Path: blob/master/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/APU.cs
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//TODO - so many integers in the square wave output keep us from exactly unbiasing the waveform. also other waves probably. consider improving the unbiasing.
//ALSO - consider whether we should even be doing it: the nonlinear-mixing behaviour probably depends on those biases being there.
//if we have a better high-pass filter somewhere then we might could cope with the weird biases
//(mix higher integer precision with the non-linear mixer and then highpass filter befoure outputting s16s)
//http://wiki.nesdev.com/w/index.php/APU_Mixer_Emulation
//http://wiki.nesdev.com/w/index.php/APU
//http://wiki.nesdev.com/w/index.php/APU_Pulse
//sequencer ref: http://wiki.nesdev.com/w/index.php/APU_Frame_Counter
//TODO - refactor length counter to be separate component
using System;
using System.Collections.Generic;
using BizHawk.Common;
using BizHawk.Common.NumberExtensions;
namespace BizHawk.Emulation.Cores.Nintendo.NES
{
public sealed class APU
{
public static bool CFG_DECLICK = true;
public int Square1V = 376;
public int Square2V = 376;
public int TriangleV = 426;
public int NoiseV = 247;
public int DMCV = 167;
public int dmc_dma_countdown = -1;
public bool call_from_write;
public bool recalculate = false;
NES nes;
public APU(NES nes, APU old, bool pal)
{
this.nes = nes;
dmc = new DMCUnit(this, pal);
noise = new NoiseUnit(this, pal);
triangle = new TriangleUnit(this);
pulse[0] = new PulseUnit(this, 0);
pulse[1] = new PulseUnit(this, 1);
if (old != null)
{
Square1V = old.Square1V;
Square2V = old.Square2V;
TriangleV = old.TriangleV;
NoiseV = old.NoiseV;
DMCV = old.DMCV;
}
}
static int[] DMC_RATE_NTSC = { 428, 380, 340, 320, 286, 254, 226, 214, 190, 160, 142, 128, 106, 84, 72, 54 };
static int[] DMC_RATE_PAL = { 398, 354, 316, 298, 276, 236, 210, 198, 176, 148, 132, 118, 98, 78, 66, 50 };
static int[] LENGTH_TABLE = { 10, 254, 20, 2, 40, 4, 80, 6, 160, 8, 60, 10, 14, 12, 26, 14, 12, 16, 24, 18, 48, 20, 96, 22, 192, 24, 72, 26, 16, 28, 32, 30 };
static byte[,] PULSE_DUTY = {
{0,1,0,0,0,0,0,0}, //(12.5%)
{0,1,1,0,0,0,0,0}, //(25%)
{0,1,1,1,1,0,0,0}, //(50%)
{1,0,0,1,1,1,1,1}, //(25% negated (75%))
};
static byte[] TRIANGLE_TABLE =
{
15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
};
static int[] NOISE_TABLE_NTSC =
{
4, 8, 16, 32, 64, 96, 128, 160, 202, 254, 380, 508, 762, 1016, 2034, 4068
};
static int[] NOISE_TABLE_PAL =
{
4, 7, 14, 30, 60, 88, 118, 148, 188, 236, 354, 472, 708, 944, 1890, 3778
};
public sealed class PulseUnit
{
public PulseUnit(APU apu, int unit) { this.unit = unit; this.apu = apu; }
public int unit;
APU apu;
//reg0
int duty_cnt, env_loop, env_constant, env_cnt_value;
public bool len_halt;
//reg1
int sweep_en, sweep_divider_cnt, sweep_negate, sweep_shiftcount;
bool sweep_reload;
//reg2/3
int len_cnt;
public int timer_raw_reload_value, timer_reload_value;
//misc..
