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397 lines
18 KiB
C++
397 lines
18 KiB
C++
//
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// CRT.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 19/07/2015.
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// Copyright © 2015 Thomas Harte. All rights reserved.
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//
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#include "CRT.hpp"
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#include "CRTOpenGL.hpp"
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#include <stdarg.h>
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#include <math.h>
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#include <algorithm>
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using namespace Outputs::CRT;
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void CRT::set_new_timing(unsigned int cycles_per_line, unsigned int height_of_display, ColourSpace colour_space, unsigned int colour_cycle_numerator, unsigned int colour_cycle_denominator, bool should_alternate) {
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openGL_output_builder_.set_colour_format(colour_space, colour_cycle_numerator, colour_cycle_denominator);
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const unsigned int syncCapacityLineChargeThreshold = 2;
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const unsigned int millisecondsHorizontalRetraceTime = 7; // source: Dictionary of Video and Television Technology, p. 234
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const unsigned int scanlinesVerticalRetraceTime = 10; // source: ibid
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// To quote:
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//
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// "retrace interval; The interval of time for the return of the blanked scanning beam of
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// a TV picture tube or camera tube to the starting point of a line or field. It is about 7 µs
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// for horizontal retrace and 500 to 750 µs for vertical retrace in NTSC and PAL TV."
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time_multiplier_ = IntermediateBufferWidth / cycles_per_line;
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phase_denominator_ = cycles_per_line * colour_cycle_denominator * time_multiplier_;
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phase_numerator_ = 0;
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colour_cycle_numerator_ = colour_cycle_numerator;
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phase_alternates_ = should_alternate;
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is_alernate_line_ &= phase_alternates_;
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cycles_per_line_ = cycles_per_line;
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unsigned int multiplied_cycles_per_line = cycles_per_line * time_multiplier_;
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// generate timing values implied by the given arguments
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sync_capacitor_charge_threshold_ = ((int)(syncCapacityLineChargeThreshold * cycles_per_line) * 3) / 4;
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// create the two flywheels
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horizontal_flywheel_.reset(new Flywheel(multiplied_cycles_per_line, (millisecondsHorizontalRetraceTime * multiplied_cycles_per_line) >> 6, multiplied_cycles_per_line >> 6));
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vertical_flywheel_.reset(new Flywheel(multiplied_cycles_per_line * height_of_display, scanlinesVerticalRetraceTime * multiplied_cycles_per_line, (multiplied_cycles_per_line * height_of_display) >> 3));
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// figure out the divisor necessary to get the horizontal flywheel into a 16-bit range
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unsigned int real_clock_scan_period = (multiplied_cycles_per_line * height_of_display) / (time_multiplier_ * common_output_divisor_);
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vertical_flywheel_output_divider_ = (uint16_t)(ceilf(real_clock_scan_period / 65536.0f) * (time_multiplier_ * common_output_divisor_));
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openGL_output_builder_.set_timing(cycles_per_line, multiplied_cycles_per_line, height_of_display, horizontal_flywheel_->get_scan_period(), vertical_flywheel_->get_scan_period(), vertical_flywheel_output_divider_);
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}
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void CRT::set_new_display_type(unsigned int cycles_per_line, DisplayType displayType) {
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switch(displayType) {
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case DisplayType::PAL50:
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set_new_timing(cycles_per_line, 312, ColourSpace::YUV, 709379, 2500, true); // i.e. 283.7516
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break;
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case DisplayType::NTSC60:
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set_new_timing(cycles_per_line, 262, ColourSpace::YIQ, 455, 2, false); // i.e. 227.5
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break;
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}
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}
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void CRT::set_composite_function_type(CompositeSourceType type, float offset_of_first_sample) {
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if(type == DiscreteFourSamplesPerCycle) {
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colour_burst_phase_adjustment_ = (uint8_t)(offset_of_first_sample * 256.0f) & 63;
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} else {
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colour_burst_phase_adjustment_ = 0xff;
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}
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}
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CRT::CRT(unsigned int common_output_divisor, unsigned int buffer_depth) :
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sync_capacitor_charge_level_(0),
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is_receiving_sync_(false),
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sync_period_(0),
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common_output_divisor_(common_output_divisor),
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is_writing_composite_run_(false),
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delegate_(nullptr),
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frames_since_last_delegate_call_(0),
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openGL_output_builder_(buffer_depth),
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is_alernate_line_(false) {}
