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275 lines
10 KiB
C++
275 lines
10 KiB
C++
///////////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2021 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
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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 as version 3 of the License, or //
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// (at your option) 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 V3 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. If not, see <http://www.gnu.org/licenses/>. //
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///////////////////////////////////////////////////////////////////////////////////////
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/*
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Quadrature amplitude modulation
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Copyright 2018 Ahmet Inan <xdsopl@gmail.com>
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*/
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#ifndef QAM_HH
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#define QAM_HH
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namespace ldpctool {
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template <int NUM, typename TYPE, typename CODE>
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struct QuadratureAmplitudeModulation;
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template <typename TYPE, typename CODE>
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struct QuadratureAmplitudeModulation<16, TYPE, CODE>
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{
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static const int NUM = 16;
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static const int BITS = 4;
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typedef TYPE complex_type;
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typedef typename TYPE::value_type value_type;
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typedef CODE code_type;
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static constexpr value_type FAC = 1.0540925533894596;
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static constexpr value_type RCP = 3 * FAC;
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static constexpr value_type AMP = 1 / RCP;
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static constexpr value_type DIST = 2 * AMP;
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static constexpr value_type amp(int i)
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{
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return AMP * i;
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}
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static code_type quantize(value_type precision, value_type value)
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{
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value *= DIST * precision;
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if (std::is_integral<code_type>::value)
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value = std::nearbyint(value);
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if (std::is_same<code_type, int8_t>::value)
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value = std::min<value_type>(std::max<value_type>(value, -128), 127);
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return value;
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}
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static void hard(code_type *b, complex_type c)
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{
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b[0] = c.real() < amp(0) ? code_type(-1) : code_type(1);
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b[1] = c.imag() < amp(0) ? code_type(-1) : code_type(1);
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b[2] = std::abs(c.real()) < amp(2) ? code_type(-1) : code_type(1);
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b[3] = std::abs(c.imag()) < amp(2) ? code_type(-1) : code_type(1);
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}
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static void soft(code_type *b, complex_type c, value_type precision)
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{
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b[0] = quantize(precision, c.real());
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b[1] = quantize(precision, c.imag());
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b[2] = quantize(precision, std::abs(c.real())-amp(2));
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b[3] = quantize(precision, std::abs(c.imag())-amp(2));
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}
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static complex_type map(code_type *b)
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{
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return AMP * complex_type(
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b[0]*(b[2]+value_type(2)),
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b[1]*(b[3]+value_type(2))
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);
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}
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};
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template <typename TYPE, typename CODE>
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struct QuadratureAmplitudeModulation<64, TYPE, CODE>
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{
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static const int NUM = 64;
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static const int BITS = 6;
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typedef TYPE complex_type;
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typedef typename TYPE::value_type value_type;
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typedef CODE code_type;
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static constexpr value_type FAC = 0.9258200997725516;
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static constexpr value_type RCP = 7 * FAC;
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static constexpr value_type AMP = 1 / RCP;
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static constexpr value_type DIST = 2 * AMP;
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static constexpr value_type amp(int i)
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{
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return AMP * i;
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}
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static code_type quantize(value_type precision, value_type value)
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{
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value *= DIST * precision;
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if (std::is_integral<code_type>::value)
