/*****************************************************************************
FFTRealPassInverse.hpp
Copyright (c) 2005 Laurent de Soras
--- Legal stuff ---
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*Tab=3***********************************************************************/
#if defined (FFTRealPassInverse_CURRENT_CODEHEADER)
#error Recursive inclusion of FFTRealPassInverse code header.
#endif
#define FFTRealPassInverse_CURRENT_CODEHEADER
#if ! defined (FFTRealPassInverse_CODEHEADER_INCLUDED)
#define FFTRealPassInverse_CODEHEADER_INCLUDED
/*\\\ INCLUDE FILES \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
#include "FFTRealUseTrigo.h"
/*\\\ PUBLIC \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
template <int PASS>
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 [])
{
process_internal (
len,
dest_ptr,
f_ptr,
cos_ptr,
cos_len,
br_ptr,
osc_list
);
FFTRealPassInverse <PASS - 1>::process_rec (
len,
src_ptr,
dest_ptr,
cos_ptr,
cos_len,
br_ptr,
osc_list
);
}
template <int PASS>
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 [])
{
process_internal (
len,
dest_ptr,
src_ptr,
cos_ptr,
cos_len,
br_ptr,
osc_list
);
FFTRealPassInverse <PASS - 1>::process_rec (
len,
src_ptr,
dest_ptr,
cos_ptr,
cos_len,
br_ptr,
osc_list
);
}
template <>
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 [])
{
// Stops recursion
}
template <int PASS>
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 [])
{
const long dist = 1L << (PASS - 1);
const long c1_r = 0;
const long c1_i = dist;
const long c2_r = dist * 2;
const long c2_i = dist * 3;
const long cend = dist * 4;
const long table_step = cos_len >> (PASS - 1);
enum { TRIGO_OSC = PASS - FFTRealFixLenParam::TRIGO_BD_LIMIT };
enum { TRIGO_DIRECT = (TRIGO_OSC >= 0) ? 1 : 0 };
long coef_index = 0;
do
{
const DataType * const sf = src_ptr + coef_index;
DataType * const df = dest_ptr + coef_index;
// Extreme coefficients are always real
df [c1_r] = sf [c1_r] + sf [c2_r];
df [c2_r] = sf [c1_r] - sf [c2_r];
df [c1_i] = sf [c1_i] * 2;
df [c2_i] = sf [c2_i] * 2;
FFTRealUseTrigo <TRIGO_DIRECT>::prepare (osc_list [TRIGO_OSC]);
// Others are conjugate complex numbers
for (long i = 1; i < dist; ++ i)
{
df [c1_r + i] = sf [c1_r + i] + sf [c2_r - i];
df [c1_i + i] = sf [c2_r + i] - sf [cend - i];
DataType c;
DataType s;
FFTRealUseTrigo <TRIGO_DIRECT>::iterate (
osc_list [TRIGO_OSC],
c,
s,
cos_ptr,
i * table_step,
(dist - i) * table_step
);
const DataType vr = sf [c1_r + i] - sf [c2_r - i];
const DataType vi = sf [c2_r + i] + sf [cend - i];
df [c2_r + i] = vr * c + vi * s;
df [c2_i + i] = vi * c - vr * s;
}
coef_index += cend;
}
while (coef_index < len);
}
template <>
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 [])
{
// Antepenultimate pass
const DataType sqrt2_2 = DataType (SQRT2 * 0.5);
long coef_index = 0;
do
{
dest_ptr [coef_index ] = src_ptr [coef_index] + src_ptr [coef_index + 4];
dest_ptr [coef_index + 4] = src_ptr [coef_index] - src_ptr [coef_index + 4];
dest_ptr [coef_index + 2] = src_ptr [coef_index + 2] * 2;
dest_ptr [coef_index + 6] = src_ptr [coef_index + 6] * 2;
dest_ptr [coef_index + 1] = src_ptr [coef_index + 1] + src_ptr [coef_index + 3];
dest_ptr [coef_index + 3] = src_ptr [coef_index + 5] - src_ptr [coef_index + 7];
const DataType vr = src_ptr [coef_index + 1] - src_ptr [coef_index + 3];
const DataType vi = src_ptr [coef_index + 5] + src_ptr [coef_index + 7];
dest_ptr [coef_index + 5] = (vr + vi) * sqrt2_2;
dest_ptr [coef_index + 7] = (vi - vr) * sqrt2_2;
coef_index += 8;
}
while (coef_index < len);
}
template <>
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 [])
{
// Penultimate and last pass at once
const long qlen = len >> 2;
long coef_index = 0;
do
{
const long ri_0 = br_ptr [coef_index >> 2];
const DataType b_0 = src_ptr [coef_index ] + src_ptr [coef_index + 2];
const DataType b_2 = src_ptr [coef_index ] - src_ptr [coef_index + 2];
const DataType b_1 = src_ptr [coef_index + 1] * 2;
const DataType b_3 = src_ptr [coef_index + 3] * 2;
dest_ptr [ri_0 ] = b_0 + b_1;
dest_ptr [ri_0 + 2 * qlen] = b_0 - b_1;
dest_ptr [ri_0 + 1 * qlen] = b_2 + b_3;
dest_ptr [ri_0 + 3 * qlen] = b_2 - b_3;
coef_index += 4;
}
while (coef_index < len);
}
/*\\\ PROTECTED \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
/*\\\ PRIVATE \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
#endif // FFTRealPassInverse_CODEHEADER_INCLUDED
#undef FFTRealPassInverse_CURRENT_CODEHEADER
/*\\\ EOF \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/