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Takes a stab at next_sequence_point.

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This commit is contained in:
Thomas Harte 2020-11-26 16:41:11 -05:00
parent 4870506f6e
commit 7a8920ee38
2 changed files with 22 additions and 3 deletions
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24
Machines/Apple/AppleIIgs/Sound.cpp
View File

@ -10,6 +10,7 @@
#include <cassert>
#include <cstdio>
#include <numeric>
// TODO: is it safe not to check for back-pressure in pending_stores_?
@ -174,11 +175,28 @@ uint8_t GLU::get_address_high() {
// MARK: - Update logic.
Cycles GLU::get_next_sequence_point() const {
uint32_t result = std::numeric_limits<decltype(result)>::max();
for(int c = 0; c < local_.oscillator_count; c++) {
// Don't do anything for halted oscillators, or for oscillators that can't hit stops.
if((local_.oscillators[c].control&3) != 2) {
continue;
}
// Determine how many cycles until a stop is hit and update the pending result
// if this is the new soonest-to-expire oscillator.
const auto first_overflow_value = (local_.oscillators[c].overflow_mask - 1) << 1;
const auto time_until_stop = (first_overflow_value - local_.oscillators[c].position + local_.oscillators[c].velocity - 1) / local_.oscillators[c].velocity;
result = std::min(result, time_until_stop);
}
return Cycles(result);
}
void GLU::skip_audio(EnsoniqState &state, size_t number_of_samples) {
// Just advance all oscillator pointers and check for interrupts.
// If a read occurs to the current-output level, generate it then.
for(int c = 0; c < local_.oscillator_count; c++) {
for(int c = 0; c < state.oscillator_count; c++) {
// Don't do anything for halted oscillators.
if(state.oscillators[c].control&1) continue;
@ -186,7 +204,7 @@ void GLU::skip_audio(EnsoniqState &state, size_t number_of_samples) {
state.oscillators[c].position += state.oscillators[c].velocity * number_of_samples;
// Check for stops, and any interrupts that therefore flow.
if((state.oscillators[c].control & 1) && (state.oscillators[c].position & state.oscillators[c].overflow_mask)) {
if((state.oscillators[c].control & 2) && (state.oscillators[c].position & state.oscillators[c].overflow_mask)) {
// Apply halt, set interrupt request flag.
state.oscillators[c].position = 0;
state.oscillators[c].control |= 1;

1
Machines/Apple/AppleIIgs/Sound.hpp
View File

@ -33,6 +33,7 @@ class GLU: public Outputs::Speaker::SampleSource {
uint8_t get_address_high();
void run_for(Cycles);
Cycles get_next_sequence_point() const;
// SampleSource.
void get_samples(std::size_t number_of_samples, std::int16_t *target);