rom/dos/fgetc.c

   1 /*
   2     Copyright © 1995-2006, 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     AROS_LIBBASE_EXT_DECL(struct DosLibrary *,DOSBase)
  58
  59     /* Get pointer to filehandle */
  60     struct FileHandle *fh = (struct FileHandle *)BADDR(file);
  61
  62     LONG  size;
  63
  64     if (fh == NULL)
  65     {
  66         return EOF;
  67     }
  68
  69     /* If the file is in write mode... */
  70     if(fh->fh_Flags & FHF_WRITE)
  71     {
  72         /* write the buffer (in many pieces if the first one isn't enough). */
  73         UBYTE  *pos = fh->fh_Buf;
  74
  75         while(pos != fh->fh_Pos)
  76         {
  77             size = Write(file, pos, fh->fh_Pos - pos);
  78
  79             /* An error happened? Return it. */
  80             if(size < 0)
  81             {
  82                 return EOF;
  83             }
  84
  85             pos += size;
  86         }
  87
  88         /* Reinit filehandle. */
  89         fh->fh_Flags &= ~FHF_WRITE;
  90         fh->fh_Pos = fh->fh_End = fh->fh_Buf;
  91     }
  92
  93     /* No normal characters left. */
  94     if(fh->fh_Pos >= fh->fh_End)
  95     {
  96         /* Check for a pushed back EOF. */
  97         if(fh->fh_Pos > fh->fh_End)
  98         {
  99             /* Reinit filehandle and return EOF. */
 100             fh->fh_Pos = fh->fh_End;
 101             SetIoErr(0);
 102
 103             return EOF;
 104         }
 105
 106         /* Is there a buffer? */
 107         if(fh->fh_Buf == NULL)
 108         {
 109             if (NULL == vbuf_alloc(fh, IOBUFSIZE, DOSBase))
 110             {
 111                 return(EOF);
 112             }
 113         }
 114
 115         /* Fill the buffer. */
 116         size = Read(file, fh->fh_Buf, fh->fh_Size);
 117
 118         /* Prepare filehandle for data. */
 119         if(size <= 0)
 120             size = 0;
 121
 122         fh->fh_Pos = fh->fh_Buf;
 123         fh->fh_End = fh->fh_Buf + size;
 124
 125         /* No data read? Return EOF. */
 126         if(size == 0)
 127         {
 128             return EOF;
 129         }
 130     }
 131
 132     /* All OK. Get data. */
 133     return *fh->fh_Pos++;
 134
 135     AROS_LIBFUNC_EXIT
 136 } /* FGetC */