
+ wTable_ = new Complex[n / 2];
+ if (wTable_ == NULL) {
+#ifdef _DEBUG_UART_
+ pc.printf("wTable_ is NULL.\n");
+#endif
+ exit(EXIT_FAILURE);
+ }
+ bTable_ = new uint16_t[n];
+ if (bTable_ == NULL) {
+#ifdef _DEBUG_UART_
+ pc.printf("bTable_ is NULL.\n");
+#endif
+ exit(EXIT_FAILURE);
+ }
+ u_ = new Complex[n];
+ if (u_ == NULL) {
+#ifdef _DEBUG_UART_
+ pc.printf("u_ is NULL.\n");
+#endif
+ exit(EXIT_FAILURE);
+ }
- // for bit reversal table
- uint16_t nShift = __clz(n) + 1;
- for (int k=0; k<n; k++)
- // __rbit(k): Reverse the bit order in a 32-bit word
- bTable_[k] = __rbit(k) >> nShift;
+ // calculation of twiddle factor
+ Complex arg = Complex(0, -6.283185f / N_FFT_);
+ for (int k = 0; k < N_FFT_ / 2; k++) {
+ wTable_[k] = exp(arg * (float)k);
}
- // Destructor
- FftReal::~FftReal()
- {
- delete[] wTable_;
- delete[] bTable_;
- delete[] u_;
+ // for bit reversal table
+ uint16_t nShift = __clz(n) + 1;
+ for (int k = 0; k < n; k++) {
+ //bTable_[k] = __rbit(k) >> nShift; // __rbit(k): Reverse the bit order in a 32-bit word
+
+ // for Cortex-M0
+ unsigned int x = (unsigned int)k;
+ x = ((x & 0x55555555) << 1) | ((x & 0xAAAAAAAA) >> 1);
+ x = ((x & 0x33333333) << 2) | ((x & 0xCCCCCCCC) >> 2);
+ x = ((x & 0x0F0F0F0F) << 4) | ((x & 0xF0F0F0F0) >> 4);
+ x = ((x & 0x00FF00FF) << 8) | ((x & 0xFF00FF00) >> 8);
+ x = ((x & 0x0000FFFF) << 16) | ((x & 0xFFFF0000) >> 16);
+ bTable_[k] = (x >> nShift);
+ }
+}
+
+// Destructor
+FftReal::~FftReal()
+{
+ delete[] wTable_;
+ delete[] bTable_;
+ delete[] u_;
+}
+
+// Execute FFT
+void FftReal::Execute(const float x[], Complex y[])
+{
+ for (int n = 0; n < N_FFT_; n++) {
+ u_[n] = x[n];
}
- // Execute FFT
- void FftReal::Execute(const float x[], Complex y[])
- {
- for (int n=0; n<N_FFT_; n++) u_[n] = x[n];
-
- // except for last stage
- ExcludeLastTtage();
+ // except for last stage
+ ExcludeLastTtage();
- // Last stage
- y[0] = u_[0] + u_[1];
- y[N_FFT_/2] = u_[0] - u_[1];
- for (int k=2; k<N_FFT_; k+=2)
- u_[k] = u_[k] + u_[k+1];
-
- // Reorder to bit reversal
- for (int k=1; k<N_FFT_/2; k++)
- y[k] = u_[bTable_[k]];
+ // Last stage
+ y[0] = u_[0] + u_[1];
+ y[N_FFT_ / 2] = u_[0] - u_[1];
+ for (int k = 2; k < N_FFT_; k += 2) {
+ u_[k] = u_[k] + u_[k+1];
}
- // Execute IFFT
- void FftReal::ExecuteIfft(const Complex y[], float x[])
+ // Reorder to bit reversal
+ for (int k = 1; k < N_FFT_ / 2; k++) {
+ y[k] = u_[bTable_[k]];
+ }
+}
+
+#if 0
+// Execute IFFT
+void FftReal::ExecuteIfft(const Complex y[], float x[])
{
int half = N_FFT_/2;
- for (int n=0; n<=half; n++) u_[n] = y[n];
- for (int n=half+1; n<N_FFT_; n++)
+ for (int n=0; n<=half; n++) {
+ u_[n] = y[n];
+ }
+ for (int n=half+1; n<N_FFT_; n++) {
u_[n] = conj(y[N_FFT_-n]);
+ }
// except for last stage
ExcludeLastTtage();
@@ -87,29 +128,27 @@
x[Index(n)] = N_INV_*(un + un1);
x[Index(n+1)] = N_INV_*(un - un1);
}
- }
+}
+#endif
- // Processing except for last stage
- void FftReal::ExcludeLastTtage()
- {
- uint16_t nHalf = N_FFT_/2;
- for (int stg=1; stg<N_FFT_/2; stg*=2)
- {
- uint16_t nHalf2 = nHalf*2;
- for (int kp=0; kp<N_FFT_; kp+=nHalf2)
- {
- uint16_t kx = 0;
- for (int k=kp; k<kp+nHalf; k++)
- {
- // Butterfly operation
- Complex uTmp = u_[k+nHalf];
- u_[k+nHalf] = (u_[k] - uTmp)*wTable_[kx];
- u_[k] = u_[k] + uTmp;
- kx = kx + stg;
- }
+// Processing except for last stage
+void FftReal::ExcludeLastTtage()
+{
+ uint16_t nHalf = N_FFT_ / 2;
+ for (int stg = 1; stg < N_FFT_ / 2; stg *= 2) {
+ uint16_t nHalf2 = nHalf * 2;
+ for (int kp = 0; kp < N_FFT_; kp += nHalf2) {
+ uint16_t kx = 0;
+ for (int k = kp; k <kp + nHalf; k++) {
+ // Butterfly operation
+ Complex uTmp = u_[k + nHalf];
+ u_[k + nHalf] = (u_[k] - uTmp) * wTable_[kx];
+ u_[k] = u_[k] + uTmp;
+ kx = kx + stg;
}
- nHalf = nHalf/2;
- }
- }
+ }
+ nHalf = nHalf / 2;
+ }
}
+