int lenctr_en;
public void SyncState(Serializer ser)
{
ser.BeginSection("Pulse" + unit);
ser.Sync("duty_cnt", ref duty_cnt);
ser.Sync("env_loop", ref env_loop);
ser.Sync("env_constant", ref env_constant);
ser.Sync("env_cnt_value", ref env_cnt_value);
ser.Sync("len_halt", ref len_halt);
ser.Sync("sweep_en", ref sweep_en);
ser.Sync("sweep_divider_cnt", ref sweep_divider_cnt);
ser.Sync("sweep_negate", ref sweep_negate);
ser.Sync("sweep_shiftcount", ref sweep_shiftcount);
ser.Sync("sweep_reload", ref sweep_reload);
ser.Sync("len_cnt", ref len_cnt);
ser.Sync("timer_raw_reload_value", ref timer_raw_reload_value);
ser.Sync("timer_reload_value", ref timer_reload_value);
ser.Sync("lenctr_en", ref lenctr_en);
ser.Sync("swp_divider_counter", ref swp_divider_counter);
ser.Sync("swp_silence", ref swp_silence);
ser.Sync("duty_step", ref duty_step);
ser.Sync("timer_counter", ref timer_counter);
ser.Sync("sample", ref sample);
ser.Sync("duty_value", ref duty_value);
ser.Sync("env_start_flag", ref env_start_flag);
ser.Sync("env_divider", ref env_divider);
ser.Sync("env_counter", ref env_counter);
ser.Sync("env_output", ref env_output);
ser.EndSection();
}
public bool IsLenCntNonZero() { return len_cnt > 0; }
public void WriteReg(int addr, byte val)
{
//Console.WriteLine("write pulse {0:X} {1:X}", addr, val);
switch (addr)
{
case 0:
env_cnt_value = val & 0xF;
env_constant = (val >> 4) & 1;
env_loop = (val >> 5) & 1;
duty_cnt = (val >> 6) & 3;
break;
case 1:
sweep_shiftcount = val & 7;
sweep_negate = (val >> 3) & 1;
sweep_divider_cnt = (val >> 4) & 7;
sweep_en = (val >> 7) & 1;
sweep_reload = true;
break;
case 2:
timer_reload_value = (timer_reload_value & 0x700) | val;
timer_raw_reload_value = timer_reload_value * 2 + 2;
//if (unit == 1) Console.WriteLine("{0} timer_reload_value: {1}", unit, timer_reload_value);
break;
case 3:
if (apu.len_clock_active)
{
if (len_cnt==0)
{
len_cnt = LENGTH_TABLE[(val >> 3) & 0x1F]+1;
}
} else
{
len_cnt = LENGTH_TABLE[(val >> 3) & 0x1F];
}
timer_reload_value = (timer_reload_value & 0xFF) | ((val & 0x07) << 8);
timer_raw_reload_value = timer_reload_value * 2 + 2;
duty_step = 0;
env_start_flag = 1;
//allow the lenctr_en to kill the len_cnt
set_lenctr_en(lenctr_en);
//serves as a useful note-on diagnostic
//if(unit==1) Console.WriteLine("{0} timer_reload_value: {1}", unit, timer_reload_value);
break;
}
}
public void set_lenctr_en(int value)
{
lenctr_en = value;
//if the length counter is not enabled, then we must disable the length system in this way
if (lenctr_en == 0) len_cnt = 0;
}
//state
//why was all of this stuff not in the savestate???????
int swp_divider_counter;
bool swp_silence;
int duty_step;
int timer_counter;
public int sample;
bool duty_value;
int env_start_flag, env_divider, env_counter;
public int env_output;
public void clock_length_and_sweep()
{
//this should be optimized to update only when `timer_reload_value` changes
int sweep_shifter = timer_reload_value >> sweep_shiftcount;
if (sweep_negate == 1)
sweep_shifter = -sweep_shifter + unit;
sweep_shifter += timer_reload_value;
//this sweep logic is always enabled:
swp_silence = (timer_reload_value < 8 || (sweep_shifter > 0x7FF)); // && sweep_negate == 0));
//does enable only block the pitch bend? does the clocking proceed?
if (sweep_en == 1)
{
//clock divider
if (swp_divider_counter != 0) swp_divider_counter--;
if (swp_divider_counter == 0)
{
swp_divider_counter = sweep_divider_cnt + 1;
//divider was clocked: process sweep pitch bend
if (sweep_shiftcount != 0 && !swp_silence)
{
timer_reload_value = sweep_shifter;
timer_raw_reload_value = (timer_reload_value << 1) + 2;
}
//TODO - does this change the user's reload value or the latched reload value?
}
//handle divider reload, after clocking happens
if (sweep_reload)
{
swp_divider_counter = sweep_divider_cnt + 1;
sweep_reload = false;
}
}
//env_loopdoubles as "halt length counter"
if ((env_loop == 0 || len_halt) && len_cnt > 0)
len_cnt--;
}
public void clock_env()
{
if (env_start_flag == 1)
{
env_start_flag = 0;
env_divider = env_cnt_value;
env_counter = 15;
}
else
{
if (env_divider != 0)
{
env_divider--;
} else if (env_divider == 0)
{
env_divider = env_cnt_value;
if (env_counter == 0)
{
if (env_loop == 1)
{
env_counter = 15;
}
}
else env_counter--;
}
}
}
public void Run()
{
if (env_constant == 1)
env_output = env_cnt_value;
else env_output = env_counter;
if (timer_counter > 0) timer_counter--;
if (timer_counter == 0 && timer_raw_reload_value != 0)
{
if (duty_step==7)
{
duty_step = 0;
} else
{
duty_step++;
}
duty_value = PULSE_DUTY[duty_cnt, duty_step] == 1;
//reload timer
timer_counter = timer_raw_reload_value;
}
int newsample;
if (duty_value) //high state of duty cycle
{
newsample = env_output;
if (swp_silence || len_cnt == 0)
newsample = 0; // silenced
}
else
newsample = 0; //duty cycle is 0, silenced.
