// T6W28_Snd_Emu

#include "defs.h"
#include "T6W28_Apu.h"

/* Copyright (C) 2003-2006 Shay Green. This module is free software; you
can redistribute it and/or modify it under the terms of the GNU Lesser
General Public License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version. This
module is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
more details. You should have received a copy of the GNU Lesser General
Public License along with this module; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */

// T6W28_Osc

namespace MDFN_IEN_NGP
{

T6W28_Osc::T6W28_Osc()
{
	outputs[0] = NULL; // always stays NULL
	outputs[1] = NULL;
	outputs[2] = NULL;
	outputs[3] = NULL;
}

void T6W28_Osc::reset()
{
	delay = 0;
	last_amp_left = 0;
	last_amp_right = 0;

	volume_left = 0;
	volume_right = 0;
}

// T6W28_Square

blip_inline void T6W28_Square::reset()
{
	period = 0;
	phase = 0;
	T6W28_Osc::reset();
}

void T6W28_Square::run(sms_time_t time, sms_time_t end_time)
{
	if ((!volume_left && !volume_right) || period <= 128)
	{
		// ignore 16kHz and higher
		if (last_amp_left)
		{
			synth->offset(time, -last_amp_left, outputs[2]);
			last_amp_left = 0;
		}

		if (last_amp_right)
		{
			synth->offset(time, -last_amp_right, outputs[1]);
			last_amp_right = 0;
		}

		time += delay;
		if (!period)
		{
			time = end_time;
		}
		else if (time < end_time)
		{
			// keep calculating phase
			int count = (end_time - time + period - 1) / period;
			phase = (phase + count) & 1;
			time += count * period;
		}
	}
	else
	{
		int amp_left = phase ? volume_left : -volume_left;
		int amp_right = phase ? volume_right : -volume_right;

		{
			int delta_left = amp_left - last_amp_left;
			int delta_right = amp_right - last_amp_right;

			if (delta_left)
			{
				last_amp_left = amp_left;
				synth->offset(time, delta_left, outputs[2]);
			}

			if (delta_right)
			{
				last_amp_right = amp_right;
				synth->offset(time, delta_right, outputs[1]);
			}
		}

		time += delay;
		if (time < end_time)
		{
			Blip_Buffer *const output_left = this->outputs[2];
			Blip_Buffer *const output_right = this->outputs[1];

			int delta_left = amp_left * 2;
			int delta_right = amp_right * 2;
			do
			{
				delta_left = -delta_left;
				delta_right = -delta_right;

				synth->offset_inline(time, delta_left, output_left);
				synth->offset_inline(time, delta_right, output_right);
				time += period;
				phase ^= 1;
			} while (time < end_time);

			this->last_amp_left = phase ? volume_left : -volume_left;
			this->last_amp_right = phase ? volume_right : -volume_right;
		}
	}
	delay = time - end_time;
}

// T6W28_Noise

static const int noise_periods[3] = {0x100, 0x200, 0x400};

blip_inline void T6W28_Noise::reset()
{
	period = &noise_periods[0];
	shifter = 0x4000;
	tap = 13;
	T6W28_Osc::reset();
}

void T6W28_Noise::run(sms_time_t time, sms_time_t end_time)
{
	int amp_left = volume_left;
	int amp_right = volume_right;

	if (shifter & 1)
	{
		amp_left = -amp_left;
		amp_right = -amp_right;
	}

	{
		int delta_left = amp_left - last_amp_left;
		int delta_right = amp_right - last_amp_right;

		if (delta_left)
		{
			last_amp_left = amp_left;
			synth.offset(time, delta_left, outputs[2]);
		}

		if (delta_right)
		{
			last_amp_right = amp_right;
			synth.offset(time, delta_right, outputs[1]);
		}
	}

	time += delay;

	if (!volume_left && !volume_right)
		time = end_time;

	if (time < end_time)
	{
		Blip_Buffer *const output_left = this->outputs[2];
		Blip_Buffer *const output_right = this->outputs[1];

		unsigned l_shifter = this->shifter;
		int delta_left = amp_left * 2;
		int delta_right = amp_right * 2;

		int l_period = *this->period * 2;
		if (!l_period)
			l_period = 16;

		do
		{
			int changed = (l_shifter + 1) & 2; // set if prev and next bits differ
			l_shifter = (((l_shifter << 14) ^ (l_shifter << tap)) & 0x4000) | (l_shifter >> 1);
			if (changed)
			{
				delta_left = -delta_left;
				synth.offset_inline(time, delta_left, output_left);

				delta_right = -delta_right;
				synth.offset_inline(time, delta_right, output_right);
			}
			time += l_period;
		} while (time < end_time);

		this->shifter = l_shifter;
		this->last_amp_left = delta_left >> 1;
		this->last_amp_right = delta_right >> 1;
	}
	delay = time - end_time;
}

