mirror of
https://github.com/TomHarte/CLK.git
synced 2024-07-07 23:29:06 +00:00
0c65385c82
I now understand, hopefully, that it's only the phase of the second colour component that alternates. That has the pointwise effect of reversing the colour signal. Hence the effect of phase errors cancelling themselves out up on successive lines up to a point.
441 lines
20 KiB
C++
441 lines
20 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 "Internals/CRTOpenGL.hpp"
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#include <cstdarg>
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#include <cmath>
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#include <algorithm>
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#include <cassert>
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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, unsigned int vertical_sync_half_lines, 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 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
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// 7 microseconds for horizontal retrace and 500 to 750 microseconds for vertical retrace
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// 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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// allow sync to be detected (and acted upon) a line earlier than the specified requirement,
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// as a simple way of avoiding not-quite-exact comparison issues while still being true enough to
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// the gist for simple debugging
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sync_capacitor_charge_threshold_ = ((vertical_sync_half_lines - 2) * cycles_per_line) >> 1;
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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_ = static_cast<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, 5, true); // i.e. 283.7516; 2.5 lines = vertical sync
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set_input_gamma(2.8f);
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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, 6, false); // i.e. 227.5, 3 lines = vertical sync
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set_input_gamma(2.2f);
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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_ = static_cast<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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void CRT::set_input_gamma(float gamma) {
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input_gamma_ = gamma;
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update_gamma();
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}
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void CRT::set_output_gamma(float gamma) {
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output_gamma_ = gamma;
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update_gamma();
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}
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void CRT::update_gamma() {
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float gamma_ratio = input_gamma_ / output_gamma_;
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openGL_output_builder_.set_gamma(gamma_ratio);
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}
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CRT::CRT(unsigned int common_output_divisor, unsigned int buffer_depth) :
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common_output_divisor_(common_output_divisor),
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openGL_output_builder_(buffer_depth) {}
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CRT::CRT( unsigned int cycles_per_line,
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unsigned int common_output_divisor,
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unsigned int height_of_display,
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ColourSpace colour_space,
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unsigned int colour_cycle_numerator, unsigned int colour_cycle_denominator,
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unsigned int vertical_sync_half_lines,
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bool should_alternate,
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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, vertical_sync_half_lines, 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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// 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() (*reinterpret_cast<uint16_t *>(&next_output_run[OutputVertexOffsetOfHorizontal + 0]))
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#define output_x2() (*reinterpret_cast<uint16_t *>(&next_output_run[OutputVertexOffsetOfHorizontal + 2]))
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#define output_position_y() (*reinterpret_cast<uint16_t *>(&next_output_run[OutputVertexOffsetOfVertical + 0]))
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#define output_tex_y() (*reinterpret_cast<uint16_t *>(&next_output_run[OutputVertexOffsetOfVertical + 2]))
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#define source_input_position_y() (*reinterpret_cast<uint16_t *>(&next_run[SourceVertexOffsetOfInputStart + 2]))
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#define source_output_position_x1() (*reinterpret_cast<uint16_t *>(&next_run[SourceVertexOffsetOfOutputStart + 0]))
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#define source_output_position_x2() (*reinterpret_cast<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 + 1]
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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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bool did_retain_source_data = openGL_output_builder_.texture_builder.retain_latest();
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if(did_retain_source_data) {
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next_run = openGL_output_builder_.array_builder.get_input_storage(SourceVertexSize);
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if(!next_run) {
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openGL_output_builder_.texture_builder.discard_latest();
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}
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}
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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 they are
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// outside of the locked region
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source_output_position_x1() = static_cast<uint16_t>(horizontal_flywheel_->get_current_output_position());
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source_phase() = colour_burst_phase_;
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// TODO: determine what the PAL phase-shift machines actually do re: the swinging burst.
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source_amplitude() = phase_alternates_ ? 128 - colour_burst_amplitude_ : 128 + 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() = static_cast<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 = static_cast<uint16_t>(horizontal_flywheel_->get_current_output_position());
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output_run_.y = static_cast<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_output_run = openGL_output_builder_.array_builder.get_output_storage(OutputVertexSize);
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if(next_output_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() = static_cast<uint16_t>(horizontal_flywheel_->get_current_output_position());
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}
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// TODO: below I've assumed a one-to-one correspondance with output runs and input data; that's
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// obviously not completely sustainable. It's a latent bug.
