3 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 Brian Gough
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 3 of the License, or (at
8 * your option) any later version.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
21 FUNCTION(fft_halfcomplex,pass_5) (const BASE in[],
27 const TYPE(gsl_complex) twiddle1[],
28 const TYPE(gsl_complex) twiddle2[],
29 const TYPE(gsl_complex) twiddle3[],
30 const TYPE(gsl_complex) twiddle4[])
33 size_t i, j, k, k1, jump;
34 size_t factor, q, m, product_1;
36 const ATOMIC sina = sin (2.0 * M_PI / 5.0);
37 const ATOMIC sinb = sin (2.0 * M_PI / 10.0);
45 product_1 = product / factor;
46 jump = (factor - 1) * q;
48 for (k1 = 0; k1 < product_1; k1++)
50 const size_t from0 = 5 * k1 * q;
51 const size_t from1 = from0 + 2 * q - 1;
52 const size_t from2 = from1 + 2 * q;
54 const ATOMIC z0_real = VECTOR(in,istride,from0);
55 const ATOMIC z1_real = VECTOR(in,istride,from1);
56 const ATOMIC z1_imag = VECTOR(in,istride,from1 + 1);
57 const ATOMIC z2_real = VECTOR(in,istride,from2);
58 const ATOMIC z2_imag = VECTOR(in,istride,from2 + 1);
60 const ATOMIC t1_real = 2 * (z1_real + z2_real);
61 const ATOMIC t2_real = 2 * (sqrt (5.0) / 4.0) * (z1_real - z2_real);
62 const ATOMIC t3_real = z0_real - t1_real / 4.0;
63 const ATOMIC t4_real = t2_real + t3_real;
64 const ATOMIC t5_real = -t2_real + t3_real;
65 const ATOMIC t6_imag = 2 * (sina * z1_imag + sinb * z2_imag);
66 const ATOMIC t7_imag = 2 * (sinb * z1_imag - sina * z2_imag);
68 const ATOMIC x0_real = z0_real + t1_real;
69 const ATOMIC x1_real = t4_real - t6_imag;
70 const ATOMIC x2_real = t5_real - t7_imag;
71 const ATOMIC x3_real = t5_real + t7_imag;
72 const ATOMIC x4_real = t4_real + t6_imag;
74 const size_t to0 = q * k1;
75 const size_t to1 = to0 + m;
76 const size_t to2 = to1 + m;
77 const size_t to3 = to2 + m;
78 const size_t to4 = to3 + m;
80 VECTOR(out,ostride,to0) = x0_real;
81 VECTOR(out,ostride,to1) = x1_real;
82 VECTOR(out,ostride,to2) = x2_real;
83 VECTOR(out,ostride,to3) = x3_real;
84 VECTOR(out,ostride,to4) = x4_real;
90 for (k = 1; k < (q + 1) / 2; k++)
92 const ATOMIC w1_real = GSL_REAL(twiddle1[k - 1]);
93 const ATOMIC w1_imag = GSL_IMAG(twiddle1[k - 1]);
94 const ATOMIC w2_real = GSL_REAL(twiddle2[k - 1]);
95 const ATOMIC w2_imag = GSL_IMAG(twiddle2[k - 1]);
96 const ATOMIC w3_real = GSL_REAL(twiddle3[k - 1]);
97 const ATOMIC w3_imag = GSL_IMAG(twiddle3[k - 1]);
98 const ATOMIC w4_real = GSL_REAL(twiddle4[k - 1]);
99 const ATOMIC w4_imag = GSL_IMAG(twiddle4[k - 1]);
101 for (k1 = 0; k1 < product_1; k1++)
103 const size_t from0 = 5 * k1 * q + 2 * k - 1;
104 const size_t from1 = from0 + 2 * q;
105 const size_t from2 = from1 + 2 * q;
106 const size_t from3 = 5 * k1 * q - 2 * k + 2 * q - 1;
107 const size_t from4 = from3 + 2 * q;
109 const ATOMIC z0_real = VECTOR(in,istride,from0);
110 const ATOMIC z0_imag = VECTOR(in,istride,from0 + 1);
112 const ATOMIC z1_real = VECTOR(in,istride,from1);
113 const ATOMIC z1_imag = VECTOR(in,istride,from1 + 1);
115 const ATOMIC z2_real = VECTOR(in,istride,from2);
116 const ATOMIC z2_imag = VECTOR(in,istride,from2 + 1);
118 const ATOMIC z3_real = VECTOR(in,istride,from4);
119 const ATOMIC z3_imag = -VECTOR(in,istride,from4 + 1);
121 const ATOMIC z4_real = VECTOR(in,istride,from3);
122 const ATOMIC z4_imag = -VECTOR(in,istride,from3 + 1);
124 /* compute x = W(5) z */
127 const ATOMIC t1_real = z1_real + z4_real;
128 const ATOMIC t1_imag = z1_imag + z4_imag;
131 const ATOMIC t2_real = z2_real + z3_real;
132 const ATOMIC t2_imag = z2_imag + z3_imag;
135 const ATOMIC t3_real = z1_real - z4_real;
136 const ATOMIC t3_imag = z1_imag - z4_imag;
139 const ATOMIC t4_real = z2_real - z3_real;
140 const ATOMIC t4_imag = z2_imag - z3_imag;
143 const ATOMIC t5_real = t1_real + t2_real;
