PabHandler.java

/*
  PabHandler.java

  (c) 2010-2013 Edward Swartz

  All rights reserved. This program and the accompanying materials
  are made available under the terms of the Eclipse Public License v1.0
  which accompanies this distribution, and is available at
  http://www.eclipse.org/legal/epl-v10.html
 */
package v9t9.engine.dsr;

import v9t9.common.dsr.IMemoryTransfer;
import v9t9.common.files.DsrException;
import v9t9.common.files.PabConstants;

public abstract class PabHandler {
	protected Short pabaddr;
	
	public String devname;
	public String fname;
	protected PabStruct pab;
	protected final IMemoryTransfer xfer;

	public PabHandler(IMemoryTransfer xfer) {
		/*  rambase+0x56 holds a pointer into VDP RAM to the end
		   of the device name (RS232|, DSK|., DSK1|.ed) */
	
		//pf.fnptr = fn;
		//fiad_tifile_clear(&pf->tf);
	
		this.xfer = xfer;

		byte len;
		short fpaddr;
		short devlen;

		fpaddr = xfer.readParamWord(0x56);
		devlen = xfer.readParamWord(0x54);
		pabaddr = (short) (fpaddr - 9 - devlen - 1);

		len = xfer.readVdpByte(fpaddr - devlen - 1);					/* length of device+filename */
		short fnaddr = (short) (fpaddr + 1);	/* addr of filename (skip period) */
		len -= devlen + 1;	/* minus length of device + period */
		fname = readFilename(fnaddr, len);
		
		devname = readFilename((short) (fnaddr - devlen - 1), devlen).toUpperCase();
	
		pab = new PabStruct();
		
		pab.path = devname + "." + fname;
		
		pab.fetch(xfer, pabaddr);
	}
	
	/**
	 * Construct handler from pre-created pab information.
	 * @param pab2
	 */
	public PabHandler(IMemoryTransfer xfer, PabStruct pab) {
		this.xfer = xfer;
		this.pab = pab;
		int idx = pab.path.indexOf('.');
		this.devname = pab.path.substring(0, idx);
		this.fname = pab.path.substring(idx + 1);
	}

	protected String readFilename(short addr, int len) {
		StringBuilder builder = new StringBuilder();
		int endAddr = addr;
		while (len-- > 0) {
			byte ch = xfer.readVdpByte(endAddr);
			builder.append((char) ch);
			endAddr++;
		}
		return builder.toString();
	}

	abstract public void run() throws DsrException;
	
	public void error(DsrException e) {
		
		int current = pab.pflags;
		current = (current & ~0xe0) | (e.getErrorCode());
		pab.pflags = current;
		
		if (e.getErrorCode() != PabConstants.e_endoffile)
			System.out.println(e.getMessage());
	}
	
	public void store() {
		if (pabaddr != null) {
			pab.store(xfer);
		}
	}

}