//newsample -= env_output >> 1; //unbias
if (newsample != sample)
{
apu.recalculate = true;
sample = newsample;
}
}
public bool Debug_IsSilenced
{
get
{
if (swp_silence || len_cnt == 0)
return true;
else return false;
}
}
public int Debug_DutyType
{
get
{
return duty_cnt;
}
}
public int Debug_Volume
{
get
{
return env_output;
}
}
}
public sealed class NoiseUnit
{
APU apu;
//reg0 (sweep)
int env_cnt_value, env_loop, env_constant;
public bool len_halt;
//reg2 (mode and period)
int mode_cnt, period_cnt;
//reg3 (length counter and envelop trigger)
int len_cnt;
//set from apu:
int lenctr_en;
//state
int shift_register = 1;
int timer_counter;
public int sample;
int env_output, env_start_flag, env_divider, env_counter;
bool noise_bit = true;
int[] NOISE_TABLE;
public NoiseUnit(APU apu, bool pal)
{
this.apu = apu;
NOISE_TABLE = pal ? NOISE_TABLE_PAL : NOISE_TABLE_NTSC;
}
public bool Debug_IsSilenced
{
get
{
if (len_cnt == 0) return true;
else return false;
}
}
public int Debug_Period
{
get
{
return period_cnt;
}
}
public int Debug_Volume
{
get
{
return env_output;
}
}
public void SyncState(Serializer ser)
{
ser.BeginSection("Noise");
ser.Sync("env_cnt_value", ref env_cnt_value);
ser.Sync("env_loop", ref env_loop);
ser.Sync("env_constant", ref env_constant);
ser.Sync("mode_cnt", ref mode_cnt);
ser.Sync("period_cnt", ref period_cnt);
ser.Sync("len_halt", ref len_halt);
//ser.Sync("mode_cnt", ref mode_cnt);
//ser.Sync("period_cnt", ref period_cnt);
ser.Sync("len_cnt", ref len_cnt);
ser.Sync("lenctr_en", ref lenctr_en);
ser.Sync("shift_register", ref shift_register);
ser.Sync("timer_counter", ref timer_counter);
ser.Sync("sample", ref sample);
ser.Sync("env_output", ref env_output);
ser.Sync("env_start_flag", ref env_start_flag);
ser.Sync("env_divider", ref env_divider);
ser.Sync("env_counter", ref env_counter);
ser.Sync("noise_bit", ref noise_bit);
ser.EndSection();
}
public bool IsLenCntNonZero() { return len_cnt > 0; }
public void WriteReg(int addr, byte val)
{
switch (addr)
{
case 0:
env_cnt_value = val & 0xF;
env_constant = (val >> 4) & 1;
//we want to delay a halt until after a length clock if they happen on the same cycle
if (env_loop==0 && ((val >> 5) & 1)==1)
{
len_halt = true;
}
env_loop = (val >> 5) & 1;
break;
case 1:
break;
case 2:
period_cnt = NOISE_TABLE[val & 0xF];
mode_cnt = (val >> 7) & 1;
//Console.WriteLine("noise period: {0}, vol: {1}", (val & 0xF), env_cnt_value);
break;
case 3:
if (apu.len_clock_active)
{
if (len_cnt == 0)
{
len_cnt = LENGTH_TABLE[(val >> 3) & 0x1F] + 1;
}
}
else
{
len_cnt = LENGTH_TABLE[(val >> 3) & 0x1F];
}
set_lenctr_en(lenctr_en);
env_start_flag = 1;
break;
}
}
public void set_lenctr_en(int value)
{
lenctr_en = value;
//Console.WriteLine("noise lenctr_en: " + lenctr_en);
//if the length counter is not enabled, then we must disable the length system in this way
if (lenctr_en == 0) len_cnt = 0;
}
public void clock_env()
{
if (env_start_flag == 1)
{
env_start_flag = 0;
env_divider = (env_cnt_value + 1);
env_counter = 15;
}
else
{
if (env_divider != 0) env_divider--;
if (env_divider == 0)
{
env_divider = (env_cnt_value + 1);
if (env_counter == 0)
{
if (env_loop == 1)
{
env_counter = 15;
}
}
else env_counter--;
}
}
}
public void clock_length_and_sweep()
{
if (len_cnt > 0 && (env_loop == 0 || len_halt))
len_cnt--;
}
public void Run()
{
if (env_constant == 1)
env_output = env_cnt_value;
else env_output = env_counter;
if (timer_counter > 0) timer_counter--;
if (timer_counter == 0 && period_cnt != 0)
{
//reload timer
timer_counter = period_cnt;
int feedback_bit;
if (mode_cnt == 1) feedback_bit = (shift_register >> 6) & 1;
else feedback_bit = (shift_register >> 1) & 1;
int feedback = feedback_bit ^ (shift_register & 1);
shift_register >>= 1;
shift_register &= ~(1 << 14);
shift_register |= (feedback << 14);
noise_bit = (shift_register & 1) != 0;
}
int newsample;
if (len_cnt == 0) newsample = 0;
else if (noise_bit) newsample = env_output; // switched, was 0?
