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411 lines
19 KiB
C++
411 lines
19 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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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)
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{
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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 = (2000 + cycles_per_line - 1) / cycles_per_line;
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// store fundamental display configuration properties
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_height_of_display = height_of_display;
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_cycles_per_line = cycles_per_line * _time_multiplier;
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// generate timing values implied by the given arbuments
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_sync_capacitor_charge_threshold = (int)(syncCapacityLineChargeThreshold * _cycles_per_line);
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// create the two flywheels
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_horizontal_flywheel = std::unique_ptr<Flywheel>(new Flywheel(_cycles_per_line, (millisecondsHorizontalRetraceTime * _cycles_per_line) >> 6));
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_vertical_flywheel = std::unique_ptr<Flywheel>(new Flywheel(_cycles_per_line * height_of_display, scanlinesVerticalRetraceTime * _cycles_per_line));
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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 = (_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, _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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{
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switch(displayType)
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{
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case DisplayType::PAL50:
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set_new_timing(cycles_per_line, 312, ColourSpace::YUV, 1135, 4);
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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, 545, 2);
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break;
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}
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}
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CRT::CRT(unsigned int common_output_divisor) :
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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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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, unsigned int buffer_depth) : CRT(common_output_divisor)
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{
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_openGL_output_builder = std::unique_ptr<OpenGLOutputBuilder>(new OpenGLOutputBuilder(buffer_depth));
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set_new_timing(cycles_per_line, height_of_display, colour_space, colour_cycle_numerator, colour_cycle_denominator);
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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) : CRT(common_output_divisor)
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{
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_openGL_output_builder = std::unique_ptr<OpenGLOutputBuilder>(new OpenGLOutputBuilder(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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{
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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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{
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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_position_x(v) (*(uint16_t *)&next_run[OutputVertexSize*v + OutputVertexOffsetOfPosition + 0])
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#define output_position_y(v) (*(uint16_t *)&next_run[OutputVertexSize*v + OutputVertexOffsetOfPosition + 2])
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#define output_tex_x(v) (*(uint16_t *)&next_run[OutputVertexSize*v + OutputVertexOffsetOfTexCoord + 0])
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#define output_tex_y(v) (*(uint16_t *)&next_run[OutputVertexSize*v + OutputVertexOffsetOfTexCoord + 2])
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#define output_lateral(v) next_run[OutputVertexSize*v + OutputVertexOffsetOfLateral]
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#define output_frame_id(v) next_run[OutputVertexSize*v + OutputVertexOffsetOfFrameID]
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#define output_timestamp(v) (*(uint32_t *)&next_run[OutputVertexSize*v + OutputVertexOffsetOfTimestamp])
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#define source_input_position_x(v) (*(uint16_t *)&next_run[SourceVertexSize*v + SourceVertexOffsetOfInputPosition + 0])
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#define source_input_position_y(v) (*(uint16_t *)&next_run[SourceVertexSize*v + SourceVertexOffsetOfInputPosition + 2])
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#define source_output_position_x(v) (*(uint16_t *)&next_run[SourceVertexSize*v + SourceVertexOffsetOfOutputPosition + 0])
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#define source_output_position_y(v) (*(uint16_t *)&next_run[SourceVertexSize*v + SourceVertexOffsetOfOutputPosition + 2])
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#define source_phase(v) next_run[SourceVertexSize*v + SourceVertexOffsetOfPhaseAmplitudeAndAlpha + 0]
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#define source_amplitude(v) next_run[SourceVertexSize*v + SourceVertexOffsetOfPhaseAmplitudeAndAlpha + 1]
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#define source_alpha(v) next_run[SourceVertexSize*v + SourceVertexOffsetOfPhaseAmplitudeAndAlpha + 2]
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#define source_phase_time(v) (*(uint16_t *)&next_run[SourceVertexSize*v + SourceVertexOffsetOfPhaseTime])
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void CRT::advance_cycles(unsigned int number_of_cycles, unsigned int source_divider, bool hsync_requested, bool vsync_requested, const bool vsync_charging, const Scan::Type type, uint16_t tex_x, uint16_t tex_y)
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{
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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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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)
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{
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next_run = (_openGL_output_builder->get_output_device() == Monitor) ? _openGL_output_builder->get_next_output_run() : _openGL_output_builder->get_next_source_run();
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}
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// Vertex output is arranged for triangle strips, as:
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//
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// 2 [4/5]
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//
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// [0/1] 3
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if(next_run)
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{
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if(_openGL_output_builder->get_output_device() == Monitor)
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{
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// set the type, initial raster position and type of this run
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output_position_x(0) = output_position_x(1) = output_position_x(2) = (uint16_t)_horizontal_flywheel->get_current_output_position();
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output_position_y(0) = output_position_y(1) = output_position_y(2) = (uint16_t)(_vertical_flywheel->get_current_output_position() / _vertical_flywheel_output_divider);
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output_timestamp(0) = output_timestamp(1) = output_timestamp(2) = _openGL_output_builder->get_current_field_time();
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output_tex_x(0) = output_tex_x(1) = output_tex_x(2) = tex_x;
