From 6e034c9b7f82ea285c53b2877c80c766935f48d0 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 11 Aug 2021 20:31:37 -0400
Subject: [PATCH] At least manages to place a pixel region on screen.

Albeit that I've suddenly realised that I've failed properly to think about high-res versus low-res.
---
 Machines/Amiga/Chipset.cpp | 68 +++++++++++++++++++++++++++++++++-----
 Machines/Amiga/Chipset.hpp | 14 ++++++--
 2 files changed, 70 insertions(+), 12 deletions(-)

diff --git a/Machines/Amiga/Chipset.cpp b/Machines/Amiga/Chipset.cpp
index 0aaeed41b..cfa83627e 100644
--- a/Machines/Amiga/Chipset.cpp
+++ b/Machines/Amiga/Chipset.cpp
@@ -206,20 +206,67 @@ template <int cycle> void Chipset::output() {
 		LINK(burst, output_default_colour_burst, burst - blank2);	// TODO: only if colour enabled.
 		LINK(blank3, output_blank, blank3 - burst);
 
-		// Output colour 0 to fill the rest of the line; Kickstart uses this
-		// colour to post the error code. TODO: actual pixels, etc.
-		if(cycle == line_length_ - 1) {
-			uint16_t *const pixels = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
-			if(pixels) {
-				*pixels = palette_[0];
+		display_horizontal_ |= (cycle*2) == fetch_window_[0];
+		display_horizontal_ &= (cycle*2) != fetch_window_[1];
+
+		if constexpr (cycle > blank3) {
+			const bool is_pixel_display = display_horizontal_ && fetch_vertical_;
+
+			if(
+				(is_pixel_display == is_border_) ||
+				(is_border_ && border_colour_ != palette_[0])) {
+				flush_output();
+
+				is_border_ = !is_pixel_display;
+				border_colour_ = palette_[0];
+			}
+
+			if(is_pixel_display) {
+				if(!pixels_) {
+					uint16_t *const new_pixels = reinterpret_cast<uint16_t *>(crt_.begin_data(4 * size_t(line_length_ - cycle)));
+					if(new_pixels) {
+						flush_output();
+					}
+					pixels_ = new_pixels;
+				}
+
+				if(pixels_) {
+					pixels_[0] = 0xffff;
+					pixels_[1] = 0x0000;
+					pixels_[2] = 0xffff;
+					pixels_[3] = 0x0000;
+					pixels_ += 4;
+				}
+			}
+			++zone_duration_;
+
+			// Output the rest of the line. TODO: optimise border area.
+			if(cycle == line_length_ - 1) {
+				flush_output();
 			}
-			crt_.output_data((cycle - blank3) * 4, 1);
 		}
 	}
 
 #undef LINK
 }
 
+void Chipset::flush_output() {
+	if(!zone_duration_) return;
+
+	if(is_border_) {
+		uint16_t *const pixels = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
+		if(pixels) {
+			*pixels = border_colour_;
+		}
+		crt_.output_data(zone_duration_ * 4, 1);
+	} else {
+		crt_.output_data(zone_duration_ * 4);
+	}
+	zone_duration_ = 0;
+	pixels_ = nullptr;
+}
+
+
 template <int cycle, bool stop_if_cpu> bool Chipset::perform_cycle() {
 	constexpr auto BlitterFlag	= DMAMask<DMAFlag::Blitter, DMAFlag::AllBelow>::value;
 	constexpr auto BitplaneFlag	= DMAMask<DMAFlag::Bitplane, DMAFlag::AllBelow>::value;
@@ -229,8 +276,8 @@ template <int cycle, bool stop_if_cpu> bool Chipset::perform_cycle() {
 	// Update state as to whether bitplane fetching should happen now.
 	//
 	// TODO: figure out how the hard stops factor into this.
-	fetch_horizontal_ |= cycle == display_window_start_[0];
-	fetch_horizontal_ &= cycle != display_window_stop_[0];
+	fetch_horizontal_ |= cycle == fetch_window_[0];
+	fetch_horizontal_ &= cycle != fetch_window_[1];
 
 	// Top priority: bitplane collection.
 	if((dma_control_ & BitplaneFlag) == BitplaneFlag) {
@@ -361,6 +408,9 @@ template <bool stop_on_cpu> Chipset::Changes Chipset::run(HalfCycles length) {
 				did_fetch_ = false;
 			}
 
+			std::fill(even_playfield_.begin(), even_playfield_.end(), 0);
+			std::fill(odd_playfield_.begin(), odd_playfield_.end(), 0);
+
 			if(y_ == frame_height_) {
 				++changes.vsyncs;
 				interrupt_requests_ |= InterruptMask<InterruptFlag::VerticalBlank>::value;
diff --git a/Machines/Amiga/Chipset.hpp b/Machines/Amiga/Chipset.hpp
index 346848203..b03fa36b4 100644
--- a/Machines/Amiga/Chipset.hpp
+++ b/Machines/Amiga/Chipset.hpp
@@ -169,8 +169,16 @@ class Chipset {
 
 		// Ephemeral bitplane collection state.
 		bool fetch_vertical_ = false, fetch_horizontal_ = false;
+		bool display_horizontal_ = false;
 		bool did_fetch_ = false;
 
+		// Output state.
+		uint16_t border_colour_ = 0;
+		bool is_border_ = true;
+		int zone_duration_ = 0;
+		uint16_t *pixels_ = nullptr;
+		void flush_output();
+
 		using BitplaneData = std::array<uint16_t, 6>;
 
 		class Bitplanes: public DMADevice<6> {
@@ -184,15 +192,15 @@ class Chipset {
 			private:
 				bool is_high_res_ = false;
 				int collection_offset_ = 0;
-				int plane_count_ = 1;
+				int plane_count_ = 0;
 
 				BitplaneData next;
 		} bitplanes_;
 
 		void post_bitplanes(const BitplaneData &data);
 
-		uint8_t even_playfield_[912];
-		uint8_t odd_playfield_[912];
+		std::array<uint8_t, 912> even_playfield_;
+		std::array<uint8_t, 912> odd_playfield_;
 		int odd_delay_ = 0, even_delay_ = 0;
 
 		// MARK: - Copper.