mayhem-firmware/firmware/baseband-tx/proc_audiotx.cpp

107 lines
2.2 KiB
C++

/*
* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
* Copyright (C) 2016 Furrtek
*
* 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 "proc_audiotx.hpp"
#include "portapack_shared_memory.hpp"
#include "sine_table.hpp"
#include "audio_output.hpp"
#include "lfsr_random.hpp"
#include <cstdint>
uint32_t lfsr(uint32_t v) {
enum {
length = 31,
tap_0 = 31,
tap_1 = 18,
shift_amount_0 = 12,
shift_amount_1 = 12,
shift_amount_2 = 8
};
const lfsr_word_t zero = 0;
v = (
(
v << shift_amount_0
) | (
(
(v >> (tap_0 - shift_amount_0)) ^
(v >> (tap_1 - shift_amount_0))
) & (
~(~zero << shift_amount_0)
)
)
);
v = (
(
v << shift_amount_1
) | (
(
(v >> (tap_0 - shift_amount_1)) ^
(v >> (tap_1 - shift_amount_1))
) & (
~(~zero << shift_amount_1)
)
)
);
v = (
(
v << shift_amount_2
) | (
(
(v >> (tap_0 - shift_amount_2)) ^
(v >> (tap_1 - shift_amount_2))
) & (
~(~zero << shift_amount_2)
)
)
);
return v;
}
void AudioTXProcessor::execute(const buffer_c8_t& buffer){
for (size_t i = 0; i<buffer.count; i++) {
sample = (sine_table_f32[(aphase & 0x03FF0000)>>18]*127); //(int8_t)lfsr(sample + i);
if (bc & 0x40)
aphase += 60000;
else
aphase += 90000;
//FM
frq = sample * 2500;
phase = (phase + frq);
sphase = phase + (256<<16);
re = (sine_table_f32[(sphase & 0x03FF0000)>>18]*127);
im = (sine_table_f32[(phase & 0x03FF0000)>>18]*127);
buffer.p[i] = {(int8_t)re,(int8_t)im};
}
bc++;
}