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230 lines
6.2 KiB
C++
230 lines
6.2 KiB
C++
/*****************************************************************************
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FFTRealPassInverse.hpp
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Copyright (c) 2005 Laurent de Soras
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--- Legal stuff ---
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*Tab=3***********************************************************************/
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#if defined (FFTRealPassInverse_CURRENT_CODEHEADER)
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#error Recursive inclusion of FFTRealPassInverse code header.
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#endif
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#define FFTRealPassInverse_CURRENT_CODEHEADER
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#if ! defined (FFTRealPassInverse_CODEHEADER_INCLUDED)
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#define FFTRealPassInverse_CODEHEADER_INCLUDED
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/*\\\ INCLUDE FILES \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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#include "FFTRealUseTrigo.h"
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/*\\\ PUBLIC \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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template <int PASS>
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void FFTRealPassInverse <PASS>::process (long len, DataType dest_ptr [], DataType src_ptr [], const DataType f_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
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{
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process_internal (
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len,
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dest_ptr,
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f_ptr,
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cos_ptr,
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cos_len,
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br_ptr,
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osc_list
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);
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FFTRealPassInverse <PASS - 1>::process_rec (
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len,
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src_ptr,
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dest_ptr,
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cos_ptr,
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cos_len,
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br_ptr,
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osc_list
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);
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}
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template <int PASS>
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void FFTRealPassInverse <PASS>::process_rec (long len, DataType dest_ptr [], DataType src_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
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{
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process_internal (
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len,
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dest_ptr,
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src_ptr,
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cos_ptr,
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cos_len,
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br_ptr,
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osc_list
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);
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FFTRealPassInverse <PASS - 1>::process_rec (
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len,
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src_ptr,
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dest_ptr,
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cos_ptr,
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cos_len,
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br_ptr,
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osc_list
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);
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}
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template <>
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void FFTRealPassInverse <0>::process_rec (long len, DataType dest_ptr [], DataType src_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
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{
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// Stops recursion
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}
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template <int PASS>
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void FFTRealPassInverse <PASS>::process_internal (long len, DataType dest_ptr [], const DataType src_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
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{
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const long dist = 1L << (PASS - 1);
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const long c1_r = 0;
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const long c1_i = dist;
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const long c2_r = dist * 2;
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const long c2_i = dist * 3;
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const long cend = dist * 4;
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const long table_step = cos_len >> (PASS - 1);
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enum { TRIGO_OSC = PASS - FFTRealFixLenParam::TRIGO_BD_LIMIT };
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enum { TRIGO_DIRECT = (TRIGO_OSC >= 0) ? 1 : 0 };
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long coef_index = 0;
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do
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{
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const DataType * const sf = src_ptr + coef_index;
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DataType * const df = dest_ptr + coef_index;
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// Extreme coefficients are always real
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df [c1_r] = sf [c1_r] + sf [c2_r];
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df [c2_r] = sf [c1_r] - sf [c2_r];
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df [c1_i] = sf [c1_i] * 2;
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df [c2_i] = sf [c2_i] * 2;
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FFTRealUseTrigo <TRIGO_DIRECT>::prepare (osc_list [TRIGO_OSC]);
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// Others are conjugate complex numbers
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for (long i = 1; i < dist; ++ i)
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{
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df [c1_r + i] = sf [c1_r + i] + sf [c2_r - i];
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df [c1_i + i] = sf [c2_r + i] - sf [cend - i];
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DataType c;
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DataType s;
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FFTRealUseTrigo <TRIGO_DIRECT>::iterate (
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osc_list [TRIGO_OSC],
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c,
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s,
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cos_ptr,
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i * table_step,
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(dist - i) * table_step
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);
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const DataType vr = sf [c1_r + i] - sf [c2_r - i];
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const DataType vi = sf [c2_r + i] + sf [cend - i];
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df [c2_r + i] = vr * c + vi * s;
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df [c2_i + i] = vi * c - vr * s;
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}
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coef_index += cend;
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}
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while (coef_index < len);
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}
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template <>
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void FFTRealPassInverse <2>::process_internal (long len, DataType dest_ptr [], const DataType src_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
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{
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// Antepenultimate pass
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const DataType sqrt2_2 = DataType (SQRT2 * 0.5);
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long coef_index = 0;
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do
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{
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dest_ptr [coef_index ] = src_ptr [coef_index] + src_ptr [coef_index + 4];
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dest_ptr [coef_index + 4] = src_ptr [coef_index] - src_ptr [coef_index + 4];
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dest_ptr [coef_index + 2] = src_ptr [coef_index + 2] * 2;
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dest_ptr [coef_index + 6] = src_ptr [coef_index + 6] * 2;
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dest_ptr [coef_index + 1] = src_ptr [coef_index + 1] + src_ptr [coef_index + 3];
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dest_ptr [coef_index + 3] = src_ptr [coef_index + 5] - src_ptr [coef_index + 7];
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const DataType vr = src_ptr [coef_index + 1] - src_ptr [coef_index + 3];
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const DataType vi = src_ptr [coef_index + 5] + src_ptr [coef_index + 7];
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dest_ptr [coef_index + 5] = (vr + vi) * sqrt2_2;
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dest_ptr [coef_index + 7] = (vi - vr) * sqrt2_2;
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coef_index += 8;
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}
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while (coef_index < len);
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}
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template <>
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void FFTRealPassInverse <1>::process_internal (long len, DataType dest_ptr [], const DataType src_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
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{
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// Penultimate and last pass at once
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const long qlen = len >> 2;
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long coef_index = 0;
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do
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{
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const long ri_0 = br_ptr [coef_index >> 2];
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const DataType b_0 = src_ptr [coef_index ] + src_ptr [coef_index + 2];
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const DataType b_2 = src_ptr [coef_index ] - src_ptr [coef_index + 2];
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const DataType b_1 = src_ptr [coef_index + 1] * 2;
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const DataType b_3 = src_ptr [coef_index + 3] * 2;
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dest_ptr [ri_0 ] = b_0 + b_1;
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dest_ptr [ri_0 + 2 * qlen] = b_0 - b_1;
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dest_ptr [ri_0 + 1 * qlen] = b_2 + b_3;
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dest_ptr [ri_0 + 3 * qlen] = b_2 - b_3;
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coef_index += 4;
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}
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while (coef_index < len);
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}
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/*\\\ PROTECTED \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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/*\\\ PRIVATE \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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#endif // FFTRealPassInverse_CODEHEADER_INCLUDED
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#undef FFTRealPassInverse_CURRENT_CODEHEADER
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/*\\\ EOF \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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