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value = std::nearbyint(value);
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if (std::is_same<code_type, int8_t>::value)
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value = std::min<value_type>(std::max<value_type>(value, -128), 127);
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return value;
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}
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static void hard(code_type *b, complex_type c)
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{
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b[0] = c.real() < amp(0) ? code_type(-1) : code_type(1);
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b[1] = c.imag() < amp(0) ? code_type(-1) : code_type(1);
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b[2] = std::abs(c.real()) < amp(4) ? code_type(-1) : code_type(1);
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b[3] = std::abs(c.imag()) < amp(4) ? code_type(-1) : code_type(1);
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b[4] = std::abs(std::abs(c.real())-amp(4)) < amp(2) ? code_type(-1) : code_type(1);
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b[5] = std::abs(std::abs(c.imag())-amp(4)) < amp(2) ? code_type(-1) : code_type(1);
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}
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static void soft(code_type *b, complex_type c, value_type precision)
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{
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b[0] = quantize(precision, c.real());
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b[1] = quantize(precision, c.imag());
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b[2] = quantize(precision, std::abs(c.real())-amp(4));
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b[3] = quantize(precision, std::abs(c.imag())-amp(4));
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b[4] = quantize(precision, std::abs(std::abs(c.real())-amp(4))-amp(2));
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b[5] = quantize(precision, std::abs(std::abs(c.imag())-amp(4))-amp(2));
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}
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static complex_type map(code_type *b)
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{
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return AMP * complex_type(
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b[0]*(b[2]*(b[4]+value_type(2))+value_type(4)),
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b[1]*(b[3]*(b[5]+value_type(2))+value_type(4))
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);
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}
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};
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template <typename TYPE, typename CODE>
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struct QuadratureAmplitudeModulation<256, TYPE, CODE>
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{
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static const int NUM = 256;
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static const int BITS = 8;
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typedef TYPE complex_type;
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typedef typename TYPE::value_type value_type;
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typedef CODE code_type;
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static constexpr value_type FAC = 0.8692269873603529;
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static constexpr value_type RCP = 15 * FAC;
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static constexpr value_type AMP = 1 / RCP;
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static constexpr value_type DIST = 2 * AMP;
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static constexpr value_type amp(int i)
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{
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return AMP * i;
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}
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static code_type quantize(value_type precision, value_type value)
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{
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value *= DIST * precision;
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if (std::is_integral<code_type>::value)
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value = std::nearbyint(value);
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if (std::is_same<code_type, int8_t>::value)
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value = std::min<value_type>(std::max<value_type>(value, -128), 127);
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return value;
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}
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static void hard(code_type *b, complex_type c)
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{
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b[0] = c.real() < amp(0) ? code_type(-1) : code_type(1);
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b[1] = c.imag() < amp(0) ? code_type(-1) : code_type(1);
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b[2] = std::abs(c.real()) < amp(8) ? code_type(-1) : code_type(1);
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b[3] = std::abs(c.imag()) < amp(8) ? code_type(-1) : code_type(1);
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b[4] = std::abs(std::abs(c.real())-amp(8)) < amp(4) ? code_type(-1) : code_type(1);
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b[5] = std::abs(std::abs(c.imag())-amp(8)) < amp(4) ? code_type(-1) : code_type(1);
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b[6] = std::abs(std::abs(std::abs(c.real())-amp(8))-amp(4)) < amp(2) ? code_type(-1) : code_type(1);
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b[7] = std::abs(std::abs(std::abs(c.imag())-amp(8))-amp(4)) < amp(2) ? code_type(-1) : code_type(1);
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}
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static void soft(code_type *b, complex_type c, value_type precision)
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{
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b[0] = quantize(precision, c.real());
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b[1] = quantize(precision, c.imag());
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b[2] = quantize(precision, std::abs(c.real())-amp(8));
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b[3] = quantize(precision, std::abs(c.imag())-amp(8));
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b[4] = quantize(precision, std::abs(std::abs(c.real())-amp(8))-amp(4));
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b[5] = quantize(precision, std::abs(std::abs(c.imag())-amp(8))-amp(4));
