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Completes documentation and rounds out implementation.

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This commit is contained in:
Thomas Harte 2018-11-04 22:17:33 -05:00
parent 1effb97b74
commit 9799aa0975
2 changed files with 64 additions and 55 deletions
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62
Outputs/CRT/CRT.cpp
View File

@ -16,10 +16,9 @@
using namespace Outputs::CRT;
void CRT::set_new_timing(int cycles_per_line, int height_of_display, Outputs::Display::ColourSpace colour_space, int colour_cycle_numerator, int colour_cycle_denominator, int vertical_sync_half_lines, bool should_alternate) {
// openGL_output_builder_.set_colour_format(colour_space, colour_cycle_numerator, colour_cycle_denominator);
const int millisecondsHorizontalRetraceTime = 7; // source: Dictionary of Video and Television Technology, p. 234
const int scanlinesVerticalRetraceTime = 8; // source: ibid
const int millisecondsHorizontalRetraceTime = 7; // Source: Dictionary of Video and Television Technology, p. 234.
const int scanlinesVerticalRetraceTime = 8; // Source: ibid.
// To quote:
//
@ -37,9 +36,9 @@ void CRT::set_new_timing(int cycles_per_line, int height_of_display, Outputs::Di
cycles_per_line_ = cycles_per_line;
const int multiplied_cycles_per_line = cycles_per_line * time_multiplier_;
// allow sync to be detected (and acted upon) a line earlier than the specified requirement,
// Allow sync to be detected (and acted upon) a line earlier than the specified requirement,
// as a simple way of avoiding not-quite-exact comparison issues while still being true enough to
// the gist for simple debugging
// the gist for simple debugging.
sync_capacitor_charge_threshold_ = ((vertical_sync_half_lines - 2) * cycles_per_line) >> 1;
// Create the two flywheels:
@ -54,10 +53,11 @@ void CRT::set_new_timing(int cycles_per_line, int height_of_display, Outputs::Di
horizontal_flywheel_.reset(new Flywheel(multiplied_cycles_per_line, (millisecondsHorizontalRetraceTime * multiplied_cycles_per_line) >> 6, multiplied_cycles_per_line >> 5));
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));
// figure out the divisor necessary to get the horizontal flywheel into a 16-bit range
// Figure out the divisor necessary to get the horizontal flywheel into a 16-bit range.
const int real_clock_scan_period = multiplied_cycles_per_line * height_of_display;
vertical_flywheel_output_divider_ = (real_clock_scan_period + 65534) / 65535;
// Communicate relevant fields to the scan target.
scan_target_modals_.output_scale.x = uint16_t(time_multiplier_ * cycles_per_line);
scan_target_modals_.output_scale.y = uint16_t((multiplied_cycles_per_line * height_of_display) / vertical_flywheel_output_divider_);
scan_target_modals_.expected_vertical_lines = height_of_display;
@ -65,16 +65,26 @@ void CRT::set_new_timing(int cycles_per_line, int height_of_display, Outputs::Di
scan_target_->set_modals(scan_target_modals_);
}
void CRT::set_new_data_type(Outputs::Display::ScanTarget::Modals::DataType data_type) {
scan_target_modals_.source_data_type = data_type;
scan_target_->set_modals(scan_target_modals_);
}
void CRT::set_visible_area(Outputs::Display::Rect visible_area) {
scan_target_modals_.visible_area = visible_area;
scan_target_->set_modals(scan_target_modals_);
}
void CRT::set_new_display_type(int cycles_per_line, Outputs::Display::Type displayType) {
switch(displayType) {
case Outputs::Display::Type::PAL50:
scan_target_modals_.intended_gamma = 2.8f;
set_new_timing(cycles_per_line, 312, Outputs::Display::ColourSpace::YUV, 709379, 2500, 5, true); // i.e. 283.7516; 2.5 lines = vertical sync
set_new_timing(cycles_per_line, 312, Outputs::Display::ColourSpace::YUV, 709379, 2500, 5, true); // i.e. 283.7516 colour cycles per line; 2.5 lines = vertical sync.
