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188 lines
6.4 KiB
C
188 lines
6.4 KiB
C
/*
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* AC-3 and E-AC-3 decoder tables
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* Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Tables taken directly from the AC-3 spec or derived from it.
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*/
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#include "ac3dec_data.h"
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#include "libavutil/thread.h"
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/**
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* Table used to ungroup 3 values stored in 5 bits.
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* Used by bap=1 mantissas and GAQ.
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* ff_ac3_ungroup_3_in_5_bits_tab[i] = { i/9, (i%9)/3, (i%9)%3 }
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*/
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const uint8_t ff_ac3_ungroup_3_in_5_bits_tab[32][3] = {
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{ 0, 0, 0 }, { 0, 0, 1 }, { 0, 0, 2 }, { 0, 1, 0 },
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{ 0, 1, 1 }, { 0, 1, 2 }, { 0, 2, 0 }, { 0, 2, 1 },
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{ 0, 2, 2 }, { 1, 0, 0 }, { 1, 0, 1 }, { 1, 0, 2 },
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{ 1, 1, 0 }, { 1, 1, 1 }, { 1, 1, 2 }, { 1, 2, 0 },
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{ 1, 2, 1 }, { 1, 2, 2 }, { 2, 0, 0 }, { 2, 0, 1 },
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{ 2, 0, 2 }, { 2, 1, 0 }, { 2, 1, 1 }, { 2, 1, 2 },
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{ 2, 2, 0 }, { 2, 2, 1 }, { 2, 2, 2 }, { 3, 0, 0 },
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{ 3, 0, 1 }, { 3, 0, 2 }, { 3, 1, 0 }, { 3, 1, 1 }
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};
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/**
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* table for ungrouping 3 values in 7 bits.
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* used for exponents and bap=2 mantissas
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*/
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uint8_t ff_ac3_ungroup_3_in_7_bits_tab[128][3];
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/**
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* Symmetrical Dequantization
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* reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
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* Tables 7.19 to 7.23
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*/
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#define SYMMETRIC_DEQUANT(code, levels) (((code - (levels >> 1)) * (1 << 24)) / levels)
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/**
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* Ungrouped mantissa tables; the extra entry is padding to avoid range checks
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*/
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/**
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* Table 7.21
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*/
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const int ff_ac3_bap3_mantissas[7 + 1] = {
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SYMMETRIC_DEQUANT(0, 7),
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SYMMETRIC_DEQUANT(1, 7),
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SYMMETRIC_DEQUANT(2, 7),
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SYMMETRIC_DEQUANT(3, 7),
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SYMMETRIC_DEQUANT(4, 7),
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SYMMETRIC_DEQUANT(5, 7),
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SYMMETRIC_DEQUANT(6, 7),
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};
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/**
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* Table 7.23
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*/
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const int ff_ac3_bap5_mantissas[15 + 1] = {
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SYMMETRIC_DEQUANT(0, 15),
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SYMMETRIC_DEQUANT(1, 15),
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SYMMETRIC_DEQUANT(2, 15),
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SYMMETRIC_DEQUANT(3, 15),
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SYMMETRIC_DEQUANT(4, 15),
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SYMMETRIC_DEQUANT(5, 15),
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SYMMETRIC_DEQUANT(6, 15),
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SYMMETRIC_DEQUANT(7, 15),
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SYMMETRIC_DEQUANT(8, 15),
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SYMMETRIC_DEQUANT(9, 15),
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SYMMETRIC_DEQUANT(10, 15),
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SYMMETRIC_DEQUANT(11, 15),
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SYMMETRIC_DEQUANT(12, 15),
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SYMMETRIC_DEQUANT(13, 15),
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SYMMETRIC_DEQUANT(14, 15),
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};
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int ff_ac3_bap1_mantissas[32][3];
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int ff_ac3_bap2_mantissas[128][3];
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int ff_ac3_bap4_mantissas[128][2];
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static inline int
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symmetric_dequant(int code, int levels)
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{
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return SYMMETRIC_DEQUANT(code, levels);
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}
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static av_cold void ac3_init_static(void)
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{
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/* generate table for ungrouping 3 values in 7 bits
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reference: Section 7.1.3 Exponent Decoding */
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for (int i = 0; i < 128; ++i) {
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ff_ac3_ungroup_3_in_7_bits_tab[i][0] = i / 25;
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ff_ac3_ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
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ff_ac3_ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
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}
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/* generate grouped mantissa tables
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reference: Section 7.3.5 Ungrouping of Mantissas */
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for (int i = 0; i < 32; ++i) {
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/* bap=1 mantissas */
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ff_ac3_bap1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
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ff_ac3_bap1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
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ff_ac3_bap1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
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}
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for (int i = 0; i < 128; ++i) {
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/* bap=2 mantissas */
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ff_ac3_bap2_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_7_bits_tab[i][0], 5);
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ff_ac3_bap2_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_7_bits_tab[i][1], 5);
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ff_ac3_bap2_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_7_bits_tab[i][2], 5);
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/* bap=4 mantissas */
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ff_ac3_bap4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
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ff_ac3_bap4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
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}
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}
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av_cold void ff_ac3_init_static(void)
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{
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static AVOnce ac3_init_static_once = AV_ONCE_INIT;
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ff_thread_once(&ac3_init_static_once, ac3_init_static);
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}
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/**
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* Quantization table: levels for symmetric. bits for asymmetric.
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* reference: Table 7.18 Mapping of bap to Quantizer
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*/
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const uint8_t ff_ac3_quantization_tab[16] = {
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0, 3, 5, 7, 11, 15,
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5, 6, 7, 8, 9, 10, 11, 12, 14, 16
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};
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/**
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* Table for default stereo downmixing coefficients
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* reference: Section 7.8.2 Downmixing Into Two Channels
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*/
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const uint8_t ff_ac3_default_coeffs[8][5][2] = {
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{ { 2, 7 }, { 7, 2 }, },
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{ { 4, 4 }, },
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{ { 2, 7 }, { 7, 2 }, },
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{ { 2, 7 }, { 5, 5 }, { 7, 2 }, },
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{ { 2, 7 }, { 7, 2 }, { 6, 6 }, },
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{ { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
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{ { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
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{ { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
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};
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const uint8_t ff_eac3_hebap_tab[64] = {
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0, 1, 2, 3, 4, 5, 6, 7, 8, 8,
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8, 8, 9, 9, 9, 10, 10, 10, 10, 11,
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11, 11, 11, 12, 12, 12, 12, 13, 13, 13,
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13, 14, 14, 14, 14, 15, 15, 15, 15, 16,
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16, 16, 16, 17, 17, 17, 17, 18, 18, 18,
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18, 18, 18, 18, 18, 19, 19, 19, 19, 19,
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19, 19, 19, 19,
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};
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/**
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* Table E2.15 Default Spectral Extension Banding Structure
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*/
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const uint8_t ff_eac3_default_spx_band_struct[17] =
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{ 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1 };
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/** Adjustments in dB gain (LFE, +10 to -21 dB) */
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const float ff_eac3_gain_levels_lfe[32] = {
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3.162275, 2.818382, 2.511886, 2.238719, 1.995261, 1.778278, 1.584893,
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1.412536, 1.258924, 1.122018, 1.000000, 0.891251, 0.794328, 0.707946,
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0.630957, 0.562341, 0.501187, 0.446683, 0.398107, 0.354813, 0.316227,
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0.281838, 0.251188, 0.223872, 0.199526, 0.177828, 0.158489, 0.141253,
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0.125892, 0.112201, 0.100000, 0.089125
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};
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