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apu.cpp
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apu.cpp
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#include "apu.h"
#include "mem.h"
#include "assert.h"
#include<iostream>
using namespace std;
uint8_t apu::noise_states[2][32767];
uint16_t apu::noise_freq_table[16];
uint8_t apu::pal_len_table[8];
uint8_t apu::ntsc_len_table[8];
uint8_t apu::general_len_table[16];
uint8_t apu::TRI_STATES[TRI_LEN];
uint8_t apu::SQ_STATES[4][SQ_LEN];
uint16_t apu::NOISE_LEN[2];
void my_callback(void * ud, Uint8 * stream, int len) {
//cout<<"Actual callback size: "<<len<<endl;
userdata * dat = (userdata *)(ud);
//dat->first = !(dat->first);
//Copy the audio data
//cout<<"Read: Index: "<<(dat->apui->buffer_read_pos)<<" Samples: "<<(len*(dat->apui->buffer_read_pos))<<" -> "<<(len*(dat->apui->buffer_read_pos+1))<<" len: "<<len<<endl;
memcpy(stream, &dat->buffer[len*(dat->apui->buffer_read_pos)], len);
if(dat->buffered >= len) {
dat->buffered -= len;
dat->apui->buffer_read_pos++;
dat->apui->buffer_read_pos%=dat->apui->SAMPLES_PER_FRAME;
//cout<<"Consume "<<len<<endl;
}
else {
cout<<"Underbuffered by "<<len - dat->buffered<<" bytes!"<<endl;
//memset(stream + dat->buffered, 0, len - dat->buffered);
}
}
SDL_AudioDeviceID apu::get_id() {
return id;
}
void apu::set_frame(int f) {
frame = f;
}
int apu::get_frame() {
return frame;
}
void apu::init(bool headless/*=false*/) {
//dat.buffer = &(buffer[0]); Set this after the number of samples has been determined
dat.apui = this;
dat.first = 1;
dat.buffered = 0;
desired.freq = SAMPLE_RATE;
desired.format = AUDIO_U8;
desired.channels = 1;
//#ifndef _WIN32
//desired.samples = SAMPLES_PER_FRAME * 2; //Works for PulseAudio
//#else
desired.samples = 1024; //Works for DirectSound
//#endif
desired.callback = my_callback;
desired.userdata = &dat;
int init_success = 0;
#ifdef _WIN32
const char * desired_driver = "directsound";
#else
const char * desired_driver = "pulseaudio";
#endif
if(headless) {
printf("In headless mode; going to init dummy audio driver.\n");
init_success = SDL_AudioInit("dummy");
}
else {
for (int i = 0; i < SDL_GetNumAudioDrivers(); ++i) {
const char* driver_name = SDL_GetAudioDriver(i);
printf("Audio driver #%d: %s\n", i, driver_name);
if(strcmp(driver_name, desired_driver) == 0) {
cout<<"Going to init "<<desired_driver<<" driver."<<endl;
init_success = SDL_AudioInit(desired_driver);
}
}
}
const char * device_name = "";
if(init_success == 0) {
cout<<"I think I successfully init'd the driver. Here are the "<<SDL_GetNumAudioDevices(0)<<" audio devices it provides: "<<endl;
for(int i=0;i<SDL_GetNumAudioDevices(0);++i) {
device_name = SDL_GetAudioDeviceName(i,0);
#ifdef _WIN32
if(i == 0 && device_name) id = SDL_OpenAudioDevice(device_name, 0, &desired, &obtained, 0);
#endif
if(device_name) {
printf("Audio device #%d: %s\n", i, device_name);
}
else
printf("Audio device #%d: NULL!?!\n", i);
}
}
#ifndef _WIN32
id = SDL_OpenAudioDevice(NULL, 0, &desired, &obtained, 0);
#endif
if(id <= 0) {
cerr<<"Couldn't open the audio device: "<<SDL_GetError()<<endl;
//return 1;
}
else {
if(SDL_GetCurrentAudioDriver()) {
