372 lines
11 KiB
C++
372 lines
11 KiB
C++
/*
|
|
* Program: REALFFTF.C
|
|
* Author: Philip Van Baren
|
|
* Date: 2 September 1993
|
|
*
|
|
* Description: These routines perform an FFT on real data to get a conjugate-symmetric
|
|
* output, and an inverse FFT on conjugate-symmetric input to get a real
|
|
* output sequence.
|
|
*
|
|
* This code is for floating point data.
|
|
*
|
|
* Modified 8/19/1998 by Philip Van Baren
|
|
* - made the InitializeFFT and EndFFT routines take a structure
|
|
* holding the length and pointers to the BitReversed and SinTable
|
|
* tables.
|
|
* Modified 5/23/2009 by Philip Van Baren
|
|
* - Added GetFFT and ReleaseFFT routines to retain common SinTable
|
|
* and BitReversed tables so they don't need to be reallocated
|
|
* and recomputed on every call.
|
|
* - Added Reorder* functions to undo the bit-reversal
|
|
*
|
|
* Copyright (C) 2009 Philip VanBaren
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
*/
|
|
|
|
|
|
#include "RealFFTf.h"
|
|
|
|
|
|
|
|
#include <vector>
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
#include <math.h>
|
|
|
|
#include <wx/thread.h>
|
|
|
|
#ifndef M_PI
|
|
#define M_PI 3.14159265358979323846 /* pi */
|
|
#endif
|
|
|
|
/*
|
|
* Initialize the Sine table and Twiddle pointers (bit-reversed pointers)
|
|
* for the FFT routine.
|
|
*/
|
|
HFFT InitializeFFT(size_t fftlen)
|
|
{
|
|
int temp;
|
|
HFFT h{ safenew FFTParam };
|
|
|
|
/*
|
|
* FFT size is only half the number of data points
|
|
* The full FFT output can be reconstructed from this FFT's output.
|
|
* (This optimization can be made since the data is real.)
|
|
*/
|
|
h->Points = fftlen / 2;
|
|
|
|
h->SinTable.reinit(2*h->Points);
|
|
|
|
h->BitReversed.reinit(h->Points);
|
|
|
|
for(size_t i = 0; i < h->Points; i++)
|
|
{
|
|
temp = 0;
|
|
for(size_t mask = h->Points / 2; mask > 0; mask >>= 1)
|
|
temp = (temp >> 1) + (i & mask ? h->Points : 0);
|
|
|
|
h->BitReversed[i] = temp;
|
|
}
|
|
|
|
for(size_t i = 0; i < h->Points; i++)
|
|
{
|
|
h->SinTable[h->BitReversed[i] ]=(fft_type)-sin(2*M_PI*i/(2*h->Points));
|
|
h->SinTable[h->BitReversed[i]+1]=(fft_type)-cos(2*M_PI*i/(2*h->Points));
|
|
}
|
|
|
|
#ifdef EXPERIMENTAL_EQ_SSE_THREADED
|
|
// NEW SSE FFT routines work on live data
|
|
for(size_t i = 0; i < 32; i++)
|
|
if((1 << i) & fftlen)
|
|
h->pow2Bits = i;
|
|
#endif
|
|
|
|
return h;
|
|
}
|
|
|
|
enum : size_t { MAX_HFFT = 10 };
|
|
|
|
// Maintain a pool:
|
|
static std::vector< std::unique_ptr<FFTParam> > hFFTArray(MAX_HFFT);
|
|
wxCriticalSection getFFTMutex;
|
|
|
|
/* Get a handle to the FFT tables of the desired length */
|
|
/* This version keeps common tables rather than allocating a NEW table every time */
|
|
HFFT GetFFT(size_t fftlen)
|
|
{
|
|
// To do: smarter policy about when to retain in the pool and when to
|
|
// allocate a unique instance.
|
|
|
|
wxCriticalSectionLocker locker{ getFFTMutex };
|
|
|
|
size_t h = 0;
|
|
auto n = fftlen/2;
|
|
auto size = hFFTArray.size();
|
|
for(;
|
|
(h < size) && hFFTArray[h] && (n != hFFTArray[h]->Points);
|
|
h++)
|
|
;
|
|
if(h < size) {
|
|
if(hFFTArray[h] == NULL) {
|
|
hFFTArray[h].reset( InitializeFFT(fftlen).release() );
|
|
}
|
|
return HFFT{ hFFTArray[h].get() };
|
|
} else {
|
|
// All buffers used, so fall back to allocating a NEW set of tables
|
|
return InitializeFFT(fftlen);
|
|
}
|
|
}
|
|
|
|
/* Release a previously requested handle to the FFT tables */
|
|
void FFTDeleter::operator() (FFTParam *hFFT) const
|
|
{
|
|
wxCriticalSectionLocker locker{ getFFTMutex };
|
|
|
|
auto it = hFFTArray.begin(), end = hFFTArray.end();
|
|
while (it != end && it->get() != hFFT)
|
|
++it;
|
|
if ( it != end )
|
|
;
|
|
else
|
|
delete hFFT;
|
|
}
|
|
|
|
/*
|
|
* Forward FFT routine. Must call GetFFT(fftlen) first!
