rom/dos/fgetc.c

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: english
   7 */
   8
   9 #include <aros/debug.h>
  10 #include <exec/memory.h>
  11 #include <proto/exec.h>
  12
  13 #include <dos/stdio.h>
  14 #include <dos/dosextens.h>
  15
  16 #include "dos_intern.h"
  17
  18
  19 /*****************************************************************************
  20
  21     NAME */
  22 #include <proto/dos.h>
  23
  24         AROS_LH1(LONG, FGetC,
  25
  26 /*  SYNOPSIS */
  27         AROS_LHA(BPTR, file, D1),
  28
  29 /*  LOCATION */
  30         struct DosLibrary *, DOSBase, 51, Dos)
  31
  32 /*  FUNCTION
  33         Get a character from a buffered file. Buffered I/O is more efficient
  34         for small amounts of data but less for big chunks. You have to
  35         use Flush() between buffered and non-buffered I/O or you'll
  36         clutter your I/O stream.
  37
  38     INPUTS
  39         file   - filehandle
  40
  41     RESULT
  42         The character read or EOF if the file ended or an error happened.
  43         IoErr() gives additional information in that case.
  44
  45     NOTES
  46
  47     EXAMPLE
  48
  49     BUGS
  50
  51     SEE ALSO
  52         IoErr(), Flush()
  53
  54     INTERNALS
  55
  56 *****************************************************************************/
  57 {
  58     AROS_LIBFUNC_INIT
  59
  60     /* Get pointer to filehandle */
  61     struct FileHandle *fh = (struct FileHandle *)BADDR(file);
  62
  63     LONG  size;
  64     LONG  bufsize;
  65
  66     if (fh == NULL)
  67     {
  68         return EOF;
  69     }
  70
  71     /* If the file is in write mode... */
  72     if(fh->fh_Flags & FHF_WRITE)
  73     {
  74         /* write the buffer (in many pieces if the first one isn't enough). */
  75         LONG pos = 0;
  76
  77         while(pos != fh->fh_Pos)
  78         {
  79             size = Write(file, BADDR(fh->fh_Buf) + pos, fh->fh_Pos - pos);
  80
  81             /* An error happened? Return it. */
  82             if(size < 0)
  83             {
  84                 return EOF;
  85             }
  86
  87             pos += size;
  88         }
  89
  90         /* Reinit filehandle. */
  91         fh->fh_Flags &= ~FHF_WRITE;
  92         fh->fh_Pos = fh->fh_End = 0;
  93     }
  94
  95     /* No normal characters left. */
  96     if(fh->fh_Pos >= fh->fh_End)
  97     {
  98         /* Check for a pushed back EOF. */
  99         if(fh->fh_Pos > fh->fh_End)
 100         {
 101             D(bug("FGetC: Weird pos: fh_Pos (%d) > fh_End (%d)\n", fh->fh_Pos, fh->fh_End));
 102             /* Return EOF. */
 103             return EOF;
 104         }
 105
 106         /* Is there a buffer? */
 107         if(fh->fh_Buf == BNULL)
 108         {
 109             if (NULL == vbuf_alloc(fh, NULL, IOBUFSIZE))
 110             {
 111                 D(bug("FGetC: Can't allocate buffer\n"));
 112                 return(EOF);
 113             }
 114         }
 115
 116         /* Fill the buffer. */
 117         if (fh->fh_Buf != fh->fh_OrigBuf) {
 118             D(bug("FGetC: Can't trust fh_BufSize. Using 208 as the buffer size.\n"));
 119             bufsize = 208;
 120         } else {
 121             bufsize = fh->fh_BufSize;
 122         }
 123         size = Read(file, BADDR(fh->fh_Buf), bufsize);
 124
 125         /* Prepare filehandle for data. */
 126         if(size <= 0)
 127             size = 0;
 128
 129         fh->fh_Pos = 0;
 130         fh->fh_End = size;
 131
 132         /* No data read? Return EOF. */
 133         if(size == 0)
 134         {
 135             D(bug("FGetC: Tried to Read() to a %d byte buffer, got 0)\n", bufsize));
 136             return EOF;
 137         }
 138     }
 139
 140     /* If fh_End == 0, simulate an EOF */
 141     if (fh->fh_End == 0) {
 142         D(bug("FGetC: Got an EOF via fh_End == 0\n"));
 143         return EOF;
 144     }
 145
 146     /* All OK. Get data. */
 147     return ((UBYTE *)BADDR(fh->fh_Buf))[fh->fh_Pos++];
 148
 149     AROS_LIBFUNC_EXIT
 150 } /* FGetC */