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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [string/] [swab.c] - Blame information for rev 258

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Line No. Rev Author Line
1 207 jeremybenn
/*
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FUNCTION
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        <<swab>>---swap adjacent bytes
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ANSI_SYNOPSIS
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        #include <unistd.h>
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        void swab(const void *<[in]>, void *<[out]>, ssize_t <[n]>);
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TRAD_SYNOPSIS
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        void swab(<[in]>, <[out]>, <[n]>
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        void *<[in]>;
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        void *<[out]>;
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        ssize_t <[n]>;
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DESCRIPTION
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        This function copies <[n]> bytes from the memory region
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        pointed to by <[in]> to the memory region pointed to by
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        <[out]>, exchanging adjacent even and odd bytes.
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PORTABILITY
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<<swab>> requires no supporting OS subroutines.
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*/
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#include <unistd.h>
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void
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_DEFUN (swab, (b1, b2, length),
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        _CONST void *b1 _AND
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        void *b2 _AND
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        ssize_t length)
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{
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  const char *from = b1;
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  char *to = b2;
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  ssize_t ptr;
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  for (ptr = 1; ptr < length; ptr += 2)
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    {
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      char p = from[ptr];
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      char q = from[ptr-1];
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      to[ptr-1] = p;
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      to[ptr  ] = q;
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    }
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  if (ptr == length) /* I.e., if length is odd, */
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    to[ptr-1] = 0;   /* then pad with a NUL. */
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}

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