sega/dsb2.cpp: add basic MPEG playback

src/mame/sega/dsb2.cpp

@@ -1,12 +1,10 @@
 // license:BSD-3-Clause
 // copyright-holders:
-/***************************************************************************
+/**************************************************************************************************
 
-  Sega Z80 Digital Sound Board
+Sega Digital Sound Board 2
 
-  used for Model 1/2/3
+**************************************************************************************************/
-
-***************************************************************************/
 
 
 #include "emu.h"
@@ -28,14 +26,15 @@ dsb2_device::dsb2_device(const machine_config &mconfig, const char *tag, device_
 	m_mp_end(0),
 	m_mp_vol(0x7f),
 	m_mp_pan(0),
-	m_mp_state(0),
 	m_lp_start(0),
 	m_lp_end(0),
 	m_start(0),
 	m_end(0),
 	m_mp_pos(0),
 	m_audio_pos(0),
-	m_audio_avail(0)
+	m_audio_avail(0),
+	m_command(mpeg_command_t::IDLE),
+	m_player(mpeg_player_t::NOT_PLAYING)
 {
 }
 
@@ -47,7 +46,7 @@ void dsb2_device::dsb2_map(address_map &map)
 //	map(0xd00001) system control?
 //	map(0xd20001) flsbeats reads here
 //	map(0xe00001) acknowledge FIFO writes?
-//	map(0xe00003) MPEG FIFO writes
+	map(0xe00003, 0xe00003).w(FUNC(dsb2_device::fifo_w));
 	// MPEG status
 	map(0xe80001, 0xe80001).lr8(NAME([] () { return 0x01; }));
 	map(0xf00000, 0xf1ffff).ram();
@@ -56,7 +55,6 @@ void dsb2_device::dsb2_map(address_map &map)
 void dsb2_device::device_add_mconfig(machine_config &config)
 {
 	// TODO: unknown clocks
-	// TODO: 1 kHz timer for irq2
 	M68000(config, m_ourcpu, 8000000);
 	m_ourcpu->set_addrmap(AS_PROGRAM, &dsb2_device::dsb2_map);
 
@@ -75,11 +73,14 @@ void dsb2_device::device_start()
 	m_decoder.reset(new mpeg_audio(&m_mpeg_rom[0], mpeg_audio::L2, false, 0));
 	stream_alloc(0, 2, 32000);
 
+	m_timer_1kHz = timer_alloc(FUNC(dsb2_device::timer_irq_cb), this);
+
 	save_item(NAME(m_mp_start));
 	save_item(NAME(m_mp_end));
 	save_item(NAME(m_mp_vol));
 	save_item(NAME(m_mp_pan));
-	save_item(NAME(m_mp_state));
+//	save_item(NAME(m_command));
+//	save_item(NAME(m_player));
 	save_item(NAME(m_lp_start));
 	save_item(NAME(m_lp_end));
 	save_item(NAME(m_start));
@@ -95,11 +96,13 @@ void dsb2_device::device_reset()
 	m_audio_pos = m_audio_avail = 0;
 	std::fill(std::begin(m_audio_buf), std::end(m_audio_buf), 0);
 	m_mp_vol = 0x7f;
-	m_mp_state = 0;
+	m_command = IDLE;
+	m_player = NOT_PLAYING;
 
 	m_uart->write_cts(0);
-}
 
+	m_timer_1kHz->adjust(attotime::from_hz(1000), 0, attotime::from_hz(1000));
+}
 
 void dsb2_device::device_stop()
 {
@@ -116,10 +119,144 @@ void dsb2_device::output_txd(int state)
 	m_rxd_handler(state);
 }
 
+TIMER_CALLBACK_MEMBER(dsb2_device::timer_irq_cb)
+{
+	m_ourcpu->set_input_line(2, HOLD_LINE);
+}
+
+void dsb2_device::fifo_w(offs_t offset, u8 data)
+{
+	switch(m_command)
+	{
+		case mpeg_command_t::START_ADDRESS_HI:
+			m_start &= 0x00ffff;
+			m_start |= (uint32_t)data << 16;
+			m_command = mpeg_command_t::START_ADDRESS_MD;
+			break;
+		case mpeg_command_t::START_ADDRESS_MD:
+			m_start &= 0xff00ff;
+			m_start |= (uint32_t)data << 8;
+			m_command = mpeg_command_t::START_ADDRESS_LO;
+			break;
+		case mpeg_command_t::START_ADDRESS_LO:
+			m_start &= 0xffff00;
+			m_start |= data;
+
+			m_mp_start = m_start;
+			m_command = mpeg_command_t::IDLE;
+			break;
+
+		case mpeg_command_t::END_ADDRESS_HI:
+			m_end &= 0x00ffff;
+			m_end |= (uint32_t)data << 16;
+			m_command = mpeg_command_t::END_ADDRESS_MD;
+			break;
+		case mpeg_command_t::END_ADDRESS_MD:
+			m_end &= 0xff00ff;
+			m_end |= (uint32_t)data << 8;
+			m_command = mpeg_command_t::END_ADDRESS_LO;
+			break;
+		case mpeg_command_t::END_ADDRESS_LO:
+			m_end &= 0xffff00;
+			m_end |= data;
+
+			m_mp_end = m_end;
+			m_command = mpeg_command_t::IDLE;
+			break;
+
+		case mpeg_command_t::IDLE:
+		default:
+		{
+			if ((data & 0xfe) == 0x14)
+				m_command = mpeg_command_t::START_ADDRESS_HI;
+			if ((data & 0xfe) == 0x24)
+				m_command = mpeg_command_t::END_ADDRESS_HI;
+			if ((data & 0xfe) == 0x74)
+			{
+				m_mp_pos = m_mp_start * 8;
+				m_player = mpeg_player_t::PLAYING;
+			}
+
+			if ((data & 0xfe) == 0x84)
+			{
+				m_player = mpeg_player_t::NOT_PLAYING;
+				m_audio_pos = m_audio_avail = 0;
+			}
+		}
+	}
+}
+
 void dsb2_device::sound_stream_update(sound_stream &stream)
 {
-	//int samples = stream.samples();
+	int samples = stream.samples();
-	//int sampindex = 0;
+	int sampindex = 0;
+	for (;;)
+	{
+		while (samples && (m_audio_pos < m_audio_avail))
+		{
+			switch (m_mp_pan)
+			{
+				case 0: // stereo
+					stream.put_int(0, sampindex, m_audio_buf[m_audio_pos*2] * m_mp_vol, 32768 * 128);
+					stream.put_int(1, sampindex, m_audio_buf[m_audio_pos*2+1] * m_mp_vol, 32768 * 128);
+					sampindex++;
+					break;
 