break;
case Outputs::Display::Type::NTSC60:
scan_target_modals_.intended_gamma = 2.2f;
set_new_timing(cycles_per_line, 262, Outputs::Display::ColourSpace::YIQ, 455, 2, 6, false); // i.e. 227.5, 3 lines = vertical sync
set_new_timing(cycles_per_line, 262, Outputs::Display::ColourSpace::YIQ, 455, 2, 6, false); // i.e. 227.5 colour cycles per line, 3 lines = vertical sync.
break;
}
}
@ -155,7 +165,7 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, bool vsync_
Outputs::Display::ScanTarget::Scan *const next_scan = is_output_segment ? scan_target_->get_scan() : nullptr;
did_output |= is_output_segment;
// If outputting, store the start location and
// If outputting, store the start location and scan constants.
if(next_scan) {
next_scan->end_points[0].x = uint16_t(horizontal_flywheel_->get_current_output_position());
next_scan->end_points[0].y = uint16_t(vertical_flywheel_->get_current_output_position() / vertical_flywheel_output_divider_);
@ -212,7 +222,7 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, bool vsync_
// MARK: - stream feeding methods
void CRT::output_scan(const Scan *const scan) {
// simplified colour burst logic: if it's within the back porch we'll take it
// Simplified colour burst logic: if it's within the back porch we'll take it.
if(scan->type == Scan::Type::ColourBurst) {
if(!colour_burst_amplitude_ && horizontal_flywheel_->get_current_time() < (horizontal_flywheel_->get_standard_period() * 12) >> 6) {
// Load phase_numerator_ as a fixed-point quantity in the range [0, 255].
@ -235,18 +245,18 @@ void CRT::output_scan(const Scan *const scan) {
const bool is_leading_edge = (!is_receiving_sync_ && this_is_sync);
is_receiving_sync_ = this_is_sync;
// horizontal sync is recognised on any leading edge that is not 'near' the expected vertical sync;
// Horizontal sync is recognised on any leading edge that is not 'near' the expected vertical sync;
// the second limb is to avoid slightly horizontal sync shifting from the common pattern of
// equalisation pulses as the inverse of ordinary horizontal sync
// equalisation pulses as the inverse of ordinary horizontal sync.
bool hsync_requested = is_leading_edge && !vertical_flywheel_->is_near_expected_sync();
if(this_is_sync) {
// if this is sync then either begin or continue a sync accumulation phase
// If this is sync then either begin or continue a sync accumulation phase.
is_accumulating_sync_ = true;
cycles_since_sync_ = 0;
} else {
// if this is not sync then check how long it has been since sync. If it's more than
// half a line then end sync accumulation and zero out the accumulating count
// If this is not sync then check how long it has been since sync. If it's more than
// half a line then end sync accumulation and zero out the accumulating count.
cycles_since_sync_ += scan->number_of_cycles;
if(cycles_since_sync_ > (cycles_per_line_ >> 2)) {
cycles_of_sync_ = 0;
@ -258,13 +268,13 @@ void CRT::output_scan(const Scan *const scan) {
int number_of_cycles = scan->number_of_cycles;
bool vsync_requested = false;
// if sync is being accumulated then accumulate it; if it crosses the vertical sync threshold then
// divide this line at the crossing point and indicate vertical sync there
// If sync is being accumulated then accumulate it; if it crosses the vertical sync threshold then
// divide this line at the crossing point and indicate vertical sync there.