else newsample = 0;
if (newsample != sample)
{
apu.recalculate = true;
sample = newsample;
}
}
}
public sealed class TriangleUnit
{
//reg0
int linear_counter_reload, control_flag;
//reg1 (n/a)
//reg2/3
int timer_cnt, halt_flag, len_cnt;
public bool halt_2;
//misc..
int lenctr_en;
int linear_counter, timer, timer_cnt_reload;
int seq = 15;
public int sample;
APU apu;
public TriangleUnit(APU apu) { this.apu = apu; }
public void SyncState(Serializer ser)
{
ser.BeginSection("Triangle");
ser.Sync("linear_counter_reload", ref linear_counter_reload);
ser.Sync("control_flag", ref control_flag);
ser.Sync("timer_cnt", ref timer_cnt);
ser.Sync("halt_flag", ref halt_flag);
ser.Sync("len_cnt", ref len_cnt);
ser.Sync("lenctr_en", ref lenctr_en);
ser.Sync("linear_counter", ref linear_counter);
ser.Sync("timer", ref timer);
ser.Sync("timer_cnt_reload", ref timer_cnt_reload);
ser.Sync("seq", ref seq);
ser.Sync("sample", ref sample);
ser.EndSection();
}
public bool IsLenCntNonZero() { return len_cnt > 0; }
public void set_lenctr_en(int value)
{
lenctr_en = value;
//if the length counter is not enabled, then we must disable the length system in this way
if (lenctr_en == 0) len_cnt = 0;
}
public void WriteReg(int addr, byte val)
{
//Console.WriteLine("tri writes addr={0}, val={1:x2}", addr, val);
switch (addr)
{
case 0:
linear_counter_reload = (val & 0x7F);
control_flag = (val >> 7) & 1;
break;
case 1: break;
case 2:
timer_cnt = (timer_cnt & ~0xFF) | val;
timer_cnt_reload = timer_cnt + 1;
break;
case 3:
timer_cnt = (timer_cnt & 0xFF) | ((val & 0x7) << 8);
timer_cnt_reload = timer_cnt + 1;
if (apu.len_clock_active)
{
if (len_cnt == 0)
{
len_cnt = LENGTH_TABLE[(val >> 3) & 0x1F] + 1;
}
}
else
{
len_cnt = LENGTH_TABLE[(val >> 3) & 0x1F];
}
halt_flag = 1;
//allow the lenctr_en to kill the len_cnt
set_lenctr_en(lenctr_en);
break;
}
//Console.WriteLine("tri timer_reload_value: {0}", timer_cnt_reload);
}
public bool Debug_IsSilenced
{
get
{
bool en = len_cnt != 0 && linear_counter != 0;
return !en;
}
}
public int Debug_PeriodValue
{
get
{
return timer_cnt;
}
}
public void Run()
{
//when clocked by timer
//seq steps forward
//except when linear counter or
//length counter is 0
//dont stop the triangle channel until its level is 0. makes it sound nicer.
bool need_declick = (seq != 16 && seq != 15);
bool en = len_cnt != 0 && linear_counter != 0 || need_declick;
//length counter and linear counter
//is clocked in frame counter.
if (en)
{
int newsample;
if (timer > 0) timer--;
if (timer == 0)
{
seq = (seq + 1) & 0x1F;
timer = timer_cnt_reload;
}
if (CFG_DECLICK) // this looks ugly...
