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36 lines
1.1 KiB
36 lines
1.1 KiB
/* |
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* Copyright 2010 Tilera Corporation. All Rights Reserved. |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public License |
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* as published by the Free Software Foundation, version 2. |
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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, GOOD TITLE or |
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* NON INFRINGEMENT. See the GNU General Public License for |
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* more details. |
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*/ |
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#include <linux/types.h> |
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#include <linux/string.h> |
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#include <linux/module.h> |
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size_t strlen(const char *s) |
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{ |
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/* Get an aligned pointer. */ |
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const uintptr_t s_int = (uintptr_t) s; |
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const uint32_t *p = (const uint32_t *)(s_int & -4); |
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/* Read the first word, but force bytes before the string to be nonzero. |
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* This expression works because we know shift counts are taken mod 32. |
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*/ |
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uint32_t v = *p | ((1 << (s_int << 3)) - 1); |
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uint32_t bits; |
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while ((bits = __insn_seqb(v, 0)) == 0) |
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v = *++p; |
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return ((const char *)p) + (__insn_ctz(bits) >> 3) - s; |
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} |
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EXPORT_SYMBOL(strlen);
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