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| Rev | Author | Line No. | Line |
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| 2 | pj | 1 | |
| 2 | /* |
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| 3 | * Copyright (c) 1997-1999 Massachusetts Institute of Technology |
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| 4 | * |
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| 5 | * This program is free software; you can redistribute it and/or modify |
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| 6 | * it under the terms of the GNU General Public License as published by |
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| 7 | * the Free Software Foundation; either version 2 of the License, or |
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| 8 | * (at your option) any later version. |
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| 9 | * |
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| 10 | * This program is distributed in the hope that it will be useful, |
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| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 13 | * GNU General Public License for more details. |
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| 14 | * |
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| 15 | * You should have received a copy of the GNU General Public License |
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| 16 | * along with this program; if not, write to the Free Software |
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| 17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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| 18 | * |
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| 19 | */ |
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| 20 | |||
| 21 | /* |
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| 22 | * rgeneric.c -- "generic" rfftw codelets. They work for all n (and |
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| 23 | * they are slow) |
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| 24 | */ |
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| 107 | pj | 25 | #include <fftw-int.h> |
| 26 | #include <rfftw.h> |
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| 2 | pj | 27 | |
| 28 | /* this code assumes that r and m are both odd */ |
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| 29 | void fftw_hc2hc_forward_generic(fftw_real *A, const fftw_complex *W, |
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| 30 | int m, int r, int n, int dist) |
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| 31 | { |
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| 32 | int i, j, k; |
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| 33 | fftw_complex *tmp = (fftw_complex *) |
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| 34 | fftw_malloc(r * sizeof(fftw_complex)); |
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| 35 | fftw_real rsum, isum; |
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| 36 | fftw_real *X, *YO, *YI; |
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| 37 | int wp, wincr; |
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| 38 | int iostride = m * dist; |
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| 39 | X = A; |
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| 40 | YO = A + r * iostride; |
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| 41 | YI = A + iostride; |
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| 42 | |||
| 43 | /* compute the transform of the r 0th elements (which are real) */ |
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| 44 | for (i = 0; i + i < r; ++i) { |
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| 45 | rsum = 0.0; |
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| 46 | isum = 0.0; |
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| 47 | wincr = m * i; |
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| 48 | for (j = 0, wp = 0; j < r; ++j) { |
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| 49 | fftw_real tw_r = c_re(W[wp]); |
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| 50 | fftw_real tw_i = c_im(W[wp]); |
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| 51 | fftw_real re = X[j * iostride]; |
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| 52 | rsum += re * tw_r; |
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| 53 | isum += re * tw_i; |
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| 54 | wp += wincr; |
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| 55 | if (wp >= n) |
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| 56 | wp -= n; |
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| 57 | } |
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| 58 | c_re(tmp[i]) = rsum; |
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| 59 | c_im(tmp[i]) = isum; |
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| 60 | } |
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| 61 | |||
| 62 | /* store the transform back onto the A array */ |
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| 63 | X[0] = c_re(tmp[0]); |
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| 64 | for (i = 1; i + i < r; ++i) { |
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| 65 | X[i * iostride] = c_re(tmp[i]); |
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| 66 | YO[-i * iostride] = c_im(tmp[i]); |
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| 67 | } |
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| 68 | |||
| 69 | X += dist; |
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| 70 | YI -= dist; |
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| 71 | YO -= dist; |
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| 72 | |||
| 73 | /* compute the transform of the middle elements (which are complex) */ |
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| 74 | for (k = 1; k + k < m; ++k, X += dist, YI -= dist, YO -= dist) { |
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| 75 | for (i = 0; i < r; ++i) { |
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| 76 | rsum = 0.0; |
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| 77 | isum = 0.0; |
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| 78 | wincr = k + m * i; |
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| 79 | for (j = 0, wp = 0; j < r; ++j) { |
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| 80 | fftw_real tw_r = c_re(W[wp]); |
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| 81 | fftw_real tw_i = c_im(W[wp]); |
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| 82 | fftw_real re = X[j * iostride]; |
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| 83 | fftw_real im = YI[j * iostride]; |
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| 84 | rsum += re * tw_r - im * tw_i; |
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| 85 | isum += re * tw_i + im * tw_r; |
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| 86 | wp += wincr; |
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| 87 | if (wp >= n) |
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| 88 | wp -= n; |
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| 89 | } |
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| 90 | c_re(tmp[i]) = rsum; |
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| 91 | c_im(tmp[i]) = isum; |
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| 92 | } |
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| 93 | |||
