mirror of
https://github.com/eried/portapack-mayhem.git
synced 2024-09-20 16:15:51 +00:00
f82fd1f8d7
Trying to get a host-testable FSK demodulator, and finding a lot of M4- and ChibiOS-specific code is getting included. Boo.
112 lines
3.1 KiB
C++
112 lines
3.1 KiB
C++
/*
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* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
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*
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* This file is part of PortaPack.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include "dsp_demodulate.hpp"
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#include "complex.hpp"
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#include "fxpt_atan2.hpp"
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#include "utility_m4.hpp"
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#include <hal.h>
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namespace dsp {
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namespace demodulate {
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buffer_s16_t AM::execute(
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buffer_c16_t src,
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buffer_s16_t dst
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) {
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/* Intermediate maximum value: 46341 (when input is -32768,-32768). */
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/* Normalized to maximum 32767 for int16_t representation. */
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const auto src_p = src.p;
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const auto src_end = &src.p[src.count];
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auto dst_p = dst.p;
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while(src_p < src_end) {
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// const auto s = *(src_p++);
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// const uint32_t r_sq = s.real() * s.real();
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// const uint32_t i_sq = s.imag() * s.imag();
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// const uint32_t mag_sq = r_sq + i_sq;
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const uint32_t sample0 = *__SIMD32(src_p)++;
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const uint32_t sample1 = *__SIMD32(src_p)++;
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const uint32_t mag_sq0 = __SMUAD(sample0, sample0);
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const uint32_t mag_sq1 = __SMUAD(sample1, sample1);
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const int32_t mag0_int = __builtin_sqrtf(mag_sq0);
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const int32_t mag0_sat = __SSAT(mag0_int, 16);
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const int32_t mag1_int = __builtin_sqrtf(mag_sq1);
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const int32_t mag1_sat = __SSAT(mag1_int, 16);
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*__SIMD32(dst_p)++ = __PKHBT(
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mag0_sat,
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mag1_sat,
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16
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);
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}
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return { dst.p, src.count, src.sampling_rate };
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}
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/*
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static inline float angle_approx_4deg0(const complex32_t t) {
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const auto x = static_cast<float>(t.imag()) / static_cast<float>(t.real());
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return 16384.0f * x;
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}
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*/
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static inline float angle_approx_0deg27(const complex32_t t) {
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const auto x = static_cast<float>(t.imag()) / static_cast<float>(t.real());
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return x / (1.0f + 0.28086f * x * x);
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}
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/*
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static inline float angle_precise(const complex32_t t) {
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return atan2f(t.imag(), t.real());
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}
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*/
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buffer_s16_t FM::execute(
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buffer_c16_t src,
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buffer_s16_t dst
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) {
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auto z = z_;
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const auto src_p = src.p;
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const auto src_end = &src.p[src.count];
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auto dst_p = dst.p;
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while(src_p < src_end) {
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const auto s0 = *__SIMD32(src_p)++;
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const auto s1 = *__SIMD32(src_p)++;
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const auto t0 = multiply_conjugate_s16_s32(s0, z);
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const auto t1 = multiply_conjugate_s16_s32(s1, s0);
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z = s1;
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const int32_t theta0_int = angle_approx_0deg27(t0) * k;
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const int32_t theta0_sat = __SSAT(theta0_int, 16);
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const int32_t theta1_int = angle_approx_0deg27(t1) * k;
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const int32_t theta1_sat = __SSAT(theta1_int, 16);
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*__SIMD32(dst_p)++ = __PKHBT(
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theta0_sat,
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theta1_sat,
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16
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);
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}
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z_ = z;
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return { dst.p, src.count, src.sampling_rate };
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}
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}
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}
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