cout<<"Opened audio device with driver: "<<SDL_GetCurrentAudioDriver()<<endl;
}
else {
cout<<"Doesn't seem like a driver was successfully init'd!"<<endl;
}
}
if(id > 0) {
//if(desired.freq != obtained.freq || desired.format != obtained.format || desired.channels != obtained.channels || desired.samples != obtained.samples) {
//cout<<"Desired:\n\tFreq: "<<desired.freq<<"\n\tFormat: "<<desired.format<<"\n\tChannels: "<<int(desired.channels)<<"\n\tSamples: "<<desired.samples<<endl<<endl;
cout<<"Obtained:\n\tFreq: "<<obtained.freq<<"\n\tFormat: "<<obtained.format<<"\n\tChannels: "<<int(obtained.channels)<<"\n\tSamples: "<<obtained.samples<<endl;
//cout<<"Bufsize: "<<bufsize<<endl;
size_t bufsize = SAMPLES_PER_FRAME * obtained.samples;
buffer.resize(bufsize,0);
dat.buffer = &(buffer[0]);
//}
//cout<<"byte size: "<<obtained.size<<endl;
//if(obtained.freq != SAMPLE_RATE) {
// cout<<"Didn't get the frequency I wanted. Should be interesting."<<endl;
//}
}
}
void apu::generate_arrays() {
shift_reg val;
val.val = 1;
bool start = true;
uint16_t count = 0;
//generate the long noise values
while (start || val.val != 1) {
start = false;
unsigned char bop = val.bit13 ^ val.bit14;
noise_states[0][count] = ((val.bit13 ^ val.bit14)?0:1);
val.val <<=(1);
val.val |= (unsigned int)(bop);
++count;
}
//cout<<"Long count: "<<count<<endl;
assert(count == 32767);
val.val = 1;
start = true;
count = 0;
//generate the short noise values
while (start || val.val != 1) {
start = false;
uint8_t bop = val.bit8 ^ val.bit14;
noise_states[1][count] = ((val.bit8 ^ val.bit14)?0:1);
val.val <<=(1);
val.val |= bop;
++count;
}
//cout<<"Short count: "<<count<<endl;
assert(count == 93);
uint16_t n_f_t[16] = { 0x002, 0x004, 0x008, 0x010,
0x020, 0x030, 0x040, 0x050,
0x065, 0x07F, 0x0BE, 0x0FE,
0x17D, 0x1FC, 0x3F9, 0x7F2 };
uint8_t g_l_t[16] = { 0x7f, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F };
int dmc_f[16] = { 0xD60, 0xBE0, 0xAA0, 0xA00, 0x8F0, 0x7F0, 0x710, 0x6B0,
0x5F0, 0x500, 0x470, 0x400, 0x350, 0x2A8, 0x240, 0x1B0 };
for(uint8_t i=0;i<16;++i) {
noise_freq_table[i] = n_f_t[i];
general_len_table[i] = g_l_t[i];
dmc_freq_table[i] = dmc_f[i];
}
uint8_t p_l_t[8] = { 0x05, 0x0A, 0x14, 0x28, 0x50, 0x1E, 0x07, 0x0D };
uint8_t n_l_t[8] = { 0x06, 0x0C, 0x18, 0x30, 0x60, 0x24, 0x08, 0x10 };
for(uint8_t i=0;i<8;++i) {
pal_len_table[i] = p_l_t[i];
ntsc_len_table[i] = n_l_t[i];
}
uint8_t t_s[TRI_LEN] = { 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 };
for(uint8_t i=0;i<32;++i) TRI_STATES[i] = t_s[i];
uint8_t s_s[4][SQ_LEN] = {{0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,1,1,1,1,0,0,0,0,0,0,0,0,0,0},
{0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0},
{1,1,0,0,0,0,1,1,1,1,1,1,1,1,1,1}};
for(uint8_t i=0;i<4;++i)
for(uint8_t j=0;j<16;++j)
SQ_STATES[i][j] = s_s[i][j];
uint16_t n_l[2] = {32767, 93};
NOISE_LEN[0] = n_l[0];
NOISE_LEN[1] = n_l[1];
}
apu::apu(bool headless/* =false */) {
//std::cout<<"apu constructor"<<std::endl;
stat.val = 0;
linear_cntr = 0;
enable_linear_cntr = false;
pin1_enabled = 0;
pin2_enabled = 0;
noise_flip_flop = false;
framecounter_pos = 0;
framecounter_reset = 89490;
