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Started attempting to move total responsibility for display-related interrupts and RAM timing into the video.

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This commit is contained in:
Thomas Harte 2016-12-11 18:34:49 -05:00
parent c5cf8d9531
commit be7e05e109
4 changed files with 146 additions and 103 deletions
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123
Machines/Electron/Electron.cpp
View File

@ -12,37 +12,15 @@
#include <algorithm>
#include <cassert>
namespace {
static const unsigned int cycles_per_line = 128;
static const unsigned int lines_per_frame = 625;
static const unsigned int cycles_per_frame = lines_per_frame * cycles_per_line;
static const unsigned int crt_cycles_multiplier = 8;
static const unsigned int crt_cycles_per_line = crt_cycles_multiplier * cycles_per_line;
static const unsigned int field_divider_line = 312; // i.e. the line, simultaneous with which, the first field's sync ends. So if
// the first line with pixels in field 1 is the 20th in the frame, the first line
// with pixels in field 2 will be 20+field_divider_line
static const unsigned int first_graphics_line = 31;
static const unsigned int first_graphics_cycle = 33;
static const unsigned int display_end_interrupt_line = 256;
static const unsigned int real_time_clock_interrupt_1 = 16704;
static const unsigned int real_time_clock_interrupt_2 = 56704;
}
using namespace Electron;
#define graphics_line(v) ((((v) >> 7) - first_graphics_line + field_divider_line) % field_divider_line)
#define graphics_column(v) ((((v) & 127) - first_graphics_cycle + 128) & 127)
Machine::Machine() :
interrupt_control_(0),
interrupt_status_(Interrupt::PowerOnReset | Interrupt::TransmitDataEmpty | 0x80),
frame_cycles_(0),
display_output_position_(0),
audio_output_position_(0),
use_fast_tape_hack_(false)
cycles_since_display_update_(0),
cycles_since_audio_update_(0),
use_fast_tape_hack_(false),
cycles_until_display_interrupt_(0)
{
memset(key_states_, 0, sizeof(key_states_));
for(int c = 0; c < 16; c++)
@ -80,27 +58,13 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
}
else
{
if(
(
((frame_cycles_ >= first_graphics_line * cycles_per_line) && (frame_cycles_ < (first_graphics_line + 256) * cycles_per_line)) ||
((frame_cycles_ >= (first_graphics_line + field_divider_line) * cycles_per_line) && (frame_cycles_ < (first_graphics_line + 256 + field_divider_line) * cycles_per_line))
)
)
update_display();
update_display();
ram_[address] = *value;
}
// for the entire frame, RAM is accessible only on odd cycles; in modes below 4
// it's also accessible only outside of the pixel regions
cycles += 1 + (frame_cycles_&1);
// if(screen_mode_ < 4)
// {
// const int current_line = graphics_line(frame_cycles_ + (frame_cycles_&1));
// const int current_column = graphics_column(frame_cycles_ + (frame_cycles_&1));
// if(current_line < 256 && current_column < 80 && !is_blank_line_)
// cycles += (unsigned int)(80 - current_column);
// }
cycles += video_output_->get_cycles_until_next_ram_availability(cycles_since_display_update_ + 1);
}
else
{
@ -145,6 +109,7 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
{
update_display();
video_output_->set_register(address, *value);
queue_next_display_interrupt();
}
break;
case 0xfe04:
