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module_reader.cpp

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/*
        $Id: module_reader.cpp,v 1.2 2001/03/13 21:43:02 sphair Exp $

        ------------------------------------------------------------------------
        ClanLib, the platform independent game SDK.

        This library is distributed under the GNU LIBRARY GENERAL PUBLIC LICENSE
        version 2. See COPYING for details.

        For a total list of contributers see CREDITS.

        ------------------------------------------------------------------------

        File purpose:
                Module reader for MikMod

*/

#include "module_reader.h"
#include "../API/Core/IOData/inputsource.h"

BOOL clanlib_reader_feof(MREADER* reader)
// eof function, returns TRUE if we are at the end of the file.
// Since CL_InputSource does not have a built-in eof function,
// we compare the current position to the size of the file.
{
        return (((CL_InputSource *) (((MCLANLIBREADER *) reader)->input))->tell()
                >= (((CL_InputSource *) (((MCLANLIBREADER *) reader)->input))->size()));
}

BOOL clanlib_reader_read(MREADER* reader,void* ptr,size_t size)
// read function, puts the data in a buffer.
// Even if the return type is BOOL, the function returns the number
// of bytes read. MikMod does the same internally.
{
        return (((CL_InputSource *) (((MCLANLIBREADER *) reader)->input))->read(ptr,size));
}

int clanlib_reader_get(MREADER* reader)
// get function, returns a single char from the file
{
        return (((CL_InputSource *) (((MCLANLIBREADER *) reader)->input))->read_char8());
}

BOOL clanlib_reader_seek(MREADER* reader,long offset,int whence)
// seek function, goes to a given position. It's important to note that
// this function is truely necessary for MikMod, and it has to be able to
// go back, ie rewind the file. ClanLib's implementation of this "go back"
// feature is really slow because files are compressed. This is a 
// compromise.
{
        CL_InputSource::SeekEnum cl_whence;

        switch (whence)
        {
        case SEEK_SET:
                cl_whence=CL_InputSource::seek_set;
                break;
        case SEEK_CUR:
                cl_whence=CL_InputSource::seek_cur;
                break;
        case SEEK_END:
                cl_whence=CL_InputSource::seek_end;
                break;
        default:
                cl_whence=CL_InputSource::seek_set;
        }

        ((CL_InputSource *) (((MCLANLIBREADER *) reader)->input))->seek(offset,cl_whence);

        return 0;
}

long clanlib_reader_tell(MREADER* reader)
// tell function, returns the current position in the file.
{
        return (((CL_InputSource *) (((MCLANLIBREADER *) reader)->input))->tell());
}

MREADER *new_clanlib_reader(void *input)
// creates a reader. We need this for MCLANLIBREADER is a plain struct
// and not a class, so we have to construct it "manually".
{
        MCLANLIBREADER* reader=new MCLANLIBREADER;
        if (reader)
        {
                reader->core.Eof =&clanlib_reader_feof;
                reader->core.Read=&clanlib_reader_read;
                reader->core.Get =&clanlib_reader_get;
                reader->core.Seek=&clanlib_reader_seek;
                reader->core.Tell=&clanlib_reader_tell;
                reader->input=input;
        }
        return (MREADER*)reader;
}

void delete_clanlib_reader (MREADER* reader)
// deletes the reader. Needed since MCLANLIBREADER is a struct and not
// a C++ class.
{
        if (reader!=NULL) delete(reader);
}

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