cog/Frameworks/GME/vgmplay/chips/np_nes_dmc.c

// Ported from NSFPlay to VGMPlay (including C++ -> C conversion)
// by Valley Bell on 25 September 2013
// Updated to NSFPlay 2.3 on 26 September 2013
// (Note: Encoding is UTF-8)

#include <stdlib.h>	// for rand()
#include <memory.h>	// for memset()
#include <stddef.h>	// for NULL
#include "mamedef.h"
#include "../stdbool.h"
#include "np_nes_apu.h"	// for NES_APU_np_FrameSequence
#include "np_nes_dmc.h"


// Master Clock: 21477272 (NTSC)
// APU Clock = Master Clock / 12
#define DEFAULT_CLOCK	1789772.0
#define DEFAULT_CLK_PAL	1662607
#define DEFAULT_RATE	44100


/** Bottom Half of APU **/
enum
{
	OPT_UNMUTE_ON_RESET=0,
	OPT_NONLINEAR_MIXER,
	OPT_ENABLE_4011,
	OPT_ENABLE_PNOISE,
	OPT_DPCM_ANTI_CLICK,
	OPT_RANDOMIZE_NOISE,
	OPT_TRI_MUTE,
	OPT_TRI_NULL,
	OPT_END
};


// Note: For increased speed, I'll inline all of NSFPlay's Counter member functions.
#define COUNTER_SHIFT	24

typedef struct _Counter Counter;
struct _Counter
{
	double ratio;
	UINT32 val, step;
};
#define COUNTER_setcycle(cntr, s)	(cntr).step = (UINT32)((cntr).ratio / (s + 1))
#define COUNTER_iup(cntr)			(cntr).val += (cntr).step
#define COUNTER_value(cntr)			((cntr).val >> COUNTER_SHIFT)
#define COUNTER_init(cntr, clk, rate)							\
{																\
	(cntr).ratio = (1 << COUNTER_SHIFT) * (1.0 * clk / rate);	\
	(cntr).step = (UINT32)((cntr).ratio + 0.5);					\
	(cntr).val = 0;												\
}


typedef struct _NES_DMC NES_DMC;
struct _NES_DMC
{
	//const int GETA_BITS;
	//static const UINT32 freq_table[2][16];
	//static const UINT32 wavlen_table[2][16];
	UINT32 tnd_table[2][16][16][128];

	int option[OPT_END];
	int mask;
	INT32 sm[2][3];
	UINT8 reg[0x10];
	UINT32 len_reg;
	UINT32 adr_reg;
	//IDevice *memory;
	const UINT8* memory;
	UINT32 out[3];
	UINT32 daddress;
	UINT32 length;
	UINT32 data;
	INT16 damp;
	int dac_lsb;
	bool dmc_pop;
	INT32 dmc_pop_offset;
	INT32 dmc_pop_follow;
	UINT32 clock;
	UINT32 rate;
	int pal;
	int mode;
	bool irq;
	bool active;

	UINT32 counter[3];	// frequency dividers
	int tphase;			// triangle phase
	UINT32 nfreq;		// noise frequency
	UINT32 dfreq;		// DPCM frequency

	UINT32 tri_freq;
	int linear_counter;
	int linear_counter_reload;
	bool linear_counter_halt;
	bool linear_counter_control;

	int noise_volume;
	UINT32 noise, noise_tap;

	// noise envelope
	bool envelope_loop;
	bool envelope_disable;
	bool envelope_write;
	int envelope_div_period;
	int envelope_div;
	int envelope_counter;

	bool enable[3];
	int length_counter[2];	// 0=tri, 1=noise

	// frame sequencer
	void* apu;	// apu is clocked by DMC's frame sequencer
	int frame_sequence_count;	// current cycle count
	int frame_sequence_length;	// CPU cycles per FrameSequence
	int frame_sequence_step;	// current step of frame sequence
	int frame_sequence_steps;	// 4/5 steps per frame
	bool frame_irq;
	bool frame_irq_enable;

	Counter tick_count;
	UINT32 tick_last;
};

