diff data/fft/FFTapi.cpp @ 226:a867be73b638

* Add non-fftw3 fft alternative

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/data/fft/FFTapi.cpp	Fri Feb 09 11:32:34 2007 +0000
@@ -0,0 +1,231 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    Sonic Visualiser
+    An audio file viewer and annotation editor.
+    Centre for Digital Music, Queen Mary, University of London.
+    This file copyright 2006 Chris Cannam and QMUL.
+    FFT code from Don Cross's public domain FFT implementation.
+    
+    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.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#include "FFTapi.h"
+
+#ifndef HAVE_FFTW3F
+
+#include <cmath>
+
+void
+fft(unsigned int n, bool inverse, double *ri, double *ii, double *ro, double *io)
+{
+    if (!ri || !ro || !io) return;
+
+    unsigned int bits;
+    unsigned int i, j, k, m;
+    unsigned int blockSize, blockEnd;
+
+    double tr, ti;
+
+    if (n < 2) return;
+    if (n & (n-1)) return;
+
+    double angle = 2.0 * M_PI;
+    if (inverse) angle = -angle;
+
+    for (i = 0; ; ++i) {
+	if (n & (1 << i)) {
+	    bits = i;
+	    break;
+	}
+    }
+
+    static unsigned int tableSize = 0;
+    static int *table = 0;
+
+    if (tableSize != n) {
+
+	delete[] table;
+
+	table = new int[n];
+
+	for (i = 0; i < n; ++i) {
+	
+	    m = i;
+
+	    for (j = k = 0; j < bits; ++j) {
+		k = (k << 1) | (m & 1);
+		m >>= 1;
+	    }
+
+	    table[i] = k;
+	}
+
+	tableSize = n;
+    }
+
+    if (ii) {
+	for (i = 0; i < n; ++i) {
+	    ro[table[i]] = ri[i];
+	    io[table[i]] = ii[i];
+	}
+    } else {
+	for (i = 0; i < n; ++i) {
+	    ro[table[i]] = ri[i];
+	    io[table[i]] = 0.0;
+	}
+    }
+
+    blockEnd = 1;
+
+    for (blockSize = 2; blockSize <= n; blockSize <<= 1) {
+
+	double delta = angle / (double)blockSize;
+	double sm2 = -sin(-2 * delta);
+	double sm1 = -sin(-delta);
+	double cm2 = cos(-2 * delta);
+	double cm1 = cos(-delta);
+	double w = 2 * cm1;
+	double ar[3], ai[3];
+
+	for (i = 0; i < n; i += blockSize) {
+
+	    ar[2] = cm2;
+	    ar[1] = cm1;
+
+	    ai[2] = sm2;
+	    ai[1] = sm1;
+
+	    for (j = i, m = 0; m < blockEnd; j++, m++) {
+
+		ar[0] = w * ar[1] - ar[2];
+		ar[2] = ar[1];
+		ar[1] = ar[0];
+
+		ai[0] = w * ai[1] - ai[2];
+		ai[2] = ai[1];
+		ai[1] = ai[0];
+
+		k = j + blockEnd;
+		tr = ar[0] * ro[k] - ai[0] * io[k];
+		ti = ar[0] * io[k] + ai[0] * ro[k];
+
+		ro[k] = ro[j] - tr;
+		io[k] = io[j] - ti;
+
+		ro[j] += tr;
+		io[j] += ti;
+	    }
+	}
+
+	blockEnd = blockSize;
+    }
+
+    if (inverse) {
+
+	double denom = (double)n;
+
+	for (i = 0; i < n; i++) {
+	    ro[i] /= denom;
+	    io[i] /= denom;
+	}
+    }
+}
+
+struct fftf_plan_ {
+    int size;
+    int inverse;
+    float *real;
+    fftf_complex *cplx;
+};
+
+fftf_plan
+fftf_plan_dft_r2c_1d(int n, float *in, fftf_complex *out, unsigned)
+{
+    if (n < 2) return 0;
+    if (n & (n-1)) return 0;
+    
+    fftf_plan_ *plan = new fftf_plan_;
+    plan->size = n;
+    plan->inverse = 0;
+    plan->real = in;
+    plan->cplx = out;
+    return plan;
+}
+
+fftf_plan
+fftf_plan_dft_c2r_1d(int n, fftf_complex *in, float *out, unsigned)
+{
+    if (n < 2) return 0;
+    if (n & (n-1)) return 0;
+    
+    fftf_plan_ *plan = new fftf_plan_;
+    plan->size = n;
+    plan->inverse = 1;
+    plan->real = out;
+    plan->cplx = in;
+    return plan;
+}
+
+void
+fftf_destroy_plan(fftf_plan p)
+{
+    delete p;
+}
+
+void
+fftf_execute(const fftf_plan p)
+{
+    //!!! doesn't work yet for inverse transforms
+
+    float *real = p->real;
+    fftf_complex *cplx = p->cplx;
+    int n = p->size;
+    int inv = p->inverse;
+
+    double *ri = new double[n];
+    double *ro = new double[n];
+    double *io = new double[n];
+
+    double *ii = 0;
+    if (inv) ii = new double[n];
+
+    if (!inv) {
+        for (int i = 0; i < n; ++i) {
+            ri[i] = real[i];
+        }
+    } else {
+        for (int i = 0; i < n/2+1; ++i) {
+            ri[i] = cplx[i][0];
+            ii[i] = cplx[i][1];
+            if (i > 0) {
+                ri[n-i] = ri[i];
+                ii[n-i] = -ii[i];
+            }
+        }
+    }
+
+    fft(n, inv, ri, ii, ro, io);
+
+    if (!inv) {
+        for (int i = 0; i < n/2+1; ++i) {
+            cplx[i][0] = ro[i];
+            cplx[i][1] = io[i];
+        }
+    } else {
+        for (int i = 0; i < n; ++i) {
+            real[i] = ro[i];
+        }
+    }
+
+    delete[] ri;
+    delete[] ro;
+    delete[] io;
+    delete[] ii;
+}
+
+#endif