@ -320,53 +285,19 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
}
}
// const int end_of_field =
// if(frame_cycles_ < (256 + first_graphics_line) << 7))
const unsigned int pixel_line_clock = frame_cycles_;// + 128 - first_graphics_cycle + 80;
const unsigned int line_before_cycle = graphics_line(pixel_line_clock);
const unsigned int line_after_cycle = graphics_line(pixel_line_clock + cycles);
// implicit assumption here: the number of 2Mhz cycles this bus operation will take
// is never longer than a line. On the Electron, it's a safe one.
if(line_before_cycle != line_after_cycle)
{
switch(line_before_cycle)
{
// case real_time_clock_interrupt_line: signal_interrupt(Interrupt::RealTimeClock); break;
// case real_time_clock_interrupt_line+1: clear_interrupt(Interrupt::RealTimeClock); break;
case display_end_interrupt_line: signal_interrupt(Interrupt::DisplayEnd); break;
// case display_end_interrupt_line+1: clear_interrupt(Interrupt::DisplayEnd); break;
}
}
if(
(pixel_line_clock < real_time_clock_interrupt_1 && pixel_line_clock + cycles >= real_time_clock_interrupt_1) ||
(pixel_line_clock < real_time_clock_interrupt_2 && pixel_line_clock + cycles >= real_time_clock_interrupt_2))
{
signal_interrupt(Interrupt::RealTimeClock);
}
frame_cycles_ += cycles;
// deal with frame wraparound by updating the two dependent subsystems
// as though the exact end of frame had been hit, then reset those
// and allow the frame cycle counter to assume its real value
if(frame_cycles_ >= cycles_per_frame)
{
unsigned int nextFrameCycles = frame_cycles_ - cycles_per_frame;
frame_cycles_ = cycles_per_frame;
update_display();
update_audio();
display_output_position_ = 0;
audio_output_position_ = 0;
frame_cycles_ = nextFrameCycles;
}
if(!(frame_cycles_&16383))
update_audio();
cycles_since_display_update_ += cycles;
cycles_since_audio_update_ += cycles;
if(cycles_since_audio_update_ > 16384) update_audio();
tape_.run_for_cycles(cycles);
cycles_until_display_interrupt_ -= cycles;
if(cycles_until_display_interrupt_ < 0)
{
signal_interrupt(next_display_interrupt_);
update_display();
queue_next_display_interrupt();
}
if(typer_) typer_->update((int)cycles);
if(plus3_) plus3_->run_for_cycles(4*cycles);
@ -473,16 +404,22 @@ inline void Machine::evaluate_interrupts()
inline void Machine::update_display()
{
video_output_->run_for_cycles((int)(frame_cycles_ - display_output_position_));
display_output_position_ = frame_cycles_;
video_output_->run_for_cycles((int)cycles_since_display_update_);
cycles_since_display_update_ = 0;
}
inline void Machine::queue_next_display_interrupt()
{
VideoOutput::Interrupt next_interrupt = video_output_->get_next_interrupt();
cycles_until_display_interrupt_ = next_interrupt.cycles;
next_display_interrupt_ = next_interrupt.interrupt;
}
inline void Machine::update_audio()
{
unsigned int difference = frame_cycles_ - audio_output_position_ + audio_output_position_error_;
audio_output_position_ = frame_cycles_;
speaker_->run_for_cycles(difference / Speaker::clock_rate_divider);
audio_output_position_error_ = difference % Speaker::clock_rate_divider;
unsigned int difference = cycles_since_audio_update_ / Speaker::clock_rate_divider;
cycles_since_audio_update_ %= Speaker::clock_rate_divider;
speaker_->run_for_cycles(difference);
}
void Machine::clear_all_keys()