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CRT::CRT(unsigned int cycles_per_line, unsigned int common_output_divisor, unsigned int height_of_display, ColourSpace colour_space, unsigned int colour_cycle_numerator, unsigned int colour_cycle_denominator, bool should_alternate, unsigned int buffer_depth) :
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CRT(common_output_divisor, buffer_depth) {
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set_new_timing(cycles_per_line, height_of_display, colour_space, colour_cycle_numerator, colour_cycle_denominator, should_alternate);
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}
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CRT::CRT(unsigned int cycles_per_line, unsigned int common_output_divisor, DisplayType displayType, unsigned int buffer_depth) :
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CRT(common_output_divisor, buffer_depth) {
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set_new_display_type(cycles_per_line, displayType);
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}
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#pragma mark - Sync loop
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Flywheel::SyncEvent CRT::get_next_vertical_sync_event(bool vsync_is_requested, unsigned int cycles_to_run_for, unsigned int *cycles_advanced) {
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return vertical_flywheel_->get_next_event_in_period(vsync_is_requested, cycles_to_run_for, cycles_advanced);
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}
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Flywheel::SyncEvent CRT::get_next_horizontal_sync_event(bool hsync_is_requested, unsigned int cycles_to_run_for, unsigned int *cycles_advanced) {
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return horizontal_flywheel_->get_next_event_in_period(hsync_is_requested, cycles_to_run_for, cycles_advanced);
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}
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#define output_x1() (*(uint16_t *)&next_run[OutputVertexOffsetOfHorizontal + 0])
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#define output_x2() (*(uint16_t *)&next_run[OutputVertexOffsetOfHorizontal + 2])
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#define output_position_y() (*(uint16_t *)&next_run[OutputVertexOffsetOfVertical + 0])
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#define output_tex_y() (*(uint16_t *)&next_run[OutputVertexOffsetOfVertical + 2])
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#define source_input_position_x1() (*(uint16_t *)&next_run[SourceVertexOffsetOfInputStart + 0])
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#define source_input_position_y() (*(uint16_t *)&next_run[SourceVertexOffsetOfInputStart + 2])
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#define source_input_position_x2() (*(uint16_t *)&next_run[SourceVertexOffsetOfEnds + 0])
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#define source_output_position_x1() (*(uint16_t *)&next_run[SourceVertexOffsetOfOutputStart + 0])
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#define source_output_position_y() (*(uint16_t *)&next_run[SourceVertexOffsetOfOutputStart + 2])
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#define source_output_position_x2() (*(uint16_t *)&next_run[SourceVertexOffsetOfEnds + 2])
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#define source_phase() next_run[SourceVertexOffsetOfPhaseTimeAndAmplitude + 0]
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#define source_amplitude() next_run[SourceVertexOffsetOfPhaseTimeAndAmplitude + 2]
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void CRT::advance_cycles(unsigned int number_of_cycles, bool hsync_requested, bool vsync_requested, const Scan::Type type) {
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std::unique_lock<std::mutex> output_lock = openGL_output_builder_.get_output_lock();
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number_of_cycles *= time_multiplier_;
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bool is_output_run = ((type == Scan::Type::Level) || (type == Scan::Type::Data));
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while(number_of_cycles) {
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unsigned int time_until_vertical_sync_event, time_until_horizontal_sync_event;
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Flywheel::SyncEvent next_vertical_sync_event = get_next_vertical_sync_event(vsync_requested, number_of_cycles, &time_until_vertical_sync_event);
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Flywheel::SyncEvent next_horizontal_sync_event = get_next_horizontal_sync_event(hsync_requested, time_until_vertical_sync_event, &time_until_horizontal_sync_event);
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// get the next sync event and its timing; hsync request is instantaneous (being edge triggered) so
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// set it to false for the next run through this loop (if any)
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unsigned int next_run_length = std::min(time_until_vertical_sync_event, time_until_horizontal_sync_event);
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phase_numerator_ += next_run_length * colour_cycle_numerator_;
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phase_numerator_ %= phase_denominator_;
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hsync_requested = false;
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vsync_requested = false;
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bool is_output_segment = ((is_output_run && next_run_length) && !horizontal_flywheel_->is_in_retrace() && !vertical_flywheel_->is_in_retrace());
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uint8_t *next_run = nullptr;
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if(is_output_segment && !openGL_output_builder_.composite_output_buffer_is_full()) {
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next_run = openGL_output_builder_.array_builder.get_input_storage(SourceVertexSize);
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}
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if(next_run) {
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// output_y and texture locations will be written later; we won't necessarily know what it is outside of the locked region
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source_output_position_x1() = (uint16_t)horizontal_flywheel_->get_current_output_position();
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source_phase() = colour_burst_phase_;
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source_amplitude() = colour_burst_amplitude_;
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}
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// decrement the number of cycles left to run for and increment the
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// horizontal counter appropriately
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number_of_cycles -= next_run_length;
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// react to the incoming event...
