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- Python static hello world now 1.8mb
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- Add Mersenne Twister and Vigna to LIBC_RAND
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- Add COUNTBRANCH() macro to help with micro-optimizations
- Make error / backtrace / asan / memory code more unbreakable
- Add fast perfect C implementation of μ-Law and a-Law audio codecs
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40 lines
2.3 KiB
C
40 lines
2.3 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 2021 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "dsp/core/core.h"
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/**
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* Compresses 16-bit signed linear audio sample with μ-Law.
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*
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* @param x is clamped to 16-bits of which the top 14 are considered
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* @return coded number in range [0..255]
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* @see ITU G.711
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*/
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int mulaw(int x) {
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int b, i, a, s, l, h;
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a = x < 0 ? (~x >> 2) + 33 : (x >> 2) + 33;
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if (a > 8191) a = 8191;
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i = a >> 6;
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s = i ? (__builtin_clz(i) ^ 31) + 2 : 1;
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h = 8 - s;
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l = (a >> s) & 15;
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l = 15 - l;
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b = (h << 4) | l;
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if (x >= 0) b |= 128;
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return b;
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}
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