7
Machines/Electron/Electron.hpp
View File

@ -108,6 +108,7 @@ class Machine:
private:
inline void update_display();
inline void queue_next_display_interrupt();
inline void update_audio();
inline void signal_interrupt(Interrupt interrupt);
@ -129,8 +130,10 @@ class Machine:
uint8_t key_states_[14];
// Counters related to simultaneous subsystems
unsigned int frame_cycles_, display_output_position_;
unsigned int audio_output_position_, audio_output_position_error_;
unsigned int cycles_since_display_update_;
unsigned int cycles_since_audio_update_;
int cycles_until_display_interrupt_;
Interrupt next_display_interrupt_;
// Tape
Tape tape_;

112
Machines/Electron/Video.cpp
View File

@ -10,6 +10,9 @@
using namespace Electron;
#define graphics_line(v) ((((v) >> 7) - first_graphics_line + field_divider_line) % field_divider_line)
#define graphics_column(v) ((((v) & 127) - first_graphics_cycle + 128) & 127)
namespace {
static const unsigned int cycles_per_line = 128;
static const unsigned int lines_per_frame = 625;
@ -23,10 +26,12 @@ namespace {
static const unsigned int first_graphics_line = 31;
static const unsigned int first_graphics_cycle = 33;
static const unsigned int display_end_interrupt_line = 256;
static const int display_end_interrupt_line = 256;
static const unsigned int real_time_clock_interrupt_1 = 16704;
static const unsigned int real_time_clock_interrupt_2 = 56704;
static const int real_time_clock_interrupt_1 = 16704;
static const int real_time_clock_interrupt_2 = 56704;
static const int display_end_interrupt_1 = (first_graphics_line + display_end_interrupt_line)*cycles_per_line;
static const int display_end_interrupt_2 = (first_graphics_line + field_divider_line + display_end_interrupt_line)*cycles_per_line;
}
VideoOutput::VideoOutput(uint8_t *memory) :
@ -481,12 +486,105 @@ void VideoOutput::set_register(int address, uint8_t value)
#pragma mark - Interrupts
int VideoOutput::get_cycles_until_next_interrupt()
//int VideoOutput::get_cycles_until_next_interrupt()
//{
// const int end_of_field =
// if(frame_cycles_ < (256 + first_graphics_line) << 7))
// const unsigned int pixel_line_clock = frame_cycles_;// + 128 - first_graphics_cycle + 80;
// const unsigned int line_before_cycle = graphics_line(pixel_line_clock);
// const unsigned int line_after_cycle = graphics_line(pixel_line_clock + cycles);
// implicit assumption here: the number of 2Mhz cycles this bus operation will take
// is never longer than a line. On the Electron, it's a safe one.
// if(line_before_cycle != line_after_cycle)
// {
// switch(line_before_cycle)
// {
// case real_time_clock_interrupt_line: signal_interrupt(Interrupt::RealTimeClock); break;
// case real_time_clock_interrupt_line+1: clear_interrupt(Interrupt::RealTimeClock); break;
// case display_end_interrupt_line: signal_interrupt(Interrupt::DisplayEnd); break;
// case display_end_interrupt_line+1: clear_interrupt(Interrupt::DisplayEnd); break;
// }
// }
// if(
// (pixel_line_clock < real_time_clock_interrupt_1 && pixel_line_clock + cycles >= real_time_clock_interrupt_1) ||
// (pixel_line_clock < real_time_clock_interrupt_2 && pixel_line_clock + cycles >= real_time_clock_interrupt_2))
// {
// signal_interrupt(Interrupt::RealTimeClock);
// }
// frame_cycles_ += cycles;
// deal with frame wraparound by updating the two dependent subsystems
// as though the exact end of frame had been hit, then reset those
// and allow the frame cycle counter to assume its real value
// if(frame_cycles_ >= cycles_per_frame)
// {
// unsigned int nextFrameCycles = frame_cycles_ - cycles_per_frame;
// frame_cycles_ = cycles_per_frame;
// update_display();
// update_audio();
// display_output_position_ = 0;
// audio_output_position_ = 0;
// frame_cycles_ = nextFrameCycles;
// }
// if(!(frame_cycles_&16383))
// update_audio();
// return 0;
//}
VideoOutput::Interrupt VideoOutput::get_next_interrupt()
{
return 0;
VideoOutput::Interrupt interrupt;
if(output_position_ < real_time_clock_interrupt_1)
{
interrupt.cycles = real_time_clock_interrupt_1 - output_position_;
interrupt.interrupt = RealTimeClock;
return interrupt;
}
if(output_position_ < display_end_interrupt_1)
{
interrupt.cycles = display_end_interrupt_1 - output_position_;
interrupt.interrupt = DisplayEnd;
return interrupt;
}
if(output_position_ < real_time_clock_interrupt_2)
{
interrupt.cycles = real_time_clock_interrupt_2 - output_position_;
interrupt.interrupt = RealTimeClock;
return interrupt;
}
if(output_position_ < display_end_interrupt_2)
{
interrupt.cycles = display_end_interrupt_2 - output_position_;
interrupt.interrupt = DisplayEnd;
return interrupt;
}
interrupt.cycles = real_time_clock_interrupt_1 + cycles_per_frame - output_position_;
interrupt.interrupt = RealTimeClock;
return interrupt;
}
Interrupt VideoOutput::get_next_interrupt()
#pragma mark - RAM timing
unsigned int VideoOutput::get_cycles_until_next_ram_availability(unsigned int from_time)
{
return DisplayEnd;
unsigned int result = 0;
// cycles += 1 + (frame_cycles_&1);
// if(screen_mode_ < 4)
// {
// const int current_line = graphics_line(frame_cycles_ + (frame_cycles_&1));
// const int current_column = graphics_column(frame_cycles_ + (frame_cycles_&1));
// if(current_line < 256 && current_column < 80 && !is_blank_line_)
// cycles += (unsigned int)(80 - current_column);
// }
return result;
}

7
Machines/Electron/Video.hpp
View File

@ -20,11 +20,16 @@ class VideoOutput {
std::shared_ptr<Outputs::CRT::CRT> get_crt();
void run_for_cycles(int number_of_cycles);
int get_cycles_until_next_interrupt();
struct Interrupt {
Electron::Interrupt interrupt;
int cycles;
};
Interrupt get_next_interrupt();
void set_register(int address, uint8_t value);
unsigned int get_cycles_until_next_ram_availability(unsigned int from_time);
private:
inline void start_pixel_line();
inline void end_pixel_line();