// This file is part of the Noddybox.Emulation C# suite.
//
// Noddybox.Emulation is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Noddybox.Emulation 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 Noddybox.Emulation.  If not, see <http://www.gnu.org/licenses/>.
//
// Copyright (c) 2012 Ian Cowburn
//
using System;

namespace Noddybox.Emulation.EightBit
{
    /// <summary>
    /// Defines a delegate that will be called after an instruction.
    /// </summary>
    /// <param name="sender">The CPU being used.  All state will be upto date prior to invoking
    /// the callback.</param>
    /// <returns>True if the CPU should continue executing, or false if not.  Users should simply
    /// return Clock.VBL if they need no other than clock control.</returns>
    public delegate bool CpuCallback(ICpu sender);

    /// <summary>
    /// Defines an 8-bit CPU.
    /// </summary>
    public interface ICpu
    {
        /// <summary>
        /// Initialise the CPU to give it access to memory and devices.
        /// </summary>
        /// <param name="memory">The memory to access.</param>
        /// <param name="device">The devices to access.</param>
        /// <param name="clock">The clock to use.</param>
        void Initialise(IMemory memory, IDevice device, Clock clock);

        /// <summary>
        /// Resets the CPU to its initial state.
        /// </summary>
        void Reset();

        /// <summary>
        /// Runs the next instruction.
        /// </summary>
        void Step();

        /// <summary>
        /// Runs the CPU until the next frame flyback.
        /// </summary>
        void Run();

        /// <summary>
        /// Runs the CPU until the callback tells it to stop.
        /// </summary>
        /// <param name="callback">A delegate that is called after every completed instruction
        /// cycle and tells the CPU when to stop running.  Note that at least one instruction
        /// is always executed as the callback is made after the cycle has completed.
        /// </param>
        void Run(CpuCallback callback);

        /// <summary>
        /// Generates a maskable interrupt to the CPU.
        /// </summary>
        /// <param name="value">Optional value from an interrupting device.  May be ignored depending on the CPU type.</param>
        void MaskableInterrupt(byte value);

        /// <summary>
        /// Generates a non-maskable interrupt to the CPU.
        /// </summary>
        /// <param name="value">Optional value from an interrupting device.  May be ignored depending on the CPU type.</param>
        void NonMaskableInterrupt(byte value);
    }
}