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// these things are constants across the line so just throw them out now
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output_tex_y(0) = output_tex_y(1) = output_tex_y(2) = output_tex_y(3) = output_tex_y(4) = output_tex_y(5) = tex_y;
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output_lateral(0) = output_lateral(1) = output_lateral(3) = 0;
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output_lateral(2) = output_lateral(4) = output_lateral(5) = 1;
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output_frame_id(0) = output_frame_id(1) = output_frame_id(2) = output_frame_id(3) = output_frame_id(4) = output_frame_id(5) = (uint8_t)_openGL_output_builder->get_current_field();
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}
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else
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{
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source_input_position_x(0) = tex_x;
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source_input_position_y(0) = source_input_position_y(1) = tex_y;
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source_output_position_x(0) = (uint16_t)_horizontal_flywheel->get_current_output_position();
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source_output_position_y(0) = source_output_position_y(1) = _openGL_output_builder->get_composite_output_y();
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source_phase(0) = source_phase(1) = _colour_burst_phase;
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source_amplitude(0) = source_amplitude(1) = _colour_burst_amplitude;
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source_phase_time(0) = source_phase_time(1) = _colour_burst_time;
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source_alpha(0) = source_alpha(1) = 255;
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}
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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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_openGL_output_builder->add_to_field_time(next_run_length);
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// either charge or deplete the vertical retrace capacitor (making sure it stops at 0)
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if (vsync_charging)
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_sync_capacitor_charge_level += next_run_length;
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else
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_sync_capacitor_charge_level = std::max(_sync_capacitor_charge_level - (int)next_run_length, 0);
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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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{
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// if this is a data run then advance the buffer pointer
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if(type == Scan::Type::Data && source_divider) tex_x += next_run_length / (_time_multiplier * source_divider);
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if(_openGL_output_builder->get_output_device() == Monitor)
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{
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// store the final raster position
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output_position_x(3) = output_position_x(4) = output_position_x(5) = (uint16_t)_horizontal_flywheel->get_current_output_position();
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output_position_y(3) = output_position_y(4) = output_position_y(5) = (uint16_t)(_vertical_flywheel->get_current_output_position() / _vertical_flywheel_output_divider);
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output_timestamp(3) = output_timestamp(4) = output_timestamp(5) = _openGL_output_builder->get_current_field_time();
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output_tex_x(3) = output_tex_x(4) = output_tex_x(5) = tex_x;
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_openGL_output_builder->complete_output_run(6);
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}
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else
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{
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source_input_position_x(1) = tex_x;
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source_output_position_x(1) = (uint16_t)_horizontal_flywheel->get_current_output_position();
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_openGL_output_builder->complete_source_run();
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}
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}
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// if(is_output_segment)
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// {
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// _openGL_output_builder->complete_output_run(6);
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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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if(_openGL_output_builder->get_output_device() == Television)
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{
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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(needs_endpoint)
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{
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uint8_t *next_run = _openGL_output_builder->get_next_output_run();
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output_position_x(0) = output_position_x(1) = output_position_x(2) = (uint16_t)_horizontal_flywheel->get_current_output_position();
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output_position_y(0) = output_position_y(1) = output_position_y(2) = (uint16_t)(_vertical_flywheel->get_current_output_position() / _vertical_flywheel_output_divider);
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output_timestamp(0) = output_timestamp(1) = output_timestamp(2) = _openGL_output_builder->get_current_field_time();
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output_tex_x(0) = output_tex_x(1) = output_tex_x(2) = (uint16_t)_horizontal_flywheel->get_current_output_position();
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output_tex_y(0) = output_tex_y(1) = output_tex_y(2) = _openGL_output_builder->get_composite_output_y();
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output_lateral(0) = 0;
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output_lateral(1) = _is_writing_composite_run ? 1 : 0;
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output_lateral(2) = 1;
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output_frame_id(0) = output_frame_id(1) = output_frame_id(2) = (uint8_t)_openGL_output_builder->get_current_field();
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_openGL_output_builder->complete_output_run(3);
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_is_writing_composite_run ^= true;
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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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{
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_openGL_output_builder->increment_composite_output_y();
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// store a run to clear the new line
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next_run = _openGL_output_builder->get_next_source_run();
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source_output_position_x(0) = 0;
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source_output_position_x(1) = IntermediateBufferWidth;
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source_output_position_y(0) = source_output_position_y(1) = _openGL_output_builder->get_composite_output_y();
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source_alpha(0) = source_alpha(1) = 0;
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_openGL_output_builder->complete_source_run();
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}
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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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{
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// TODO: how to communicate did_detect_vsync? Bring the delegate back?