|
|
*
|
|
* Note: Output is BIT-REVERSED! so you must use the BitReversed to
|
|
* get legible output, (i.e. Real_i = buffer[ h->BitReversed[i] ]
|
|
* Imag_i = buffer[ h->BitReversed[i]+1 ] )
|
|
* Input is in normal order.
|
|
*
|
|
* Output buffer[0] is the DC bin, and output buffer[1] is the Fs/2 bin
|
|
* - this can be done because both values will always be real only
|
|
* - this allows us to not have to allocate an extra complex value for the Fs/2 bin
|
|
*
|
|
* Note: The scaling on this is done according to the standard FFT definition,
|
|
* so a unit amplitude DC signal will output an amplitude of (N)
|
|
* (Older revisions would progressively scale the input, so the output
|
|
* values would be similar in amplitude to the input values, which is
|
|
* good when using fixed point arithmetic)
|
|
*/
|
|
void RealFFTf(fft_type *buffer, const FFTParam *h)
|
|
{
|
|
fft_type *A,*B;
|
|
const fft_type *sptr;
|
|
const fft_type *endptr1,*endptr2;
|
|
const int *br1,*br2;
|
|
fft_type HRplus,HRminus,HIplus,HIminus;
|
|
fft_type v1,v2,sin,cos;
|
|
|
|
auto ButterfliesPerGroup = h->Points/2;
|
|
|
|
/*
|
|
* Butterfly:
|
|
* Ain-----Aout
|
|
* \ /
|
|
* / \
|
|
* Bin-----Bout
|
|
*/
|
|
|
|
endptr1 = buffer + h->Points * 2;
|
|
|
|
while(ButterfliesPerGroup > 0)
|
|
{
|
|
A = buffer;
|
|
B = buffer + ButterfliesPerGroup * 2;
|
|
sptr = h->SinTable.get();
|
|
|
|
while(A < endptr1)
|
|
{
|
|
sin = *sptr;
|
|
cos = *(sptr+1);
|
|
endptr2 = B;
|
|
while(A < endptr2)
|
|
{
|
|
v1 = *B * cos + *(B + 1) * sin;
|
|
v2 = *B * sin - *(B + 1) * cos;
|
|
*B = (*A + v1);
|
|
*(A++) = *(B++) - 2 * v1;
|
|
*B = (*A - v2);
|
|
*(A++) = *(B++) + 2 * v2;
|
|
}
|
|
A = B;
|
|
B += ButterfliesPerGroup * 2;
|
|
sptr += 2;
|
|
}
|
|
ButterfliesPerGroup >>= 1;
|
|
}
|
|
/* Massage output to get the output for a real input sequence. */
|
|
br1 = h->BitReversed.get() + 1;
|
|
br2 = h->BitReversed.get() + h->Points - 1;
|
|
|
|
while(br1<br2)
|
|
{
|
|
sin=h->SinTable[*br1];
|
|
cos=h->SinTable[*br1+1];
|
|
A=buffer+*br1;
|
|
B=buffer+*br2;
|
|
HRplus = (HRminus = *A - *B ) + (*B * 2);
|
|
HIplus = (HIminus = *(A+1) - *(B+1)) + (*(B+1) * 2);
|
|
v1 = (sin*HRminus - cos*HIplus);
|
|
v2 = (cos*HRminus + sin*HIplus);
|
|
*A = (HRplus + v1) * (fft_type)0.5;
|
|
*B = *A - v1;
|
|
*(A+1) = (HIminus + v2) * (fft_type)0.5;
|
|
*(B+1) = *(A+1) - HIminus;
|
|
|
|
br1++;
|
|
br2--;
|
|
}
|
|
/* Handle the center bin (just need a conjugate) */
|
|
A=buffer+*br1+1;
|
|
*A=-*A;
|
|
/* Handle DC bin separately - and ignore the Fs/2 bin
|
|
buffer[0]+=buffer[1];
|
|
buffer[1]=(fft_type)0;*/
|
|
/* Handle DC and Fs/2 bins separately */
|
|
/* Put the Fs/2 value into the imaginary part of the DC bin */
|
|
v1=buffer[0]-buffer[1];
|
|
buffer[0]+=buffer[1];
|
|
buffer[1]=v1;
|
|
}
|
|
|
|
|
|
/* Description: This routine performs an inverse FFT to real data.
|
|
* This code is for floating point data.
|
|
*
|
|
* Note: Output is BIT-REVERSED! so you must use the BitReversed to
|
|
* get legible output, (i.e. wave[2*i] = buffer[ BitReversed[i] ]
|
|
* wave[2*i+1] = buffer[ BitReversed[i]+1 ] )
|
|
* Input is in normal order, interleaved (real,imaginary) complex data
|
|
* You must call GetFFT(fftlen) first to initialize some buffers!