newsample = TRIANGLE_TABLE[(seq + 8) & 0x1F];
else
newsample = TRIANGLE_TABLE[seq];
//special hack: frequently, games will use the maximum frequency triangle in order to mute it
//apparently this results in the DAC for the triangle wave outputting a steady level at about 7.5
//so we'll emulate it at the digital level
if (timer_cnt_reload == 1) newsample = 8;
//newsample -= 8; //unbias
if (newsample != sample)
{
apu.recalculate = true;
sample = newsample;
}
}
}
public void clock_length_and_sweep()
{
//env_loopdoubles as "halt length counter"
if (len_cnt > 0 && halt_flag == 0)
len_cnt--;
}
public void clock_linear_counter()
{
// Console.WriteLine("linear_counter: {0}", linear_counter);
if (halt_flag == 1)
{
linear_counter = linear_counter_reload;
}
else if (linear_counter != 0)
{
linear_counter--;
}
//declick when the sound begins
//if (halt_flag == 1 && control_flag == 0)
//{
// seq = 16;
// Console.WriteLine("declicked triangle");
//}
//declick on end of sound
//bool en = len_cnt != 0 && linear_counter != 0;
//if (!en)
// if (sample < 0) sample++; else if (sample > 0) sample--;
halt_flag = control_flag;
}
} //class TriangleUnit
sealed class DMCUnit
{
APU apu;
int[] DMC_RATE;
public DMCUnit(APU apu, bool pal)
{
this.apu = apu;
out_silence = true;
DMC_RATE = pal ? DMC_RATE_PAL : DMC_RATE_NTSC;
timer_reload = DMC_RATE[0];
timer = timer_reload;
sample_buffer_filled = false;
out_deltacounter = 64;
out_bits_remaining = 0;
}
bool irq_enabled;
bool loop_flag;
int timer_reload;
//dmc delay per visual 2a03
int delay;
// this timer never stops, ever, so it is convenient to use for even/odd timing used elsewhere
public int timer;
int user_address;
public uint user_length, sample_length;
int sample_address, sample_buffer;
bool sample_buffer_filled;
int out_shift, out_bits_remaining, out_deltacounter;
bool out_silence;
public int sample { get { return out_deltacounter /* - 64*/; } }
public void SyncState(Serializer ser)
{
ser.BeginSection("DMC");
ser.Sync("irq_enabled", ref irq_enabled);
ser.Sync("loop_flag", ref loop_flag);
ser.Sync("timer_reload", ref timer_reload);
ser.Sync("timer", ref timer);
ser.Sync("user_address", ref user_address);
ser.Sync("user_length", ref user_length);
ser.Sync("sample_address", ref sample_address);
ser.Sync("sample_length", ref sample_length);
ser.Sync("sample_buffer", ref sample_buffer);
ser.Sync("sample_buffer_filled", ref sample_buffer_filled);
ser.Sync("out_shift", ref out_shift);
ser.Sync("out_bits_remaining", ref out_bits_remaining);
ser.Sync("out_deltacounter", ref out_deltacounter);
ser.Sync("out_silence", ref out_silence);
ser.Sync("dmc_call_delay", ref delay);
//int sample = 0; //junk
//ser.Sync("sample", ref sample);
ser.EndSection();
}
public void Run()
{
if (timer > 0) timer--;
if (timer == 0)
{
timer = timer_reload;
Clock();
}
//Any time the sample buffer is in an empty state and bytes remaining is not zero, the following occur:
// also note that the halt for DMC DMA occurs on APU cycles only (hence the timer check)
if (!sample_buffer_filled && sample_length > 0 && apu.dmc_dma_countdown == -1 && delay==0)
{
// calls from write take one less cycle, but start on a write instead of a read
if (!apu.call_from_write)
{
if (timer % 2 == 1)
{
delay = 3;
} else
{
delay = 2;
}
} else
{
if (timer % 2 == 1)
{
delay = 2;
}
else
{
delay = 3;
}
}
}
// I did some tests in Visual 2A03 and there seems to be some delay betwen when a DMC is first needed and when the
// process to execute the DMA starts. The details are not currently known, but it seems to be a 2 cycle delay
if (delay != 0)
{
delay--;
if (delay == 0)
{
if (!apu.call_from_write)
{
apu.dmc_dma_countdown = 4;
}
else
{
apu.dmc_dma_countdown = 3;
apu.call_from_write = false;
}
}
}
}
void Clock()
{
//If the silence flag is clear, bit 0 of the shift register is applied to the counter as follows:
//if bit 0 is clear and the delta-counter is greater than 1, the counter is decremented by 2;
//otherwise, if bit 0 is set and the delta-counter is less than 126, the counter is incremented by 2
if (!out_silence)
{
//apply current sample bit to delta counter
if (out_shift.Bit(0))
{
if (out_deltacounter < 126)
out_deltacounter += 2;
}
else
{
if (out_deltacounter > 1)
out_deltacounter -= 2;
}
//apu.nes.LogLine("dmc out sample: {0}", out_deltacounter);
apu.recalculate = true;
}
//The right shift register is clocked.
out_shift >>= 1;
//The bits-remaining counter is decremented. If it becomes zero, a new cycle is started.
if (out_bits_remaining == 0)
{
//The bits-remaining counter is loaded with 8.
out_bits_remaining = 7;
//If the sample buffer is empty then the silence flag is set
if (!sample_buffer_filled)
{
out_silence = true;
//out_deltacounter = 64; //gonna go out on a limb here and guess this gets reset. could make some things pop, though, if they dont end at 0.
}
else
//otherwise, the silence flag is cleared and the sample buffer is emptied into the shift register.
{
out_silence = false;
out_shift = sample_buffer;
sample_buffer_filled = false;
}
}
else out_bits_remaining--;
}
public void set_lenctr_en(bool en)
{
if (!en)
{
//If the DMC bit is clear, the DMC bytes remaining will be set to 0
sample_length = 0;
//and the DMC will silence when it empties.