| 94 | /* store the transform back onto the A array */ |
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| 95 | for (i = 0; i + i < r; ++i) { |
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| 96 | X[i * iostride] = c_re(tmp[i]); |
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| 97 | YO[-i * iostride] = c_im(tmp[i]); |
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| 98 | } |
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| 99 | for (; i < r; ++i) { |
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| 100 | X[i * iostride] = -c_im(tmp[i]); |
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| 101 | YO[-i * iostride] = c_re(tmp[i]); |
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| 102 | } |
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| 103 | } |
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| 104 | |||
| 105 | /* no final element, since m is odd */ |
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| 106 | fftw_free(tmp); |
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| 107 | } |
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| 108 | |||
| 109 | void fftw_hc2hc_backward_generic(fftw_real *A, const fftw_complex *W, |
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| 110 | int m, int r, int n, int dist) |
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| 111 | { |
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| 112 | int i, j, k; |
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| 113 | int wp, wincr; |
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| 114 | fftw_complex *tmp = (fftw_complex *) |
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| 115 | fftw_malloc(r * sizeof(fftw_complex)); |
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| 116 | fftw_real rsum, isum; |
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| 117 | fftw_real *X, *YO, *YI; |
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| 118 | int iostride = m * dist; |
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| 119 | X = A; |
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| 120 | YO = A + iostride; |
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| 121 | YI = A + r * iostride; |
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| 122 | |||
| 123 | /* |
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| 124 | * compute the transform of the r 0th elements (which are halfcomplex) |
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| 125 | * yielding real numbers |
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| 126 | */ |
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| 127 | /* copy the input into the temporary array */ |
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| 128 | c_re(tmp[0]) = X[0]; |
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| 129 | for (i = 1; i + i < r; ++i) { |
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| 130 | c_re(tmp[i]) = X[i * iostride]; |
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| 131 | c_im(tmp[i]) = YI[-i * iostride]; |
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| 132 | } |
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| 133 | |||
| 134 | for (i = 0; i < r; ++i) { |
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| 135 | rsum = 0.0; |
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| 136 | wincr = m * i; |
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| 137 | for (j = 1, wp = wincr; j + j < r; ++j) { |
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| 138 | fftw_real tw_r = c_re(W[wp]); |
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| 139 | fftw_real tw_i = c_im(W[wp]); |
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| 140 | fftw_real re = c_re(tmp[j]); |
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| 141 | fftw_real im = c_im(tmp[j]); |
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| 142 | rsum += re * tw_r + im * tw_i; |
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| 143 | wp += wincr; |
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| 144 | if (wp >= n) |
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| 145 | wp -= n; |
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| 146 | } |
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| 147 | X[i * iostride] = 2.0 * rsum + c_re(tmp[0]); |
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| 148 | } |
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| 149 | |||
| 150 | X += dist; |
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| 151 | YI -= dist; |
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| 152 | YO -= dist; |
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| 153 | |||
| 154 | /* compute the transform of the middle elements (which are complex) */ |
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| 155 | for (k = 1; k + k < m; ++k, X += dist, YI -= dist, YO -= dist) { |
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| 156 | /* copy the input into the temporary array */ |
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| 157 | for (i = 0; i + i < r; ++i) { |
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| 158 | c_re(tmp[i]) = X[i * iostride]; |
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| 159 | c_im(tmp[i]) = YI[-i * iostride]; |
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| 160 | } |
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| 161 | for (; i < r; ++i) { |
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| 162 | c_im(tmp[i]) = -X[i * iostride]; |
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| 163 | c_re(tmp[i]) = YI[-i * iostride]; |
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| 164 | } |
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| 165 | |||
| 166 | for (i = 0; i < r; ++i) { |
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| 167 | rsum = 0.0; |
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| 168 | isum = 0.0; |
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| 169 | wincr = m * i; |
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| 170 | for (j = 0, wp = k * i; j < r; ++j) { |
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| 171 | fftw_real tw_r = c_re(W[wp]); |
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| 172 | fftw_real tw_i = c_im(W[wp]); |
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| 173 | fftw_real re = c_re(tmp[j]); |
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| 174 | fftw_real im = c_im(tmp[j]); |
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| 175 | rsum += re * tw_r + im * tw_i; |
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| 176 | isum += im * tw_r - re * tw_i; |
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| 177 | wp += wincr; |
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| 178 | if (wp >= n) |
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| 179 | wp -= n; |
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| 180 | } |
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| 181 | X[i * iostride] = rsum; |
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| 182 | YO[i * iostride] = isum; |
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| 183 | } |
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| 184 | } |
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| 185 | |||
| 186 | /* no final element, since m is odd */ |
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| 187 | fftw_free(tmp); |
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| 188 | } |