INLINE UINT32 calc_tri(NES_DMC* dmc, UINT32 clocks);
INLINE UINT32 calc_dmc(NES_DMC* dmc, UINT32 clocks);
INLINE UINT32 calc_noise(NES_DMC* dmc, UINT32 clocks);
static void FrameSequence(NES_DMC* dmc, int s);
static void TickFrameSequence(NES_DMC* dmc, UINT32 clocks);
static void Tick(NES_DMC* dmc, UINT32 clocks);

#define GETA_BITS	20
static const UINT32 wavlen_table[2][16] = {
{	// NTSC
	4, 8, 16, 32, 64, 96, 128, 160, 202, 254, 380, 508, 762, 1016, 2034, 4068
},
{	// PAL
	4, 8, 14, 30, 60, 88, 118, 148, 188, 236, 354, 472, 708,  944, 1890, 3778
}};

static const UINT32 freq_table[2][16] = {
{	// NTSC
	428, 380, 340, 320, 286, 254, 226, 214, 190, 160, 142, 128, 106,  84,  72,  54
},
{	// PAL
	398, 354, 316, 298, 276, 236, 210, 198, 176, 148, 132, 118,  98,  78,  66,  50
}};

void* NES_DMC_np_Create(int clock, int rate)
{
	NES_DMC* dmc;
	int c, t;

	dmc = (NES_DMC*)malloc(sizeof(NES_DMC));
	if (dmc == NULL)
		return NULL;
	memset(dmc, 0x00, sizeof(NES_DMC));

	//NES_DMC_np_SetClock(dmc, DEFAULT_CLOCK);
	//NES_DMC_np_SetRate(dmc, DEFAULT_RATE);
	//NES_DMC_np_SetPal(dmc, false);
	NES_DMC_np_SetClock(dmc, clock);	// does SetPal, too
	NES_DMC_np_SetRate(dmc, rate);
	dmc->option[OPT_ENABLE_4011] = 1;
	dmc->option[OPT_ENABLE_PNOISE] = 1;
	dmc->option[OPT_UNMUTE_ON_RESET] = 1;
	dmc->option[OPT_DPCM_ANTI_CLICK] = 0;
	dmc->option[OPT_NONLINEAR_MIXER] = 1;
	dmc->option[OPT_RANDOMIZE_NOISE] = 1;
	dmc->option[OPT_TRI_MUTE] = 1;
	dmc->tnd_table[0][0][0][0] = 0;
	dmc->tnd_table[1][0][0][0] = 0;

	dmc->apu = NULL;
	dmc->frame_sequence_count = 0;
	dmc->frame_sequence_length = 7458;
	dmc->frame_sequence_steps = 4;

	for(c=0;c<2;++c)
		for(t=0;t<3;++t)
			dmc->sm[c][t] = 128;

	return dmc;
}


void NES_DMC_np_Destroy(void* chip)
{
	free(chip);
}

int NES_DMC_np_GetDamp(void* chip)
{
	NES_DMC* dmc = (NES_DMC*)chip;

	return (dmc->damp<<1)|dmc->dac_lsb;
}

void NES_DMC_np_SetMask(void* chip, int m)
{
	NES_DMC* dmc = (NES_DMC*)chip;

	dmc->mask = m;
}

void NES_DMC_np_SetStereoMix(void* chip, int trk, INT16 mixl, INT16 mixr)
{
	NES_DMC* dmc = (NES_DMC*)chip;

	if (trk < 0) return;
	if (trk > 2) return;
	dmc->sm[0][trk] = mixl;
	dmc->sm[1][trk] = mixr;
}

static void FrameSequence(NES_DMC* dmc, int s)
{
	//DEBUG_OUT("FrameSequence: %d\n",s);

	if (s > 3) return;	// no operation in step 4

	if (dmc->apu != NULL)
	{
		NES_APU_np_FrameSequence(dmc->apu, s);
	}

	if (s == 0 && (dmc->frame_sequence_steps == 4))
	{
		dmc->frame_irq = true;
	}

	// 240hz clock
	{
		bool divider = false;
		
		// triangle linear counter
		if (dmc->linear_counter_halt)
		{
			dmc->linear_counter = dmc->linear_counter_reload;
		}
		else
		{
			if (dmc->linear_counter > 0) --dmc->linear_counter;
		}
		if (!dmc->linear_counter_control)
		{
			dmc->linear_counter_halt = false;
		}

