From 635e18a50d2cbaee0ee6279930f19aebc23b40f6 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 30 Oct 2019 22:42:06 -0400
Subject: [PATCH] Ensures the MFP requests and receives real-time clocking when
needed.
---
Components/68901/MFP68901.cpp | 77 ++++++++++++++++++++---------------
Components/68901/MFP68901.hpp | 8 +++-
Machines/AtariST/AtariST.cpp | 26 +++++++++---
3 files changed, 71 insertions(+), 40 deletions(-)
diff --git a/Components/68901/MFP68901.cpp b/Components/68901/MFP68901.cpp
index fd5bf1133..6c9f211e8 100644
--- a/Components/68901/MFP68901.cpp
+++ b/Components/68901/MFP68901.cpp
@@ -16,6 +16,17 @@
using namespace Motorola::MFP68901;
+ClockingHint::Preference MFP68901::preferred_clocking() {
+ // Rule applied: if any timer is actively running and permitted to produce an
+ // interrupt, request real-time running.
+ return
+ (timers_[0].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerA) ||
+ (timers_[1].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerB) ||
+ (timers_[2].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerC) ||
+ (timers_[3].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerD)
+ ? ClockingHint::Preference::RealTime : ClockingHint::Preference::JustInTime;
+}
+
uint8_t MFP68901::read(int address) {
address &= 0x1f;
@@ -94,9 +105,14 @@ void MFP68901::write(int address, uint8_t value) {
// Whatever just happened may have affected the state of the interrupt line.
update_interrupts();
+ update_clocking_observer();
return;
}
+ const int timer_prescales[] = {
+ 1, 4, 10, 16, 50, 64, 100, 200
+ };
+
switch(address) {
// GPIP block: output and configuration of active edge and direction values.
case 0x00:
@@ -141,26 +157,8 @@ void MFP68901::write(int address, uint8_t value) {
} break;
case 0x0e:
timer_cd_control_ = value;
- switch(value & 7) {
- case 0: set_timer_mode(3, TimerMode::Stopped, 1, false); break;
- case 1: set_timer_mode(3, TimerMode::Delay, 4, false); break;
- case 2: set_timer_mode(3, TimerMode::Delay, 10, false); break;
- case 3: set_timer_mode(3, TimerMode::Delay, 16, false); break;
- case 4: set_timer_mode(3, TimerMode::Delay, 50, false); break;
- case 5: set_timer_mode(3, TimerMode::Delay, 64, false); break;
- case 6: set_timer_mode(3, TimerMode::Delay, 100, false); break;
- case 7: set_timer_mode(3, TimerMode::Delay, 200, false); break;
- }
- switch((value >> 4) & 7) {
- case 0: set_timer_mode(2, TimerMode::Stopped, 1, false); break;
- case 1: set_timer_mode(2, TimerMode::Delay, 4, false); break;
- case 2: set_timer_mode(2, TimerMode::Delay, 10, false); break;
- case 3: set_timer_mode(2, TimerMode::Delay, 16, false); break;
- case 4: set_timer_mode(2, TimerMode::Delay, 50, false); break;
- case 5: set_timer_mode(2, TimerMode::Delay, 64, false); break;
- case 6: set_timer_mode(2, TimerMode::Delay, 100, false); break;
- case 7: set_timer_mode(2, TimerMode::Delay, 200, false); break;
- }
+ set_timer_mode(3, (value & 7) ? TimerMode::Delay : TimerMode::Stopped, timer_prescales[value & 7], false);
+ set_timer_mode(2, ((value >> 4) & 7) ? TimerMode::Delay : TimerMode::Stopped, timer_prescales[(value >> 4) & 7], false);
break;
case 0x0f: case 0x10: case 0x11: case 0x12:
set_timer_data(address - 0xf, value);
@@ -173,6 +171,8 @@ void MFP68901::write(int address, uint8_t value) {
case 0x16: LOG("Write: transmitter status"); break;
case 0x17: LOG("Write: USART data"); break;
}
+
+ update_clocking_observer();
}
void MFP68901::run_for(HalfCycles time) {
@@ -186,11 +186,20 @@ void MFP68901::run_for(HalfCycles time) {
--timers_[c].divisor;
if(!timers_[c].divisor) {
timers_[c].divisor = timers_[c].prescale;
- decrement_timer(c);
+ decrement_timer(c, 1);
}
}
}
}
+// const int cycles = int(cycles_left_.flush<Cycles>().as_integral());
+// for(int c = 0; c < 4; ++c) {
+// if(timers_[c].mode >= TimerMode::Delay) {
+// const int dividend = (cycles + timers_[c].prescale - timers_[c].divisor);
+// const int decrements = dividend / timers_[c].prescale;
+// timers_[c].divisor = timers_[c].prescale - (dividend % timers_[c].prescale);
+// if(decrements) decrement_timer(c, decrements);
+// }
+// }
}
HalfCycles MFP68901::get_next_sequence_point() {
@@ -224,21 +233,23 @@ void MFP68901::set_timer_event_input(int channel, bool value) {
timers_[channel].event_input = value;
if(timers_[channel].mode == TimerMode::EventCount && !value) { /* TODO: which edge is counted? "as defined by the associated Interrupt Channel’s edge bit"? */
- decrement_timer(channel);
+ decrement_timer(channel, 1);
}
}
-void MFP68901::decrement_timer(int timer) {
- --timers_[timer].value;
- if(!timers_[timer].value) {
- switch(timer) {
- case 0: begin_interrupts(Interrupt::TimerA); break;
- case 1: begin_interrupts(Interrupt::TimerB); break;
- case 2: begin_interrupts(Interrupt::TimerC); break;
- case 3: begin_interrupts(Interrupt::TimerD); break;
- }
- if(timers_[timer].mode == TimerMode::Delay) {
- timers_[timer].value = timers_[timer].reload_value;
+void MFP68901::decrement_timer(int timer, int amount) {
+ while(amount--) {
+ --timers_[timer].value;
+ if(timers_[timer].value < 1) {
+ switch(timer) {
+ case 0: begin_interrupts(Interrupt::TimerA); break;
+ case 1: begin_interrupts(Interrupt::TimerB); break;
+ case 2: begin_interrupts(Interrupt::TimerC); break;
+ case 3: begin_interrupts(Interrupt::TimerD); break;
+ }
+ if(timers_[timer].mode == TimerMode::Delay) {
+ timers_[timer].value += timers_[timer].reload_value; // TODO: properly.
