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Merge pull request #173 from TomHarte/TimingFixes

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Corrects two misimplementations of the CPC's interrupt counter
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Thomas Harte 2017-08-04 09:06:42 -04:00 committed by GitHub
commit c2bb019381
2 changed files with 10 additions and 8 deletions
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3
Components/6845/CRTC6845.hpp
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@ -106,7 +106,8 @@ template <class T> class CRTC6845 {
// check for start of vertical sync // check for start of vertical sync
if(line_counter_ == registers_[7]) { if(line_counter_ == registers_[7]) {
bus_state_.vsync = true; bus_state_.vsync = true;
vsync_down_counter_ = 16; // TODO vsync_down_counter_ = registers_[3] >> 4;
if(!vsync_down_counter_) vsync_down_counter_ = 16;
} }
// check for entry into the overflow area // check for entry into the overflow area

15
Machines/AmstradCPC/AmstradCPC.cpp
View File

@ -30,9 +30,9 @@ class InterruptTimer {
InterruptTimer() : timer_(0), interrupt_request_(false) {} InterruptTimer() : timer_(0), interrupt_request_(false) {}
/*! /*!
Indicates that a new hsync pulse has been recognised. Per documentation Indicates that a new hsync pulse has been recognised. This should be
difficulties, it is not presently clear to me whether this should be supplied on the falling edge of the CRTC HSYNC signal, which is the
the leading or trailing edge of horizontal sync. trailing edge because it is active high.
*/ */
inline void signal_hsync() { inline void signal_hsync() {
// Increment the timer and if it has hit 52 then reset it and // Increment the timer and if it has hit 52 then reset it and
@ -49,7 +49,7 @@ class InterruptTimer {
if(reset_counter_) { if(reset_counter_) {
reset_counter_--; reset_counter_--;
if(!reset_counter_) { if(!reset_counter_) {
if(timer_ < 32) { if(timer_ & 32) {
interrupt_request_ = true; interrupt_request_ = true;
} }
timer_ = 0; timer_ = 0;
@ -76,6 +76,7 @@ class InterruptTimer {
/// Resets the timer. /// Resets the timer.
inline void reset_count() { inline void reset_count() {
timer_ = 0; timer_ = 0;
interrupt_request_ = false;
} }
private: private:
@ -504,8 +505,8 @@ class ConcreteMachine:
// will do as it's safe to conclude that nobody else has touched video RAM // will do as it's safe to conclude that nobody else has touched video RAM
// during that whole window // during that whole window
crtc_counter_ += cycle.length; crtc_counter_ += cycle.length;
int crtc_cycles = crtc_counter_.divide(HalfCycles(8)).as_int(); Cycles crtc_cycles = crtc_counter_.divide_cycles(Cycles(4));
if(crtc_cycles) crtc_.run_for(Cycles(1)); if(crtc_cycles > Cycles(0)) crtc_.run_for(crtc_cycles);
z80_.set_interrupt_line(interrupt_timer_.get_request()); z80_.set_interrupt_line(interrupt_timer_.get_request());
// TODO (in the player, not here): adapt it to accept an input clock rate and // TODO (in the player, not here): adapt it to accept an input clock rate and
@ -541,7 +542,7 @@ class ConcreteMachine:
read_pointers_[3] = (*cycle.value & 8) ? &ram_[49152] : basic_.data(); read_pointers_[3] = (*cycle.value & 8) ? &ram_[49152] : basic_.data();
// Reset the interrupt timer if requested. // Reset the interrupt timer if requested.
if(*cycle.value & 15) interrupt_timer_.reset_count(); if(*cycle.value & 0x10) interrupt_timer_.reset_count();
// Post the next mode. // Post the next mode.
crtc_bus_handler_.set_next_mode(*cycle.value & 3); crtc_bus_handler_.set_next_mode(*cycle.value & 3);