144 const ATOMIC t5_imag = t1_imag + t2_imag;
146 /* t6 = (sqrt(5)/4)(t1 - t2) */
147 const ATOMIC t6_real = (sqrt (5.0) / 4.0) * (t1_real - t2_real);
148 const ATOMIC t6_imag = (sqrt (5.0) / 4.0) * (t1_imag - t2_imag);
150 /* t7 = z0 - ((t5)/4) */
151 const ATOMIC t7_real = z0_real - t5_real / 4.0;
152 const ATOMIC t7_imag = z0_imag - t5_imag / 4.0;
155 const ATOMIC t8_real = t7_real + t6_real;
156 const ATOMIC t8_imag = t7_imag + t6_imag;
159 const ATOMIC t9_real = t7_real - t6_real;
160 const ATOMIC t9_imag = t7_imag - t6_imag;
162 /* t10 = sin(2 pi/5) t3 + sin(2 pi/10) t4 */
163 const ATOMIC t10_real = sina * t3_real + sinb * t4_real;
164 const ATOMIC t10_imag = sina * t3_imag + sinb * t4_imag;
166 /* t11 = sin(2 pi/10) t3 - sin(2 pi/5) t4 */
167 const ATOMIC t11_real = sinb * t3_real - sina * t4_real;
168 const ATOMIC t11_imag = sinb * t3_imag - sina * t4_imag;
171 const ATOMIC x0_real = z0_real + t5_real;
172 const ATOMIC x0_imag = z0_imag + t5_imag;
174 /* x1 = t8 + i t10 */
175 const ATOMIC x1_real = t8_real - t10_imag;
176 const ATOMIC x1_imag = t8_imag + t10_real;
178 /* x2 = t9 + i t11 */
179 const ATOMIC x2_real = t9_real - t11_imag;
180 const ATOMIC x2_imag = t9_imag + t11_real;
182 /* x3 = t9 - i t11 */
183 const ATOMIC x3_real = t9_real + t11_imag;
184 const ATOMIC x3_imag = t9_imag - t11_real;
186 /* x4 = t8 - i t10 */
187 const ATOMIC x4_real = t8_real + t10_imag;
188 const ATOMIC x4_imag = t8_imag - t10_real;
190 const size_t to0 = k1 * q + 2 * k - 1;
191 const size_t to1 = to0 + m;
192 const size_t to2 = to1 + m;
193 const size_t to3 = to2 + m;
194 const size_t to4 = to3 + m;
196 /* apply twiddle factors */
199 VECTOR(out,ostride,to0) = x0_real;
200 VECTOR(out,ostride,to0 + 1) = x0_imag;
203 VECTOR(out,ostride,to1) = w1_real * x1_real - w1_imag * x1_imag;
204 VECTOR(out,ostride,to1 + 1) = w1_real * x1_imag + w1_imag * x1_real;
207 VECTOR(out,ostride,to2) = w2_real * x2_real - w2_imag * x2_imag;
208 VECTOR(out,ostride,to2 + 1) = w2_real * x2_imag + w2_imag * x2_real;
211 VECTOR(out,ostride,to3) = w3_real * x3_real - w3_imag * x3_imag;
212 VECTOR(out,ostride,to3 + 1) = w3_real * x3_imag + w3_imag * x3_real;
215 VECTOR(out,ostride,to4) = w4_real * x4_real - w4_imag * x4_imag;
216 VECTOR(out,ostride,to4 + 1) = w4_real * x4_imag + w4_imag * x4_real;
223 for (k1 = 0; k1 < product_1; k1++)
225 const size_t from0 = 5 * k1 * q + q - 1;
226 const size_t from1 = from0 + 2 * q;
227 const size_t from2 = from1 + 2 * q;
229 const ATOMIC z0_real = 2 * VECTOR(in,istride,from0);
230 const ATOMIC z0_imag = 2 * VECTOR(in,istride,from0 + 1);
232 const ATOMIC z1_real = 2 * VECTOR(in,istride,from1);
233 const ATOMIC z1_imag = 2 * VECTOR(in,istride,from1 + 1);
235 const ATOMIC z2_real = VECTOR(in,istride,from2);
237 const ATOMIC t1_real = z0_real + z1_real;
238 const ATOMIC t2_real = (t1_real / 4.0) - z2_real;
239 const ATOMIC t3_real = (sqrt (5.0) / 4.0) * (z0_real - z1_real);
240 const ATOMIC t4_real = sinb * z0_imag + sina * z1_imag;
241 const ATOMIC t5_real = sina * z0_imag - sinb * z1_imag;
242 const ATOMIC t6_real = t3_real + t2_real;
243 const ATOMIC t7_real = t3_real - t2_real;
245 const ATOMIC x0_real = t1_real + z2_real;
246 const ATOMIC x1_real = t6_real - t4_real;
247 const ATOMIC x2_real = t7_real - t5_real;
248 const ATOMIC x3_real = -t7_real - t5_real;
249 const ATOMIC x4_real = -t6_real - t4_real;
251 const size_t to0 = k1 * q + q - 1;
252 const size_t to1 = to0 + m;
253 const size_t to2 = to1 + m;
254 const size_t to3 = to2 + m;
255 const size_t to4 = to3 + m;
257 VECTOR(out,ostride,to0) = x0_real;
258 VECTOR(out,ostride,to1) = x1_real;
259 VECTOR(out,ostride,to2) = x2_real;
260 VECTOR(out,ostride,to3) = x3_real;
261 VECTOR(out,ostride,to4) = x4_real;