// Register description for APU http://wiki.nesdev.com/w/index.php/APU
public void write(ushort addr, byte val)
{
// Write to a pulse settings register
if (addr >= 0x4000 && addr <= 0x4007)
{
Pulse pulse;
if (addr < 0x4004)
{
pulse = PULSE_ONE;
}
else
{
pulse = PULSE_TWO;
}
int normalizedAddress = addr & 0x3;
switch (normalizedAddress)
{
case 0: // 0x4000 or 0x4004
pulse.DUTY = (byte)((val >> 6) & 0x3);
pulse.LENGTH_COUNTER_HALT = ((val >> 5) & 0x1) == 1;
pulse.CONSTANT_VOLUME = ((val >> 4) & 0x1) == 1;
pulse.ENVELOPE_DIVIDER_PERIOD_OR_VOLUME = (byte)(val & 0xF);
pulse.envelope_volume = 15;
pulse.envelope_counter = pulse.ENVELOPE_DIVIDER_PERIOD_OR_VOLUME;
break;
case 1: // 0x4001 or 0x4005
pulse.SWEEP_ENABLED = ((val >> 7) & 0x1) == 1;
pulse.SWEEP_PERIOD = (byte)((val >> 4) & 0x7);
pulse.sweep_period_counter = pulse.SWEEP_PERIOD;
pulse.SWEEP_NEGATE = ((val >> 3) & 0x1) == 1;
pulse.SWEEP_SHIFT = (byte)((val >> 4) & 0x7);
break;
case 2: // 0x4002 or 0x4006
pulse.TIMER = (ushort)((pulse.TIMER & 0xFF00) | val);
break;
case 3: // 0x4003 or 0x4007
pulse.LENGTH_COUNTER_LOAD = (byte)((val >> 3) & 0x1F);
pulse.current_length_counter = lengthCounterLookupTable[pulse.LENGTH_COUNTER_LOAD];
pulse.TIMER = (ushort)((pulse.TIMER & 0x00FF) | ((val & 0x7) << 8));
break;
default:
break;
}
}
else
{
// All other register writes
switch (addr)
{
case 0x4008:
TRIANGLE.LENGTH_COUNTER_HALT = (((val >> 7) & 0x1) == 1);
TRIANGLE.LINEAR_COUNTER_LOAD = (byte)(val & 0x7F);
TRIANGLE.current_linear_counter = TRIANGLE.LINEAR_COUNTER_LOAD;
break;
case 0x4009: // Unused register
break;
case 0x400A:
TRIANGLE.TIMER = (ushort)((TRIANGLE.TIMER & 0xFF00) | val);
break;
case 0x400B:
TRIANGLE.LENGTH_COUNTER_LOAD = (byte)((val >> 3) & 0x1F);
TRIANGLE.current_length_counter = lengthCounterLookupTable[TRIANGLE.LENGTH_COUNTER_LOAD];
TRIANGLE.current_linear_counter = TRIANGLE.LINEAR_COUNTER_LOAD;
TRIANGLE.TIMER = (ushort)((TRIANGLE.TIMER & 0x00FF) | ((val & 0x7) << 8));
break;
case 0x400C:
NOISE.ENVELOPE_LOOP = (((val >> 5) & 0x1) == 1);
NOISE.CONSTANT_VOLUME = (((val >> 4) & 0x1) == 1);
NOISE.VOLUME_ENVELOP = (byte)(val & 0xF);
break;
case 0x400D: // Unused register
break;
case 0x400E:
NOISE.LOOP_NOISE = (((val >> 7) & 0x1) == 1);
NOISE.NOISE_PERIOD = (byte)(val & 0xF);
break;
case 0x400F:
NOISE.LENGTH_COUNTER_LOAD = (byte)((val >> 3) & 0xF);
break;
case 0x4010:
DMC.IRQ_ENABLE = (((val >> 7) & 0x1) == 1);
DMC.LOOP = (((val >> 6) & 0x1) == 1);
DMC.FREQUENCY = (byte)(val & 0xF);
break;
case 0x4011:
DMC.LOAD_COUNTER = (byte)(val & 0x7F);
break;
case 0x4012:
DMC.SAMPLE_ADDRESS = val;
break;
case 0x4013:
DMC.SAMPLE_LENGTH = val;
break;
case 0x4015:
DMC.ENABLED = (((val >> 4) & 0x1) == 1);
NOISE.ENABLED = (((val >> 3) & 0x1) == 1);
TRIANGLE.ENABLED = (((val >> 2) & 0x1) == 1);
PULSE_TWO.ENABLED = (((val >> 1) & 0x1) == 1);
PULSE_ONE.ENABLED = (((val >> 0) & 0x1) == 1);
break;
case 0x4017:
FRAME_COUNTER_MODE = (((val >> 7) & 0x1) == 1) ? FrameCounterMode.FIVE_STEP : FrameCounterMode.FOUR_STEP;
IRQ_INHIBIT = (((val >> 6) & 0x1) == 1);
break;
default:
log.error("Attempting to write to unknown address {0:X4}", addr);
break;
}
}
}
