/*
    JPC: An x86 PC Hardware Emulator for a pure Java Virtual Machine

    Copyright (C) 2012-2013 Ian Preston

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License version 2 as published by
    the Free Software Foundation.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

    Details (including contact information) can be found at:

    jpc.sourceforge.net
    or the developer website
    sourceforge.net/projects/jpc/

    End of licence header
*/

package org.jpc.emulator.execution.codeblock;

import org.jpc.emulator.execution.decoder.*;
import org.jpc.emulator.execution.*;
import org.jpc.emulator.processor.*;
import static org.jpc.emulator.execution.Executable.*;

public class InterpretedVM86ModeBlock implements Virtual8086ModeCodeBlock
{
    private final BasicBlock b;
    private boolean valid = true;

    public InterpretedVM86ModeBlock(BasicBlock b)
    {
        this.b = b;
    }

    public int getX86Length() {
        return b.getX86Length();
    }

    public int getX86Count() {
        return b.getX86Count();
    }

    public Branch execute(Processor cpu)
    {
        Executable current = b.start;
        Executable.Branch ret;

        b.preBlock(cpu);
        try
        {
            while ((ret = current.execute(cpu)) == Executable.Branch.None)
            {
                b.postInstruction(cpu, current);
                if (!valid)
                    throw new SelfModifyingCodeException("Block modified itself!");
                current = current.next;
            }
            b.postInstruction(cpu, current);
            return ret;
        } catch (ProcessorException e)
        {
            cpu.eip += current.delta;
            if (current.next == null) // branches have already updated eip
                cpu.eip -= getX86Length(); // so eip points at the branch that barfed
            if (!e.pointsToSelf())
            {
                if (current.next == null)
                    cpu.eip += getX86Length() - current.delta;
                else
                    cpu.eip += current.next.delta - current.delta;
            }

            cpu.handleVirtual8086ModeException(e);
            return Branch.Exception;
        }
        catch (ModeSwitchException e)
        {
            int count = 1;
            Executable p = b.start;
            while (p != current)
            {
                count++;
                p = p.next;
            }
            e.setX86Count(count);
            throw e;
        }
        catch (SelfModifyingCodeException e)
        {
            cpu.eip += current.next.delta;
            return Branch.Exception;
        }
        finally
        {
            b.postBlock(cpu);
        }
    }

    public String getDisplayString() {
        return "Interpreted Virtual 8086 Mode Block:\n"+b.getDisplayString();
    }

    public Instruction getInstructions() {
        return b.getInstructions();
    }

    public boolean handleMemoryRegionChange(int startAddress, int endAddress) {
        valid =  b.handleMemoryRegionChange(startAddress, endAddress);
        return valid;
    }


}