File indexing completed on 2024-05-12 04:50:07

 /*
     FHT - Fast Hartley Transform Class
 
     SPDX-FileCopyrightText: 2004 Melchior FRANZ <mfranz@kde.org>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #include "fht.h"
 
 #include <math.h>
 #include <string.h>
 
 FHT::FHT(int n)
     : m_buf(nullptr)
     , m_tab(nullptr)
     , m_log(nullptr)
 {
     if (n < 3) {
         m_num = 0;
         m_exp2 = -1;
         return;
     }
     m_exp2 = n;
     m_num = 1 << n;
     if (n > 3) {
         m_buf = new float[m_num];
         m_tab = new float[m_num * 2];
         makeCasTable();
     }
 }
 
 FHT::~FHT()
 {
     delete[] m_buf;
     delete[] m_tab;
     delete[] m_log;
 }
 
 void FHT::makeCasTable(void)
 {
     float d, *costab, *sintab;
     int ul, ndiv2 = m_num / 2;
 
     for (costab = m_tab, sintab = m_tab + m_num / 2 + 1, ul = 0; ul < m_num; ul++) {
         d = M_PI * ul / ndiv2;
         *costab = *sintab = cos(d);
 
         costab += 2, sintab += 2;
         if (sintab > m_tab + m_num * 2)
             sintab = m_tab + 1;
     }
 }
 
 float *FHT::copy(float *d, float *s)
 {
     return (float *)memcpy(d, s, m_num * sizeof(float));
 }
 
 float *FHT::clear(float *d)
 {
     return (float *)memset(d, 0, m_num * sizeof(float));
 }
 
 void FHT::scale(float *p, float d)
 {
     for (int i = 0; i < (m_num / 2); i++)
         *p++ *= d;
 }
 
 void FHT::ewma(float *d, float *s, float w)
 {
     for (int i = 0; i < (m_num / 2); i++, d++, s++)
         *d = *d * w + *s * (1 - w);
 }
 
 void FHT::logSpectrum(float *out, float *p)
 {
     int n = m_num / 2, i, j, k, *r;
     if (!m_log) {
         m_log = new int[n];
         float f = n / log10((double)n);
         for (i = 0, r = m_log; i < n; i++, r++) {
             j = int(rint(log10(i + 1.0) * f));
             *r = j >= n ? n - 1 : j;
         }
     }
     semiLogSpectrum(p);
     *out++ = *p = *p / 100;
     for (k = i = 1, r = m_log; i < n; ++i) {
         j = *r++;
         if (i == j)
             *out++ = p[i];
         else {
             float base = p[k - 1];
             float step = (p[j] - base) / (j - (k - 1));
             for (float corr = 0; k <= j; k++, corr += step)
                 *out++ = base + corr;
         }
     }
 }
 
 void FHT::semiLogSpectrum(float *p)
 {
     float e;
     power2(p);
     for (int i = 0; i < (m_num / 2); i++, p++) {
         e = 10.0 * log10(sqrt(*p * .5));
         *p = e < 0 ? 0 : e;
     }
 }
 
 void FHT::spectrum(float *p)
 {
     power2(p);
     for (int i = 0; i < (m_num / 2); i++, p++)
         *p = (float)sqrt(*p * .5);
 }
 
 void FHT::power(float *p)
 {
     power2(p);
     for (int i = 0; i < (m_num / 2); i++)
         *p++ *= .5;
 }
 
 void FHT::power2(float *p)
 {
     int i;
     float *q;
     _transform(p, m_num, 0);
 
     *p = (*p * *p), *p += *p, p++;
 
     for (i = 1, q = p + m_num - 2; i < (m_num / 2); i++, --q)
         *p = (*p * *p) + (*q * *q), p++;
 }
 
 void FHT::transform(float *p)
 {
     if (m_num == 8)
         transform8(p);
     else
         _transform(p, m_num, 0);
 }
 
 void FHT::transform8(float *p)
 {
     float a, b, c, d, e, f, g, h, b_f2, d_h2;
     float a_c_eg, a_ce_g, ac_e_g, aceg, b_df_h, bdfh;
 
     a = *p++, b = *p++, c = *p++, d = *p++;
     e = *p++, f = *p++, g = *p++, h = *p;
     b_f2 = (b - f) * M_SQRT2;
     d_h2 = (d - h) * M_SQRT2;
 
     a_c_eg = a - c - e + g;
     a_ce_g = a - c + e - g;
     ac_e_g = a + c - e - g;
     aceg = a + c + e + g;
 
     b_df_h = b - d + f - h;
     bdfh = b + d + f + h;
 
     *p = a_c_eg - d_h2;
     *--p = a_ce_g - b_df_h;
     *--p = ac_e_g - b_f2;
     *--p = aceg - bdfh;
     *--p = a_c_eg + d_h2;
     *--p = a_ce_g + b_df_h;
     *--p = ac_e_g + b_f2;
     *--p = aceg + bdfh;
 }
 
 void FHT::_transform(float *p, int n, int k)
 {
     if (n == 8) {
         transform8(p + k);
         return;
     }
 
     int i, j, ndiv2 = n / 2;
     float a, *t1, *t2, *t3, *t4, *ptab, *pp;
 
     for (i = 0, t1 = m_buf, t2 = m_buf + ndiv2, pp = &p[k]; i < ndiv2; i++)
         *t1++ = *pp++, *t2++ = *pp++;
 
     memcpy(p + k, m_buf, sizeof(float) * n);
 
     _transform(p, ndiv2, k);
     _transform(p, ndiv2, k + ndiv2);
 
     j = m_num / ndiv2 - 1;
     t1 = m_buf;
     t2 = t1 + ndiv2;
     t3 = p + k + ndiv2;
     ptab = m_tab;
     pp = p + k;
 
     a = *ptab++ * *t3++;
     a += *ptab * *pp;
     ptab += j;
 
     *t1++ = *pp + a;
     *t2++ = *pp++ - a;
 
     for (i = 1, t4 = p + k + n; i < ndiv2; i++, ptab += j) {
         a = *ptab++ * *t3++;
         a += *ptab * *--t4;
 
         *t1++ = *pp + a;
         *t2++ = *pp++ - a;
     }
     memcpy(p + k, m_buf, sizeof(float) * n);
 }