// Register description for APU http://wiki.nesdev.com/w/index.php/APU
public void write(ushort addr, byte val)
{
// Write to a pulse settings register
if (addr >= 0x4000 && addr <= 0x4007)
{
Pulse pulse;
if (addr < 0x4004)
{
pulse = PULSE_ONE;
}
else
{
pulse = PULSE_TWO;
}
int normalizedAddress = addr & 0x3;
switch (normalizedAddress)
{
case 0: // 0x4000 or 0x4004
pulse.DUTY = (byte)((val >> 6) & 0x3);
pulse.LENGTH_COUNTER_HALT = ((val >> 5) & 0x1) == 1;
pulse.CONSTANT_VOLUME = ((val >> 4) & 0x1) == 1;
pulse.ENVELOPE_DIVIDER_PERIOD_OR_VOLUME = (byte)(val & 0xF);
pulse.envelope_volume = 15;
pulse.envelope_counter = pulse.ENVELOPE_DIVIDER_PERIOD_OR_VOLUME;
break;
case 1: // 0x4001 or 0x4005
pulse.SWEEP_ENABLED = ((val >> 7) & 0x1) == 1;
pulse.SWEEP_PERIOD = (byte)((val >> 4) & 0x7);
pulse.sweep_period_counter = pulse.SWEEP_PERIOD;
pulse.SWEEP_NEGATE = ((val >> 3) & 0x1) == 1;
pulse.SWEEP_SHIFT = (byte)((val >> 4) & 0x7);
break;
case 2: // 0x4002 or 0x4006
pulse.TIMER = (ushort)((pulse.TIMER & 0xFF00) | val);
break;
case 3: // 0x4003 or 0x4007
pulse.LENGTH_COUNTER_LOAD = (byte)((val >> 3) & 0x1F);
pulse.current_length_counter = lengthCounterLookupTable[pulse.LENGTH_COUNTER_LOAD];
pulse.TIMER = (ushort)((pulse.TIMER & 0x00FF) | ((val & 0x7) << 8));
break;
default:
break;
}
}
else
{
// All other register writes
switch (addr)
{
case 0x4008:
TRIANGLE.LENGTH_COUNTER_HALT = (((val >> 7) & 0x1) == 1);
TRIANGLE.LINEAR_COUNTER_LOAD = (byte)(val & 0x7F);
TRIANGLE.current_linear_counter = TRIANGLE.LINEAR_COUNTER_LOAD;
break;
case 0x4009: // Unused register
break;
case 0x400A:
TRIANGLE.TIMER = (ushort)((TRIANGLE.TIMER & 0xFF00) | val);
break;
case 0x400B:
TRIANGLE.LENGTH_COUNTER_LOAD = (byte)((val >> 3) & 0x1F);
TRIANGLE.current_length_counter = lengthCounterLookupTable[TRIANGLE.LENGTH_COUNTER_LOAD];
TRIANGLE.current_linear_counter = TRIANGLE.LINEAR_COUNTER_LOAD;
TRIANGLE.TIMER = (ushort)((TRIANGLE.TIMER & 0x00FF) | ((val & 0x7) << 8));
break;
case 0x400C:
NOISE.ENVELOPE_LOOP = (((val >> 5) & 0x1) == 1);
NOISE.CONSTANT_VOLUME = (((val >> 4) & 0x1) == 1);
NOISE.VOLUME_ENVELOP = (byte)(val & 0xF);
break;
case 0x400D: // Unused register
break;
case 0x400E:
NOISE.LOOP_NOISE = (((val >> 7) & 0x1) == 1);
NOISE.NOISE_PERIOD = (byte)(val & 0xF);
break;
case 0x400F:
NOISE.LENGTH_COUNTER_LOAD = (byte)((val >> 3) & 0xF);
break;
case 0x4010:
DMC.IRQ_ENABLE = (((val >> 7) & 0x1) == 1);
DMC.LOOP = (((val >> 6) & 0x1) == 1);
DMC.FREQUENCY = (byte)(val & 0xF);
break;
case 0x4011:
DMC.LOAD_COUNTER = (byte)(val & 0x7F);
break;
case 0x4012:
DMC.SAMPLE_ADDRESS = val;
break;
case 0x4013:
DMC.SAMPLE_LENGTH = val;
break;
case 0x4015:
DMC.ENABLED = (((val >> 4) & 0x1) == 1);
NOISE.ENABLED = (((val >> 3) & 0x1) == 1);
TRIANGLE.ENABLED = (((val >> 2) & 0x1) == 1);
PULSE_TWO.ENABLED = (((val >> 1) & 0x1) == 1);
PULSE_ONE.ENABLED = (((val >> 0) & 0x1) == 1);
break;
case 0x4017:
FRAME_COUNTER_MODE = (((val >> 7) & 0x1) == 1) ? FrameCounterMode.FIVE_STEP : FrameCounterMode.FOUR_STEP;
IRQ_INHIBIT = (((val >> 6) & 0x1) == 1);
break;
default:
log.error("Attempting to write to unknown address {0:X4}", addr);
break;
}
}
}
