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/*

 * Copyright (c) 1990 The Regents of the University of California.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms are permitted

 * provided that the above copyright notice and this paragraph are

 * duplicated in all such forms and that any documentation,

 * advertising materials, and other materials related to such

 * distribution and use acknowledge that the software was developed

 * by the University of California, Berkeley.  The name of the

 * University may not be used to endorse or promote products derived

 * from this software without specific prior written permission.

 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

 */

/*

FUNCTION

<<fread>>---read array elements from a file

INDEX

        fread

ANSI_SYNOPSIS

        #include <stdio.h>

        size_t fread(void *<[buf]>, size_t <[size]>, size_t <[count]>,

                     FILE *<[fp]>);

TRAD_SYNOPSIS

        #include <stdio.h>

        size_t fread(<[buf]>, <[size]>, <[count]>, <[fp]>)

        char *<[buf]>;

        size_t <[size]>;

        size_t <[count]>;

        FILE *<[fp]>;

DESCRIPTION

<<fread>> attempts to copy, from the file or stream identified by

<[fp]>, <[count]> elements (each of size <[size]>) into memory,

starting at <[buf]>.   <<fread>> may copy fewer elements than

<[count]> if an error, or end of file, intervenes.

<<fread>> also advances the file position indicator (if any) for

<[fp]> by the number of @emph{characters} actually read.

RETURNS

The result of <<fread>> is the number of elements it succeeded in

reading.

PORTABILITY

ANSI C requires <<fread>>.

Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,

<<lseek>>, <<read>>, <<sbrk>>, <<write>>.

*/

#include <stdio.h>

#include <string.h>

#include "local.h"

size_t

_DEFUN (fread, (buf, size, count, fp),

        _PTR buf _AND

        size_t size _AND

        size_t count _AND

        FILE * fp)

{

  register size_t resid;

  register char *p;

  register int r;

  size_t total;

  if ((resid = count * size) == 0)

    return 0;

  if (fp->_r < 0)

    fp->_r = 0;

  total = resid;

  p = buf;

  while (resid > (r = fp->_r))

    {

      (void) memcpy ((void *) p, (void *) fp->_p, (size_t) r);

      fp->_p += r;

      /* fp->_r = 0 ... done in __srefill */

      p += r;

      resid -= r;

      if (__srefill (fp))

        {

          /* no more input: return partial result */

          return (total - resid) / size;

        }

    }

  (void) memcpy ((void *) p, (void *) fp->_p, resid);

  fp->_r -= resid;

  fp->_p += resid;

  return count;

}