newlib/libc/stdio/getc.c

   1 /*
   2  * Copyright (c) 1990 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms are permitted
   6  * provided that the above copyright notice and this paragraph are
   7  * duplicated in all such forms and that any documentation,
   8  * and/or other materials related to such
   9  * distribution and use acknowledge that the software was developed
  10  * by the University of California, Berkeley.  The name of the
  11  * University may not be used to endorse or promote products derived
  12  * from this software without specific prior written permission.
  13  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  16  */
  17
  18 /*
  19 FUNCTION
  20 <<getc>>---read a character (macro)
  21
  22 INDEX
  23         getc
  24 INDEX
  25         _getc_r
  26
  27 SYNOPSIS
  28         #include <stdio.h>
  29         int getc(FILE *<[fp]>);
  30
  31         #include <stdio.h>
  32         int _getc_r(struct _reent *<[ptr]>, FILE *<[fp]>);
  33
  34 DESCRIPTION
  35 <<getc>> is a macro, defined in <<stdio.h>>.  You can use <<getc>>
  36 to get the next single character from the file or stream
  37 identified by <[fp]>.  As a side effect, <<getc>> advances the file's
  38 current position indicator.
  39
  40 For a subroutine version of this macro, see <<fgetc>>.
  41
  42 The <<_getc_r>> function is simply the reentrant version of <<getc>>
  43 which passes an additional reentrancy structure pointer argument: <[ptr]>.
  44
  45 RETURNS
  46 The next character (read as an <<unsigned char>>, and cast to
  47 <<int>>), unless there is no more data, or the host system reports a
  48 read error; in either of these situations, <<getc>> returns <<EOF>>.
  49
  50 You can distinguish the two situations that cause an <<EOF>> result by
  51 using the <<ferror>> and <<feof>> functions.
  52
  53 PORTABILITY
  54 ANSI C requires <<getc>>; it suggests, but does not require, that
  55 <<getc>> be implemented as a macro.  The standard explicitly permits
  56 macro implementations of <<getc>> to use the argument more than once;
  57 therefore, in a portable program, you should not use an expression
  58 with side effects as the <<getc>> argument.
  59
  60 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  61 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
  62 */
  63
  64 #if defined(LIBC_SCCS) && !defined(lint)
  65 static char sccsid[] = "%W% (Berkeley) %G%";
  66 #endif /* LIBC_SCCS and not lint */
  67
  68 #include <_ansi.h>
  69 #include <stdio.h>
  70 #include "local.h"
  71
  72 /*
  73  * A subroutine version of the macro getc.
  74  */
  75
  76 #undef getc
  77
  78 int
  79 _getc_r (struct _reent *ptr,
  80        register FILE *fp)
  81 {
  82   int result;
  83   CHECK_INIT (ptr, fp);
  84   _newlib_flockfile_start (fp);
  85   result = __sgetc_r (ptr, fp);
  86   _newlib_flockfile_end (fp);
  87   return result;
  88 }
  89
  90 #ifndef _REENT_ONLY
  91
  92 int
  93 getc (register FILE *fp)
  94 {
  95   int result;
  96   struct _reent *reent = _REENT;
  97
  98   CHECK_INIT (reent, fp);
  99   _newlib_flockfile_start (fp);
 100   result = __sgetc_r (reent, fp);
 101   _newlib_flockfile_end (fp);
 102   return result;
 103 }
 104
 105 #endif /* !_REENT_ONLY */