enable_irq = false;
counter_mode = 0;
dmc_pcm_data = 0;
dmc_addr=0;
dmc_addr_reset=0xc000;
dmc_freq_cnt=0;
dmc_freq=0;
dmc_length=0;
dmc_gen_irq=false;
dmc_loop=false;
buffer_read_pos = 0;
buffer_write_pos = 0;
for(int i=0; i<5; ++i) {
enabled[i] = false;
vol[i] = 0;
decay_count[i] = 0;
enable_decay[i] = false;
loop_decay[i] = false;
decay_vol_lvl[i] = 0;
duty_cycle[i] = 0;
sweep_enable[i] = false;
sweep_shift[i] = 0;
sweep_dir[i] = 0;
sweep_rate[i] = 0;
sweep_count[i] = 0;
length[i] = 0;
wavelength_count_reset[i] = 0;
wave_pos[i] = 0;
}
id = 0;
frame = 0;
write_pos = 1;
init(headless);
generate_arrays();
//Unpause the audio stream
if(id > 0)
SDL_PauseAudioDevice(id, false);
}
void apu::setmem(mem * m) {
memi = m;
}
void apu::clock_quarter() {
if(enable_linear_cntr && linear_cntr > 0) --linear_cntr;
//Envelope decay and looping
for(uint8_t voice = 0; voice < 4; ++voice) {
if(voice == TRI) continue;
if(enabled[voice] && enable_decay[voice] && length[voice] > 0) {
if(decay_count[voice] == 0) {
--decay_vol_lvl[voice];
if(decay_vol_lvl[voice] > 15 && loop_decay[voice]) {
decay_vol_lvl[voice] = 15;
}
else if(decay_vol_lvl[voice] > 15) {
decay_vol_lvl[voice] = 0;
//enabled[voice] = false;
length[voice] = 0;
}
else {
decay_count[voice] = vol[voice];
}
//cout<<"Voice: "<<int(voice)<<" new vol: "<<decay_vol_lvl[voice]<<endl;
}
else {
--decay_count[voice];
}
}
}
}
void apu::clock_half() {
for(uint8_t voice = 0; voice < 4; ++voice) {
//clock length counter
if(enabled[voice] && length[voice] > 0 && !loop_decay[voice] && (voice != TRI || !enable_linear_cntr)) length[voice]--;
//Wavelength sweep
if(voice < 2 && enabled[voice] && length[voice] > 0 && sweep_enable[voice]) {
--sweep_count[voice];
if(sweep_count[voice] == 0) {
int sweep_amount = wavelength_count_reset[voice];
sweep_amount>>=(sweep_shift[voice]);
if(sweep_dir[voice] == 1) //decrease wavelength
sweep_amount *= -1;
if(wavelength_count_reset[voice] + sweep_amount < 0x7ff && wavelength_count_reset[voice] + sweep_amount > 0x08) {
wavelength_count_reset[voice] += sweep_amount;
if(sweep_count[voice] == 0) sweep_count[voice] = sweep_rate[voice] + 1;
}
else {
length[voice] = 0;
//enabled[voice] = 0;
}
}
}
}
}
void apu::clock_full() {
}
void apu::clock_every() {
if(!enabled[DMC]||!dmc_length) {
//cout<<"returning"<<endl;
return;
}
//CLK_PER_FRAME is the *pixel clock* which runs 3x faster than the CPU clock, which is where the *3 comes from.
const int clocks_per_sample = int(double(CLK_PER_FRAME) / double(SAMPLES_PER_FRAME * 3));
int accum = 0; //Generating either 1 or 2 samples, so this is where I'm collecting them
int samples = 0; //Number of samples generated, so that I can divide accum by the right number
//"clock" represents a CPU clock. The goal is to generate samples faster than incrementing/decrementing the PCM value by 1 at a time
for(int clock = 0; clock < clocks_per_sample;) {
samples++;
int sign = ((dmc_cur_byte & (1<<(dmc_bit))) > 0)?2:-2;
//Either run up to the wavelength count, or the number of CPU cycles we need to simulate, whichever is less
//If we still need to simulate more cycles, that'll happen in the next loop iteration.
