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Made an attempt to eliminate what amounts to manual division.

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This commit is contained in:
Thomas Harte 2016-10-21 22:16:44 -04:00
parent 46a3c0922f
commit 33e628a096
2 changed files with 10 additions and 11 deletions
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16
Components/AY38910/AY38910.cpp
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@ -12,7 +12,7 @@ using namespace GI;
AY38910::AY38910() :
_selected_register(0),
_channel_output{0, 0, 0}, _channel_dividers{0, 0, 0}, _tone_generator_controls{0, 0, 0},
_tone_counters{0, 0, 0}, _tone_dividers{0, 0, 0},
_noise_shift_register(0xffff), _noise_divider(0), _noise_output(0),
_envelope_divider(0), _envelope_period(0), _envelope_position(0),
_output_registers{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
@ -89,9 +89,7 @@ void AY38910::get_samples(unsigned int number_of_samples, int16_t *target)
for(; c < 16 && c < _master_divider; c++) target[c - offset] = _output_volume;
while(c < _master_divider)
{
#define step_channel(c) \
if(_channel_dividers[c]) _channel_dividers[c] --; \
else { _channel_dividers[c] = _tone_generator_controls[c]; _channel_output[c] ^= 1; }
#define step_channel(c) _tone_counters[c] = (_tone_counters[c] + 1) % (2 * (_tone_dividers[c] + 1))
// update the tone channels
step_channel(0);
@ -142,7 +140,7 @@ void AY38910::evaluate_output_volume()
// 0 if either tone or noise is enabled and its value is low.
// (which is implemented here with reverse logic, assuming _channel_output and _noise_output are already inverted)
#define level(c, tb, nb) \
(((((_output_registers[7] >> tb)&1)^1) & _channel_output[c]) | ((((_output_registers[7] >> nb)&1)^1) & _noise_output)) ^ 1
(((((_output_registers[7] >> tb)&1)^1) & (_tone_counters[c] / (_tone_dividers[c] + 1))) | ((((_output_registers[7] >> nb)&1)^1) & _noise_output)) ^ 1
int channel_levels[3] = {
level(0, 0, 3),
@ -195,11 +193,13 @@ void AY38910::set_register_value(uint8_t value)
case 1: case 3: case 5:
{
int channel = selected_register >> 1;
_tone_counters[channel] /= _tone_dividers[channel] + 1;
if(selected_register & 1)
_tone_generator_controls[channel] = (_tone_generator_controls[channel] & 0xff) | (uint16_t)((value&0xf) << 8);
_tone_dividers[channel] = (_tone_dividers[channel] & 0xff) | (uint16_t)((value&0xf) << 8);
else
_tone_generator_controls[channel] = (_tone_generator_controls[channel] & ~0xff) | value;
_channel_dividers[channel] = _tone_generator_controls[channel];
_tone_dividers[channel] = (_tone_dividers[channel] & ~0xff) | value;
_tone_counters[channel] *= _tone_dividers[channel] + 1;
}
break;

5
Components/AY38910/AY38910.hpp
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@ -55,9 +55,8 @@ class AY38910: public ::Outputs::Filter<AY38910> {
int _selected_register;
uint8_t _registers[16], _output_registers[16];
int _tone_generator_controls[3];
int _channel_dividers[3];
int _channel_output[3];
int _tone_dividers[3];
int _tone_counters[3];
int _volumes[16];