workbench/libs/iffparse/writechunkrecords.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_LH4(LONG, WriteChunkRecords,
  14
  15 /*  SYNOPSIS */
  16         AROS_LHA(struct IFFHandle *, iff, A0),
  17         AROS_LHA(APTR              , buf, A1),
  18         AROS_LHA(LONG              , bytesPerRecord, D0),
  19         AROS_LHA(LONG              , numRecords, D1),
  20
  21 /*  LOCATION */
  22         struct Library *, IFFParseBase, 13, IFFParse)
  23
  24 /*  FUNCTION
  25         Write numRecods records of bytesPerRecord bytes to the current chunk.
  26         Attempts to write past the end of the chunk will be truncated.
  27
  28     INPUTS
  29          iff              - pointer to IFFHandle struct.
  30         buf              -  pointer to a buffer containig the data to be written.
  31         bytesPerRecord  - number of bytes per record.
  32         numRecords      -  number of records to write.
  33
  34     RESULT
  35         actual -   (positive) the actual number of whole records written.
  36                   (negative) IFFERR_#? error code if not succesfull.
  37
  38     NOTES
  39
  40     EXAMPLE
  41
  42     BUGS
  43
  44     SEE ALSO
  45         WriteChunkBytes()
  46
  47     INTERNALS
  48
  49 *****************************************************************************/
  50 {
  51     AROS_LIBFUNC_INIT
  52
  53     struct ContextNode *cn;
  54
  55     /* Number of bytes possible to write in the chunk */
  56     LONG lefttowrite;
  57     /* Number of bytes actually written */
  58     LONG byteswritten;
  59     /* Number of bytes to write into the chunk */
  60     LONG bytestowrite;
  61
  62     DEBUG_WRITECHUNKRECORDS(dprintf("WriteChunkRecords: iff %p buf %p bytesPerRecord %ld numRecords %ld\n",
  63                                     iff, buf, bytesPerRecord, numRecords));
  64
  65     /* Calculate number of bytes to write */
  66     bytestowrite = bytesPerRecord * numRecords;
  67
  68     /* Get the top contextnode */
  69     cn = TopChunk(iff);
  70
  71     /* Is the numBytes known for this chunk ? */
  72     if (cn->cn_Size != IFFSIZE_UNKNOWN)
  73     {
  74         /* We must truncate attempts to write larger than the chunksize */
  75         lefttowrite = cn->cn_Size - cn->cn_Scan;
  76         if  (bytestowrite > lefttowrite)
  77         {
  78             bytestowrite = lefttowrite;
  79
  80             /* See to it that we only write whole records */
  81             bytestowrite -= (lefttowrite % bytesPerRecord);
  82         }
  83     }
  84
  85
  86     /* Actually write the chunk */
  87     byteswritten = WriteStream(iff, buf, bytestowrite, IPB(IFFParseBase));
  88
  89     if (byteswritten < 0)
  90         /* IFFERR_#? returned by WriteStream() */
  91         numRecords = byteswritten;
  92     else
  93     {
  94         /* No error */
  95         cn->cn_Scan += byteswritten;
  96
  97         numRecords = (byteswritten / bytesPerRecord);
  98     }
  99
 100     DEBUG_WRITECHUNKRECORDS(dprintf("WriteChunkRecords: return %ld\n", numRecords));
 101     return (numRecords);
 102
 103     AROS_LIBFUNC_EXIT
 104 } /* WriteChunkRecords */