| /* fft/c_pass_5.c |
| * |
| * Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough |
| * |
| * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| */ |
| |
| static int |
| FUNCTION(fft_complex,pass_5) (const BASE in[], |
| const size_t istride, |
| BASE out[], |
| const size_t ostride, |
| const gsl_fft_direction sign, |
| const size_t product, |
| const size_t n, |
| const TYPE(gsl_complex) twiddle1[], |
| const TYPE(gsl_complex) twiddle2[], |
| const TYPE(gsl_complex) twiddle3[], |
| const TYPE(gsl_complex) twiddle4[]) |
| { |
| size_t i = 0, j = 0; |
| size_t k, k1; |
| |
| const size_t factor = 5; |
| const size_t m = n / factor; |
| const size_t q = n / product; |
| const size_t p_1 = product / factor; |
| const size_t jump = (factor - 1) * p_1; |
| |
| const ATOMIC sin_2pi_by_5 = sin (2.0 * M_PI / 5.0); |
| const ATOMIC sin_2pi_by_10 = sin (2.0 * M_PI / 10.0); |
| |
| for (k = 0; k < q; k++) |
| { |
| |
| ATOMIC w1_real, w1_imag, w2_real, w2_imag, w3_real, w3_imag, w4_real, |
| w4_imag; |
| |
| if (k == 0) |
| { |
| w1_real = 1.0; |
| w1_imag = 0.0; |
| w2_real = 1.0; |
| w2_imag = 0.0; |
| w3_real = 1.0; |
| w3_imag = 0.0; |
| w4_real = 1.0; |
| w4_imag = 0.0; |
| } |
| else |
| { |
| if (sign == gsl_fft_forward) |
| { |
| /* forward tranform */ |
| w1_real = GSL_REAL(twiddle1[k - 1]); |
| w1_imag = GSL_IMAG(twiddle1[k - 1]); |
| w2_real = GSL_REAL(twiddle2[k - 1]); |
| w2_imag = GSL_IMAG(twiddle2[k - 1]); |
| w3_real = GSL_REAL(twiddle3[k - 1]); |
| w3_imag = GSL_IMAG(twiddle3[k - 1]); |
| w4_real = GSL_REAL(twiddle4[k - 1]); |
| w4_imag = GSL_IMAG(twiddle4[k - 1]); |
| } |
| else |
| { |
| /* backward tranform: w -> conjugate(w) */ |
| w1_real = GSL_REAL(twiddle1[k - 1]); |
| w1_imag = -GSL_IMAG(twiddle1[k - 1]); |
| w2_real = GSL_REAL(twiddle2[k - 1]); |
| w2_imag = -GSL_IMAG(twiddle2[k - 1]); |
| w3_real = GSL_REAL(twiddle3[k - 1]); |
| w3_imag = -GSL_IMAG(twiddle3[k - 1]); |
| w4_real = GSL_REAL(twiddle4[k - 1]); |
| w4_imag = -GSL_IMAG(twiddle4[k - 1]); |
| } |
| } |
| |
| for (k1 = 0; k1 < p_1; k1++) |
| { |
| |
| ATOMIC x0_real, x0_imag, x1_real, x1_imag, x2_real, x2_imag, |
| x3_real, x3_imag, x4_real, x4_imag; |
| |
| const ATOMIC z0_real = REAL(in,istride,i); |
| const ATOMIC z0_imag = IMAG(in,istride,i); |
| const ATOMIC z1_real = REAL(in,istride,i + m); |
| const ATOMIC z1_imag = IMAG(in,istride,i + m); |
| const ATOMIC z2_real = REAL(in,istride,i + 2*m); |
| const ATOMIC z2_imag = IMAG(in,istride,i + 2*m); |
| const ATOMIC z3_real = REAL(in,istride,i + 3*m); |
| const ATOMIC z3_imag = IMAG(in,istride,i + 3*m); |
| const ATOMIC z4_real = REAL(in,istride,i + 4*m); |
| const ATOMIC z4_imag = IMAG(in,istride,i + 4*m); |
| |
| /* compute x = W(5) z */ |
| |
| /* t1 = z1 + z4 */ |
| const ATOMIC t1_real = z1_real + z4_real; |
| const ATOMIC t1_imag = z1_imag + z4_imag; |
| |
| /* t2 = z2 + z3 */ |
