Attempts to hatch a Sinclair namespace.

2026-04-26 03:29:40 +00:00 · 2021-03-17 22:40:29 -04:00
parent 0ddf09ac0f
commit b63ca16ce2
12 changed files with 61 additions and 59 deletions
@@ -0,0 +1,115 @@
+//
+//  Video.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 06/06/2017.
+//  Copyright 2017 Thomas Harte. All rights reserved.
+//
+
+#include "Video.hpp"
+
+#include <algorithm>
+
+using namespace ZX8081;
+
+namespace {
+
+/*!
+	The number of bytes of PCM data to allocate at once; if/when more are required,
+	the class will simply allocate another batch.
+*/
+const std::size_t StandardAllocationSize = 320;
+
+}
+
+Video::Video() :
+	crt_(207 * 2, 1, Outputs::Display::Type::PAL50, Outputs::Display::InputDataType::Luminance1) {
+
+	// Show only the centre 80% of the TV frame.
+	crt_.set_display_type(Outputs::Display::DisplayType::CompositeMonochrome);
+	crt_.set_visible_area(Outputs::Display::Rect(0.1f, 0.1f, 0.8f, 0.8f));
+}
+
+void Video::run_for(const HalfCycles half_cycles) {
+	// Just keep a running total of the amount of time that remains owed to the CRT.
+	time_since_update_ += half_cycles;
+}
+
+void Video::flush() {
+	flush(sync_);
+}
+
+void Video::flush(bool next_sync) {
+	if(sync_) {
+		// If in sync, that takes priority. Output the proper amount of sync.
+		crt_.output_sync(int(time_since_update_.as_integral()));
+	} else {
+		// If not presently in sync, then...
+
+		if(line_data_) {
+			// If there is output data queued, output it either if it's being interrupted by
+			// sync, or if we're past its end anyway. Otherwise let it be.
+			int data_length = int(line_data_pointer_ - line_data_);
+			if(data_length < int(time_since_update_.as_integral()) || next_sync) {
+				auto output_length = std::min(data_length, int(time_since_update_.as_integral()));
+				crt_.output_data(output_length);
+				line_data_pointer_ = line_data_ = nullptr;
+				time_since_update_ -= HalfCycles(output_length);
+			} else return;
+		}
+
+		// Any pending pixels being dealt with, pad with the white level.
+		uint8_t *colour_pointer = static_cast<uint8_t *>(crt_.begin_data(1));
+		if(colour_pointer) *colour_pointer = 0xff;
+		crt_.output_level(int(time_since_update_.as_integral()));
+	}
+
+	time_since_update_ = 0;
+}
+
+void Video::set_sync(bool sync) {
+	// Do nothing if sync hasn't changed.
+	if(sync_ == sync) return;
+
+	// Complete whatever was being drawn, and update sync.
+	flush(sync);
+	sync_ = sync;
+}
+
+void Video::output_byte(uint8_t byte) {
+	// Complete whatever was going on.
+	if(sync_) return;
+	flush();
+
+	// Grab a buffer if one isn't already available.
+	if(!line_data_) {
+		line_data_pointer_ = line_data_ = crt_.begin_data(StandardAllocationSize);
+	}
+
+	// If a buffer was obtained, serialise the new pixels.
+	if(line_data_) {
+		// If the buffer is full, output it now and obtain a new one
+		if(line_data_pointer_ - line_data_ == StandardAllocationSize) {
+			crt_.output_data(StandardAllocationSize, StandardAllocationSize);
+			time_since_update_ -= StandardAllocationSize;
+			line_data_pointer_ = line_data_ = crt_.begin_data(StandardAllocationSize);
+			if(!line_data_) return;
+		}
+
+		// Convert to one-byte-per-pixel where any non-zero value will act as white.
+		uint8_t mask = 0x80;
+		for(int c = 0; c < 8; c++) {
+			line_data_pointer_[c] = byte & mask;
+			mask >>= 1;
+		}
+		line_data_pointer_ += 8;
+	}
+}
+
+void Video::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
+	crt_.set_scan_target(scan_target);
+}
+
+Outputs::Display::ScanStatus Video::get_scaled_scan_status() const {
+	return crt_.get_scaled_scan_status() / 2.0f;
+}