// (what does this mean? does out_deltacounter get reset to 0? maybe just that the out_silence flag gets set, but this is natural)
}
else
{
//only start playback if playback is stopped
//Console.Write(sample_length); Console.Write(" "); Console.Write(sample_buffer_filled); Console.Write(" "); Console.Write(apu.dmc_irq); Console.Write("\n");
if (sample_length == 0)
{
sample_address = user_address;
sample_length = user_length;
}
if (!sample_buffer_filled)
{
// apparently the dmc is different if called from a cpu write, let's try
apu.call_from_write = true;
}
}
//irq is acknowledged or sure to be clear, in either case
apu.dmc_irq = false;
apu.SyncIRQ();
}
public bool IsLenCntNonZero()
{
return sample_length != 0;
}
public void WriteReg(int addr, byte val)
{
//Console.WriteLine("DMC writes addr={0}, val={1:x2}", addr, val);
switch (addr)
{
case 0:
irq_enabled = val.Bit(7);
loop_flag = val.Bit(6);
timer_reload = DMC_RATE[val & 0xF];
if (!irq_enabled) apu.dmc_irq = false;
//apu.dmc_irq = false;
apu.SyncIRQ();
break;
case 1:
out_deltacounter = val & 0x7F;
//apu.nes.LogLine("~~ out_deltacounter set to {0}", out_deltacounter);
apu.recalculate = true;
break;
case 2:
user_address = 0xC000 | (val << 6);
break;
case 3:
user_length = ((uint)val << 4) + 1;
break;
}
}
public void Fetch()
{
if (sample_length != 0)
{
sample_buffer = apu.nes.ReadMemory((ushort)sample_address);
sample_buffer_filled = true;
sample_address = (ushort)(sample_address + 1);
//Console.WriteLine(sample_length);
//Console.WriteLine(user_length);
sample_length--;
//apu.pending_length_change = 1;
}
if (sample_length == 0)
{
if (loop_flag)
{
sample_address = user_address;
sample_length = user_length;
}
else if (irq_enabled) apu.dmc_irq = true;
}
//Console.WriteLine("fetching dmc byte: {0:X2}", sample_buffer);
}
}
public void SyncState(Serializer ser)
{
ser.Sync("irq_pending", ref irq_pending);
ser.Sync("dmc_irq", ref dmc_irq);
ser.Sync("pending_reg", ref pending_reg);
ser.Sync("pending_val", ref pending_val);
ser.Sync("sequencer_counter", ref sequencer_counter);
ser.Sync("sequencer_step", ref sequencer_step);
ser.Sync("sequencer_mode", ref sequencer_mode);
ser.Sync("sequencer_irq_inhibit;", ref sequencer_irq_inhibit);
ser.Sync("sequencer_irq", ref sequencer_irq);
ser.Sync("sequence_reset_pending", ref sequence_reset_pending);
ser.Sync("sequencer_irq_clear_pending", ref sequencer_irq_clear_pending);
ser.Sync("sequencer_irq_assert", ref sequencer_irq_assert);
ser.Sync("dmc_dma_countdown", ref dmc_dma_countdown);
ser.Sync("sample_length_delay", ref pending_length_change);
ser.Sync("dmc_called_from_write", ref call_from_write);
ser.Sync("sequencer_tick_delay", ref seq_tick);
ser.Sync("seq_val_to_apply", ref seq_val);
ser.Sync("sequencer_irq_flag", ref sequencer_irq_flag);
ser.Sync("len_clock_active", ref len_clock_active);
pulse[0].SyncState(ser);
pulse[1].SyncState(ser);
triangle.SyncState(ser);
noise.SyncState(ser);
dmc.SyncState(ser);
SyncIRQ();
}
public PulseUnit[] pulse = new PulseUnit[2];
public TriangleUnit triangle;
public NoiseUnit noise;
DMCUnit dmc;
bool irq_pending;
bool dmc_irq;
int pending_reg = -1;
byte pending_val = 0;
public int seq_tick;
public byte seq_val;
public bool len_clock_active;
int sequencer_counter, sequencer_step, sequencer_mode, sequencer_irq_inhibit, sequencer_irq_assert;
bool sequencer_irq, sequence_reset_pending, sequencer_irq_clear_pending, sequencer_irq_flag;
public void RunDMCFetch()
{
dmc.Fetch();
}
void sequencer_reset()
{
sequencer_counter = 0;
if (sequencer_mode == 1)
{
sequencer_step = 0;
QuarterFrame();
HalfFrame();
}
else
sequencer_step = 0;
}
//these figures are not valid for PAL. they must be recalculated with nintendulator's values above
