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Added triangle wave sound channel support #43

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Added triangle wave sound channel support #43

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45 changes: 44 additions & 1 deletion Part #7 - Mappers & Basic Sounds/olc2A03.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -145,6 +145,19 @@ void olc2A03::cpuWrite(uint16_t addr, uint8_t data)
break;

case 0x4008:
triangle_lc.counter = (data & 0x7F);
triangle_halt = (data & 0x80);
break;

case 0x400A:
triangle_seq.reload = (triangle_seq.reload & 0xFF00) | data;
break;

case 0x400B:
triangle_seq.reload = (uint16_t)((data & 0x07)) << 8 | (triangle_seq.reload & 0x00FF);
triangle_seq.timer = triangle_seq.reload;
// TODO: length counter + linear counter
//triangle_lc.additional_counter = (data & 0xF8) >> 3;
break;

case 0x400C:
Expand Down Expand Up @@ -179,6 +192,7 @@ void olc2A03::cpuWrite(uint16_t addr, uint8_t data)
pulse1_enable = data & 0x01;
pulse2_enable = data & 0x02;
noise_enable = data & 0x04;
triangle_enable = data & 0x08;
break;

case 0x400F:
Expand Down Expand Up @@ -264,6 +278,7 @@ void olc2A03::clock()
pulse1_lc.clock(pulse1_enable, pulse1_halt);
pulse2_lc.clock(pulse2_enable, pulse2_halt);
noise_lc.clock(noise_enable, noise_halt);
triangle_lc.clock(triangle_enable, triangle_halt);
pulse1_sweep.clock(pulse1_seq.reload, 0);
pulse2_sweep.clock(pulse2_seq.reload, 1);
}
Expand Down Expand Up @@ -326,9 +341,33 @@ void olc2A03::clock()
noise_output = (double)noise_seq.output * ((double)(noise_env.output-1) / 16.0);
}

{
// Update triangle Channel ================================
triangle_seq.clock(triangle_enable, [](uint32_t& s)
{
// Shift right by 1 bit, wrapping around
s = ((s & 0x0001) << 7) | ((s & 0x00FE) >> 1);
});

}
// else
{
triangle_osc.frequency = 1789773.0 / (32.0 * (double)(triangle_seq.reload + 1));
triangle_osc.amplitude = (double)1.0;
triangle_sample = triangle_osc.sample(dGlobalTime);

if (triangle_lc.counter > 0 && triangle_seq.timer >= 8)
triangle_output += (triangle_sample - triangle_output) * 0.5;
else
triangle_output = 0;
}



if (!pulse1_enable) pulse1_output = 0;
if (!pulse2_enable) pulse2_output = 0;
if (!noise_enable) noise_output = 0;
if (!triangle_enable) triangle_output = 0;

}

Expand All @@ -339,6 +378,7 @@ void olc2A03::clock()
pulse1_visual = (pulse1_enable && pulse1_env.output > 1 && !pulse1_sweep.mute) ? pulse1_seq.reload : 2047;
pulse2_visual = (pulse2_enable && pulse2_env.output > 1 && !pulse2_sweep.mute) ? pulse2_seq.reload : 2047;
noise_visual = (noise_enable && noise_env.output > 1) ? noise_seq.reload : 2047;
triangle_visual = (triangle_enable) ? triangle_seq.reload : 2047;

clock_counter++;
}
Expand All @@ -352,9 +392,12 @@ double olc2A03::GetOutputSample()
}
else
{
//return
// ((1.0 * triangle_output) - 0.5) * 0.2;
return ((1.0 * pulse1_output) - 0.8) * 0.1 +
((1.0 * pulse2_output) - 0.8) * 0.1 +
((2.0 * (noise_output - 0.5))) * 0.1;
((2.0 * (noise_output - 0.5))) * 0.1 +
((1.0 * triangle_output) - 0.8) * 0.1;
}
}

Expand Down
34 changes: 34 additions & 0 deletions Part #7 - Mappers & Basic Sounds/olc2A03.h
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Original file line number Diff line number Diff line change
Expand Up @@ -238,6 +238,32 @@ class olc2A03
}
};

struct osctriangle
{
double frequency = 0;
double amplitude = 1;
double pi = 3.14159;
//double harmonics = 20;

double sample(double t)
{
double a = 0;
double b = 0;

auto approxsin = [](float t)
{
float j = t * 0.15915;
j = j - (int)j;
return 20.785 * j * (j - 0.5) * (j - 1.0f);
};

a = approxsin(2 * pi * frequency * t);
b = approxsin(2 * pi * frequency * t * 3) / 9 - approxsin(2 * pi * frequency * t * 5) / 25 + approxsin(2 * pi * frequency * t * 7) / 49;

return (2.0 * amplitude / pi) * (a - b);
}
};

struct sweeper
{
bool enabled = false;
Expand Down Expand Up @@ -327,6 +353,14 @@ class olc2A03
double noise_sample = 0;
double noise_output = 0;

// Triangle Wave Channel
bool triangle_enable = false;
bool triangle_halt = false;
double triangle_sample = 0.0;
double triangle_output = 0.0;
sequencer triangle_seq;
osctriangle triangle_osc;
lengthcounter triangle_lc;

public:
uint16_t pulse1_visual = 0;
Expand Down