PabStruct.java

/*
  PabStruct.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.FDR;
import v9t9.common.files.PabConstants;
import v9t9.common.files.V9t9FDR;

import static v9t9.common.files.PabConstants.*;

public class PabStruct 
{
	/** 0 file operation (f_xxx) */
	public int	opcode;		
	/** 1 file access code (fp_xxx) + open mode (m_xxx) [IN]
	<br> error code [OUT] */
	public int	pflags;		
	/** 2 VDP record address */
	public int	bufaddr;	
	/** 4 file record length */
	public int	preclen;	
	/** 5 characters used in record */
	public int	charcount;	
	/** 6 current record (seek position), or byte count for load/save */
	public int	recnum;	
	/** 8 screen offset (for CSx) */
	public int	scrnoffs;	
	/** 9 length of filename following */
	public int	namelen;	
	/** device.filename */
	public String	path;
	public short pabaddr;		
	
	/**
	 * Read the pab contents from memory.
	 * @throws DsrException
	 */
	public void fetch(IMemoryTransfer xfer, short pabaddr) {
		this.pabaddr = pabaddr;
		
		this.opcode = xfer.readVdpByte(pabaddr) & 0xff;
		this.pflags = xfer.readVdpByte(pabaddr + 1) & 0xff;
		this.bufaddr = xfer.readVdpShort(pabaddr + 2) & 0xffff;
		this.preclen = xfer.readVdpByte(pabaddr + 4) & 0xff;
		this.charcount = xfer.readVdpByte(pabaddr + 5) & 0xff;
		this.recnum = xfer.readVdpShort(pabaddr + 6) & 0xffff;
		this.scrnoffs = xfer.readVdpByte(pabaddr + 8) & 0xff;
		this.namelen = xfer.readVdpByte(pabaddr + 9) & 0xff;
	}
	

	/**
	 * 	Copy PAB from file struct into VDP after a file operation
	 */
	public void store(IMemoryTransfer xfer) {
		xfer.writeVdpByte(pabaddr, (byte) this.opcode);
		xfer.writeVdpByte(pabaddr + 1, (byte) this.pflags);
		xfer.writeVdpByte(pabaddr + 2, (byte) (this.bufaddr >> 8));
		xfer.writeVdpByte(pabaddr + 3, (byte) (this.bufaddr & 0xff));
		xfer.writeVdpByte(pabaddr + 4, (byte) this.preclen);
		xfer.writeVdpByte(pabaddr + 5, (byte) this.charcount);
		xfer.writeVdpByte(pabaddr + 6, (byte) (this.recnum >> 8));
		xfer.writeVdpByte(pabaddr + 7, (byte) (this.recnum & 0xff));
		xfer.writeVdpByte(pabaddr + 8, (byte) this.scrnoffs);
		xfer.writeVdpByte(pabaddr + 9, (byte) this.namelen);
	}


	public int getAccess() {
		 return pflags & fp_access_mask;
	}
	
	public int getOpenMode() {
		return pflags & m_mode_mask;
	}
	
	public boolean isOverwriting() {
		return getOpenMode() == m_output;
	}
	
	public boolean canCreate() {
		int mode = getOpenMode();
		return mode == m_append || mode == m_output || mode == m_update; 
	}


	/**
	 * Compare the FDR with the PAB, making sure the PAB operation is compatile
	 * with the FDR, and that record sizes and file types match.
	 */
	public void checkCompatibleFDR(FDR fdr) throws DsrException {
		int fflags;

		if (fdr instanceof V9t9FDR) {
			int index = path.lastIndexOf('.');
			String fdrFileName = ((V9t9FDR) fdr).getFileName();
			String pabFileName = path.substring(index + 1);
			if (fdrFileName.equals(pabFileName)) {
				System.err.println("Filename in FDR does not match filename: " + pabFileName + " vs. " + fdrFileName);
			}
		}
		
		fflags = fdr.getFlags();

		/* program files are easy */
		if (opcode == op_load || opcode == op_save)
			if ((fflags & FDR.ff_program) != 0)
				return;

		/* both must be fixed or variable */
		if (((pflags & fp_variable) != 0) == ((fflags & FDR.ff_variable) != 0)) {
			/*  fixup the PAB if it doesn't know record size */
			if (preclen == 0)
				preclen = fdr.getRecordLength();

			/* both must have same record length */
			if (preclen != fdr.getRecordLength())
				throw new DsrException(PabConstants.e_badopenmode, "record length differs: " + preclen + " vs " + fdr.getRecordLength());

			/* and no "var,relative" files */
			if ((pflags & (fp_relative | fp_variable)) == (fp_relative | fp_variable))
				throw new DsrException(PabConstants.e_badopenmode, "var vs relative file");
		} else {
			throw new DsrException(PabConstants.e_badopenmode, "DSKcomparefdrandpab: fixed/variable flag differs");
		}
	}


	/**
	 * @return
	 */
	public boolean isDisVar() {
		return isVariable() && (pflags & PabConstants.fp_internal) == 0;
	}


	/**
	 * @return
	 */
	public boolean isVariable() {
		return (pflags & PabConstants.fp_variable) != 0;
	}


	/**
	 * @return
	 */
	public boolean isReading() {
		int mode = (pflags & PabConstants.m_mode_mask);
		return mode != PabConstants.m_output && mode != PabConstants.m_append;
	}


	/**
	 * @return
	 */
	public boolean isRelative() {
		return (pflags & PabConstants.fp_relative + PabConstants.fp_variable) == PabConstants.fp_relative;
	}


	/**
	 * @return
	 */
	public boolean isWriting() {
		return (pflags & PabConstants.m_mode_mask) != PabConstants.m_input;
	}
}