		// noise envelope
		//bool divider = false;
		if (dmc->envelope_write)
		{
			dmc->envelope_write = false;
			dmc->envelope_counter = 15;
			dmc->envelope_div = 0;
		}
		else
		{
			++dmc->envelope_div;
			if (dmc->envelope_div > dmc->envelope_div_period)
			{
				divider = true;
				dmc->envelope_div = 0;
			}
		}
		if (divider)
		{
			if (dmc->envelope_loop && dmc->envelope_counter == 0)
				dmc->envelope_counter = 15;
			else if (dmc->envelope_counter > 0)
				--dmc->envelope_counter;	// TODO: Make this work.
		}
	}

	// 120hz clock
	if ((s&1) == 0)
	{
		// triangle length counter
		if (!dmc->linear_counter_control && (dmc->length_counter[0] > 0))
			--dmc->length_counter[0];

		// noise length counter
		if (!dmc->envelope_loop && (dmc->length_counter[1] > 0))
			--dmc->length_counter[1];
	}

}

// 三角波チャンネルの計算 戻り値は0-15
UINT32 calc_tri(NES_DMC* dmc, UINT32 clocks)
{
	static UINT32 tritbl[32] = 
	{
	  0, 1, 2, 3, 4, 5, 6, 7,
	  8, 9,10,11,12,13,14,15,
	 15,14,13,12,11,10, 9, 8,
	  7, 6, 5, 4, 3, 2, 1, 0
	};

	if (dmc->linear_counter > 0 && dmc->length_counter[0] > 0
		&& (!dmc->option[OPT_TRI_MUTE] || dmc->tri_freq > 0))
	{
		dmc->counter[0] += clocks;
		while (dmc->counter[0] > dmc->tri_freq)
		{
			dmc->tphase = (dmc->tphase + 1) & 31;
			dmc->counter[0] -= (dmc->tri_freq + 1);
		}
	}
	// Note: else-block added by VB
	else if (dmc->option[OPT_TRI_NULL])
	{
		if (dmc->tphase && dmc->tphase < 31)
		{
			// Finish the Triangle wave to prevent clicks.
			dmc->counter[0] += clocks;
			while(dmc->counter[0] > dmc->tri_freq && dmc->tphase)
			{
				dmc->tphase = (dmc->tphase + 1) & 31;
				dmc->counter[0] -= (dmc->tri_freq + 1);
			}
		}
	}

	//UINT32 ret = tritbl[tphase];
	//return ret;
	return tritbl[dmc->tphase];
}

// ノイズチャンネルの計算 戻り値は0-127
// 低サンプリングレートで合成するとエイリアスノイズが激しいので
// ノイズだけはこの関数内で高クロック合成し、簡易なサンプリングレート
// 変換を行っている。
UINT32 calc_noise(NES_DMC* dmc, UINT32 clocks)
{
	UINT32 env, last, count, accum, clocks_accum;
	
	env = dmc->envelope_disable ? dmc->noise_volume : dmc->envelope_counter;
	if (dmc->length_counter[1] < 1) env = 0;

	last = (dmc->noise & 0x4000) ? env : 0;
	if (clocks < 1) return last;

	// simple anti-aliasing (noise requires it, even when oversampling is off)
	count = 0;
	accum = 0;

	dmc->counter[1] += clocks;
//	assert(dmc->nfreq > 0);	// prevent infinite loop
	if (dmc->nfreq <= 0)	// prevent infinite loop -VB
		return last;
	while (dmc->counter[1] >= dmc->nfreq)
	{
		// tick the noise generator
		UINT32 feedback = (dmc->noise&1) ^ ((dmc->noise&dmc->noise_tap)?1:0);
		dmc->noise = (dmc->noise>>1) | (feedback<<14);

