105 lines
2.2 KiB
C
105 lines
2.2 KiB
C
/*
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FUNCTION
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<<strcat>>---concatenate strings
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INDEX
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strcat
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ANSI_SYNOPSIS
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#include <string.h>
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char *strcat(char *restrict <[dst]>, const char *restrict <[src]>);
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TRAD_SYNOPSIS
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#include <string.h>
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char *strcat(<[dst]>, <[src]>)
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char *<[dst]>;
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char *<[src]>;
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DESCRIPTION
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<<strcat>> appends a copy of the string pointed to by <[src]>
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(including the terminating null character) to the end of the
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string pointed to by <[dst]>. The initial character of
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<[src]> overwrites the null character at the end of <[dst]>.
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RETURNS
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This function returns the initial value of <[dst]>
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PORTABILITY
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<<strcat>> is ANSI C.
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<<strcat>> requires no supporting OS subroutines.
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QUICKREF
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strcat ansi pure
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*/
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#include <string.h>
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#include <limits.h>
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/* Nonzero if X is aligned on a "long" boundary. */
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#define ALIGNED(X) \
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(((long)X & (sizeof (long) - 1)) == 0)
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#if LONG_MAX == 2147483647L
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#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
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#else
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#if LONG_MAX == 9223372036854775807L
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/* Nonzero if X (a long int) contains a NULL byte. */
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#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
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#else
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#error long int is not a 32bit or 64bit type.
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#endif
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#endif
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#ifndef DETECTNULL
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#error long int is not a 32bit or 64bit byte
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#endif
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/*SUPPRESS 560*/
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/*SUPPRESS 530*/
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char *
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_DEFUN (strcat, (s1, s2),
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char *__restrict s1 _AND
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_CONST char *__restrict s2)
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{
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#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
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char *s = s1;
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while (*s1)
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s1++;
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while (*s1++ = *s2++)
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;
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return s;
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#else
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char *s = s1;
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/* Skip over the data in s1 as quickly as possible. */
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if (ALIGNED (s1))
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{
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unsigned long *aligned_s1 = (unsigned long *)s1;
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while (!DETECTNULL (*aligned_s1))
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aligned_s1++;
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s1 = (char *)aligned_s1;
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}
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while (*s1)
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s1++;
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/* s1 now points to the its trailing null character, we can
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just use strcpy to do the work for us now.
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?!? We might want to just include strcpy here.
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Also, this will cause many more unaligned string copies because
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s1 is much less likely to be aligned. I don't know if its worth
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tweaking strcpy to handle this better. */
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strcpy (s1, s2);
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return s;
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#endif /* not PREFER_SIZE_OVER_SPEED */
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}
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