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// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/***************************************************************************

    Amiga audio hardware

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

#include "amiga.h"
#include "includes/amiga.h"


//**************************************************************************
//  CONSTANTS / MACROS
//**************************************************************************

#define VERBOSE 0
#define LOG(x) do { if (VERBOSE) logerror x; } while (0)


//**************************************************************************
//  DEVICE DEFINITIONS
//**************************************************************************

const device_type AMIGA = &device_creator<amiga_sound_device>;


//*************************************************************************
//  LIVE DEVICE
//**************************************************************************

//-------------------------------------------------
//  amiga_sound_device - constructor
//-------------------------------------------------

amiga_sound_device::amiga_sound_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
	: device_t(mconfig, AMIGA, "Amiga Paula", tag, owner, clock, "amiga_paula", __FILE__),
	device_sound_interface(mconfig, *this),
	m_stream(nullptr)
{
}

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

void amiga_sound_device::device_start()
{
	// initialize channels
	for (int i = 0; i < 4; i++)
	{
		m_channel[i].index = i;
		m_channel[i].curticks = 0;
		m_channel[i].manualmode = false;
		m_channel[i].curlocation = 0;
		m_channel[i].irq_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(amiga_sound_device::signal_irq), this));
	}

	// create the stream
	m_stream = machine().sound().stream_alloc(*this, 0, 4, clock() / CLOCK_DIVIDER);
}


//*************************************************************************
//  IMPLEMENTATION
//**************************************************************************

//-------------------------------------------------
//  signal_irq - irq signaling
//-------------------------------------------------

TIMER_CALLBACK_MEMBER( amiga_sound_device::signal_irq )
{
	amiga_state *state = machine().driver_data<amiga_state>();

	state->custom_chip_w(REG_INTREQ, INTENA_SETCLR | (0x80 << param));
}

//-------------------------------------------------
//  dma_reload
//-------------------------------------------------

void amiga_sound_device::dma_reload(audio_channel *chan)
{
	amiga_state *state = machine().driver_data<amiga_state>();

	chan->curlocation = CUSTOM_REG_LONG(REG_AUD0LCH + chan->index * 8);
	chan->curlength = CUSTOM_REG(REG_AUD0LEN + chan->index * 8);
	chan->irq_timer->adjust(attotime::from_hz(15750), chan->index);

	LOG(("dma_reload(%d): offs=%05X len=%04X\n", chan->index, chan->curlocation, chan->curlength));
}

//-------------------------------------------------
//  data_w - manual mode data writer
//-------------------------------------------------

void amiga_sound_device::data_w(int which, UINT16 data)
{
	m_channel[which].manualmode = true;
}

//-------------------------------------------------
//  update - stream updater
//-------------------------------------------------

void amiga_sound_device::update()
{
	m_stream->update();
}

//-------------------------------------------------
//  sound_stream_update - handle a stream update
//-------------------------------------------------

void amiga_sound_device::sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples)
{
	amiga_state *state = machine().driver_data<amiga_state>();
	int channum, sampoffs = 0;

	// if all DMA off, disable all channels
	if (!(CUSTOM_REG(REG_DMACON) & 0x0200))
	{
		m_channel[0].dma_enabled =
		m_channel[1].dma_enabled =
		m_channel[2].dma_enabled =
		m_channel[3].dma_enabled = false;

		// clear the sample data to 0
		for (channum = 0; channum < 4; channum++)
			memset(outputs[channum], 0, sizeof(stream_sample_t) * samples);
		return;
	}

	samples *= CLOCK_DIVIDER;

	// update the DMA states on each channel and reload if fresh
	for (channum = 0; channum < 4; channum++)
	{
		audio_channel *chan = &m_channel[channum];
		if (!chan->dma_enabled && ((CUSTOM_REG(REG_DMACON) >> channum) & 1))
			dma_reload(chan);
		chan->dma_enabled = (CUSTOM_REG(REG_DMACON) >> channum) & 1;
	}

	// loop until done
	while (samples > 0)
	{
		int nextper, nextvol;
		int ticks = samples;

		// determine the number of ticks we can do in this chunk
		if (ticks > m_channel[0].curticks)
			ticks = m_channel[0].curticks;
		if (ticks > m_channel[1].curticks)
			ticks = m_channel[1].curticks;
		if (ticks > m_channel[2].curticks)
			ticks = m_channel[2].curticks;
		if (ticks > m_channel[3].curticks)
			ticks = m_channel[3].curticks;

		// loop over channels
		nextper = nextvol = -1;
		for (channum = 0; channum < 4; channum++)
		{
			int volume = (nextvol == -1) ? CUSTOM_REG(REG_AUD0VOL + channum * 8) : nextvol;
			int period = (nextper == -1) ? CUSTOM_REG(REG_AUD0PER + channum * 8) : nextper;
			audio_channel *chan = &m_channel[channum];
			stream_sample_t sample;
			int i;

			// normalize the volume value
			volume = (volume & 0x40) ? 64 : (volume & 0x3f);
			volume *= 4;

			// are we modulating the period of the next channel?
			if ((CUSTOM_REG(REG_ADKCON) >> channum) & 0x10)
			{
				nextper = CUSTOM_REG(REG_AUD0DAT + channum * 8);
				nextvol = -1;
				sample = 0;
			}

			// are we modulating the volume of the next channel?
			else if ((CUSTOM_REG(REG_ADKCON) >> channum) & 0x01)
			{
				nextper = -1;
				nextvol = CUSTOM_REG(REG_AUD0DAT + channum * 8);
				sample = 0;
			}

			// otherwise, we are generating data
			else
			{
				nextper = nextvol = -1;
				sample = chan->latched * volume;
			}

			// fill the buffer with the sample
			for (i = 0; i < ticks; i += CLOCK_DIVIDER)
				outputs[channum][(sampoffs + i) / CLOCK_DIVIDER] = sample;

			// account for the ticks; if we hit 0, advance
			chan->curticks -= ticks;
			if (chan->curticks == 0)
			{
				// reset the clock and ensure we're above the minimum ticks
				chan->curticks = period;
				if (chan->curticks < 124)
					chan->curticks = 124;

				// move forward one byte; if we move to an even byte, fetch new
				if (chan->dma_enabled || chan->manualmode)
					chan->curlocation++;
				if (chan->dma_enabled && !(chan->curlocation & 1))
				{
					CUSTOM_REG(REG_AUD0DAT + channum * 8) = state->chip_ram_r(chan->curlocation);
					if (chan->curlength != 0)
						chan->curlength--;

					// if we run out of data, reload the dma
					if (chan->curlength == 0)
						dma_reload(chan);
				}

				// latch the next byte of the sample
				if (!(chan->curlocation & 1))
					chan->latched = CUSTOM_REG(REG_AUD0DAT + channum * 8) >> 8;
				else
					chan->latched = CUSTOM_REG(REG_AUD0DAT + channum * 8) >> 0;

				// if we're in manual mode, signal an interrupt once we latch the low byte
				if (!chan->dma_enabled && chan->manualmode && (chan->curlocation & 1))
				{
					signal_irq(nullptr, channum);
					chan->manualmode = false;
				}
			}
		}

		// bump ourselves forward by the number of ticks
		sampoffs += ticks;
		samples -= ticks;
	}
}