|
|
*
|
|
* Input buffer[0] is the DC bin, and input buffer[1] is the Fs/2 bin
|
|
* - this can be done because both values will always be real only
|
|
* - this allows us to not have to allocate an extra complex value for the Fs/2 bin
|
|
*
|
|
* Note: The scaling on this is done according to the standard FFT definition,
|
|
* so a unit amplitude DC signal will output an amplitude of (N)
|
|
* (Older revisions would progressively scale the input, so the output
|
|
* values would be similar in amplitude to the input values, which is
|
|
* good when using fixed point arithmetic)
|
|
*/
|
|
void InverseRealFFTf(fft_type *buffer, const FFTParam *h)
|
|
{
|
|
fft_type *A,*B;
|
|
const fft_type *sptr;
|
|
const fft_type *endptr1,*endptr2;
|
|
const int *br1;
|
|
fft_type HRplus,HRminus,HIplus,HIminus;
|
|
fft_type v1,v2,sin,cos;
|
|
|
|
auto ButterfliesPerGroup = h->Points / 2;
|
|
|
|
/* Massage input to get the input for a real output sequence. */
|
|
A = buffer + 2;
|
|
B = buffer + h->Points * 2 - 2;
|
|
br1 = h->BitReversed.get() + 1;
|
|
while(A<B)
|
|
{
|
|
sin=h->SinTable[*br1];
|
|
cos=h->SinTable[*br1+1];
|
|
HRplus = (HRminus = *A - *B ) + (*B * 2);
|
|
HIplus = (HIminus = *(A+1) - *(B+1)) + (*(B+1) * 2);
|
|
v1 = (sin*HRminus + cos*HIplus);
|
|
v2 = (cos*HRminus - sin*HIplus);
|
|
*A = (HRplus + v1) * (fft_type)0.5;
|
|
*B = *A - v1;
|
|
*(A+1) = (HIminus - v2) * (fft_type)0.5;
|
|
*(B+1) = *(A+1) - HIminus;
|
|
|
|
A+=2;
|
|
B-=2;
|
|
br1++;
|
|
}
|
|
/* Handle center bin (just need conjugate) */
|
|
*(A+1)=-*(A+1);
|
|
/* Handle DC bin separately - this ignores any Fs/2 component
|
|
buffer[1]=buffer[0]=buffer[0]/2;*/
|
|
/* Handle DC and Fs/2 bins specially */
|
|
/* The DC bin is passed in as the real part of the DC complex value */
|
|
/* The Fs/2 bin is passed in as the imaginary part of the DC complex value */
|
|
/* (v1+v2) = buffer[0] == the DC component */
|
|
/* (v1-v2) = buffer[1] == the Fs/2 component */
|
|
v1=0.5f*(buffer[0]+buffer[1]);
|
|
v2=0.5f*(buffer[0]-buffer[1]);
|
|
buffer[0]=v1;
|
|
buffer[1]=v2;
|
|
|
|
/*
|
|
* Butterfly:
|
|
* Ain-----Aout
|
|
* \ /
|
|
* / \
|
|
* Bin-----Bout
|
|
*/
|
|
|
|
endptr1 = buffer + h->Points * 2;
|
|
|
|
while(ButterfliesPerGroup > 0)
|
|
{
|
|
A = buffer;
|
|
B = buffer + ButterfliesPerGroup * 2;
|
|
sptr = h->SinTable.get();
|
|
|
|
while(A < endptr1)
|
|
{
|
|
sin = *(sptr++);
|
|
cos = *(sptr++);
|
|
endptr2 = B;
|
|
while(A < endptr2)
|
|
{
|
|
v1 = *B * cos - *(B + 1) * sin;
|
|
v2 = *B * sin + *(B + 1) * cos;
|
|
*B = (*A + v1) * (fft_type)0.5;
|
|
*(A++) = *(B++) - v1;
|
|
*B = (*A + v2) * (fft_type)0.5;
|
|
*(A++) = *(B++) - v2;
|
|
}
|
|
A = B;
|
|
B += ButterfliesPerGroup * 2;
|
|
}
|
|
ButterfliesPerGroup >>= 1;
|
|
}
|
|
}
|
|
|
|
void ReorderToFreq(const FFTParam *hFFT, const fft_type *buffer,
|
|
fft_type *RealOut, fft_type *ImagOut)
|
|
{
|
|
// Copy the data into the real and imaginary outputs
|
|
for(size_t i = 1; i < hFFT->Points; i++) {
|
|
RealOut[i] = buffer[hFFT->BitReversed[i] ];
|
|
ImagOut[i] = buffer[hFFT->BitReversed[i]+1];
|
|
}
|
|
RealOut[0] = buffer[0]; // DC component
|
|
ImagOut[0] = 0;
|
|
RealOut[hFFT->Points] = buffer[1]; // Fs/2 component
|
|
ImagOut[hFFT->Points] = 0;
|
|
}
|
|
|
|
void ReorderToTime(const FFTParam *hFFT, const fft_type *buffer, fft_type *TimeOut)
|
|
{
|
|
// Copy the data into the real outputs
|
|
for(size_t i = 0; i < hFFT->Points; i++) {
|
|
TimeOut[i*2 ]=buffer[hFFT->BitReversed[i] ];
|
|
TimeOut[i*2+1]=buffer[hFFT->BitReversed[i]+1];
|
|
}
|
|
}
|