51 lines
2.6 KiB
C
51 lines
2.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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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; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ 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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│ 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; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "dsp/core/core.h"
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#include "libc/bits/bits.h"
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#include "libc/bits/safemacros.internal.h"
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#include "libc/limits.h"
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/**
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* Increases or decreases audio volume.
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*
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* @param 𝑝 is two-power w/ effective range [-15,15]
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*/
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void scalevolume(size_t n, int16_t pcm[n][8], int p) {
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/* TODO(jart): This isn't acceptable. */
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size_t i, j;
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if (p > 0) {
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if (p > 15) p = 15;
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for (i = 0; i < n; ++i) {
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for (j = 0; j < 8; ++j) {
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pcm[i][j] =
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MIN(SHRT_MAX, MAX(SHRT_MIN, (int)((unsigned)pcm[i][j] << p)));
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}
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}
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} else if (p < 0) {
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p = -p;
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if (p > 15) p = 15;
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for (i = 0; i < n; ++i) {
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for (j = 0; j < 8; ++j) {
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pcm[i][j] = pcm[i][j] >> p;
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}
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}
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}
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}
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