int increment = (dmc_freq_cnt > (clocks_per_sample - clock)) ? (clocks_per_sample - clock) : dmc_freq_cnt;
dmc_pcm_data += (increment*sign);
//The PCM data doesn't wrap like an X86 register, it "saturates" to stay in the range [0,127]
if(dmc_pcm_data < 0) dmc_pcm_data = 0;
else if(dmc_pcm_data > 127) dmc_pcm_data = 127;
accum +=dmc_pcm_data;
dmc_freq_cnt-=increment;
clock += increment;
//Clock the DMC registers if we're at the end of the wavelength counter
if(!dmc_freq_cnt) {
dmc_freq_cnt = dmc_freq;
dmc_bit++;
dmc_bit%=8;
if(!dmc_bit) {
//TODO: Fix so that it ends when the length runs out, but also wraps around to 0x8000 if it doesn't
dmc_addr++;
if(dmc_addr==dmc_addr_reset+dmc_length && !dmc_loop) {
dmc_addr = dmc_addr_reset;
enabled[DMC] = false;
return;
}
else if (dmc_addr==dmc_addr_reset+dmc_length) {
dmc_addr = dmc_addr_reset;
dmc_bit = 0;
dmc_freq_cnt = dmc_freq;
}
//Grab the next byte both if we're not done going through samples and if we're done, but looping.
dmc_cur_byte = memi->read(dmc_addr);
}
}
}
dmc_pcm_data = accum/samples;
//cout<<"Final data: "<<dmc_pcm_data<<endl;
}
void apu::gen_audio(uint16_t to_gen) { //To be run once per frame, to generate audio
//cout<<"Gen_audio"<<endl;
write_pos = !write_pos;
//assert(to_gen == SAMPLES_PER_FRAME);
//std::cout<<"apu::gen_audio("<<to_gen<<")"<<std::endl;
uint16_t reg_audio_sample = SAMPLES_PER_FRAME + 20;
int write_cycle = 0;
int write_frame = 0;
if(writes.size() > 0) { //If there are reg writes left on the queue, find the frame where the next one should apply
//cout<<writes.size()<<" reg writes in queue"<<endl;
write_frame = writes.front().first.first;
//frame = write_frame;
write_cycle = writes.front().first.second; //Write cycle is in terms of PPU cycle
reg_audio_sample = uint16_t(double(write_cycle) * double(SAMPLES_PER_FRAME) / double(CLK_PER_FRAME)); //Convert it to which sample the change applies to
//if(writes.size() > 50) {
//cout<<"writes.size() = "<<writes.size()<<" next reg at sample: "<<reg_audio_sample<<endl;
//}
}
for(int i = 0; i < SAMPLES_PER_FRAME; ++i) {
//cout<<"Sample "<<i<<endl;
//clock the 60Hz, 120Hz, and 240Hz things
if(i == SAMPLES_PER_FRAME / 4) {
clock_quarter();
}
else if(i == SAMPLES_PER_FRAME / 2) {
clock_quarter();
clock_half();
}
else if(i == (SAMPLES_PER_FRAME * 3) / 4) {
clock_quarter();
}
else if(i == (SAMPLES_PER_FRAME - 1)) {
clock_quarter();
clock_half();
}
//Clock the things that need updated *every* cycle (but we've got to emulate that, since this loop only covers every sample)
clock_every();
while(writes.size() > 0 && ((write_frame == frame && reg_audio_sample <= i) || write_frame < frame)) { //Apply Register writes that go here
//cout<<"Woot, applying a reg write with "<<writes.size()<<"writes remaining"<<endl;
reg_dequeue();
if(writes.size() > 0) {
write_frame = writes.front().first.first;
write_cycle = writes.front().first.second;
reg_audio_sample = uint16_t(double(write_cycle) * double(SAMPLES_PER_FRAME) / double(CLK_PER_FRAME));
