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85 lines
1.7 KiB
C
85 lines
1.7 KiB
C
/* Copyright (C) 1991,1997,2011 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but 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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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <string.h>
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#ifdef _LIBC
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# include <memcopy.h>
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#else
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typedef char reg_char;
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#endif
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#ifndef STRNCAT
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# undef strncat
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# define STRNCAT strncat
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#endif
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char *
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STRNCAT (char *s1, const char *s2, size_t n)
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{
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reg_char c;
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char *s = s1;
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/* Find the end of S1. */
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do
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c = *s1++;
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while (c != '\0');
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/* Make S1 point before next character, so we can increment
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it while memory is read (wins on pipelined cpus). */
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s1 -= 2;
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if (n >= 4)
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{
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size_t n4 = n >> 2;
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do
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{
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c = *s2++;
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*++s1 = c;
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if (c == '\0')
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return s;
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c = *s2++;
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*++s1 = c;
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if (c == '\0')
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return s;
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c = *s2++;
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*++s1 = c;
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if (c == '\0')
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return s;
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c = *s2++;
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*++s1 = c;
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if (c == '\0')
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return s;
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} while (--n4 > 0);
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n &= 3;
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}
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while (n > 0)
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{
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c = *s2++;
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*++s1 = c;
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if (c == '\0')
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return s;
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n--;
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}
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if (c != '\0')
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*++s1 = '\0';
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return s;
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}
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