static int[][] sequencer_lut = new int[][]{
new int[]{7457,14913,22371,29830},
new int[]{7457,14913,22371,29830,37282}
};
void sequencer_write_tick(byte val)
{
if (seq_tick>0)
{
seq_tick--;
if (seq_tick==0)
{
sequencer_mode = (val >> 7) & 1;
//Console.WriteLine("apu 4017 = {0:X2}", val);
sequencer_irq_inhibit = (val >> 6) & 1;
if (sequencer_irq_inhibit == 1)
{
sequencer_irq_flag = false;
}
sequencer_reset();
}
}
}
void sequencer_tick()
{
sequencer_counter++;
if (sequencer_mode==0 && sequencer_counter==29829)
{
if (sequencer_irq_inhibit==0)
{
sequencer_irq_assert = 2;
sequencer_irq_flag = true;
}
HalfFrame();
}
if (sequencer_mode == 0 && sequencer_counter == 29828 && sequencer_irq_inhibit == 0)
{
//sequencer_irq_assert = 2;
sequencer_irq_flag = true;
}
if (sequencer_mode == 1 && sequencer_counter == 37281)
{
HalfFrame();
}
if (sequencer_lut[sequencer_mode][sequencer_step] != sequencer_counter)
return;
sequencer_check();
}
public void SyncIRQ()
{
irq_pending = sequencer_irq | dmc_irq;
}
void sequencer_check()
{
//Console.WriteLine("sequencer mode {0} step {1}", sequencer_mode, sequencer_step);
bool quarter, half, reset;
switch (sequencer_mode)
{
case 0: //4-step
quarter = true;
half = sequencer_step == 1;
reset = sequencer_step == 3;
if (reset && sequencer_irq_inhibit == 0)
{
//Console.WriteLine("{0} {1,5} set irq_assert", nes.Frame, sequencer_counter);
//sequencer_irq_assert = 2;
sequencer_irq_flag = true;
}
break;
case 1: //5-step
quarter = sequencer_step != 3;
half = sequencer_step == 1;
reset = sequencer_step == 4;
break;
default:
throw new InvalidOperationException();
}
if (reset)
{
sequencer_counter = 0;
sequencer_step = 0;
}
else sequencer_step++;
if (quarter) QuarterFrame();
if (half) HalfFrame();
}
void HalfFrame()
{
pulse[0].clock_length_and_sweep();
pulse[1].clock_length_and_sweep();
triangle.clock_length_and_sweep();
noise.clock_length_and_sweep();
}
void QuarterFrame()
{
pulse[0].clock_env();
pulse[1].clock_env();
triangle.clock_linear_counter();
noise.clock_env();
}
public void NESSoftReset()
{
//need to study what happens to apu and stuff..
sequencer_irq = false;
sequencer_irq_flag = false;
_WriteReg(0x4015, 0);
//for 4017, its as if the last value written gets rewritten
sequencer_mode = (seq_val >> 7) & 1;
sequencer_irq_inhibit = (seq_val >> 6) & 1;
if (sequencer_irq_inhibit == 1)
{
sequencer_irq_flag = false;
}
sequencer_counter = 0;
sequencer_step = 0;
}
public void NESHardReset()
{
// "at power on it is as if $00 was written to $4017 9-12 cycles before the reset vector"
// that translates to a starting value for the counter of 6
sequencer_counter = 6;
}
public void WriteReg(int addr, byte val)
{
pending_reg = addr;
pending_val = val;
}
void _WriteReg(int addr, byte val)
{
//Console.WriteLine("{0:X4} = {1:X2}", addr, val);
int index = addr - 0x4000;
int reg = index & 3;
int channel = index >> 2;
switch (channel)
{
case 0:
pulse[0].WriteReg(reg, val);
break;
case 1:
pulse[1].WriteReg(reg, val);
break;
case 2:
triangle.WriteReg(reg, val);
break;
case 3:
noise.WriteReg(reg, val);
break;
case 4:
dmc.WriteReg(reg, val);
break;
case 5:
if (addr == 0x4015)
{
pulse[0].set_lenctr_en(val & 1);
pulse[1].set_lenctr_en((val >> 1) & 1);
triangle.set_lenctr_en((val >> 2) & 1);
noise.set_lenctr_en((val >> 3) & 1);
dmc.set_lenctr_en(val.Bit(4));
}
else if (addr == 0x4017)
{
if (dmc.timer%2==0)
{
seq_tick = 3;
} else
{
seq_tick = 4;
}
seq_val = val;
}
break;
}
}
public byte PeekReg(int addr)
{
switch (addr)
{
case 0x4015:
{
//notice a missing bit here. should properly emulate with empty / Data bus
//if an interrupt flag was set at the same moment of the read, it will read back as 1 but it will not be cleared.