+ }
}
}
}
diff --git a/Components/68901/MFP68901.hpp b/Components/68901/MFP68901.hpp
index 88b423afa..a9d4325ff 100644
--- a/Components/68901/MFP68901.hpp
+++ b/Components/68901/MFP68901.hpp
@@ -11,6 +11,7 @@
#include <cstdint>
#include "../../ClockReceiver/ClockReceiver.hpp"
+#include "../../ClockReceiver/ClockingHintSource.hpp"
namespace Motorola {
namespace MFP68901 {
@@ -20,7 +21,7 @@ class PortHandler {
// TODO: announce changes in output.
};
-class MFP68901 {
+class MFP68901: public ClockingHint::Source {
public:
uint8_t read(int address);
void write(int address, uint8_t value);
@@ -42,6 +43,9 @@ class MFP68901 {
};
void set_interrupt_delegate(InterruptDelegate *delegate);
+ // ClockingHint::Source.
+ ClockingHint::Preference preferred_clocking() final;
+
private:
// MARK: - Timers
enum class TimerMode {
@@ -50,7 +54,7 @@ class MFP68901 {
void set_timer_mode(int timer, TimerMode, int prescale, bool reset_timer);
void set_timer_data(int timer, uint8_t);
uint8_t get_timer_data(int timer);
- void decrement_timer(int timer);
+ void decrement_timer(int timer, int amount);
struct Timer {
TimerMode mode = TimerMode::Stopped;
diff --git a/Machines/AtariST/AtariST.cpp b/Machines/AtariST/AtariST.cpp
index 047b504cf..338ea7283 100644
--- a/Machines/AtariST/AtariST.cpp
+++ b/Machines/AtariST/AtariST.cpp
@@ -278,6 +278,7 @@ class ConcreteMachine:
midi_acia_->set_clocking_hint_observer(this);
keyboard_acia_->set_clocking_hint_observer(this);
ikbd_.set_clocking_hint_observer(this);
+ mfp_->set_clocking_hint_observer(this);
mfp_->set_interrupt_delegate(this);
dma_->set_interrupt_delegate(this);
@@ -573,22 +574,34 @@ class ConcreteMachine:
private:
forceinline void advance_time(HalfCycles length) {
+ // Advance the relevant counters.
cycles_since_audio_update_ += length;
mfp_ += length;
dma_ += length;
-
keyboard_acia_ += length;
midi_acia_ += length;
- if(!may_defer_acias_) {
- keyboard_acia_.flush();
- midi_acia_.flush();
- }
+ // Don't even count time for the keyboard unless it has requested it.
if(keyboard_needs_clock_) {
cycles_since_ikbd_update_ += length;
ikbd_.run_for(cycles_since_ikbd_update_.divide(HalfCycles(512)));
}
+ // Flush anything that needs real-time updating.
+ if(!may_defer_acias_) {
+ keyboard_acia_.flush();
+ midi_acia_.flush();
+ }
+
+ if(mfp_is_realtime_) {
+ mfp_.flush();
+ }
+
+ if(dma_is_realtime_) {
+ dma_.flush();
+ }
+
+ // Update the video output, checking whether a sequence point has been hit.
while(length >= cycles_until_video_event_) {
length -= cycles_until_video_event_;
video_ += cycles_until_video_event_;
@@ -635,6 +648,8 @@ class ConcreteMachine:
// MARK: - Clocking Management.
bool may_defer_acias_ = true;
bool keyboard_needs_clock_ = false;
+ bool mfp_is_realtime_ = false;
+ bool dma_is_realtime_ = false;
void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference clocking) final {
// This is being called by one of the components; avoid any time flushing here as that's
// already dealt with (and, just to be absolutely sure, to avoid recursive mania).
@@ -642,6 +657,7 @@ class ConcreteMachine:
(keyboard_acia_.last_valid()->preferred_clocking() != ClockingHint::Preference::RealTime) &&
(midi_acia_.last_valid()->preferred_clocking() != ClockingHint::Preference::RealTime);
keyboard_needs_clock_ = ikbd_.preferred_clocking() != ClockingHint::Preference::None;
+ mfp_is_realtime_ = mfp_.last_valid()->preferred_clocking() == ClockingHint::Preference::RealTime;
}
// MARK: - GPIP input.