}
else {
reg_audio_sample = SAMPLES_PER_FRAME + 20; //i.e. don't trigger a dequeue again
}
}
char accum = 0;
for(int voice = 0; voice < 4; ++voice) {
//cout<<"Doing voice "<<voice<<endl;
//Get sample value for each voice, put into appropriate buffer location
if(enabled[voice] && length[voice] != 0 && (voice != TRI || !enable_linear_cntr || linear_cntr != 0)) {
//cout<<"getting sample =)"<<endl;
accum += get_sample(voice);
}
//else
// cout<<"Not getting sample for voice "<<voice<<endl;
}
//if(int(accum) + pcm_data > 255) cout<<"Too big: accum="<<int(accum)<<", pcm="<<pcm_data<<endl;
//if(pcm_data != 0) cout<<"pcm="<<pcm_data<<endl;
//cout<<"first: "<<dat.first<<"loc: "<<dat.first*SAMPLES_PER_FRAME<<endl;
dat.buffer[i+(buffer_write_pos * SAMPLES_PER_FRAME)] = accum + dmc_pcm_data/4;
}
//cout<<hex<<val.first<<": 0x"<<val.second.first<<" val: 0x"<<val.second.second<<endl;
//frame++;
//if(write_pos) write_pos = 0;
//else write_pos = 1;
//cout<<"End of gen_audio"<<endl;
dat.buffered+=SAMPLES_PER_FRAME;
buffer_write_pos++;
buffer_write_pos %= obtained.samples;
//cout<<"Generate 735"<<endl;
//cout<<"Write: Frame: "<<frame<<" buffer index: "<<buffer_write_pos<<" samples: "<<buffer_write_pos*SAMPLES_PER_FRAME<<" -> "<<(buffer_write_pos+1)*SAMPLES_PER_FRAME<<endl;
}
//Mem class writes here, and I process the register writes at the end of the frame while generating audio data
void apu::reg_write(int frame, int cycle, int addr, int val) {
writes.push_back(make_pair(make_pair(frame, cycle), make_pair(addr, val)));
//cout<<"Pushing ("<<cycle<<", "<<addr<<", "<<val<<")"<<endl;
}
//Read the play status of the channels
//The mem class can probably handle the interrupt info
int apu::read_status() {
status_reg a;
a.sq1_on = (length[SQ1] > 0);
a.sq2_on = (length[SQ2] > 0);
a.tri_on = (length[TRI] > 0);
a.noise_on = (length[NOISE] > 0);
a.dmc_on = (length[DMC] > 0);
return a.val;
}
//Process and apply the next register value
void apu::reg_dequeue() {
if(writes.size() > 0) {
int addr = writes.front().second.first - 0x4000;
int chan = addr / 4;
int reg = addr % 4;
if(addr == 0x10) reg = 0x10;
if(addr == 0x11) reg = 0x11;
if(addr == 0x12) reg = 0x12;
if(addr == 0x13) reg = 0x13;
if(addr == 0x15) reg = 0x15;
if(addr == 0x17) reg = 0x17;
int val = writes.front().second.second;
if(reg < 4 && addr > 0x10) writes.pop_front();
switch(reg) {
case 0:
if(chan != TRI) {
vol_reg a;
a.val = val;
vol[chan] = a.vol;
enable_decay[chan] = !a.disable_decay;
loop_decay[chan] = a.loop_decay;
decay_count[chan] = a.vol;
//cout<<"Chan: "<<chan<<" Enable decay: "<<enable_decay[chan]<<" loop: "<<a.loop_decay<<" rate: "<<a.vol<<endl;
decay_vol_lvl[chan] = 15;
if(chan != NOISE) {
duty_cycle[chan] = a.duty_cycle;
}
}
else {
lin_ctr_reg a;
a.val = val;
linear_cntr = a.count;
enable_linear_cntr = a.length_disable;
}
break;
case 1: {
sweep_reg a;
a.val = val;
sweep_enable[chan] = a.enable;
sweep_shift[chan] = a.shift;
sweep_rate[chan] = a.rate;
