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2611874a50
Namely the part that creates a temporary LUT. Reviewed-by: Zhao Zhili <quinkblack@foxmail.com> Reviewed-by: Lynne <dev@lynne.ee> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
61 lines
2.1 KiB
C
61 lines
2.1 KiB
C
/*
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* Common code for AAC cube-root table
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*
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* Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
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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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#include <math.h>
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#include "cbrt_data.h"
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#include "libavutil/attributes.h"
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#ifdef HAVE_AV_CONFIG_H // Only include libm.h when building for the target, not the host
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#include "libavutil/libm.h"
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#endif
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av_cold void ff_cbrt_dbl_tableinit(double tmp_lut[TMP_LUT_SIZE])
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{
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for (int idx = 0; idx < TMP_LUT_SIZE; ++idx)
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tmp_lut[idx] = 1;
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/* have to take care of non-squarefree numbers; notice that sqrt(LUT_SIZE) = 90;
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* idx == 44 corresponds to 89. */
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for (int idx = 1; idx < 45; ++idx) {
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if (tmp_lut[idx] == 1) {
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int i = 2 * idx + 1;
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double cbrt_val = i * cbrt(i);
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for (int k = i; k < LUT_SIZE; k *= i) {
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// We only have to handle k, 3 * k, 5 * k,...,
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// because only these are odd. The corresponding indices are
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// k >> 1, (k >> 1) + k, (k >> 1) + 2 * k,...
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for (int idx2 = k >> 1; idx2 < TMP_LUT_SIZE; idx2 += k)
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tmp_lut[idx2] *= cbrt_val;
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}
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}
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}
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for (int idx = 45; idx < TMP_LUT_SIZE; ++idx) {
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if (tmp_lut[idx] == 1) {
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int i = 2 * idx + 1;
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double cbrt_val = i * cbrt(i);
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for (int idx2 = idx; idx2 < TMP_LUT_SIZE; idx2 += i)
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tmp_lut[idx2] *= cbrt_val;
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}
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}
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}
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