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Adds various method definitions.

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This commit is contained in:
Thomas Harte 2021-07-03 12:56:56 -04:00
parent f384370b18
commit c5944efe50
1 changed files with 25 additions and 3 deletions
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28
Machines/Enterprise/Dave.hpp
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@ -32,6 +32,9 @@ class Audio: public Outputs::Speaker::SampleSource {
public:
Audio(Concurrency::DeferringAsyncTaskQueue &audio_queue);
/// Modifies an register in the audio range; only the low 4 bits are
/// used for register decoding so it's assumed that the caller has
/// already identified this write as being to an audio register.
void write(uint16_t address, uint8_t value);
// MARK: - SampleSource.
@ -115,27 +118,43 @@ class Audio: public Outputs::Speaker::SampleSource {
Provides Dave's timed interrupts — those that are provided at 1 kHz,
50 Hz or according to the rate of tone generators 0 or 1, plus the fixed
1 Hz interrupt.
*/
class TimedInterruptSource {
public:
/// Modifies an register in the audio range; only the low 4 bits are
/// used for register decoding so it's assumed that the caller has
/// already identified this write as being to an audio register.
void write(uint16_t address, uint8_t value);
/// Returns a bitmask of interrupts that have become active since
/// the last time this method was called; flags are as defined in
/// @c Enterprise::Dave::Interrupt
uint8_t get_new_interrupts();
/// Returns the current high or low states of the inputs that trigger
/// the interrupts modelled here, as a bit mask compatible with that
/// exposed by Dave as the register at 0xb4.
uint8_t get_divider_state();
/// Advances the interrupt source.
void run_for(Cycles);
/// @returns The amount of time from now until the earliest that
/// @c get_new_interrupts() _might_ have new interrupts to report.
Cycles get_next_sequence_point() const;
private:
uint8_t interrupts_ = 0;
static constexpr Cycles clock_rate{250000};
static constexpr Cycles half_clock_rate{125000};
// Interrupts that have fired since get_new_interrupts()
// was last called.
uint8_t interrupts_ = 0;
// A counter for the 1Hz interrupt.
Cycles one_hz_offset_ = clock_rate;
// A counter specific to the 1kHz and 50Hz timers, if in use.
enum class InterruptRate {
OnekHz,
FiftyHz,
@ -145,6 +164,9 @@ class TimedInterruptSource {
int programmable_offset_ = programmble_reload(InterruptRate::OnekHz);
bool programmable_level_ = false;
// A local duplicate of the counting state of the first two audio
// channels, maintained in case either of those is used as an
// interrupt source.
struct Channel {
int value = 100, reload = 100;
bool sync = false;