sweep_count[chan] = a.rate + 1;
sweep_dir[chan] = a.dir;
}
break;
case 2:
if(chan != NOISE) {
freq_len_reg a;
a.freq = wavelength_count_reset[chan];
a.low = val;
wavelength_count_reset[chan] = a.freq;
}
else {
freq_len_reg a;
a.low = val;
wavelength_count_reset[chan] = noise_freq(a);
wavelength_count[chan] = noise_freq(a);
duty_cycle[chan] = a.noise_type;
}
break;
case 3:
if(chan != NOISE) {
freq_len_reg a;
a.freq = wavelength_count_reset[chan];
a.high = val;
wavelength_count_reset[chan] = a.freq;
wavelength_count[chan] = a.freq;
length[chan] = play_length(a);
}
else {
freq_len_reg a;
a.high = val;
length[chan] = play_length(a);
if(chan == SQ1 || chan == SQ2 || chan == NOISE)
decay_vol_lvl[chan] = 15;
}
break;
case 0x10:
//cout<<"0x4010: Mode: "<<hex<<((val&0xC0)>>(6))<<" Speed: "<<(val&0x0F)<<endl;
dmc_loop = ((val&0x40) > 0);
dmc_gen_irq = ((val >= 0x80) && !dmc_loop);
dmc_freq = dmc_freq_table[val&0x0f]/8;
dmc_freq_cnt = dmc_freq;
//cout<<"0x4010: Loop: "<<dmc_loop<<" gen_irq: "<<dmc_gen_irq<<" freq: "<<dmc_freq<<endl;
if(dmc_gen_irq) cerr<<"DMC can't generate an IRQ, so this game may not work right."<<endl;
break;
case 0x11:
//cout<<"0x4011: PCM/counter val: "<<hex<<val<<endl;
dmc_pcm_data = (val&0x7f); //The data's just 7 bits
break;
case 0x12:
//cout<<"0x4012: DMC load address: "<<hex<<(((int(val))<<(6))|0xc000)<<endl;
dmc_addr = (((int(val))<<(6))|0xc000);
dmc_addr_reset = dmc_addr;
dmc_bit = 0;
dmc_cur_byte = memi->read(dmc_addr);
break;
case 0x13:
//cout<<"0x4013: DMC length val: "<<hex<<((int(val))<<(4))<<endl;
dmc_length = ((int(val))<<(4));
if(!dmc_length) enabled[DMC] = false;
break;
case 0x15: {
//cout<<"Set 0x15 to "<<val<<endl;
status_reg a;
a.val = val;
enabled[SQ1] = a.sq1_on;
enabled[SQ2] = a.sq2_on;
enabled[TRI] = a.tri_on;
enabled[NOISE] = a.noise_on;
enabled[DMC] = a.dmc_on;
//if(enabled[DMC]) cout<<"0x4015 DMC enabled"<<endl;
//else cout<<"0x4015 DMC disabled"<<endl;
pin1_enabled = a.sq1_on + a.sq2_on;
pin2_enabled = a.tri_on + a.noise_on + a.dmc_on;
}
break;
case 0x17: {
frame_counter_reg a;
a.val = val;
if(a.counter_mode) {
clock_quarter();
clock_full();
framecounter_reset = 111846;
}
else {
framecounter_reset = 89490;
}
enable_irq = !a.irq_disable;
//cout<<"0x4017: IRQ enable: "<<enable_irq<<endl;
counter_mode = a.counter_mode;
framecounter_pos = 0;
}
break;
default:
cout<<"Not implemented"<<endl;
break;
}
writes.pop_front();
}
}
//Do the lookup for the actual noise wavelength
const int apu::noise_freq(freq_len_reg val) {
return noise_freq_table[val.noise_freq];
}
//Convert the data in the struct into a frame count for how long the note should play
const int apu::play_length(freq_len_reg val) {
if(!(val.bit3 || val.bit7))
return pal_len_table[val.mid];
else if(!val.bit3 && val.bit7)
return ntsc_len_table[val.mid];
else
return general_len_table[val.mid + val.bit7*128];
}
//Do the downsampling of audio samples transparently, and provide that to the audio generation function