if(is_accumulating_sync_ && !is_refusing_sync_) {
cycles_of_sync_ += scan->number_of_cycles;
if(this_is_sync && cycles_of_sync_ >= sync_capacitor_charge_threshold_) {
int overshoot = std::min(cycles_of_sync_ - sync_capacitor_charge_threshold_, number_of_cycles);
const int overshoot = std::min(cycles_of_sync_ - sync_capacitor_charge_threshold_, number_of_cycles);
if(overshoot) {
number_of_cycles -= overshoot;
advance_cycles(number_of_cycles, hsync_requested, false, scan->type, 0);
@ -342,9 +352,9 @@ Outputs::Display::Rect CRT::get_rect_for_area(int first_line_after_sync, int num
number_of_lines += 4;
// determine prima facie x extent
int horizontal_period = horizontal_flywheel_->get_standard_period();
int horizontal_scan_period = horizontal_flywheel_->get_scan_period();
int horizontal_retrace_period = horizontal_period - horizontal_scan_period;
const int horizontal_period = horizontal_flywheel_->get_standard_period();
const int horizontal_scan_period = horizontal_flywheel_->get_scan_period();
const int horizontal_retrace_period = horizontal_period - horizontal_scan_period;
// make sure that the requested range is visible
if(static_cast<int>(first_cycle_after_sync) < horizontal_retrace_period) first_cycle_after_sync = static_cast<int>(horizontal_retrace_period);
@ -354,9 +364,9 @@ Outputs::Display::Rect CRT::get_rect_for_area(int first_line_after_sync, int num
float width = static_cast<float>(number_of_cycles) / static_cast<float>(horizontal_scan_period);
// determine prima facie y extent
int vertical_period = vertical_flywheel_->get_standard_period();
int vertical_scan_period = vertical_flywheel_->get_scan_period();
int vertical_retrace_period = vertical_period - vertical_scan_period;
const int vertical_period = vertical_flywheel_->get_standard_period();
const int vertical_scan_period = vertical_flywheel_->get_scan_period();
const int vertical_retrace_period = vertical_period - vertical_scan_period;
// make sure that the requested range is visible
// if(static_cast<int>(first_line_after_sync) * horizontal_period < vertical_retrace_period)
@ -368,8 +378,8 @@ Outputs::Display::Rect CRT::get_rect_for_area(int first_line_after_sync, int num
float height = static_cast<float>(static_cast<int>(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;
const float adjusted_aspect_ratio = (3.0f*aspect_ratio / 4.0f);
const float ideal_width = height * adjusted_aspect_ratio;
if(ideal_width > width) {
start_x -= (ideal_width - width) * 0.5f;
width = ideal_width;

57
Outputs/CRT/CRT.hpp
View File

@ -25,13 +25,20 @@ class Delegate {
virtual void crt_did_end_batch_of_frames(CRT *crt, int number_of_frames, int number_of_unexpected_vertical_syncs) = 0;
};
/*! Models a class 2d analogue output device, accepting a serial stream of data including syncs
and generating the proper set of output spans. Attempts to act and react exactly as a real
TV would have to things like irregular or off-spec sync, and includes logic properly to track
colour phase for colour composite video.
*/
class CRT {
private:
// the incoming clock lengths will be multiplied by something to give at least 1000
// sample points per line
// The incoming clock lengths will be multiplied by @c time_multiplier_; this increases
// precision across the line.
int time_multiplier_ = 1;
// the two flywheels regulating scanning
// Two flywheels regulate scanning; the vertical will have a range much greater than the horizontal;
// the output divider is what that'll need to be divided by to reduce it into a 16-bit range as
// posted on to the scan target.
std::unique_ptr<Flywheel> horizontal_flywheel_, vertical_flywheel_;
int vertical_flywheel_output_divider_ = 1;
@ -58,25 +65,19 @@ class CRT {
int64_t colour_cycle_numerator_ = 1;
bool is_alernate_line_ = false, phase_alternates_ = false;
// the outer entry point for dispatching output_sync, output_blank, output_level and output_data
void advance_cycles(int number_of_cycles, bool hsync_requested, bool vsync_requested, const Scan::Type type, int number_of_samples);
// the inner entry point that determines whether and when the next sync event will occur within
// the current output window
Flywheel::SyncEvent get_next_vertical_sync_event(bool vsync_is_requested, int cycles_to_run_for, int *cycles_advanced);
Flywheel::SyncEvent get_next_horizontal_sync_event(bool hsync_is_requested, int cycles_to_run_for, int *cycles_advanced);
// the delegate
Delegate *delegate_ = nullptr;
int frames_since_last_delegate_call_ = 0;
// sync counter, for determining vertical sync
bool is_receiving_sync_ = false; // true if the CRT is currently receiving sync (i.e. this is for edge triggering of horizontal sync)
bool is_accumulating_sync_ = false; // true if a sync level has triggered the suspicion that a vertical sync might be in progress
bool is_refusing_sync_ = false; // true once a vertical sync has been detected, until a prolonged period of non-sync has ended suspicion of an ongoing vertical sync
int sync_capacitor_charge_threshold_ = 0; // this charges up during times of sync and depletes otherwise; needs to hit a required threshold to trigger a vertical sync
int cycles_of_sync_ = 0; // the number of cycles since the potential vertical sync began
int cycles_since_sync_ = 0; // the number of cycles since last in sync, for defeating the possibility of this being a vertical sync
bool is_receiving_sync_ = false; // @c true if the CRT is currently receiving sync (i.e. this is for edge triggering of horizontal sync); @c false otherwise.