int dmc_nonzero = dmc.IsLenCntNonZero() ? 1 : 0;
int noise_nonzero = noise.IsLenCntNonZero() ? 1 : 0;
int tri_nonzero = triangle.IsLenCntNonZero() ? 1 : 0;
int pulse1_nonzero = pulse[1].IsLenCntNonZero() ? 1 : 0;
int pulse0_nonzero = pulse[0].IsLenCntNonZero() ? 1 : 0;
int ret = ((dmc_irq ? 1 : 0) << 7) | ((sequencer_irq_flag ? 1 : 0) << 6) | (dmc_nonzero << 4) | (noise_nonzero << 3) | (tri_nonzero << 2) | (pulse1_nonzero << 1) | (pulse0_nonzero);
return (byte)ret;
}
default:
//don't return 0xFF here or SMB will break
return 0x00;
}
}
public byte ReadReg(int addr)
{
switch (addr)
{
case 0x4015:
{
byte ret = PeekReg(0x4015);
//Console.WriteLine("{0} {1,5} $4015 clear irq, was at {2}", nes.Frame, sequencer_counter, sequencer_irq);
sequencer_irq_flag = false;
SyncIRQ();
return ret;
}
default:
//don't return 0xFF here or SMB will break
return 0x00;
}
}
public Action DebugCallback;
public int DebugCallbackDivider;
public int DebugCallbackTimer;
int pending_length_change;
public void RunOne(bool read)
{
if (read)
{
pulse[0].Run();
pulse[1].Run();
triangle.Run();
noise.Run();
dmc.Run();
pulse[0].len_halt = false;
pulse[1].len_halt = false;
noise.len_halt = false;
}
else
{
if (pending_length_change>0)
{
pending_length_change--;
if (pending_length_change==0)
{
dmc.sample_length--;
}
}
EmitSample();
//we need to predict if there will be a length clock here, because the sequencer ticks last, but the
// timer reload shouldn't happen if length clock and write happen simultaneously
// I'm not sure if we can avoid this by simply processing the sequencer first
// but at the moment that would break everything, so this is good enough for now
if (sequencer_counter==14912 ||
(sequencer_counter == 29828 && sequencer_mode==0) ||
(sequencer_counter == 37280 && sequencer_mode == 1))
{
len_clock_active = true;
}
//handle writes
//notes: this set up is a bit convoluded at the moment, mainly because APU behaviour is not entirely understood
//in partiuclar, there are several clock pulses affecting the APU, and when new written are latched is not known in detail
//the current code simply matches known behaviour
if (pending_reg != -1)
{
if (pending_reg == 0x4015 || pending_reg == 0x4017 || pending_reg==0x4003 || pending_reg==0x4007)
{
_WriteReg(pending_reg, pending_val);
pending_reg = -1;
}
else if (dmc.timer%2==0)
{
_WriteReg(pending_reg, pending_val);
pending_reg = -1;
}
}
len_clock_active = false;
sequencer_tick();
sequencer_write_tick(seq_val);
if (sequencer_irq_assert>0) {
sequencer_irq_assert--;
if (sequencer_irq_assert==0)
{
sequencer_irq = true;
}
}
SyncIRQ();
nes.irq_apu = irq_pending;
//since the units run concurrently, the APU frame sequencer is ran last because
//it can change the ouput values of the pulse/triangle channels
//we want the changes to affect it on the *next* cycle.
if (sequencer_irq_flag == false)
sequencer_irq = false;
if (DebugCallbackDivider != 0)
{
if (DebugCallbackTimer == 0)
{
if (DebugCallback != null)
DebugCallback();
DebugCallbackTimer = DebugCallbackDivider;
}
else DebugCallbackTimer--;
}
}
}
public struct Delta
{
public uint time;
public int value;
public Delta(uint time, int value)
{
this.time = time;
this.value = value;
}
}
public List<Delta> dlist = new List<Delta>();
/// <summary>only call in board.ClockCPU()</summary>
/// <param name="value"></param>
public void ExternalQueue(int value)
{
// sampleclock is incremented right before board.ClockCPU()
dlist.Add(new Delta(sampleclock - 1, value));
}
public uint sampleclock = 0;
int oldmix = 0;
void EmitSample()
{
if (recalculate)
{
recalculate = false;
int s_pulse0 = pulse[0].sample;
int s_pulse1 = pulse[1].sample;
int s_tri = triangle.sample;
int s_noise = noise.sample;
int s_dmc = dmc.sample;
//int s_ext = 0; //gamepak
/*
if (!EnableSquare1) s_pulse0 = 0;
if (!EnableSquare2) s_pulse1 = 0;
if (!EnableTriangle) s_tri = 0;
if (!EnableNoise) s_noise = 0;
if (!EnableDMC) s_dmc = 0;
*/
//more properly correct
float pulse_out, tnd_out;
if (s_pulse0 == 0 && s_pulse1 == 0)
pulse_out = 0;
else pulse_out = 95.88f / ((8128.0f / (s_pulse0 + s_pulse1)) + 100.0f);
if (s_tri == 0 && s_noise == 0 && s_dmc == 0)
tnd_out = 0;
else tnd_out = 159.79f / (1 / ((s_tri / 8227.0f) + (s_noise / 12241.0f /* * NOISEADJUST*/) + (s_dmc / 22638.0f)) + 100);
float output = pulse_out + tnd_out;
//output = output * 2 - 1;
//this needs to leave enough headroom for straying DC bias due to the DMC unit getting stuck outputs. smb3 is bad about that.
int mix = (int)(20000 * output);
dlist.Add(new Delta(sampleclock, mix - oldmix));
oldmix = mix;
}
sampleclock++;
}
}
}