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Made an attempt to implement noise and envelopes. Not quite right yet.
This commit is contained in:
Thomas Harte
parent
5a808d789a
commit
ada37abe23
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@ -10,9 +10,59 @@
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using namespace GI;
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AY38910::AY38910() : _selected_register(0), _channel_ouput{0, 0, 0}, _channel_dividers{0, 0, 0}, _tone_generator_controls{0, 0, 0}
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AY38910::AY38910() :
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_selected_register(0),
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_channel_output{0, 0, 0}, _channel_dividers{0, 0, 0}, _tone_generator_controls{0, 0, 0},
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_noise_shift_register(0xffff), _noise_divider(0), _noise_output(0),
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_envelope_divider(0), _envelope_period(0)
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{
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_output_registers[8] = _output_registers[9] = _output_registers[10] = 0;
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// set up envelope lookup tables
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for(int c = 0; c < 16; c++)
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{
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for(int p = 0; p < 32; p++)
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{
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switch(c)
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{
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case 0: case 1: case 2: case 3: case 9:
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_envelope_shapes[c][p] = (p < 16) ? (p^0xf) : 0;
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_envelope_overflow_masks[c] = 0x1f;
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break;
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case 4: case 5: case 6: case 7: case 15:
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_envelope_shapes[c][p] = (p < 16) ? p : 0;
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_envelope_overflow_masks[c] = 0x1f;
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break;
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case 8:
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_envelope_shapes[c][p] = (p & 0xf) ^ 0xf;
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_envelope_overflow_masks[c] = 0x00;
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break;
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case 12:
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_envelope_shapes[c][p] = (p & 0xf);
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_envelope_overflow_masks[c] = 0x00;
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break;
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case 10:
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_envelope_shapes[c][p] = (p & 0xf) ^ ((p < 16) ? 0xf : 0x0);
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_envelope_overflow_masks[c] = 0x00;
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break;
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case 14:
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_envelope_shapes[c][p] = (p & 0xf) ^ ((p < 16) ? 0x0 : 0xf);
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_envelope_overflow_masks[c] = 0x00;
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break;
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case 11:
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_envelope_shapes[c][p] = (p < 16) ? (p^0xf) : 0xf;
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_envelope_overflow_masks[c] = 0x1f;
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break;
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case 13:
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_envelope_shapes[c][p] = (p < 16) ? p : 0xf;
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_envelope_overflow_masks[c] = 0x1f;
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break;
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}
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}
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}
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}
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void AY38910::set_clock_rate(double clock_rate)
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@ -30,12 +80,12 @@ void AY38910::get_samples(unsigned int number_of_samples, int16_t *target)
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int resulting_steps = ((_master_divider ^ former_master_divider) >> 4) & 1;
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// from that the three channels count down
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#define step(c) {\
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int did_underflow;
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#define step(c) \
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_channel_dividers[c] -= resulting_steps; \
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int did_underflow = (_channel_dividers[c] >> 15)&1; \
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_channel_ouput[c] ^= did_underflow; \
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_channel_dividers[c] = did_underflow * _tone_generator_controls[c] + (did_underflow^1) * _channel_dividers[c]; \
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}
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did_underflow = (_channel_dividers[c] >> 15)&1; \
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_channel_output[c] ^= did_underflow; \
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_channel_dividers[c] = did_underflow * _tone_generator_controls[c] + (did_underflow^1) * _channel_dividers[c];
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step(0);
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step(1);
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@ -43,19 +93,51 @@ void AY38910::get_samples(unsigned int number_of_samples, int16_t *target)
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#undef step
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// ... as does the envelope generator
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// _envelope_divider -= resulting_steps;
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// if(!_envelope_divider)
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// ... as does the noise generator
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_noise_divider -= resulting_steps;
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did_underflow = (_noise_divider >> 15)&1;
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_noise_divider = did_underflow * (_output_registers[6]&0x1f) + (did_underflow^1) * _noise_divider;
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_noise_output ^= did_underflow&_noise_shift_register&1;
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_noise_shift_register |= ((_noise_shift_register ^ (_noise_shift_register >> 3))&1) << 17;
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_noise_shift_register >>= did_underflow;
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// ... and the envelope generator
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_envelope_divider -= resulting_steps;
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did_underflow = (_envelope_divider >> 15)&1;
