// PWM (Pulse Width Modulated) output services using libsimpleio

// Copyright (C)2017-2026, Philip Munts dba Munts Technologies.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

package com.munts.libsimpleio;

import com.munts.interfaces.PWM.Output;
import com.munts.libsimpleio.bindings.libpwm;
import com.munts.libsimpleio.Designator;
import com.munts.libsimpleio.errno;
import com.sun.jna.ptr.IntByReference;

public final class PWM
{
  private PWM()
  {
  }

  public enum Polarity
  {
    ActiveLow,
    ActiveHigh
  }

  private static class OutputSubclass implements Output
  {
    int fd;
    int period;

    // PWM output object constructor

    OutputSubclass(Designator desg, int frequency,
      double dutycycle, Polarity polarity)
    {
      int ontime;
      IntByReference fd = new IntByReference();
      IntByReference error = new IntByReference();

      // Validate parameters

      if (frequency < 1)
        throw new RuntimeException("ERROR: frequency is invalid");

      if ((dutycycle < Output.MIN_DUTYCYCLE) ||
          (dutycycle > Output.MAX_DUTYCYCLE))
        throw new RuntimeException("ERROR: Invalid duty cycle parameter");

      if ((polarity.ordinal() < libpwm.ACTIVELOW) ||
          (polarity.ordinal() > libpwm.ACTIVEHIGH))
        throw new RuntimeException("ERROR: Invalid polarity parameter");

      // Calculate the period

      this.period = (int) Math.round(1.0E9/frequency);

      // Calculate the initial on time in nanoseconds

      ontime = (int) Math.round(dutycycle/100.0*this.period);

      // Configure the PWM output

      libpwm.PWM_configure(desg.chip(), desg.channel(), this.period, ontime,
        polarity.ordinal(), error);

      if (error.getValue() != errno.EOK)
        throw new RuntimeException("ERROR: PWM_configure() failed, " +
          errno.strerror(error.getValue()));

      // Open the PWM output device node

      libpwm.PWM_open(desg.chip(), desg.channel(), fd, error);

      if (error.getValue() != errno.EOK)
        throw new RuntimeException("ERROR: PWM_open() failed, " +
          errno.strerror(error.getValue()));

      this.fd = fd.getValue();
    }

    public void write(double dutycycle)
    {
      int ontime;
      IntByReference error = new IntByReference();

      ontime = (int) Math.round(dutycycle/100.0*this.period);

      libpwm.PWM_write(this.fd, ontime, error);

      if (error.getValue() != errno.EOK)
        throw new RuntimeException("ERROR: PWM_write() failed, " +
          errno.strerror(error.getValue()));
    }

    public void finalize()
    {
      IntByReference error = new IntByReference();

      libpwm.PWM_close(this.fd, error);

      this.fd = -1;
    }
  }

  // Configure a PWM output

  public static Output Create(Designator desg, int frequency, double dutycycle,
    Polarity polarity)
  {
    return new OutputSubclass(desg, frequency, dutycycle, polarity);
  }

  // Configure a PWM output with default polarity

  public static Output Create(Designator desg, int frequency, double dutycycle)
  {
    return new OutputSubclass(desg, frequency, dutycycle, Polarity.ActiveHigh);
  }

  // Configure a PWM output with default duty cycle and default polarity

  public static Output Create(Designator desg, int frequency)
  {
    return new OutputSubclass(desg, frequency, Output.MIN_DUTYCYCLE,
      Polarity.ActiveHigh);
  }
}