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horizontal_flywheel_->apply_event(next_run_length, (next_run_length == time_until_horizontal_sync_event) ? next_horizontal_sync_event : Flywheel::SyncEvent::None);
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vertical_flywheel_->apply_event(next_run_length, (next_run_length == time_until_vertical_sync_event) ? next_vertical_sync_event : Flywheel::SyncEvent::None);
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if(next_run) {
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source_output_position_x2() = (uint16_t)horizontal_flywheel_->get_current_output_position();
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}
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// if this is horizontal retrace then advance the output line counter and bookend an output run
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Flywheel::SyncEvent honoured_event = Flywheel::SyncEvent::None;
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if(next_run_length == time_until_vertical_sync_event && next_vertical_sync_event != Flywheel::SyncEvent::None) honoured_event = next_vertical_sync_event;
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if(next_run_length == time_until_horizontal_sync_event && next_horizontal_sync_event != Flywheel::SyncEvent::None) honoured_event = next_horizontal_sync_event;
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bool needs_endpoint =
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(honoured_event == Flywheel::SyncEvent::StartRetrace && is_writing_composite_run_) ||
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(honoured_event == Flywheel::SyncEvent::EndRetrace && !horizontal_flywheel_->is_in_retrace() && !vertical_flywheel_->is_in_retrace());
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if(next_run_length == time_until_horizontal_sync_event && next_horizontal_sync_event == Flywheel::SyncEvent::StartRetrace) is_alernate_line_ ^= phase_alternates_;
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if(needs_endpoint) {
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if(
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!openGL_output_builder_.array_builder.is_full() &&
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!openGL_output_builder_.composite_output_buffer_is_full()) {
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if(!is_writing_composite_run_) {
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output_run_.x1 = (uint16_t)horizontal_flywheel_->get_current_output_position();
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output_run_.y = (uint16_t)(vertical_flywheel_->get_current_output_position() / vertical_flywheel_output_divider_);
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} else {
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// Get and write all those previously unwritten output ys
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const uint16_t output_y = openGL_output_builder_.get_composite_output_y();
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// Construct the output run
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uint8_t *next_run = openGL_output_builder_.array_builder.get_output_storage(OutputVertexSize);
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if(next_run) {
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output_x1() = output_run_.x1;
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output_position_y() = output_run_.y;
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output_tex_y() = output_y;
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output_x2() = (uint16_t)horizontal_flywheel_->get_current_output_position();
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}
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openGL_output_builder_.array_builder.flush(
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[output_y, this] (uint8_t *input_buffer, size_t input_size, uint8_t *output_buffer, size_t output_size) {
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openGL_output_builder_.texture_builder.flush(
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[output_y, input_buffer] (const std::vector<TextureBuilder::WriteArea> &write_areas, size_t number_of_write_areas) {
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for(size_t run = 0; run < number_of_write_areas; run++) {
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*(uint16_t *)&input_buffer[run * SourceVertexSize + SourceVertexOffsetOfInputStart + 0] = write_areas[run].x;
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*(uint16_t *)&input_buffer[run * SourceVertexSize + SourceVertexOffsetOfInputStart + 2] = write_areas[run].y;
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*(uint16_t *)&input_buffer[run * SourceVertexSize + SourceVertexOffsetOfEnds + 0] = write_areas[run].x + write_areas[run].length;
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}
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});
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for(size_t position = 0; position < input_size; position += SourceVertexSize) {
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(*(uint16_t *)&input_buffer[position + SourceVertexOffsetOfOutputStart + 2]) = output_y;
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}
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});
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colour_burst_amplitude_ = 0;
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}
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is_writing_composite_run_ ^= true;
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}
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}
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if(next_run_length == time_until_horizontal_sync_event && next_horizontal_sync_event == Flywheel::SyncEvent::StartRetrace) {
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openGL_output_builder_.increment_composite_output_y();
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}
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// if this is vertical retrace then adcance a field
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if(next_run_length == time_until_vertical_sync_event && next_vertical_sync_event == Flywheel::SyncEvent::EndRetrace) {
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if(delegate_) {
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frames_since_last_delegate_call_++;
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if(frames_since_last_delegate_call_ == 20) {
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output_lock.unlock();
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delegate_->crt_did_end_batch_of_frames(this, frames_since_last_delegate_call_, vertical_flywheel_->get_and_reset_number_of_surprises());
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output_lock.lock();
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frames_since_last_delegate_call_ = 0;