		++count;
		accum += last;
		last = (dmc->noise & 0x4000) ? env : 0;

		dmc->counter[1] -= dmc->nfreq;
	}

	if (count < 1) // no change over interval, don't anti-alias
	{
		return last;
	}

	clocks_accum = clocks - dmc->counter[1];
	// count = number of samples in accum
	// counter[1] = number of clocks since last sample

	accum = (accum * clocks_accum) + (last * dmc->counter[1] * count);
	// note accum as an average is already premultiplied by count

	return accum / (clocks * count);
}

// DMCチャンネルの計算 戻り値は0-127
UINT32 calc_dmc(NES_DMC* dmc, UINT32 clocks)
{
	dmc->counter[2] += clocks;
//	assert(dmc->dfreq > 0);	// prevent infinite loop
	if (dmc->dfreq <= 0)	// prevent infinite loop -VB
		return (dmc->damp<<1) + dmc->dac_lsb;
	while (dmc->counter[2] >= dmc->dfreq)
	{
		if ( dmc->data != 0x100 )	// data = 0x100 は EMPTY を意味する。
		{
			if ((dmc->data & 1) && (dmc->damp < 63))
				dmc->damp++;
			else if (!(dmc->data & 1) && (0 < dmc->damp))
				dmc->damp--;
			dmc->data >>=1;
		}

		if ( dmc->data == 0x100 && dmc->active )
		{
			//dmc->memory->Read(dmc->daddress, dmc->data);
			dmc->data = dmc->memory[dmc->daddress];
			dmc->data |= (dmc->data&0xFF)|0x10000;	// 8bitシフトで 0x100 になる
			if ( dmc->length > 0 ) 
			{
				dmc->daddress = ((dmc->daddress+1)&0xFFFF)|0x8000 ;
				dmc->length --;
			}
		}
		
		if ( dmc->length == 0 )	// 最後のフェッチが終了したら(再生完了より前に)即座に終端処理
		{
			if (dmc->mode & 1)
			{
				dmc->daddress = ((dmc->adr_reg<<6)|0xC000);
				dmc->length = (dmc->len_reg<<4)+1;
			}
			else
			{
				dmc->irq = (dmc->mode==2&&dmc->active)?1:0;	// 直前がactiveだったときはIRQ発行
				dmc->active = false;
			}
		}

		dmc->counter[2] -= dmc->dfreq;
	}

	return (dmc->damp<<1) + dmc->dac_lsb;
}

static void TickFrameSequence(NES_DMC* dmc, UINT32 clocks)
{
	dmc->frame_sequence_count += clocks;
	while (dmc->frame_sequence_count > dmc->frame_sequence_length)
	{
		FrameSequence(dmc, dmc->frame_sequence_step);
		dmc->frame_sequence_count -= dmc->frame_sequence_length;
		++dmc->frame_sequence_step;
		if(dmc->frame_sequence_step >= dmc->frame_sequence_steps)
			dmc->frame_sequence_step = 0;
	}
}

static void Tick(NES_DMC* dmc, UINT32 clocks)
{
	dmc->out[0] = calc_tri(dmc, clocks);
	dmc->out[1] = calc_noise(dmc, clocks);
	dmc->out[2] = calc_dmc(dmc, clocks);
}

UINT32 NES_DMC_np_Render(void* chip, INT32 b[2])
{
	NES_DMC* dmc = (NES_DMC*)chip;
	UINT32 clocks;
	INT32 m[3];

	COUNTER_iup(dmc->tick_count);	// increase counter (overflows after 255)
	clocks = (COUNTER_value(dmc->tick_count) - dmc->tick_last) & 0xFF;
	TickFrameSequence(dmc, clocks);
	Tick(dmc, clocks);
	dmc->tick_last = COUNTER_value(dmc->tick_count);

	dmc->out[0] = (dmc->mask & 1) ? 0 : dmc->out[0];
	dmc->out[1] = (dmc->mask & 2) ? 0 : dmc->out[1];
	dmc->out[2] = (dmc->mask & 4) ? 0 : dmc->out[2];

	m[0] = dmc->tnd_table[0][dmc->out[0]][0][0];
	m[1] = dmc->tnd_table[0][0][dmc->out[1]][0];
	m[2] = dmc->tnd_table[0][0][0][dmc->out[2]];

	if (dmc->option[OPT_NONLINEAR_MIXER])
	{
		INT32 ref = m[0] + m[1] + m[2];
		INT32 voltage = dmc->tnd_table[1][dmc->out[0]][dmc->out[1]][dmc->out[2]];
		int i;
		if (ref)
		{
			for (i=0; i < 3; ++i)
				m[i] = (m[i] * voltage) / ref;
		}
		else
		{
			for (i=0; i < 3; ++i)
				m[i] = voltage;
		}
	}

