workbench/libs/iffparse/writechunkbytes.c

   1 /*
   2     Copyright © 1995-2007, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include "iffparse_intern.h"
   7
   8 /*****************************************************************************
   9
  10     NAME */
  11 #include <proto/iffparse.h>
  12
  13         AROS_LH3(LONG, WriteChunkBytes,
  14
  15 /*  SYNOPSIS */
  16         AROS_LHA(struct IFFHandle *, iff, A0),
  17         AROS_LHA(APTR              , buf, A1),
  18         AROS_LHA(LONG              , numBytes, D0),
  19
  20 /*  LOCATION */
  21         struct Library *, IFFParseBase, 11, IFFParse)
  22
  23 /*  FUNCTION
  24         Writes given number of bytes in the supplied buffer into the
  25         current chunk. Attempts to write past the endo of the chunk will
  26         be truncated.
  27
  28     INPUTS
  29         iff        - pointer to IFFHandle struct.
  30         buf        -  buffer with data to write.
  31         numBytes  - number of bytes to write.
  32
  33     RESULT
  34         actual    -  (positive) number of bytes actually written.
  35                     (negative) IFFERR_#? indicating unsuccesfull write.
  36     NOTES
  37
  38     EXAMPLE
  39
  40     BUGS
  41
  42     SEE ALSO
  43         PushChunk(), PopChunk(), WriteChunkRecords()
  44
  45     INTERNALS
  46
  47 *****************************************************************************/
  48 {
  49     AROS_LIBFUNC_INIT
  50
  51     struct ContextNode *cn;
  52
  53     LONG placeleft;
  54     LONG byteswritten;
  55
  56     DEBUG_WRITECHUNKBYTES(dprintf("WriteChunkBytes: iff 0x%lx buf 0x%lx size %d\n",
  57                             iff, buf, numBytes));
  58
  59     /* Get the top contextnode */
  60     cn = TopChunk(iff);
  61
  62     /* Is the numBytes known for this chunk ? */
  63     if (cn->cn_Size != IFFSIZE_UNKNOWN)
  64     {
  65         /* We must truncate attempts to write larger than the chunksize */
  66         placeleft = cn->cn_Size - cn->cn_Scan;
  67         if  (numBytes > placeleft)
  68
  69         numBytes = placeleft;
  70     }
  71
  72
  73     /* Actually write the chunk */
  74     byteswritten = WriteStream(iff, buf, numBytes, IPB(IFFParseBase));
  75
  76     if (byteswritten > 0)
  77     {
  78         /* No error */
  79         cn->cn_Scan += byteswritten;
  80     }
  81
  82     DEBUG_WRITECHUNKBYTES(dprintf("WriteChunkBytes: return %ld\n", byteswritten));
  83     return (byteswritten);
  84
  85     AROS_LIBFUNC_EXIT
  86 } /* WriteChunkBytes */