bool is_accumulating_sync_ = false; // @c true if a sync level has triggered the suspicion that a vertical sync might be in progress; @c false otherwise.
bool is_refusing_sync_ = false; // @c true once a vertical sync has been detected, until a prolonged period of non-sync has ended suspicion of an ongoing vertical sync.
int sync_capacitor_charge_threshold_ = 0; // Charges up during times of sync and depletes otherwise; needs to hit a required threshold to trigger a vertical sync.
int cycles_of_sync_ = 0; // The number of cycles since the potential vertical sync began.
int cycles_since_sync_ = 0; // The number of cycles since last in sync, for defeating the possibility of this being a vertical sync.
int cycles_per_line_ = 1;
@ -91,7 +92,8 @@ class CRT {
@param cycles_per_line The clock rate at which this CRT will be driven, specified as the number
of cycles expected to take up one whole scanline of the display.
@param minimum_cycles_per_pixel TODO.
@param clocks_per_pixel_greatest_common_divisor The GCD of all potential lengths of a pixel
in terms of the clock rate given as @c cycles_per_line.
@param height_of_display The number of lines that nominally form one field of the display, rounded
up to the next whole integer.
@ -104,14 +106,12 @@ class CRT {
@param vertical_sync_half_lines The expected length of vertical synchronisation (equalisation pulses aside),
in multiples of half a line.
@param data_type TODO.
@param data_type The format that the caller will use for input data.
@param scan_target TODO.
@see @c set_rgb_sampling_function , @c set_composite_sampling_function
@param scan_target The destination for generated scans.
*/
CRT(int cycles_per_line,
int minimum_cycles_per_pixel,
int clocks_per_pixel_greatest_common_divisor,
int height_of_display,
Outputs::Display::ColourSpace colour_space,
int colour_cycle_numerator,
@ -121,11 +121,7 @@ class CRT {
Outputs::Display::ScanTarget::Modals::DataType data_type,
Outputs::Display::ScanTarget *scan_target);
/*! Constructs the CRT with the specified clock rate, with the display height and colour
subcarrier frequency dictated by a standard display type and with the requested number of
buffers, each with the requested number of bytes per pixel.
Exactly identical to calling the designated constructor with colour subcarrier information
/*! Exactly identical to calling the designated constructor with colour subcarrier information
looked up by display type.
*/
CRT(int cycles_per_line,
@ -151,7 +147,8 @@ class CRT {
int cycles_per_line,
Outputs::Display::Type display_type);
// TODO.
/*! Changes the type of data being supplied as input.
*/
void set_new_data_type(Outputs::Display::ScanTarget::Modals::DataType data_type);
/*! Output at the sync level.
@ -252,9 +249,10 @@ class CRT {
*/
void set_composite_function_type(CompositeSourceType type, float offset_of_first_sample = 0.0f);
inline void set_visible_area(Outputs::Display::Rect visible_area) {
}
/*! Nominates a section of the display to crop to for output. */
void set_visible_area(Outputs::Display::Rect visible_area);
/*! @returns The rectangle describing a subset of the display, allowing for sync periods. */
Outputs::Display::Rect get_rect_for_area(
int first_line_after_sync,
int number_of_lines,
@ -262,6 +260,7 @@ class CRT {
int number_of_cycles,
float aspect_ratio);
/*! Sets the CRT delegate; set to @c nullptr if no delegate is desired. */
inline void set_delegate(Delegate *delegate) {
delegate_ = delegate;
}