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49 lines
2.7 KiB
C
49 lines
2.7 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 "libc/dce.h"
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#include "libc/intrin/asan.internal.h"
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#include "libc/str/str.h"
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typedef char16_t xmm_t __attribute__((__vector_size__(16), __aligned__(16)));
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/**
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* Returns length of NUL-terminated utf-16 string.
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*
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* @param s is non-null NUL-terminated string pointer
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* @return number of shorts (excluding NUL)
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* @asyncsignalsafe
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*/
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dontasan size_t strlen16(const char16_t *s) {
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#if defined(__x86_64__) && !defined(__chibicc__)
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size_t n;
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xmm_t z = {0};
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unsigned m, k = (uintptr_t)s & 15;
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const xmm_t *p = (const xmm_t *)((uintptr_t)s & -16);
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if (IsAsan()) __asan_verify(s, 2);
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m = __builtin_ia32_pmovmskb128(*p == z) >> k << k;
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while (!m) m = __builtin_ia32_pmovmskb128(*++p == z);
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n = (const char16_t *)p + (__builtin_ctzl(m) >> 1) - s;
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if (IsAsan()) __asan_verify(s, n * 2);
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return n;
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#else
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size_t n = 0;
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while (*s++) ++n;
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return n;
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#endif
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}
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