-	// ...
+				case 1: // left only
+					stream.put_int(0, sampindex, m_audio_buf[m_audio_pos*2] * m_mp_vol, 32768 * 128);
+					stream.put_int(1, sampindex, m_audio_buf[m_audio_pos*2] * m_mp_vol, 32768 * 128);
+					sampindex++;
+					break;
+
+				case 2: // right only
+					stream.put_int(0, sampindex, m_audio_buf[m_audio_pos*2+1] * m_mp_vol, 32768 * 128);
+					stream.put_int(1, sampindex, m_audio_buf[m_audio_pos*2+1] * m_mp_vol, 32768 * 128);
+					sampindex++;
+					break;
+			}
+			m_audio_pos++;
+			samples--;
+		}
+
+		if (!samples)
+		{
+			break;
+		}
+
+		if (m_player == mpeg_player_t::NOT_PLAYING)
+		{
+			break;
+		}
+		else
+		{
+			int sample_rate, channel_count;
+			bool const ok = m_decoder->decode_buffer(m_mp_pos, m_mp_end * 8, m_audio_buf, m_audio_avail, sample_rate, channel_count);
+
+			if (ok)
+			{
+				m_audio_pos = 0;
+			}
+			else
+			{
+				//if (m_mp_state == 2)
+				//{
+				//	if (m_mp_pos == m_lp_start * 8)
+				//	{
+				//		// We're looping on un-decodable crap, abort abort abort
+				//		m_mp_state = 0;
+				//	}
+				//	m_mp_pos = m_lp_start * 8;
+//
+				//	if (m_lp_end)
+				//	{
+				//		m_mp_end = m_lp_end;
+				//	}
+				//}
+				//else
+				{
+					m_player = mpeg_player_t::NOT_PLAYING;
+				}
+			}
+		}
+	}
 }

src/mame/sega/dsb2.h

@@ -13,10 +13,6 @@
 #include <memory>
 
 
-//**************************************************************************
-//  TYPE DEFINITIONS
-//**************************************************************************
-
 class dsb2_device : public device_t, public device_sound_interface
 {
 public:
@@ -47,19 +43,36 @@ private:
 
 	std::unique_ptr<mpeg_audio> m_decoder;
 	int16_t m_audio_buf[1152*2];
-	uint32_t m_mp_start, m_mp_end, m_mp_vol, m_mp_pan, m_mp_state, m_lp_start, m_lp_end, m_start, m_end;
+	uint32_t m_mp_start, m_mp_end, m_mp_vol, m_mp_pan, m_lp_start, m_lp_end, m_start, m_end;
 	int32_t m_mp_pos, m_audio_pos, m_audio_avail;
 
+	emu_timer *m_timer_1kHz;
+	TIMER_CALLBACK_MEMBER(timer_irq_cb);
+
 	void output_txd(int state);
 
-//	void mpeg_trigger_w(uint8_t data);
-//	void mpeg_start_w(offs_t offset, uint8_t data);
-//	void mpeg_end_w(offs_t offset, uint8_t data);
-//	void mpeg_volume_w(uint8_t data);
-//	void mpeg_stereo_w(uint8_t data);
-//	uint8_t mpeg_pos_r(offs_t offset);
-
 	void dsb2_map(address_map &map) ATTR_COLD;
+
+	enum mpeg_command_t : u8 {
+		IDLE,
+		START_ADDRESS_HI,
+		START_ADDRESS_MD,
+		START_ADDRESS_LO,
+		END_ADDRESS_HI,
+		END_ADDRESS_MD,
+		END_ADDRESS_LO
+	};
+
+	enum mpeg_player_t : u8 {
+		NOT_PLAYING,
+		PLAYING
+	};
+
+	mpeg_command_t m_command;
+	mpeg_player_t m_player;
+
+
+	void fifo_w(offs_t offset, u8 data);
 };