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b[6] = quantize(precision, std::abs(std::abs(std::abs(c.real())-amp(8))-amp(4))-amp(2));
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b[7] = quantize(precision, std::abs(std::abs(std::abs(c.imag())-amp(8))-amp(4))-amp(2));
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}
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static complex_type map(code_type *b)
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{
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return AMP * complex_type(
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b[0]*(b[2]*(b[4]*(b[6]+value_type(2))+value_type(4))+value_type(8)),
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b[1]*(b[3]*(b[5]*(b[7]+value_type(2))+value_type(4))+value_type(8))
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);
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}
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};
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template <typename TYPE, typename CODE>
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struct QuadratureAmplitudeModulation<1024, TYPE, CODE>
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{
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static const int NUM = 1024;
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static const int BITS = 10;
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typedef TYPE complex_type;
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typedef typename TYPE::value_type value_type;
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typedef CODE code_type;
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static constexpr value_type FAC = 0.8424235391742344;
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static constexpr value_type RCP = 31 * FAC;
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static constexpr value_type AMP = 1 / RCP;
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static constexpr value_type DIST = 2 * AMP;
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static constexpr value_type amp(int i)
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{
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return AMP * i;
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}
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static code_type quantize(value_type precision, value_type value)
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{
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value *= DIST * precision;
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if (std::is_integral<code_type>::value)
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value = std::nearbyint(value);
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if (std::is_same<code_type, int8_t>::value)
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value = std::min<value_type>(std::max<value_type>(value, -128), 127);
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return value;
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}
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static void hard(code_type *b, complex_type c)
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{
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b[0] = c.real() < amp(0) ? code_type(-1) : code_type(1);
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b[1] = c.imag() < amp(0) ? code_type(-1) : code_type(1);
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b[2] = std::abs(c.real()) < amp(16) ? code_type(-1) : code_type(1);
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b[3] = std::abs(c.imag()) < amp(16) ? code_type(-1) : code_type(1);
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b[4] = std::abs(std::abs(c.real())-amp(16)) < amp(8) ? code_type(-1) : code_type(1);
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b[5] = std::abs(std::abs(c.imag())-amp(16)) < amp(8) ? code_type(-1) : code_type(1);
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b[6] = std::abs(std::abs(std::abs(c.real())-amp(16))-amp(8)) < amp(4) ? code_type(-1) : code_type(1);
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b[7] = std::abs(std::abs(std::abs(c.imag())-amp(16))-amp(8)) < amp(4) ? code_type(-1) : code_type(1);
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b[8] = std::abs(std::abs(std::abs(std::abs(c.real())-amp(16))-amp(8))-amp(4)) < amp(2) ? code_type(-1) : code_type(1);
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b[9] = std::abs(std::abs(std::abs(std::abs(c.imag())-amp(16))-amp(8))-amp(4)) < amp(2) ? code_type(-1) : code_type(1);
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}
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static void soft(code_type *b, complex_type c, value_type precision)
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{
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b[0] = quantize(precision, c.real());
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b[1] = quantize(precision, c.imag());
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b[2] = quantize(precision, std::abs(c.real())-amp(16));
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b[3] = quantize(precision, std::abs(c.imag())-amp(16));
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b[4] = quantize(precision, std::abs(std::abs(c.real())-amp(16))-amp(8));
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b[5] = quantize(precision, std::abs(std::abs(c.imag())-amp(16))-amp(8));
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b[6] = quantize(precision, std::abs(std::abs(std::abs(c.real())-amp(16))-amp(8))-amp(4));
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b[7] = quantize(precision, std::abs(std::abs(std::abs(c.imag())-amp(16))-amp(8))-amp(4));
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b[8] = quantize(precision, std::abs(std::abs(std::abs(std::abs(c.real())-amp(16))-amp(8))-amp(4))-amp(2));
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b[9] = quantize(precision, std::abs(std::abs(std::abs(std::abs(c.imag())-amp(16))-amp(8))-amp(4))-amp(2));
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}
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static complex_type map(code_type *b)
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{
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return AMP * complex_type(
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b[0]*(b[2]*(b[4]*(b[6]*(b[8]+value_type(2))+value_type(4))+value_type(8))+value_type(16)),
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b[1]*(b[3]*(b[5]*(b[7]*(b[9]+value_type(2))+value_type(4))+value_type(8))+value_type(16))
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);
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}
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};
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} // namespace ldpctool
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#endif
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