/*
    Copyright (C) 1995-2016, The AROS Development Team. All rights reserved.
*/

#include "iffparse_intern.h"

/*****************************************************************************

    NAME */
#include <proto/iffparse.h>

        AROS_LH4(LONG, WriteChunkRecords,

/*  SYNOPSIS */
        AROS_LHA(struct IFFHandle *, iff, A0),
        AROS_LHA(APTR              , buf, A1),
        AROS_LHA(LONG              , bytesPerRecord, D0),
        AROS_LHA(LONG              , numRecords, D1),

/*  LOCATION */
        struct Library *, IFFParseBase, 13, IFFParse)

/*  FUNCTION
        Write numRecods records of bytesPerRecord bytes to the current chunk.
        Attempts to write past the end of the chunk will be truncated.

    INPUTS
         iff              - pointer to IFFHandle struct.
        buf              -  pointer to a buffer containig the data to be written.
        bytesPerRecord  - number of bytes per record.
        numRecords      -  number of records to write.

    RESULT
        actual -   (positive) the actual number of whole records written.
                  (negative) IFFERR_#? error code if not successful.

    NOTES

    EXAMPLE

    BUGS

    SEE ALSO
        WriteChunkBytes()

    INTERNALS

*****************************************************************************/
{
    AROS_LIBFUNC_INIT

    struct ContextNode *cn;

    /* Number of bytes possible to write in the chunk */
    LONG lefttowrite;
    /* Number of bytes actually written */
    LONG byteswritten;
    /* Number of bytes to write into the chunk */
    LONG bytestowrite;

    DEBUG_WRITECHUNKRECORDS(dprintf("WriteChunkRecords: iff %p buf %p bytesPerRecord %ld numRecords %ld\n",
                                    iff, buf, bytesPerRecord, numRecords));

    /* Calculate number of bytes to write */
    bytestowrite = bytesPerRecord * numRecords;

    /* Get the top contextnode */
    cn = TopChunk(iff);

    /* Is the numBytes known for this chunk ? */
    if (cn->cn_Size != IFFSIZE_UNKNOWN)
    {
        /* We must truncate attempts to write larger than the chunksize */
        lefttowrite = cn->cn_Size - cn->cn_Scan;
        if  (bytestowrite > lefttowrite)
        {
            bytestowrite = lefttowrite;

            /* See to it that we only write whole records */
            bytestowrite -= (lefttowrite % bytesPerRecord);
        }
    }


    /* Actually write the chunk */
    byteswritten = WriteStream(iff, buf, bytestowrite, IPB(IFFParseBase));

    if (byteswritten < 0)
        /* IFFERR_#? returned by WriteStream() */
        numRecords = byteswritten;
    else
    {
        /* No error */
        cn->cn_Scan += byteswritten;

        numRecords = (byteswritten / bytesPerRecord);
    }

    DEBUG_WRITECHUNKRECORDS(dprintf("WriteChunkRecords: return %ld\n", numRecords));
    return (numRecords);

    AROS_LIBFUNC_EXIT
} /* WriteChunkRecords */