	// anti-click nullifies any 4011 write but preserves nonlinearity
	if (dmc->option[OPT_DPCM_ANTI_CLICK])
	{
		if (dmc->dmc_pop) // $4011 will cause pop this frame
		{
			// adjust offset to counteract pop
			dmc->dmc_pop_offset += dmc->dmc_pop_follow - m[2];
			dmc->dmc_pop = false;

			// prevent overflow, keep headspace at edges
			//const INT32 OFFSET_MAX = (1 << 30) - (4 << 16);
#define OFFSET_MAX	((1 << 30) - (4 << 16))
			if (dmc->dmc_pop_offset >  OFFSET_MAX) dmc->dmc_pop_offset =  OFFSET_MAX;
			if (dmc->dmc_pop_offset < -OFFSET_MAX) dmc->dmc_pop_offset = -OFFSET_MAX;
		}
		dmc->dmc_pop_follow = m[2]; // remember previous position

		m[2] += dmc->dmc_pop_offset; // apply offset

		// TODO implement this in a better way
		// roll off offset (not ideal, but prevents overflow)
		if (dmc->dmc_pop_offset > 0) --dmc->dmc_pop_offset;
		else if (dmc->dmc_pop_offset < 0) ++dmc->dmc_pop_offset;
	}

	b[0]  = m[0] * dmc->sm[0][0];
	b[0] += m[1] * dmc->sm[0][1];
	b[0] +=-m[2] * dmc->sm[0][2];
	b[0] >>= 7-2;

	b[1]  = m[0] * dmc->sm[1][0];
	b[1] += m[1] * dmc->sm[1][1];
	b[1] +=-m[2] * dmc->sm[1][2];
	b[1] >>= 7-2;

	return 2;
}


void NES_DMC_np_SetClock(void* chip, double c)
{
	NES_DMC* dmc = (NES_DMC*)chip;

	dmc->clock = (UINT32)(c);
	
	if (abs(dmc->clock - DEFAULT_CLK_PAL) <= 1000)	// check for approximately DEFAULT_CLK_PAL
		NES_DMC_np_SetPal(dmc, true);
	else
		NES_DMC_np_SetPal(dmc, false);
}

void NES_DMC_np_SetRate(void* chip, double r)
{
	NES_DMC* dmc = (NES_DMC*)chip;

	dmc->rate = (UINT32)(r?r:DEFAULT_RATE);

	COUNTER_init(dmc->tick_count, dmc->clock, dmc->rate);
	dmc->tick_last = 0;
}

void NES_DMC_np_SetPal(void* chip, bool is_pal)
{
	NES_DMC* dmc = (NES_DMC*)chip;

	dmc->pal = (is_pal ? 1 : 0);
	// set CPU cycles in frame_sequence
	dmc->frame_sequence_length = is_pal ? 8314 : 7458;
}

void NES_DMC_np_SetAPU(void* chip, void* apu_)
{
	NES_DMC* dmc = (NES_DMC*)chip;

	dmc->apu = apu_;
}

// Initializing TRI, NOISE, DPCM mixing table
static void InitializeTNDTable(NES_DMC* dmc, double wt, double wn, double wd)
{
	// volume adjusted by 0.75 based on empirical measurements
	const double MASTER = 8192.0 * 0.75;
	// truthfully, the nonlinear curve does not appear to match well
	// with my tests, triangle in particular seems too quiet relatively.
	// do more testing of the APU/DMC DAC later

	int t, n, d;

	{	// Linear Mixer
		for(t=0; t<16 ; t++) {
			for(n=0; n<16; n++) {
				for(d=0; d<128; d++) {
						dmc->tnd_table[0][t][n][d] = (UINT32)(MASTER*(3.0*t+2.0*n+d)/208.0);
				}
			}
		}
	}
	{	// Non-Linear Mixer
		dmc->tnd_table[1][0][0][0] = 0;
		for(t=0; t<16 ; t++) {
			for(n=0; n<16; n++) {
				for(d=0; d<128; d++) {
					if(t!=0||n!=0||d!=0)
						dmc->tnd_table[1][t][n][d] = (UINT32)((MASTER*159.79)/(100.0+1.0/((double)t/wt+(double)n/wn+(double)d/wd)));
				}
			}
		}
	}

