PIT8253.h

/*
  Created by Fabrizio Di Vittorio (fdivitto2013@gmail.com) - <http://www.fabgl.com>
  Copyright (c) 2019-2022 Fabrizio Di Vittorio.
  All rights reserved.
 
 
* Please contact fdivitto2013@gmail.com if you need a commercial license.
 
 
* This library and related software is available under GPL v3.
 
  FabGL 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.
 
  FabGL 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 FabGL.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 
#pragma once
 
#include "fabgl.h"
 
 
namespace fabgl {
 
 
 
// PIT (timers) frequency in Hertz
#define PIT_TICK_FREQ        1193182
 
// FRC1 timer prescaler and frequency
#define PIT_FRC1_PRESCALER   FRC_TIMER_PRESCALER_16
#define PIT_FRC1_FREQUENCY   5000000                // 80000000 / 16 = 5000000
 
 
 
// PIT 8253 (Programmable Interval Timers)
 
class PIT8253 {
 
public:
 
  typedef void (*ChangeOut)(void * context, int timerIndex);
 
  struct TimerInfo {
    bool    BCD;          // BCD mode
    int32_t mode;         // Timer mode
    int32_t RLMode;       // Read/Load mode
    int32_t resetHolding; // Holding area for timer reset count
    int32_t resetCount;   // Reload value when count is zero
    int32_t count;        // Current timer counter
    int32_t latch;        // Latched timer count (-1 = not latched)
    bool    LSBToggle;    // true: Read load LSB, false: Read load MSB
    bool    out;          // out state
    bool    gate;         // date (1 = timer running)
    bool    running;      // counting down in course
    bool    ctrlSet;      // control word set
  };
 
  PIT8253();
  ~PIT8253();
 
  void setCallbacks(void * context, ChangeOut changeOut) {
    m_context   = context;
    m_changeOut = changeOut;
  }
 
  void reset();
 
  void tick();
 
  void write(int reg, uint8_t value);
  uint8_t read(int reg);
 
  bool getOut(int timerIndex)  { return m_timer[timerIndex].out; }
  bool getGate(int timerIndex) { return m_timer[timerIndex].gate; }
 
  void setGate(int timerIndex, bool value);
 
  TimerInfo const & timerInfo(int timerIndex) { return m_timer[timerIndex]; }
 
 
private:
 
  void changeOut(int timer, bool value);
 
 
  TimerInfo         m_timer[3];
  
  // callbacks
  void *            m_context;
  ChangeOut         m_changeOut;
  uint32_t          m_lastTickTime;
  uint32_t          m_acc;
 
};
 
 
} // namespace fabgl