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// _delegate->crt_did_end_frame(this, &_current_frame_builder->frame, _did_detect_vsync);
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_openGL_output_builder->increment_field();
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}
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}
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}
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#undef output_position_x
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#undef output_position_y
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#undef output_tex_x
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#undef output_tex_y
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#undef output_lateral
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#undef output_timestamp
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#undef input_input_position_x
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#undef input_input_position_y
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#undef input_output_position_x
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#undef input_output_position_y
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#undef input_phase
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#undef input_amplitude
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#undef input_phase_age
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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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{
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const bool this_is_sync = (scan->type == Scan::Type::Sync);
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const bool is_trailing_edge = (_is_receiving_sync && !this_is_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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// 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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const bool vsync_requested = is_trailing_edge && (_sync_capacitor_charge_level >= _sync_capacitor_charge_threshold);
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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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{
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if(_horizontal_flywheel->get_current_time() < (_horizontal_flywheel->get_standard_period() * 12) >> 6)
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{
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_colour_burst_time = (uint16_t)_colour_burst_time;
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_colour_burst_phase = scan->phase;
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_colour_burst_amplitude = scan->amplitude;
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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, scan->source_divider, hsync_requested, vsync_requested, this_is_sync, scan->type, scan->tex_x, scan->tex_y);
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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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{
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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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{
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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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{
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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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.tex_x = _openGL_output_builder->get_last_write_x_posiiton(),
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.tex_y = _openGL_output_builder->get_last_write_y_posiiton()
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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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{
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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_data(unsigned int number_of_cycles, unsigned int source_divider)
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{
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_openGL_output_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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.tex_x = _openGL_output_builder->get_last_write_x_posiiton(),
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.tex_y = _openGL_output_builder->get_last_write_y_posiiton(),
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.source_divider = source_divider
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|
};
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|
output_scan(&scan);
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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;
|
|
number_of_lines++;
|
|
|
|
// determine prima facie x extent
|
|
unsigned int horizontal_period = _horizontal_flywheel->get_standard_period();
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|
unsigned int horizontal_scan_period = _horizontal_flywheel->get_scan_period();
|
|
unsigned int horizontal_retrace_period = horizontal_period - horizontal_scan_period;
|
|
|
|
float start_x = (float)((unsigned)first_cycle_after_sync - horizontal_retrace_period) / (float)horizontal_scan_period;
|
|
float width = (float)number_of_cycles / (float)horizontal_scan_period;
|
|
|
|
// determine prima facie y extent
|
|
unsigned int vertical_period = _vertical_flywheel->get_standard_period();
|
|
unsigned int vertical_scan_period = _vertical_flywheel->get_scan_period();
|
|
unsigned int vertical_retrace_period = vertical_period - vertical_scan_period;
|
|
float start_y = (float)(((unsigned)first_line_after_sync * horizontal_period) - vertical_retrace_period) / (float)vertical_scan_period;
|
|
float height = (float)((unsigned)number_of_lines * horizontal_period) / vertical_scan_period;
|
|
|
|
// adjust to ensure aspect ratio is correct
|
|
float adjusted_aspect_ratio = (3.0f*aspect_ratio / 4.0f);
|
|
float ideal_width = height * adjusted_aspect_ratio;
|
|
if(ideal_width > width)
|
|
{
|
|
start_x -= (ideal_width - width) * 0.5f;
|
|
width = ideal_width;
|
|
}
|
|
else
|
|
{
|
|
float ideal_height = width / adjusted_aspect_ratio;
|
|
start_y -= (ideal_height - height) * 0.5f;
|
|
height = ideal_height;
|
|
}
|
|
|
|
return Rect(start_x, start_y, width, height);
|
|
}
|