// Copyright 2008-2010  Segher Boessenkool  <segher@kernel.crashing.org>
// Licensed under the terms of the GNU GPL, version 2
// http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt

#include <stdio.h>
	#include <math.h>

#include "types.h"
#include "emu.h"

#include "audio.h"


int mute_audio;


void audio_store(u16 val, u32 addr)
{
	if (addr == 0x340b)
		mem[addr] &= ~val;
	else
		mem[addr] = val;

	if (addr < 0x3200) {		// XXX
		return;
	} else if (addr < 0x3400) {	// XXX
		return;
	} else {			// XXX control regs
		return;
	}

	printf("AUDIO STORE %04x to %04x\n", val, addr);
}

u16 audio_load(u32 addr)
{
	u16 val = mem[addr];

	if (addr >= 0x3000 && addr < 0x3200) {		// audio something
		//printf("LOAD %04x from %04x\n", val, addr);
		return val;
	}
	if (addr >= 0x3200 && addr < 0x3300) {		// audio something
		//printf("LOAD %04x from %04x\n", val, addr);
		return val;
	}
	if (addr >= 0x3400 && addr < 0x3500) {		// audio something
		//printf("LOAD %04x from %04x\n", val, addr);
		return val;
	}

	printf("UNKNOWN AUDIO LOAD from %04x\n", addr);
	return val;
}

static u32 get_channel_bit(u32 ch, u32 reg)
{
	reg += 0x3400;
	if (ch >= 16) {
		reg += 0x0100;
		ch -= 16;
	}
	return (mem[reg] >> ch) & 1;
}

static u32 n_left[24];
static u16 bits_left[24];
static void do_next_sample(u32 ch)
{
loop:
	if (n_left[ch] == 0) {
		u32 addr = ((mem[0x3001 + 16*ch] & 0x3f) << 16) | mem[0x3000 + 16*ch];
		bits_left[ch] = mem[addr];
		if (bits_left[ch] == 0xffff) {
			mem[0x3000 + 16*ch] = mem[0x3002 + 16*ch];
			mem[0x3001 + 16*ch] &= 0xffc0;
			mem[0x3001 + 16*ch] |= (mem[0x3001 + 16*ch] >> 6) & 0x3f;
			goto loop;
		}
		n_left[ch] = 2;
		mem[0x3000 + 16*ch]++;
		if (mem[0x3000 + 16*ch] == 0)
			mem[0x3001 + 16*ch]++;	// XXX: mask?
//printf("--> addr = %06x\n", addr);
	}

	mem[0x300b + 16*ch] = bits_left[ch] << 8;
	bits_left[ch] >>= 8;
	n_left[ch]--;
}

#define FREQ 440
static u16 next_channel_sample(u32 ch)
{
//	if (ch)
//		return 0x8000;

//	static u32 xxx[24] = {0};
//	u16 sample = 0x8000 + (int)(20000*sin(2*M_PI*xxx[ch]*FREQ/281250));
//	xxx[ch]++;
//	if (xxx[ch] == 281250)
//		xxx[ch] = 0;
//	return sample;

	u16 sample = mem[0x300b + 16*ch];
	u32 acc = (mem[0x3201 + 16*ch] << 16) | mem[0x3205 + 16*ch];
	u32 inc = (mem[0x3200 + 16*ch] << 16) | mem[0x3204 + 16*ch];
	acc += inc;
	if (acc >= 0x80000) {
		do_next_sample(ch);
		acc -= 0x80000;
	}
	mem[0x3201 + 16*ch] = acc >> 16;
	mem[0x3205 + 16*ch] = acc;

	return sample;
}

static u16 next_sample(void)
{
	static u32 ch = 0;
	u16 sample;
	if (get_channel_bit(ch, 0))
		sample = next_channel_sample(ch);
	else
		sample = 0x8000;
	ch++;
	if (ch == 24)
		ch = 0;
	return sample;
}

static s16 next_host_sample(void)
{
	if (mem[0x3d20] & 0x0002)	// audio DAC disable
		return 0;

return 0;
	u32 acc = 0;
	u32 i;
	for (i = 0; i < 153; i++)
		acc += next_sample();
	return (acc / 153) - 0x8000;
}

void audio_render(s16 *data, u32 n)
{
	u32 i;
	for (i = 0; i < n; i++)
		data[i] = next_host_sample();
}

void audio_init(void)
{
}