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77 lines
1.7 KiB
C
77 lines
1.7 KiB
C
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/* Copyright (C) 1991 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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <ansidecl.h>
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#include <string.h>
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#include <memcopy.h>
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char *
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DEFUN(strncat, (s1, s2, n), char *s1 AND CONST char *s2 AND 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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