Add ymfm library

src/sound/ymfm/ymfm_misc.cpp

@@ -0,0 +1,175 @@
+// BSD 3-Clause License
+//
+// Copyright (c) 2021, Aaron Giles
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this
+//    list of conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its
+//    contributors may be used to endorse or promote products derived from
+//    this software without specific prior written permission.
+//
+// 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.
+
+#include "ymfm_misc.h"
+
+namespace ymfm
+{
+
+//*********************************************************
+//  YM2149
+//*********************************************************
+
+//-------------------------------------------------
+//  ym2149 - constructor
+//-------------------------------------------------
+
+ym2149::ym2149(ymfm_interface &intf) :
+	m_address(0),
+	m_ssg(intf)
+{
+}
+
+
+//-------------------------------------------------
+//  reset - reset the system
+//-------------------------------------------------
+
+void ym2149::reset()
+{
+	// reset the engines
+	m_ssg.reset();
+}
+
+
+//-------------------------------------------------
+//  save_restore - save or restore the data
+//-------------------------------------------------
+
+void ym2149::save_restore(ymfm_saved_state &state)
+{
+	state.save_restore(m_address);
+	m_ssg.save_restore(state);
+}
+
+
+//-------------------------------------------------
+//  read_data - read the data register
+//-------------------------------------------------
+
+uint8_t ym2149::read_data()
+{
+	return m_ssg.read(m_address & 0x0f);
+}
+
+
+//-------------------------------------------------
+//  read - handle a read from the device
+//-------------------------------------------------
+
+uint8_t ym2149::read(uint32_t offset)
+{
+	uint8_t result = 0xff;
+	switch (offset & 3)	// BC2,BC1
+	{
+		case 0: // inactive
+			break;
+
+		case 1: // address
+			break;
+
+		case 2: // inactive
+			break;
+
+		case 3: // read
+			result = read_data();
+			break;
+	}
+	return result;
+}
+
+
+//-------------------------------------------------
+//  write_address - handle a write to the address
+//  register
+//-------------------------------------------------
+
+void ym2149::write_address(uint8_t data)
+{
+	// just set the address
+	m_address = data;
+}
+
+
+//-------------------------------------------------
+//  write - handle a write to the register
+//  interface
+//-------------------------------------------------
+
+void ym2149::write_data(uint8_t data)
+{
+	m_ssg.write(m_address & 0x0f, data);
+}
+
+
+//-------------------------------------------------
+//  write - handle a write to the register
+//  interface
+//-------------------------------------------------
+
+void ym2149::write(uint32_t offset, uint8_t data)
+{
+	switch (offset & 3)	// BC2,BC1
+	{
+		case 0: // address
+			write_address(data);
+			break;
+
+		case 1: // inactive
+			break;
+
+		case 2: // write
+			write_data(data);
+			break;
+
+		case 3: // address
+			write_address(data);
+			break;
+	}
+}
+
+
+//-------------------------------------------------
+//  generate - generate samples of SSG sound
+//-------------------------------------------------
+
+void ym2149::generate(output_data *output, uint32_t numsamples)
+{
+	for (uint32_t samp = 0; samp < numsamples; samp++, output++)
+	{
+		// clock the SSG
+		m_ssg.clock();
+
+		// YM2149 keeps the three SSG outputs independent
+		m_ssg.output(*output);
+	}
+}
+
+}