rom/dos/fgetc.c

   1 /*
   2     Copyright © 1995-2007, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: english
   7 */
   8 #include <exec/memory.h>
   9 #include <proto/exec.h>
  10
  11 #include <dos/stdio.h>
  12 #include <dos/dosextens.h>
  13
  14 #include "dos_intern.h"
  15
  16
  17 /*****************************************************************************
  18
  19     NAME */
  20 #include <proto/dos.h>
  21
  22         AROS_LH1(LONG, FGetC,
  23
  24 /*  SYNOPSIS */
  25         AROS_LHA(BPTR, file, D1),
  26
  27 /*  LOCATION */
  28         struct DosLibrary *, DOSBase, 51, Dos)
  29
  30 /*  FUNCTION
  31         Get a character from a buffered file. Buffered I/O is more efficient
  32         for small amounts of data but less for big chunks. You have to
  33         use Flush() between buffered and non-buffered I/O or you'll
  34         clutter your I/O stream.
  35
  36     INPUTS
  37         file   - filehandle
  38
  39     RESULT
  40         The character read or EOF if the file ended or an error happened.
  41         IoErr() gives additional information in that case.
  42
  43     NOTES
  44
  45     EXAMPLE
  46
  47     BUGS
  48
  49     SEE ALSO
  50         IoErr(), Flush()
  51
  52     INTERNALS
  53
  54 *****************************************************************************/
  55 {
  56     AROS_LIBFUNC_INIT
  57
  58     /* Get pointer to filehandle */
  59     struct FileHandle *fh = (struct FileHandle *)BADDR(file);
  60
  61     LONG  size;
  62
  63     if (fh == NULL)
  64     {
  65         return EOF;
  66     }
  67
  68     /* If the file is in write mode... */
  69     if(fh->fh_Flags & FHF_WRITE)
  70     {
  71         /* write the buffer (in many pieces if the first one isn't enough). */
  72         UBYTE  *pos = fh->fh_Buf;
  73
  74         while(pos != fh->fh_Pos)
  75         {
  76             size = Write(file, pos, fh->fh_Pos - pos);
  77
  78             /* An error happened? Return it. */
  79             if(size < 0)
  80             {
  81                 return EOF;
  82             }
  83
  84             pos += size;
  85         }
  86
  87         /* Reinit filehandle. */
  88         fh->fh_Flags &= ~FHF_WRITE;
  89         fh->fh_Pos = fh->fh_End = fh->fh_Buf;
  90     }
  91
  92     /* No normal characters left. */
  93     if(fh->fh_Pos >= fh->fh_End)
  94     {
  95         /* Check for a pushed back EOF. */
  96         if(fh->fh_Pos > fh->fh_End)
  97         {
  98             /* Reinit filehandle and return EOF. */
  99             fh->fh_Pos = fh->fh_End;
 100             SetIoErr(0);
 101
 102             return EOF;
 103         }
 104
 105         /* Is there a buffer? */
 106         if(fh->fh_Buf == NULL)
 107         {
 108             if (NULL == vbuf_alloc(fh, IOBUFSIZE, DOSBase))
 109             {
 110                 return(EOF);
 111             }
 112         }
 113
 114         /* Fill the buffer. */
 115         size = Read(file, fh->fh_Buf, fh->fh_Size);
 116
 117         /* Prepare filehandle for data. */
 118         if(size <= 0)
 119             size = 0;
 120
 121         fh->fh_Pos = fh->fh_Buf;
 122         fh->fh_End = fh->fh_Buf + size;
 123
 124         /* No data read? Return EOF. */
 125         if(size == 0)
 126         {
 127             return EOF;
 128         }
 129     }
 130
 131     /* All OK. Get data. */
 132     return *fh->fh_Pos++;
 133
 134     AROS_LIBFUNC_EXIT
 135 } /* FGetC */