[444] | 1 | /* Copyright (c) 2017 SiFive Inc. All rights reserved. |
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| 2 | |
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| 3 | This copyrighted material is made available to anyone wishing to use, |
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| 4 | modify, copy, or redistribute it subject to the terms and conditions |
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| 5 | of the FreeBSD License. This program is distributed in the hope that |
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| 6 | it will be useful, but WITHOUT ANY WARRANTY expressed or implied, |
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| 7 | including the implied warranties of MERCHANTABILITY or FITNESS FOR |
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| 8 | A PARTICULAR PURPOSE. A copy of this license is available at |
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| 9 | http://www.opensource.org/licenses. |
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| 10 | */ |
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| 11 | |
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| 12 | #include <string.h> |
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| 13 | #include <stdint.h> |
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| 14 | |
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| 15 | size_t strlen(const char *str) |
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| 16 | { |
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| 17 | const char *start = str; |
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| 18 | |
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| 19 | #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) |
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| 20 | while (*str++) |
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| 21 | ; |
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| 22 | return str - start - 1; |
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| 23 | #else |
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| 24 | if (__builtin_expect ((uintptr_t)str & (sizeof (long) - 1), 0)) do |
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| 25 | { |
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| 26 | char ch = *str; |
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| 27 | str++; |
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| 28 | if (!ch) |
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| 29 | return str - start - 1; |
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| 30 | } while ((uintptr_t)str & (sizeof (long) - 1)); |
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| 31 | |
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| 32 | unsigned long *ls = (unsigned long *)str; |
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| 33 | while (!__libc_detect_null (*ls++)) |
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| 34 | ; |
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| 35 | asm volatile ("" : "+r"(ls)); /* prevent "optimization" */ |
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| 36 | |
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| 37 | str = (const char *)ls; |
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| 38 | size_t ret = str - start, sl = sizeof (long); |
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| 39 | |
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| 40 | char c0 = str[0 - sl], c1 = str[1 - sl], c2 = str[2 - sl], c3 = str[3 - sl]; |
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| 41 | if (c0 == 0) return ret + 0 - sl; |
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| 42 | if (c1 == 0) return ret + 1 - sl; |
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| 43 | if (c2 == 0) return ret + 2 - sl; |
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| 44 | if (sl == 4 || c3 == 0) return ret + 3 - sl; |
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| 45 | |
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| 46 | c0 = str[4 - sl], c1 = str[5 - sl], c2 = str[6 - sl], c3 = str[7 - sl]; |
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| 47 | if (c0 == 0) return ret + 4 - sl; |
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| 48 | if (c1 == 0) return ret + 5 - sl; |
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| 49 | if (c2 == 0) return ret + 6 - sl; |
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| 50 | |
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| 51 | return ret + 7 - sl; |
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| 52 | #endif /* not PREFER_SIZE_OVER_SPEED */ |
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| 53 | } |
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