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}
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}
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}
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}
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}
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#undef output_x1
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#undef output_x2
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#undef output_position_y
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#undef output_tex_y
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#undef source_input_position_x1
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#undef source_input_position_y
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#undef source_input_position_x2
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#undef source_output_position_x1
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#undef source_output_position_y
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#undef source_output_position_x2
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#undef source_phase
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#undef source_amplitude
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#undef source_phase_time
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#pragma mark - stream feeding methods
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void CRT::output_scan(const Scan *const scan) {
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const bool this_is_sync = (scan->type == Scan::Type::Sync);
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const bool is_leading_edge = (!is_receiving_sync_ && this_is_sync);
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is_receiving_sync_ = this_is_sync;
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// Accumulate: (i) a total of the amount of time in sync; and (ii) the amount of time since sync.
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if(this_is_sync) { cycles_of_sync_ += scan->number_of_cycles; cycles_since_sync_ = 0; }
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else cycles_since_sync_ += scan->number_of_cycles;
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bool vsync_requested = false;
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// If it has been at least half a line since sync ended, then it is safe to decide whether what ended
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// was vertical sync.
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if(cycles_since_sync_ > (cycles_per_line_ >> 1)) {
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// If it was vertical sync, set that flag. If it wasn't, clear the summed amount of sync to avoid
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// a mistaken vertical sync due to an aggregate of horizontals.
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vsync_requested = (cycles_of_sync_ > sync_capacitor_charge_threshold_);
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if(vsync_requested || cycles_of_sync_ < (cycles_per_line_ >> 2))
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cycles_of_sync_ = 0;
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}
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// This introduces a blackout period close to the expected vertical sync point in which horizontal syncs are not
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// recognised, effectively causing the horizontal flywheel to freewheel during that period. This attempts to seek
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// the problem that vertical sync otherwise often starts halfway through a scanline, which confuses the horizontal
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// flywheel. I'm currently unclear whether this is an accurate solution to this problem.
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const bool hsync_requested = is_leading_edge && !vertical_flywheel_->is_near_expected_sync();
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// simplified colour burst logic: if it's within the back porch we'll take it
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if(scan->type == Scan::Type::ColourBurst) {
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if(!colour_burst_amplitude_ && horizontal_flywheel_->get_current_time() < (horizontal_flywheel_->get_standard_period() * 12) >> 6) {
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unsigned int position_phase = (horizontal_flywheel_->get_current_time() * colour_cycle_numerator_ * 256) / phase_denominator_;
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colour_burst_phase_ = (position_phase + scan->phase) & 255;
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colour_burst_amplitude_ = scan->amplitude;
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if(colour_burst_phase_adjustment_ != 0xff)
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colour_burst_phase_ = (colour_burst_phase_ & ~63) + colour_burst_phase_adjustment_;
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}
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}
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// TODO: inspect raw data for potential colour burst if required
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sync_period_ = is_receiving_sync_ ? (sync_period_ + scan->number_of_cycles) : 0;
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advance_cycles(scan->number_of_cycles, hsync_requested, vsync_requested, scan->type);
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}
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/*
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These all merely channel into advance_cycles, supplying appropriate arguments
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*/
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void CRT::output_sync(unsigned int number_of_cycles) {
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Scan scan{
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.type = Scan::Type::Sync,
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.number_of_cycles = number_of_cycles
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};
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output_scan(&scan);
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}
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void CRT::output_blank(unsigned int number_of_cycles) {
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Scan scan {
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.type = Scan::Type::Blank,
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.number_of_cycles = number_of_cycles
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};
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output_scan(&scan);
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}
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void CRT::output_level(unsigned int number_of_cycles) {