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openGL_output_builder_.array_builder.flush(
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[=] (uint8_t *input_buffer, std::size_t input_size, uint8_t *output_buffer, std::size_t output_size) {
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openGL_output_builder_.texture_builder.flush(
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[=] (const std::vector<TextureBuilder::WriteArea> &write_areas, std::size_t number_of_write_areas) {
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// assert(number_of_write_areas * SourceVertexSize == input_size);
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if(number_of_write_areas * SourceVertexSize == input_size) {
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for(std::size_t run = 0; run < number_of_write_areas; run++) {
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*reinterpret_cast<uint16_t *>(&input_buffer[run * SourceVertexSize + SourceVertexOffsetOfInputStart + 0]) = write_areas[run].x;
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*reinterpret_cast<uint16_t *>(&input_buffer[run * SourceVertexSize + SourceVertexOffsetOfInputStart + 2]) = write_areas[run].y;
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*reinterpret_cast<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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});
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for(std::size_t position = 0; position < input_size; position += SourceVertexSize) {
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(*reinterpret_cast<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_y
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#undef source_output_position_x1
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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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// MARK: - stream feeding methods
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void CRT::output_scan(const Scan *const scan) {
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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; the DPLL and some zero crossing logic
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// will probably be sufficient but some test data would be helpful
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// sync logic: mark whether this is currently sync and check for a leading edge
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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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// horizontal sync is recognised on any leading edge that is not 'near' the expected vertical sync;
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// the second limb is to avoid slightly horizontal sync shifting from the common pattern of
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// equalisation pulses as the inverse of ordinary horizontal sync
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bool hsync_requested = is_leading_edge && !vertical_flywheel_->is_near_expected_sync();
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if(this_is_sync) {
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// if this is sync then either begin or continue a sync accumulation phase
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is_accumulating_sync_ = true;
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cycles_since_sync_ = 0;
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} else {
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// if this is not sync then check how long it has been since sync. If it's more than
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// half a line then end sync accumulation and zero out the accumulating count
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cycles_since_sync_ += scan->number_of_cycles;
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if(cycles_since_sync_ > (cycles_per_line_ >> 2)) {
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cycles_of_sync_ = 0;
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is_accumulating_sync_ = false;
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is_refusing_sync_ = false;
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}
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}
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unsigned int number_of_cycles = scan->number_of_cycles;
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bool vsync_requested = false;
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// if sync is being accumulated then accumulate it; if it crosses the vertical sync threshold then
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// divide this line at the crossing point and indicate vertical sync there
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if(is_accumulating_sync_ && !is_refusing_sync_) {
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cycles_of_sync_ += scan->number_of_cycles;
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if(this_is_sync && cycles_of_sync_ >= sync_capacitor_charge_threshold_) {
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unsigned int overshoot = std::min(cycles_of_sync_ - sync_capacitor_charge_threshold_, number_of_cycles);
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if(overshoot) {
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number_of_cycles -= overshoot;
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advance_cycles(number_of_cycles, hsync_requested, false, scan->type);
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hsync_requested = false;
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number_of_cycles = overshoot;
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}
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is_refusing_sync_ = true;
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vsync_requested = true;
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}
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}
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advance_cycles(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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scan.type = Scan::Type::Sync;
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scan.number_of_cycles = number_of_cycles;
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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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scan.type = Scan::Type::Blank;
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scan.number_of_cycles = number_of_cycles;
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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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openGL_output_builder_.texture_builder.reduce_previous_allocation_to(1);
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Scan scan;
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scan.type = Scan::Type::Level;
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scan.number_of_cycles = number_of_cycles;
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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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scan.type = Scan::Type::ColourBurst;
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scan.number_of_cycles = number_of_cycles;
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scan.phase = phase;
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scan.amplitude = amplitude >> 1;
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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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output_colour_burst(number_of_cycles, static_cast<uint8_t>((phase_numerator_ * 256) / phase_denominator_));
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}
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void CRT::set_immediate_default_phase(float phase) {
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phase = fmodf(phase, 1.0f);
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phase_numerator_ = static_cast<unsigned int>(phase * static_cast<float>(phase_denominator_));
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}
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void CRT::output_data(unsigned int number_of_cycles, unsigned int number_of_samples) {
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openGL_output_builder_.texture_builder.reduce_previous_allocation_to(number_of_samples);
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Scan scan;
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scan.type = Scan::Type::Data;
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scan.number_of_cycles = number_of_cycles;
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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(static_cast<unsigned int>(first_cycle_after_sync) < horizontal_retrace_period) first_cycle_after_sync = static_cast<int>(horizontal_retrace_period);
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if(static_cast<unsigned int>(first_cycle_after_sync + number_of_cycles) > horizontal_scan_period) number_of_cycles = static_cast<int>(horizontal_scan_period - static_cast<unsigned int>(first_cycle_after_sync));
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float start_x = static_cast<float>(static_cast<unsigned int>(first_cycle_after_sync) - horizontal_retrace_period) / static_cast<float>(horizontal_scan_period);
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float width = static_cast<float>(number_of_cycles) / static_cast<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(static_cast<unsigned int>(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 = static_cast<int>(horizontal_scan_period - static_cast<unsigned int>(first_cycle_after_sync));
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float start_y = static_cast<float>((static_cast<unsigned int>(first_line_after_sync) * horizontal_period) - vertical_retrace_period) / static_cast<float>(vertical_scan_period);
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float height = static_cast<float>(static_cast<unsigned int>(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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