}

void NES_DMC_np_Reset(void* chip)
{
	NES_DMC* dmc = (NES_DMC*)chip;
	int i;
	dmc->mask = 0;

	InitializeTNDTable(dmc,8227,12241,22638);

	dmc->counter[0] = 0;
	dmc->counter[1] = 0;
	dmc->counter[2] = 0;
	dmc->tphase = 0;
	dmc->nfreq = wavlen_table[0][0];
	dmc->dfreq = freq_table[0][0];

	dmc->envelope_div = 0;
	dmc->length_counter[0] = 0;
	dmc->length_counter[1] = 0;
	dmc->linear_counter = 0;
	dmc->envelope_counter = 0;

	dmc->frame_irq = false;
	dmc->frame_irq_enable = false;
	dmc->frame_sequence_count = 0;
	dmc->frame_sequence_steps = 4;
	dmc->frame_sequence_step = 0;

	for (i = 0; i < 0x10; i++)
		NES_DMC_np_Write(dmc, 0x4008 + i, 0);

	dmc->irq = false;
	NES_DMC_np_Write(dmc, 0x4015, 0x00);
	if (dmc->option[OPT_UNMUTE_ON_RESET])
		NES_DMC_np_Write(dmc, 0x4015, 0x0f);

	dmc->out[0] = dmc->out[1] = dmc->out[2] = 0;
	dmc->tri_freq = 0;
	dmc->damp = 0;
	dmc->dmc_pop = false;
	dmc->dmc_pop_offset = 0;
	dmc->dmc_pop_follow = 0;
	dmc->dac_lsb = 0;
	dmc->data = 0x100;
	dmc->adr_reg = 0;
	dmc->active = false;
	dmc->length = 0;
	dmc->len_reg = 0;
	dmc->daddress = 0;
	dmc->noise = 1;
	dmc->noise_tap = (1<<1);
	if (dmc->option[OPT_RANDOMIZE_NOISE])
	{
		dmc->noise |= rand();
	}

	NES_DMC_np_SetRate(dmc, dmc->rate);
}

void NES_DMC_np_SetMemory(void* chip, const UINT8* r)
{
	NES_DMC* dmc = (NES_DMC*)chip;

	dmc->memory = r;
}

void NES_DMC_np_SetOption(void* chip, int id, int val)
{
	NES_DMC* dmc = (NES_DMC*)chip;

	if(id<OPT_END)
	{
		dmc->option[id] = val;
		if(id==OPT_NONLINEAR_MIXER)
			InitializeTNDTable(dmc, 8227,12241,22638);
	}
}

bool NES_DMC_np_Write(void* chip, UINT32 adr, UINT32 val)
{
	static const UINT8 length_table[32] = {
		0x0A, 0xFE,
		0x14, 0x02,
		0x28, 0x04,
		0x50, 0x06,
		0xA0, 0x08,
		0x3C, 0x0A,
		0x0E, 0x0C,
		0x1A, 0x0E,
		0x0C, 0x10,
		0x18, 0x12,
		0x30, 0x14,
		0x60, 0x16,
		0xC0, 0x18,
		0x48, 0x1A,
		0x10, 0x1C,
		0x20, 0x1E
	};
	NES_DMC* dmc = (NES_DMC*)chip;

	if (adr == 0x4015)
	{
		dmc->enable[0] = (val & 4) ? true : false;
		dmc->enable[1] = (val & 8) ? true : false;

		if (!dmc->enable[0])
		{
			dmc->length_counter[0] = 0;
		}
		if (!dmc->enable[1])
		{
			dmc->length_counter[1] = 0;
		}

		if ((val & 16)&&!dmc->active)
		{
			dmc->enable[2] = dmc->active = true;
			dmc->daddress = (0xC000 | (dmc->adr_reg << 6));
			dmc->length = (dmc->len_reg << 4) + 1;
			dmc->irq = 0;
		}
		else if (!(val & 16))
		{
			dmc->enable[2] = dmc->active = false;
		}