// T6W28_Apu

T6W28_Apu::T6W28_Apu()
{
	for (int i = 0; i < 3; i++)
	{
		squares[i].synth = &square_synth;
		oscs[i] = &squares[i];
	}
	oscs[3] = &noise;

	volume(1.0);
	reset();
}

T6W28_Apu::~T6W28_Apu()
{
}

void T6W28_Apu::volume(double vol)
{
	vol *= 0.85 / (osc_count * 64 * 2);
	square_synth.volume(vol);
	noise.synth.volume(vol);
}

void T6W28_Apu::treble_eq(const blip_eq_t &eq)
{
	square_synth.treble_eq(eq);
	noise.synth.treble_eq(eq);
}

void T6W28_Apu::osc_output(int index, Blip_Buffer *center, Blip_Buffer *left, Blip_Buffer *right)
{
	require((unsigned)index < osc_count);
	require((center && left && right) || (!center && !left && !right));
	T6W28_Osc &osc = *oscs[index];
	osc.outputs[1] = right;
	osc.outputs[2] = left;
	osc.outputs[3] = center;
}

void T6W28_Apu::output(Blip_Buffer *center, Blip_Buffer *left, Blip_Buffer *right)
{
	for (int i = 0; i < osc_count; i++)
		osc_output(i, center, left, right);
}

void T6W28_Apu::reset()
{
	last_time = 0;
	latch_left = 0;
	latch_right = 0;

	squares[0].reset();
	squares[1].reset();
	squares[2].reset();
	noise.reset();
}

void T6W28_Apu::run_until(sms_time_t end_time)
{
	require(end_time >= last_time); // end_time must not be before previous time

	if (end_time > last_time)
	{
		// run oscillators
		for (int i = 0; i < osc_count; ++i)
		{
			T6W28_Osc &osc = *oscs[i];
			if (osc.outputs[1])
			{
				if (i < 3)
					squares[i].run(last_time, end_time);
				else
					noise.run(last_time, end_time);
			}
		}

		last_time = end_time;
	}
}

bool T6W28_Apu::end_frame(sms_time_t end_time)
{
	if (end_time > last_time)
		run_until(end_time);

	assert(last_time >= end_time);
	last_time -= end_time;

	return (1);
}

static const unsigned char volumes[16] = {
	// volumes [i] = 64 * pow( 1.26, 15 - i ) / pow( 1.26, 15 )
	64, 50, 39, 31, 24, 19, 15, 12, 9, 7, 5, 4, 3, 2, 1, 0};

void T6W28_Apu::write_data_left(sms_time_t time, int data)
{
	require((unsigned)data <= 0xFF);

	run_until(time);

	if (data & 0x80)
		latch_left = data;

	int index = (latch_left >> 5) & 3;

	if (latch_left & 0x10)
	{
		oscs[index]->volume_left = volumes[data & 15];
	}
	else if (index < 3)
	{
		T6W28_Square &sq = squares[index];
		if (data & 0x80)
			sq.period = (sq.period & 0xFF00) | (data << 4 & 0x00FF);
		else
			sq.period = (sq.period & 0x00FF) | (data << 8 & 0x3F00);
	}
}

void T6W28_Apu::write_data_right(sms_time_t time, int data)
{
	require((unsigned)data <= 0xFF);

	run_until(time);

	if (data & 0x80)
		latch_right = data;

	int index = (latch_right >> 5) & 3;
	//printf("%d\n", index);

	if (latch_right & 0x10)
	{
		oscs[index]->volume_right = volumes[data & 15];
	}
	else if (index == 2)
	{
		if (data & 0x80)
			noise.period_extra = (noise.period_extra & 0xFF00) | (data << 4 & 0x00FF);
		else
			noise.period_extra = (noise.period_extra & 0x00FF) | (data << 8 & 0x3F00);
	}
	else if (index == 3)
	{
		int select = data & 3;
		if (select < 3)
			noise.period = &noise_periods[select];
		else
			noise.period = &noise.period_extra;

		int const tap_disabled = 16;
		noise.tap = (data & 0x04) ? 13 : tap_disabled;
		noise.shifter = 0x4000;
	}
}

void T6W28_Apu::save_state(T6W28_ApuState *ret)
{
	for (int x = 0; x < 4; x++)
	{
		ret->volume_left[x] = oscs[x]->volume_left;
		ret->volume_right[x] = oscs[x]->volume_right;
	}
	for (int x = 0; x < 3; x++)
	{
		ret->sq_period[x] = squares[x].period;
		ret->sq_phase[x] = squares[x].phase;
	}
	ret->noise_shifter = noise.shifter;
	ret->noise_tap = noise.tap;
	ret->noise_period_extra = noise.period_extra;

	if (noise.period == &noise_periods[0])
		ret->noise_period = 0;
	else if (noise.period == &noise_periods[1])
		ret->noise_period = 1;
	else if (noise.period == &noise_periods[2])
		ret->noise_period = 2;
	else
		ret->noise_period = 3;

	ret->latch_left = latch_left;
	ret->latch_right = latch_right;
}

void T6W28_Apu::load_state(const T6W28_ApuState *state)
{
	for (int x = 0; x < 4; x++)
	{
		oscs[x]->volume_left = state->volume_left[x];
		oscs[x]->volume_right = state->volume_right[x];
	}
	for (int x = 0; x < 3; x++)
	{
		squares[x].period = state->sq_period[x] & 0x3FFF;
		squares[x].phase = state->sq_phase[x];
	}
	noise.shifter = state->noise_shifter;
	noise.tap = state->noise_tap;
	noise.period_extra = state->noise_period_extra & 0x3FFF;

	unsigned select = state->noise_period;

	if (select < 3)
		noise.period = &noise_periods[select];
	else
		noise.period = &noise.period_extra;

	latch_left = state->latch_left;
	latch_right = state->latch_right;
}
}