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Scan scan {
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.type = Scan::Type::Level,
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.number_of_cycles = number_of_cycles,
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};
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output_scan(&scan);
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}
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void CRT::output_colour_burst(unsigned int number_of_cycles, uint8_t phase, uint8_t amplitude) {
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Scan scan {
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.type = Scan::Type::ColourBurst,
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.number_of_cycles = number_of_cycles,
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.phase = phase,
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.amplitude = amplitude
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};
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output_scan(&scan);
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}
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void CRT::output_default_colour_burst(unsigned int number_of_cycles) {
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Scan scan {
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.type = Scan::Type::ColourBurst,
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.number_of_cycles = number_of_cycles,
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.phase = (uint8_t)((phase_numerator_ * 256) / phase_denominator_ + (is_alernate_line_ ? 128 : 0)),
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.amplitude = 32
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};
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output_scan(&scan);
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}
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void CRT::output_data(unsigned int number_of_cycles, unsigned int source_divider) {
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openGL_output_builder_.texture_builder.reduce_previous_allocation_to(number_of_cycles / source_divider);
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Scan scan {
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.type = Scan::Type::Data,
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.number_of_cycles = number_of_cycles,
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};
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output_scan(&scan);
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}
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Outputs::CRT::Rect CRT::get_rect_for_area(int first_line_after_sync, int number_of_lines, int first_cycle_after_sync, int number_of_cycles, float aspect_ratio) {
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first_cycle_after_sync *= time_multiplier_;
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number_of_cycles *= time_multiplier_;
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first_line_after_sync -= 2;
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number_of_lines += 4;
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// determine prima facie x extent
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unsigned int horizontal_period = horizontal_flywheel_->get_standard_period();
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unsigned int horizontal_scan_period = horizontal_flywheel_->get_scan_period();
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unsigned int horizontal_retrace_period = horizontal_period - horizontal_scan_period;
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// make sure that the requested range is visible
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if(first_cycle_after_sync < horizontal_retrace_period) first_cycle_after_sync = (int)horizontal_retrace_period;
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if(first_cycle_after_sync + number_of_cycles > horizontal_scan_period) number_of_cycles = (int)(horizontal_scan_period - (unsigned)first_cycle_after_sync);
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float start_x = (float)((unsigned)first_cycle_after_sync - horizontal_retrace_period) / (float)horizontal_scan_period;
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float width = (float)number_of_cycles / (float)horizontal_scan_period;
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// determine prima facie y extent
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unsigned int vertical_period = vertical_flywheel_->get_standard_period();
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unsigned int vertical_scan_period = vertical_flywheel_->get_scan_period();
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unsigned int vertical_retrace_period = vertical_period - vertical_scan_period;
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// make sure that the requested range is visible
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// if((unsigned)first_line_after_sync * horizontal_period < vertical_retrace_period)
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// first_line_after_sync = (vertical_retrace_period + horizontal_period - 1) / horizontal_period;
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// if((first_line_after_sync + number_of_lines) * horizontal_period > vertical_scan_period)
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// number_of_lines = (int)(horizontal_scan_period - (unsigned)first_cycle_after_sync);
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float start_y = (float)(((unsigned)first_line_after_sync * horizontal_period) - vertical_retrace_period) / (float)vertical_scan_period;
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float height = (float)((unsigned)number_of_lines * horizontal_period) / vertical_scan_period;
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// adjust to ensure aspect ratio is correct
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float adjusted_aspect_ratio = (3.0f*aspect_ratio / 4.0f);
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float ideal_width = height * adjusted_aspect_ratio;
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if(ideal_width > width) {
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start_x -= (ideal_width - width) * 0.5f;
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width = ideal_width;
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} else {
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float ideal_height = width / adjusted_aspect_ratio;
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start_y -= (ideal_height - height) * 0.5f;
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height = ideal_height;
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}
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return Rect(start_x, start_y, width, height);
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}
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