toolchain/gcc/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  * advertising materials, and 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
  25 ANSI_SYNOPSIS
  26         #include <stdio.h>
  27         int getc(FILE *<[fp]>);
  28
  29 TRAD_SYNOPSIS
  30         #include <stdio.h>
  31         int getc(<[fp]>)
  32         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 RETURNS
  43 The next character (read as an <<unsigned char>>, and cast to
  44 <<int>>), unless there is no more data, or the host system reports a
  45 read error; in either of these situations, <<getc>> returns <<EOF>>.
  46
  47 You can distinguish the two situations that cause an <<EOF>> result by
  48 using the <<ferror>> and <<feof>> functions.
  49
  50 PORTABILITY
  51 ANSI C requires <<getc>>; it suggests, but does not require, that
  52 <<getc>> be implemented as a macro.  The standard explicitly permits
  53 macro implementations of <<getc>> to use the argument more than once;
  54 therefore, in a portable program, you should not use an expression
  55 with side effects as the <<getc>> argument.
  56
  57 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  58 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
  59 */
  60
  61 #if defined(LIBC_SCCS) && !defined(lint)
  62 static char sccsid[] = "%W% (Berkeley) %G%";
  63 #endif /* LIBC_SCCS and not lint */
  64
  65 #include <stdio.h>
  66
  67 /*
  68  * A subroutine version of the macro getc.
  69  */
  70
  71 #undef getc
  72
  73 int
  74 getc (fp)
  75      register FILE *fp;
  76 {
  77   int result;
  78   _flockfile(fp);
  79   /* CHECK_INIT is called (eventually) by __srefill.  */
  80   result = __sgetc (fp);
  81   _funlockfile(fp);
  82   return result;
  83 }