int apu::get_sample(int voice) {
if(!enabled[voice] || length[voice] == 0 || wavelength_count_reset[voice] == 0) {
//cout<<"Returning 0"<<endl;
//cout<<"Enabled: "<<enabled[voice]<<" wavelength: "<<wavelength_count[voice]<<endl;
return 0;
}
//cout<<"Generating something."<<endl;
int to_gen = 0;
float interleave = float(CLK_PER_FRAME * 20) / float(SAMPLE_RATE);
if(interleave - int(interleave) >= 0.5) to_gen = int(interleave) + 1;
else to_gen = int(interleave);
//cout<<"to_gen: "<<to_gen<<endl;
int accum = 0;
int vol = 0;
while(to_gen > 0) {
//cout<<to_gen<<" left to go!"<<endl;
int this_one = 0;
if(wavelength_count[voice] == 0) clock_duty(voice);
if(wavelength_count[voice] >= to_gen) {
this_one = to_gen;
}
else this_one = wavelength_count[voice];
//cout<<"Doing "<<this_one<<" for this iteration"<<endl;
switch(voice) {
case SQ1:
vol = sq1_duty();
break;
case SQ2:
vol = sq2_duty();
break;
case TRI:
vol = tri_duty();
break;
case NOISE:
vol = noise_duty();
break;
}
//if(vol != 0) cout<<"Vol: "<<vol<<endl;
to_gen -= this_one;
wavelength_count[voice] -= this_one;
accum += (vol * this_one);
if(wavelength_count[voice] == 0) {
//clock the channel's duty thingie
clock_duty(voice);
}
}
//cout<<"Accum: "<<accum<<" returning: "<<accum/41<<endl;
return accum / 41;
}
void apu::clock_duty(int voice) {
wavelength_count[voice] = wavelength_count_reset[voice];
if(voice != NOISE)
++wave_pos[voice];
switch(voice) {
case SQ1:
case SQ2:
wave_pos[voice] %= SQ_LEN;
break;
case TRI:
wave_pos[voice] %= TRI_LEN;
break;
case NOISE:
if(noise_flip_flop) ++wave_pos[voice];
noise_flip_flop = !noise_flip_flop;
wave_pos[voice] %= NOISE_LEN[duty_cycle[voice]];
break;
}
}
const int apu::sq1_duty() {
int retval = 0;
if(enable_decay[SQ1]) retval = SQ_STATES[duty_cycle[SQ1]][wave_pos[SQ1]] * decay_vol_lvl[SQ1];
else retval = SQ_STATES[duty_cycle[SQ1]][wave_pos[SQ1]] * vol[SQ1];
//cout<<"wave_pos[SQ1]: "<<wave_pos[SQ1]<<" vol: "<<retval<<endl;
//if(retval > 15) cout<<"SQ1 decay: "<<enable_decay[SQ1]<<" vol: "<<retval<<endl;
return retval;
}
const int apu::sq2_duty() {
int retval = 0;
if(enable_decay[SQ2]) retval = SQ_STATES[duty_cycle[SQ2]][wave_pos[SQ2]] * decay_vol_lvl[SQ2];
else retval = SQ_STATES[duty_cycle[SQ2]][wave_pos[SQ2]] * vol[SQ2];
//cout<<"wave_pos[SQ2]: "<<wave_pos[SQ2]<<" vol: "<<retval<<endl;
//if(retval > 15) cout<<"SQ2 decay: "<<enable_decay[SQ2]<<" vol: "<<retval<<endl;
return retval;
}
const int apu::tri_duty() {
int retval = TRI_STATES[wave_pos[TRI]];
//cout<<"wave_pos[TRI]: "<<wave_pos[TRI]<<endl;
return retval;
}
const int apu::noise_duty() {
int retval = 0;
if(enable_decay[NOISE]) retval = noise_states[duty_cycle[NOISE]][wave_pos[NOISE]] * decay_vol_lvl[NOISE];
else retval = noise_states[duty_cycle[NOISE]][wave_pos[NOISE]] * vol[NOISE];
//cout<<"wave_pos[NOISE]: "<<wave_pos[NOISE]<<endl;
return ((retval*3)/4);
}
apu::~apu() {
SDL_PauseAudioDevice(id, true);
SDL_CloseAudioDevice(id);
//std::cout<<"apu destructor"<<std::endl;
}