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/*****************************************************************************
FFTRealPassDirect.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 (FFTRealPassDirect_CURRENT_CODEHEADER)
#error Recursive inclusion of FFTRealPassDirect code header.
#endif
#define FFTRealPassDirect_CURRENT_CODEHEADER
#if ! defined (FFTRealPassDirect_CODEHEADER_INCLUDED)
#define FFTRealPassDirect_CODEHEADER_INCLUDED
/*\\\ INCLUDE FILES \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
#include "FFTRealUseTrigo.h"
/*\\\ PUBLIC \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
template <>
void FFTRealPassDirect <1>::process (long len, DataType dest_ptr [], DataType src_ptr [], const DataType x_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
{
// First and second pass at once
const long qlen = len >> 2;
long coef_index = 0;
do
{
// To do: unroll the loop (2x).
const long ri_0 = br_ptr [coef_index >> 2];
const long ri_1 = ri_0 + 2 * qlen; // bit_rev_lut_ptr [coef_index + 1];
const long ri_2 = ri_0 + 1 * qlen; // bit_rev_lut_ptr [coef_index + 2];
const long ri_3 = ri_0 + 3 * qlen; // bit_rev_lut_ptr [coef_index + 3];
DataType * const df2 = dest_ptr + coef_index;
df2 [1] = x_ptr [ri_0] - x_ptr [ri_1];
df2 [3] = x_ptr [ri_2] - x_ptr [ri_3];
const DataType sf_0 = x_ptr [ri_0] + x_ptr [ri_1];
const DataType sf_2 = x_ptr [ri_2] + x_ptr [ri_3];
df2 [0] = sf_0 + sf_2;
df2 [2] = sf_0 - sf_2;
coef_index += 4;
}
while (coef_index < len);
}
template <>
void FFTRealPassDirect <2>::process (long len, DataType dest_ptr [], DataType src_ptr [], const DataType x_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
{
// Executes "previous" passes first. Inverts source and destination buffers
FFTRealPassDirect <1>::process (
len,
src_ptr,
dest_ptr,
x_ptr,
cos_ptr,
cos_len,
br_ptr,
osc_list
);
// Third 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];
dest_ptr [coef_index + 6] = src_ptr [coef_index + 6];
DataType v;
v = (src_ptr [coef_index + 5] - src_ptr [coef_index + 7]) * sqrt2_2;
dest_ptr [coef_index + 1] = src_ptr [coef_index + 1] + v;
dest_ptr [coef_index + 3] = src_ptr [coef_index + 1] - v;
v = (src_ptr [coef_index + 5] + src_ptr [coef_index + 7]) * sqrt2_2;
dest_ptr [coef_index + 5] = v + src_ptr [coef_index + 3];
dest_ptr [coef_index + 7] = v - src_ptr [coef_index + 3];
coef_index += 8;
}
while (coef_index < len);
}
template <int PASS>
void FFTRealPassDirect <PASS>::process (long len, DataType dest_ptr [], DataType src_ptr [], const DataType x_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
{
// Executes "previous" passes first. Inverts source and destination buffers
FFTRealPassDirect <PASS - 1>::process (
len,
src_ptr,
dest_ptr,
x_ptr,
cos_ptr,
cos_len,
br_ptr,
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];
df [c2_i] = sf [c2_i];
FFTRealUseTrigo <TRIGO_DIRECT>::prepare (osc_list [TRIGO_OSC]);
// Others are conjugate complex numbers
for (long i = 1; i < dist; ++ 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 sf_r_i = sf [c1_r + i];
const DataType sf_i_i = sf [c1_i + i];
const DataType v1 = sf [c2_r + i] * c - sf [c2_i + i] * s;
df [c1_r + i] = sf_r_i + v1;
df [c2_r - i] = sf_r_i - v1;
const DataType v2 = sf [c2_r + i] * s + sf [c2_i + i] * c;
df [c2_r + i] = v2 + sf_i_i;
df [cend - i] = v2 - sf_i_i;
}
coef_index += cend;
}
while (coef_index < len);
}
/*\\\ PROTECTED \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
/*\\\ PRIVATE \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
#endif // FFTRealPassDirect_CODEHEADER_INCLUDED
#undef FFTRealPassDirect_CURRENT_CODEHEADER
/*\\\ EOF \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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