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// license:BSD-3-Clause
// copyright-holders:Olivier Galibert, R. Belmont
/***************************************************************************

    ymz770.c

    Emulation by R. Belmont
    AMM decode by Olivier Galibert

-----
TODO:
- A lot of unimplemented features, even simple ones like panning,
  these should be added once we find out any software that uses it.
- Is channel volume linear(current implementation) or logarithmic?
- Sequencer is very preliminary
- What does channel ATBL mean?
- Is YMZ774(and other variants) the same family as this chip?
  What are the differences?

***************************************************************************/

#include "emu.h"
#include "ymz770.h"
#include "mpeg_audio.h"

// device type definition
const device_type YMZ770 = &device_creator<ymz770_device>;

//-------------------------------------------------
//  ymz770_device - constructor
//-------------------------------------------------

ymz770_device::ymz770_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
	: device_t(mconfig, YMZ770, "Yamaha YMZ770", tag, owner, clock, "ymz770", __FILE__),
		device_sound_interface(mconfig, *this), m_stream(nullptr),
		m_cur_reg(0),
		m_mute(0),
		m_doen(0),
		m_vlma(0),
		m_bsl(0),
		m_cpl(0), m_rom_base(nullptr), m_rom_limit(0)
{
}


//-------------------------------------------------
//  device_start - device-specific startup
//-------------------------------------------------

void ymz770_device::device_start()
{
	// create the stream
	m_stream = machine().sound().stream_alloc(*this, 0, 2, 16000);
	m_rom_base = region()->base();
	m_rom_limit = region()->bytes() * 8;

	for (auto & elem : m_channels)
	{
		elem.is_playing = false;
		elem.is_seq_playing = false;
		elem.decoder = new mpeg_audio(m_rom_base, mpeg_audio::AMM, false, 0);
	}

	// register for save states
	save_item(NAME(m_cur_reg));
	save_item(NAME(m_mute));
	save_item(NAME(m_doen));
	save_item(NAME(m_vlma));
	save_item(NAME(m_bsl));
	save_item(NAME(m_cpl));

	for (int ch = 0; ch < 8; ch++)
	{
		save_item(NAME(m_channels[ch].phrase), ch);
		save_item(NAME(m_channels[ch].pan), ch);
		save_item(NAME(m_channels[ch].volume), ch);
		save_item(NAME(m_channels[ch].control), ch);
		save_item(NAME(m_channels[ch].is_playing), ch);
		save_item(NAME(m_channels[ch].last_block), ch);
		save_item(NAME(m_channels[ch].output_remaining), ch);
		save_item(NAME(m_channels[ch].output_ptr), ch);
		save_item(NAME(m_channels[ch].atbl), ch);
		save_item(NAME(m_channels[ch].pptr), ch);
		save_item(NAME(m_channels[ch].sequence), ch);
		save_item(NAME(m_channels[ch].seqcontrol), ch);
		save_item(NAME(m_channels[ch].seqdelay), ch);
		save_item(NAME(m_channels[ch].is_seq_playing), ch);
		save_item(NAME(m_channels[ch].output_data), ch);
	}
}


//-------------------------------------------------
//  device_reset - device-specific reset
//-------------------------------------------------

void ymz770_device::device_reset()
{
	for (auto & elem : m_channels)
	{
		elem.phrase = 0;
		elem.pan = 8;
		elem.volume = 0;
		elem.control = 0;
		elem.sequence = 0;
		elem.seqcontrol = 0;
		elem.seqdelay = 0;
		elem.is_playing = false;
		elem.is_seq_playing = false;
		elem.output_remaining = 0;
		elem.decoder->clear();
	}
}


//-------------------------------------------------
//  sound_stream_update - handle update requests for
//  our sound stream
//-------------------------------------------------

void ymz770_device::sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples)
{
	stream_sample_t *outL, *outR;

	outL = outputs[0];
	outR = outputs[1];

	for (int i = 0; i < samples; i++)
	{
		// run sequencers (should probably be in separate timer callbacks)
		for (auto & elem : m_channels)
		{
			if (elem.is_seq_playing)
			{
				if (elem.seqdelay > 0)
				{
					elem.seqdelay--;
				}
				else
				{
					int reg = *elem.seqdata++;
					UINT8 data = *elem.seqdata++;
					switch (reg)
					{
						case 0x0f:
							if (elem.seqcontrol & 1)
							{
								// loop sequence
								UINT8 sqn = elem.sequence;
								UINT32 pptr = m_rom_base[(4*sqn)+1+0x400]<<16 | m_rom_base[(4*sqn)+2+0x400]<<8 | m_rom_base[(4*sqn)+3+0x400];
								elem.seqdata = &m_rom_base[pptr];
							}
							else
							{
								elem.is_seq_playing = false;
							}
							break;
						case 0x0e:
							elem.seqdelay = 32 - 1;
							break;
						default:
							internal_reg_write(reg, data);
							break;
					}
				}
			}
		}