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_envelope_divider = did_underflow * _envelope_period + (did_underflow^1) * _envelope_divider;
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_envelope_position += did_underflow;
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// if(_output_registers[13] == 13)
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// {
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// _envelope_divider = _envelope_period;
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// printf("[%d] %d", _envelope_divider, _envelope_position);
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// }
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// if(_output_registers[9]) printf("%d %d / %d\n", _channel_ouput[1], _channel_dividers[1], _tone_generator_controls[1]);
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int refill = _envelope_overflow_masks[_output_registers[13]] * (_envelope_position >> 5);
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_envelope_position = (_envelope_position & 0x1f) | refill;
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int envelope_volume = _envelope_shapes[_output_registers[13]][_envelope_position & 0xf];
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// if(_output_registers[13] == 13)
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// {
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// printf(": %d\n", envelope_volume);
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// }
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int channel_levels[3] = {
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(((((_output_registers[7] >> 0)&1)^1) & _channel_output[0]) | ((((_output_registers[7] >> 1)&1)^1) & _noise_output)) ^ 1,
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(((((_output_registers[7] >> 2)&1)^1) & _channel_output[1]) | ((((_output_registers[7] >> 3)&1)^1) & _noise_output)) ^ 1,
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(((((_output_registers[7] >> 4)&1)^1) & _channel_output[2]) | ((((_output_registers[7] >> 5)&1)^1) & _noise_output)) ^ 1,
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};
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int volumes[3] = {
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((_output_registers[8] >> 4)&1) * envelope_volume + (((_output_registers[8] >> 4)&1)^1) * (_output_registers[8]&0x1f),
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((_output_registers[9] >> 4)&1) * envelope_volume + (((_output_registers[9] >> 4)&1)^1) * (_output_registers[9]&0x1f),
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((_output_registers[10] >> 4)&1) * envelope_volume + (((_output_registers[10] >> 4)&1)^1) * (_output_registers[10]&0x1f),
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};
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target[c] = (int16_t)((
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(_output_registers[8]&0xf) * _channel_ouput[0] +
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(_output_registers[9]&0xf) * _channel_ouput[1] +
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(_output_registers[10]&0xf) * _channel_ouput[2]
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volumes[0] * channel_levels[0] +
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volumes[1] * channel_levels[1] +
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volumes[2] * channel_levels[2]
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) * 512);
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}
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}
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@ -78,6 +160,7 @@ void AY38910::set_register_value(uint8_t value)
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{
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int selected_register = _selected_register;
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enqueue([=] () {
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uint8_t masked_value = value;
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switch(selected_register)
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{
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case 0: case 2: case 4:
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@ -92,13 +175,21 @@ void AY38910::set_register_value(uint8_t value)
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case 11:
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_envelope_period = (_envelope_period & ~0xff) | value;
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// printf("e: %d", _envelope_period);
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break;
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case 12:
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_envelope_period = (_envelope_period & 0xff) | (uint16_t)(value << 8);
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_envelope_period = (_envelope_period & 0xff) | (int)(value << 8);
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// printf("e: %d", _envelope_period);
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break;
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case 13:
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masked_value &= 0xf;
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_envelope_position = 0;
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// printf("envelope %d\n", masked_value);
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break;
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}
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_output_registers[selected_register] = value;
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_output_registers[selected_register] = masked_value;
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});
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}
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}
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@ -37,13 +37,22 @@ class AY38910: public ::Outputs::Filter<AY38910> {
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uint8_t _registers[16], _output_registers[16];
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uint16_t _tone_generator_controls[3];
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uint16_t _envelope_period;
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int _channel_dividers[3];
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int _channel_output[3];
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int _master_divider;
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int _channel_dividers[3];
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int _noise_divider;
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int _noise_shift_register;
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int _noise_output;
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int _envelope_period;
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int _envelope_divider;
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int _evelope_volume;
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int _channel_ouput[3];
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int _envelope_position;
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int _envelope_shapes[16][32];
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int _envelope_overflow_masks[16];
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enum ControlState {
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Inactive,
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