Adds a first attempt at CRAM dot output. With a TODO.

Components/9918/9918.cpp

@@ -93,7 +93,6 @@ TMS9918::TMS9918(Personality p):
 		"}");
 	crt_->set_video_signal(Outputs::CRT::VideoSignal::RGB);
 	crt_->set_visible_area(Outputs::CRT::Rect(0.055f, 0.025f, 0.9f, 0.9f));
-	crt_->set_input_gamma(2.8f);
 
 	// The TMS remains in-phase with the NTSC colour clock; this is an empirical measurement
 	// intended to produce the correct relationship between the hard edges between pixels and
@@ -321,16 +320,31 @@ void TMS9918::run_for(const HalfCycles cycles) {
 
 		if(read_cycles_pool) {
 			// Determine how much time has passed in the remainder of this line, and proceed.
-			const int read_cycles = std::min(342 - read_pointer_.column, read_cycles_pool);
+			const int target_read_cycles = std::min(342 - read_pointer_.column, read_cycles_pool);
+			int read_cycles_performed = 0;
+			uint32_t next_cram_value = 0;
+
+			while(read_cycles_performed < target_read_cycles) {
+				const uint32_t cram_value = next_cram_value;
+				next_cram_value = 0;
+				int read_cycles = target_read_cycles - read_cycles_performed;
+				if(!upcoming_cram_dots_.empty() && upcoming_cram_dots_.front().location.row == read_pointer_.row) {
+					int time_until_dot = upcoming_cram_dots_.front().location.column - read_pointer_.column;
+
+					if(time_until_dot < read_cycles) {
+						read_cycles = time_until_dot;
+						next_cram_value = upcoming_cram_dots_.front().value;
+						upcoming_cram_dots_.erase(upcoming_cram_dots_.begin());
+					}
+				}
+
+				if(!read_cycles) continue;
+				read_cycles_performed += read_cycles;
+
 				const int end_column = read_pointer_.column + read_cycles;
 				LineBuffer &line_buffer = line_buffers_[read_pointer_.row];
 
 
-			// TODO: actually perform these dots, at least in part by further subdividing
-			// the period to run for.
-			upcoming_cram_dots_.clear();
-
-
 				// --------------------
 				// Output video stream.
 				// --------------------
@@ -344,7 +358,7 @@ void TMS9918::run_for(const HalfCycles cycles) {
 		}\
 	}
 
-#define border(left, right)	intersect(left, right, output_border(end - start))
+#define border(left, right)	intersect(left, right, output_border(end - start, cram_value))
 
 				if(line_buffer.line_mode == LineMode::Refresh || read_pointer_.row > mode_timing_.pixel_lines) {
 					if(read_pointer_.row >= mode_timing_.first_vsync_line && read_pointer_.row < mode_timing_.first_vsync_line+4) {
@@ -401,7 +415,7 @@ void TMS9918::run_for(const HalfCycles cycles) {
 							const int relative_start = start - line_buffer.first_pixel_output_column;
 							const int relative_end = end - line_buffer.first_pixel_output_column;
 							switch(line_buffer.line_mode) {
-							case LineMode::SMS:			draw_sms(relative_start, relative_end, 0);				break;
+								case LineMode::SMS:			draw_sms(relative_start, relative_end, cram_value);		break;
 								case LineMode::Character:	draw_tms_character(relative_start, relative_end);		break;
 								case LineMode::Text:		draw_tms_text(relative_start, relative_end);			break;
 
@@ -432,8 +446,9 @@ void TMS9918::run_for(const HalfCycles cycles) {
 				// Advance time.
 				// -------------
 				read_pointer_.column = end_column;
-			read_cycles_pool -= read_cycles;
+			}
 
+			read_cycles_pool -= target_read_cycles;
 			if(read_pointer_.column == 342) {
 				read_pointer_.column = 0;
 				read_pointer_.row = (read_pointer_.row + 1) % mode_timing_.total_lines;
@@ -444,16 +459,25 @@ void TMS9918::run_for(const HalfCycles cycles) {
 	}
 }
 
-void Base::output_border(int cycles) {
+void Base::output_border(int cycles, uint32_t cram_dot) {
+	cycles *= 4;
+	uint32_t border_colour =
+		is_sega_vdp(personality_) ?
+			master_system_.colour_ram[16 + background_colour_] :
+			palette[background_colour_];
+
+	if(cram_dot) {
 		uint32_t *const pixel_target = reinterpret_cast<uint32_t *>(crt_->allocate_write_area(1));
-	if(pixel_target) {
+		*pixel_target = border_colour | cram_dot;
-		if(is_sega_vdp(personality_)) {
+		crt_->output_level(4);
-			*pixel_target = master_system_.colour_ram[16 + background_colour_];
+		cycles -= 4;
-		} else {
-			*pixel_target = palette[background_colour_];
 	}
+
+	if(cycles) {
+		uint32_t *const pixel_target = reinterpret_cast<uint32_t *>(crt_->allocate_write_area(1));
+		*pixel_target = border_colour;
+		crt_->output_level(static_cast<unsigned int>(cycles));
 	}
-	crt_->output_level(static_cast<unsigned int>(cycles) * 4);
 }
 
 void TMS9918::set_register(int address, uint8_t value) {

Components/9918/Implementation/9918Base.hpp

@@ -127,7 +127,7 @@ class Base {
 
 		// A helper function to output the current border colour for
 		// the number of cycles supplied.
-		void output_border(int cycles);
+		void output_border(int cycles, uint32_t cram_dot);
 
 		// A struct to contain timing information for the current mode.
 		struct {
@@ -343,9 +343,13 @@ class Base {
 						// Schedule a CRAM dot.
 						upcoming_cram_dots_.emplace_back();
 						CRAMDot &dot = upcoming_cram_dots_.back();
-						dot.location.row = write_pointer_.row;
+						dot.location.row = write_pointer_.row + (access_column / 342);
-						dot.location.column = access_column;
+						dot.location.column = access_column % 342;
 						dot.value = master_system_.colour_ram[ram_pointer_ & 0x1f];
+
+						// TODO: the location should actually be slightly in the past, as
+						// output trails memory reading; expose the length of that gap
+						// somewhere that makes it visible to here and adjust.
 					} else {
 						ram_[ram_pointer_ & 16383] = read_ahead_buffer_;
 					}