mirror of
https://github.com/eried/portapack-mayhem.git
synced 2024-10-01 01:26:06 -04:00
92 lines
3.1 KiB
C++
92 lines
3.1 KiB
C++
/*
|
|
* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
|
|
*
|
|
* This file is part of PortaPack.
|
|
*
|
|
* 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, 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; see the file COPYING. If not, write to
|
|
* the Free Software Foundation, Inc., 51 Franklin Street,
|
|
* Boston, MA 02110-1301, USA.
|
|
*/
|
|
|
|
#include "channel_decimator.hpp"
|
|
|
|
buffer_c16_t ChannelDecimator::execute_decimation(const buffer_c8_t& buffer) {
|
|
const buffer_c16_t work_baseband_buffer {
|
|
work_baseband.data(),
|
|
work_baseband.size()
|
|
};
|
|
|
|
const buffer_s16_t work_audio_buffer {
|
|
(int16_t*)work_baseband.data(),
|
|
sizeof(work_baseband) / sizeof(int16_t)
|
|
};
|
|
|
|
/* 3.072MHz complex<int8_t>[2048], [-128, 127]
|
|
* -> Shift by -fs/4
|
|
* -> 3rd order CIC: -0.1dB @ 0.028fs, -1dB @ 0.088fs, -60dB @ 0.468fs
|
|
* -0.1dB @ 86kHz, -1dB @ 270kHz, -60dB @ 1.44MHz
|
|
* -> gain of 256
|
|
* -> decimation by 2
|
|
* -> 1.544MHz complex<int16_t>[1024], [-32768, 32512] */
|
|
auto stage_0_out = execute_stage_0(buffer, work_baseband_buffer);
|
|
if( decimation_factor == DecimationFactor::By2 ) {
|
|
return stage_0_out;
|
|
}
|
|
|
|
/* 1.536MHz complex<int16_t>[1024], [-32768, 32512]
|
|
* -> 3rd order CIC: -0.1dB @ 0.028fs, -1dB @ 0.088fs, -60dB @ 0.468fs
|
|
* -0.1dB @ 43kHz, -1dB @ 136kHz, -60dB @ 723kHz
|
|
* -> gain of 1
|
|
* -> decimation by 2
|
|
* -> 768kHz complex<int16_t>[512], [-8192, 8128] */
|
|
auto cic_1_out = cic_1.execute(stage_0_out, work_baseband_buffer);
|
|
if( decimation_factor == DecimationFactor::By4 ) {
|
|
return cic_1_out;
|
|
}
|
|
|
|
/* 768kHz complex<int16_t>[512], [-32768, 32512]
|
|
* -> 3rd order CIC decimation by 2, gain of 1
|
|
* -> 384kHz complex<int16_t>[256], [-32768, 32512] */
|
|
auto cic_2_out = cic_2.execute(cic_1_out, work_baseband_buffer);
|
|
if( decimation_factor == DecimationFactor::By8 ) {
|
|
return cic_2_out;
|
|
}
|
|
|
|
/* 384kHz complex<int16_t>[256], [-32768, 32512]
|
|
* -> 3rd order CIC decimation by 2, gain of 1
|
|
* -> 192kHz complex<int16_t>[128], [-32768, 32512] */
|
|
auto cic_3_out = cic_3.execute(cic_2_out, work_baseband_buffer);
|
|
if( decimation_factor == DecimationFactor::By16 ) {
|
|
return cic_3_out;
|
|
}
|
|
|
|
/* 192kHz complex<int16_t>[128], [-32768, 32512]
|
|
* -> 3rd order CIC decimation by 2, gain of 1
|
|
* -> 96kHz complex<int16_t>[64], [-32768, 32512] */
|
|
auto cic_4_out = cic_4.execute(cic_3_out, work_baseband_buffer);
|
|
|
|
return cic_4_out;
|
|
}
|
|
|
|
buffer_c16_t ChannelDecimator::execute_stage_0(
|
|
const buffer_c8_t& buffer,
|
|
const buffer_c16_t& work_baseband_buffer
|
|
) {
|
|
if( fs_over_4_downconvert ) {
|
|
return translate.execute(buffer, work_baseband_buffer);
|
|
} else {
|
|
return cic_0.execute(buffer, work_baseband_buffer);
|
|
}
|
|
}
|