		dmc->reg[adr-0x4008] = val;
		return true;
	}

	if (adr == 0x4017)
	{
		//DEBUG_OUT("4017 = %02X\n", val);
		dmc->frame_irq_enable = ((val & 0x40) == 0x40);
		dmc->frame_irq = (dmc->frame_irq_enable ? dmc->frame_irq : 0);
		dmc->frame_sequence_count = 0;
		if (val & 0x80)
		{
			dmc->frame_sequence_steps = 5;
			dmc->frame_sequence_step = 0;
			FrameSequence(dmc, dmc->frame_sequence_step);
			++dmc->frame_sequence_step;
		}
		else
		{
			dmc->frame_sequence_steps = 4;
			dmc->frame_sequence_step = 1;
		}
	}

	if (adr<0x4008||0x4013<adr)
		return false;

	dmc->reg[adr-0x4008] = val&0xff;

	//DEBUG_OUT("$%04X %02X\n", adr, val);

	switch (adr)
	{

	// tri

	case 0x4008:
		dmc->linear_counter_control = (val >> 7) & 1;
		dmc->linear_counter_reload = val & 0x7F;
		break;

	case 0x4009:
		break;

	case 0x400a:
		dmc->tri_freq = val | (dmc->tri_freq & 0x700) ;
		if (dmc->counter[0] > dmc->tri_freq) dmc->counter[0] = dmc->tri_freq;
		break;

	case 0x400b:
		dmc->tri_freq = (dmc->tri_freq & 0xff) | ((val & 0x7) << 8) ;
		if (dmc->counter[0] > dmc->tri_freq) dmc->counter[0] = dmc->tri_freq;
		dmc->linear_counter_halt = true;
		if (dmc->enable[0])
		{
			dmc->length_counter[0] = length_table[(val >> 3) & 0x1f];
		}
		break;

	// noise

	case 0x400c:
		dmc->noise_volume = val & 15;
		dmc->envelope_div_period = val & 15;
		dmc->envelope_disable = (val >> 4) & 1;
		dmc->envelope_loop = (val >> 5) & 1;
		break;

	case 0x400d:
		break;

	case 0x400e:
		if (dmc->option[OPT_ENABLE_PNOISE])
			dmc->noise_tap = (val & 0x80) ? (1<<6) : (1<<1);
		else
			dmc->noise_tap = (1<<1);
		dmc->nfreq = wavlen_table[dmc->pal][val&15];
		if (dmc->counter[1] > dmc->nfreq) dmc->counter[1] = dmc->nfreq;
		break;

	case 0x400f:
		if (dmc->enable[1])
		{
			dmc->length_counter[1] = length_table[(val >> 3) & 0x1f];
		}
		dmc->envelope_write = true;
		break;

	// dmc

	case 0x4010:
		dmc->mode = (val >> 6) & 3;
		dmc->dfreq = freq_table[dmc->pal][val&15];
		if (dmc->counter[2] > dmc->dfreq) dmc->counter[2] = dmc->dfreq;
		break;

	case 0x4011:
		if (dmc->option[OPT_ENABLE_4011])
		{
			dmc->damp = (val >> 1) & 0x3f;
			dmc->dac_lsb = val & 1;
			dmc->dmc_pop = true;
		}
		break;

	case 0x4012:
		dmc->adr_reg = val&0xff;
		// ここでdaddressは更新されない
		break;

	case 0x4013:
		dmc->len_reg = val&0xff;
		// ここでlengthは更新されない
		break;

	default:
		return false;
	}

	return true;
}

bool NES_DMC_np_Read(void* chip, UINT32 adr, UINT32* val)
{
	NES_DMC* dmc = (NES_DMC*)chip;

	if (adr == 0x4015)
	{
		*val |= (dmc->irq?128:0)
			 | (dmc->frame_irq ? 0x40 : 0)
			 | (dmc->active?16:0)
			 | (dmc->length_counter[1]?8:0)
			 | (dmc->length_counter[0]?4:0)
			 ;

		dmc->frame_irq = false;
		return true;
	}
	else if (0x4008<=adr&&adr<=0x4014)
	{
		*val |= dmc->reg[adr-0x4008];
		return true;
	}
	else
		return false;
}