| const ATOMIC t2_real = z2_real + z3_real; |
| const ATOMIC t2_imag = z2_imag + z3_imag; |
| |
| /* t3 = z1 - z4 */ |
| const ATOMIC t3_real = z1_real - z4_real; |
| const ATOMIC t3_imag = z1_imag - z4_imag; |
| |
| /* t4 = z2 - z3 */ |
| const ATOMIC t4_real = z2_real - z3_real; |
| const ATOMIC t4_imag = z2_imag - z3_imag; |
| |
| /* t5 = t1 + t2 */ |
| const ATOMIC t5_real = t1_real + t2_real; |
| const ATOMIC t5_imag = t1_imag + t2_imag; |
| |
| /* t6 = (sqrt(5)/4)(t1 - t2) */ |
| const ATOMIC t6_real = (sqrt (5.0) / 4.0) * (t1_real - t2_real); |
| const ATOMIC t6_imag = (sqrt (5.0) / 4.0) * (t1_imag - t2_imag); |
| |
| /* t7 = z0 - ((t5)/4) */ |
| const ATOMIC t7_real = z0_real - t5_real / 4.0; |
| const ATOMIC t7_imag = z0_imag - t5_imag / 4.0; |
| |
| /* t8 = t7 + t6 */ |
| const ATOMIC t8_real = t7_real + t6_real; |
| const ATOMIC t8_imag = t7_imag + t6_imag; |
| |
| /* t9 = t7 - t6 */ |
| const ATOMIC t9_real = t7_real - t6_real; |
| const ATOMIC t9_imag = t7_imag - t6_imag; |
| |
| /* t10 = sin(2 pi/5) t3 + sin(2 pi/10) t4 */ |
| const ATOMIC t10_real = ((int) sign) * (sin_2pi_by_5 * t3_real + |
| sin_2pi_by_10 * t4_real); |
| const ATOMIC t10_imag = ((int) sign) * (sin_2pi_by_5 * t3_imag + |
| sin_2pi_by_10 * t4_imag); |
| |
| /* t11 = sin(2 pi/10) t3 - sin(2 pi/5) t4 */ |
| const ATOMIC t11_real = ((int) sign) * (sin_2pi_by_10 * t3_real - |
| sin_2pi_by_5 * t4_real); |
| const ATOMIC t11_imag = ((int) sign) * (sin_2pi_by_10 * t3_imag - |
| sin_2pi_by_5 * t4_imag); |
| |
| /* x0 = z0 + t5 */ |
| x0_real = z0_real + t5_real; |
| x0_imag = z0_imag + t5_imag; |
| |
| /* x1 = t8 + i t10 */ |
| x1_real = t8_real - t10_imag; |
| x1_imag = t8_imag + t10_real; |
| |
| /* x2 = t9 + i t11 */ |
| x2_real = t9_real - t11_imag; |
| x2_imag = t9_imag + t11_real; |
| |
| /* x3 = t9 - i t11 */ |
| x3_real = t9_real + t11_imag; |
| x3_imag = t9_imag - t11_real; |
| |
| /* x4 = t8 - i t10 */ |
| x4_real = t8_real + t10_imag; |
| x4_imag = t8_imag - t10_real; |
| |
| /* apply twiddle factors */ |
| |
| /* to0 = 1 * x0 */ |
| REAL(out,ostride,j) = x0_real; |
| IMAG(out,ostride,j) = x0_imag; |
| |
| /* to1 = w1 * x1 */ |
| REAL(out,ostride,j + p_1) = w1_real * x1_real - w1_imag * x1_imag; |
| IMAG(out,ostride,j + p_1) = w1_real * x1_imag + w1_imag * x1_real; |
| |
| /* to2 = w2 * x2 */ |
| REAL(out,ostride,j + 2*p_1) = w2_real * x2_real - w2_imag * x2_imag; |
| IMAG(out,ostride,j+2*p_1) = w2_real * x2_imag + w2_imag * x2_real; |
| |
| /* to3 = w3 * x3 */ |
| REAL(out,ostride,j+3*p_1) = w3_real * x3_real - w3_imag * x3_imag; |
| IMAG(out,ostride,j+3*p_1) = w3_real * x3_imag + w3_imag * x3_real; |
| |
| /* to4 = w4 * x4 */ |
| REAL(out,ostride,j+4*p_1) = w4_real * x4_real - w4_imag * x4_imag; |
| IMAG(out,ostride,j+4*p_1) = w4_real * x4_imag + w4_imag * x4_real; |
| |
| i++; |
| j++; |
| } |
| j += jump; |
| } |
| return 0; |
| } |