		// process channels
		INT32 mix = 0;

		for (auto & elem : m_channels)
		{
			if (elem.output_remaining > 0)
			{
				// force finish current block
				mix += (elem.output_data[elem.output_ptr++]*elem.volume);
				elem.output_remaining--;

				if (elem.output_remaining == 0 && !elem.is_playing)
					elem.decoder->clear();
			}

			else if (elem.is_playing)
			{
retry:
				if (elem.last_block)
				{
					if (elem.control & 1)
					{
						// loop sample
						UINT8 phrase = elem.phrase;
						elem.atbl = m_rom_base[(4*phrase)+0] >> 4 & 7;
						elem.pptr = 8*(m_rom_base[(4*phrase)+1]<<16 | m_rom_base[(4*phrase)+2]<<8 | m_rom_base[(4*phrase)+3]);
					}
					else
					{
						elem.is_playing = false;
						elem.output_remaining = 0;
						elem.decoder->clear();
					}
				}

				if (elem.is_playing)
				{
					// next block
					int sample_rate, channel_count;
					if (!elem.decoder->decode_buffer(elem.pptr, m_rom_limit, elem.output_data, elem.output_remaining, sample_rate, channel_count) || elem.output_remaining == 0)
					{
						elem.is_playing = !elem.last_block; // detect infinite retry loop
						elem.last_block = true;
						elem.output_remaining = 0;
						goto retry;
					}

					elem.last_block = elem.output_remaining < 1152;
					elem.output_remaining--;
					elem.output_ptr = 1;

					mix += (elem.output_data[0]*elem.volume);
				}
			}
		}

		outL[i] = outR[i] = mix>>8;
	}
}


//-------------------------------------------------
//  write - write to the chip's registers
//-------------------------------------------------

WRITE8_MEMBER( ymz770_device::write )
{
	if (offset & 1)
	{
		m_stream->update();
		internal_reg_write(m_cur_reg, data);
	}
	else
	{
		m_cur_reg = data;
	}
}


void ymz770_device::internal_reg_write(UINT8 reg, UINT8 data)
{
	// global registers
	if (reg < 0x40)
	{
		switch (reg)
		{
			case 0x00:
				m_mute = data & 1;
				m_doen = data >> 1 & 1;
				break;

			case 0x01:
				m_vlma = data;
				break;

			case 0x02:
				m_bsl = data & 7;
				m_cpl = data >> 4 & 7;
				break;

			// unused
			default:
				break;
		}
	}

	// playback registers
	else if (reg < 0x60)
	{
		int ch = reg >> 2 & 0x07;

		switch (reg & 0x03)
		{
			case 0:
				m_channels[ch].phrase = data;
				break;

			case 1:
				m_channels[ch].volume = data;
				break;

			case 2:
				m_channels[ch].pan = data;
				break;

			case 3:
				if (data & 6)
				{
					UINT8 phrase = m_channels[ch].phrase;
					m_channels[ch].atbl = m_rom_base[(4*phrase)+0] >> 4 & 7;
					m_channels[ch].pptr = 8*(m_rom_base[(4*phrase)+1]<<16 | m_rom_base[(4*phrase)+2]<<8 | m_rom_base[(4*phrase)+3]);
					m_channels[ch].last_block = false;

					m_channels[ch].is_playing = true;
				}
				else
				{
					m_channels[ch].is_playing = false;
				}

				m_channels[ch].control = data;
				break;
		}
	}

	// sequencer registers
	else
	{
		int ch = reg >> 4 & 0x07;

		switch (reg & 0x0f)
		{
			case 0:
				m_channels[ch].sequence = data;
				break;
			case 1:
				if (data & 6)
				{
					UINT8 sqn = m_channels[ch].sequence;
					UINT32 pptr = m_rom_base[(4*sqn)+1+0x400]<<16 | m_rom_base[(4*sqn)+2+0x400]<<8 | m_rom_base[(4*sqn)+3+0x400];
					m_channels[ch].seqdata = &m_rom_base[pptr];
					m_channels[ch].seqdelay = 0;
					m_channels[ch].is_seq_playing = true;
				}
				else
				{
					m_channels[ch].is_seq_playing = false;
				}

				m_channels[ch].seqcontrol = data;
				break;

			default:
				break;
		}
	}
}