Moves the stuff of generating pixels out of the main loop.

2025-11-04 00:16:26 +00:00 · 2018-08-18 18:44:31 -04:00
parent f8d46f8f3d
commit 17bf1a64bf
2 changed files with 264 additions and 167 deletions
--- a/Machines/AppleII/Video.cpp
+++ b/Machines/AppleII/Video.cpp
@@ -10,8 +10,9 @@

 using namespace AppleII::Video;

-VideoBase::VideoBase() :
-	crt_(new Outputs::CRT::CRT(910, 1, Outputs::CRT::DisplayType::NTSC60, 1)) {
+VideoBase::VideoBase(bool is_iie) :
+	crt_(new Outputs::CRT::CRT(910, 1, Outputs::CRT::DisplayType::NTSC60, 1)),
+	is_iie_(is_iie) {

 	// Set a composite sampling function that assumes one byte per pixel input, and
 	// accepts any non-zero value as being fully on, zero being fully off.
@@ -115,3 +116,180 @@ void VideoBase::set_character_rom(const std::vector<uint8_t> &character_rom) {
 		}
 	}
 }
+
+uint8_t *VideoBase::output_text(uint8_t *target, uint8_t *source, size_t length, size_t pixel_row) {
+	const uint8_t inverses[] = {
+		0xff,
+		is_iie_ ? static_cast<uint8_t>(0xff) : static_cast<uint8_t>((flash_ / flash_length) * 0xff),
+		is_iie_ ? static_cast<uint8_t>(0xff) : static_cast<uint8_t>(0x00),
+		is_iie_ ? static_cast<uint8_t>(0xff) : static_cast<uint8_t>(0x00)
+	};
+	const int or_mask = alternative_character_set_ ? 0x100 : 0x000;
+	const int and_mask = is_iie_ ? ~0 : 0x3f;
+
+	for(size_t c = 0; c < length; ++c) {
+		const int character = (source[c] | or_mask) & and_mask;
+		const uint8_t xor_mask = inverses[character >> 6];
+		const std::size_t character_address = static_cast<std::size_t>(character << 3) + pixel_row;
+		const uint8_t character_pattern = character_rom_[character_address] ^ xor_mask;
+
+		// The character ROM is output MSB to LSB rather than LSB to MSB.
+		target[0] = character_pattern & 0x40;
+		target[1] = character_pattern & 0x20;
+		target[2] = character_pattern & 0x10;
+		target[3] = character_pattern & 0x08;
+		target[4] = character_pattern & 0x04;
+		target[5] = character_pattern & 0x02;
+		target[6] = character_pattern & 0x01;
+		graphics_carry_ = character_pattern & 0x01;
+		target += 7;
+	}
+
+	return target;
+}
+
+uint8_t *VideoBase::output_double_text(uint8_t *target, uint8_t *source, uint8_t *auxiliary_source, size_t length, size_t pixel_row) {
+	for(size_t c = 0; c < length; ++c) {
+		const std::size_t character_addresses[2] = {
+			static_cast<std::size_t>(
+				auxiliary_source[c] << 3
+			) + pixel_row,
+			static_cast<std::size_t>(
+				source[c] << 3
+			) + pixel_row,
+		};
+
+		const size_t pattern_offset = alternative_character_set_ ? (256*8) : 0;
+		const uint8_t character_patterns[2] = {
+			character_rom_[character_addresses[0] + pattern_offset],
+			character_rom_[character_addresses[1] + pattern_offset],
+		};
+
+		// The character ROM is output MSB to LSB rather than LSB to MSB.
+		target[0] = character_patterns[0] & 0x40;
+		target[1] = character_patterns[0] & 0x20;
+		target[2] = character_patterns[0] & 0x10;
+		target[3] = character_patterns[0] & 0x08;
+		target[4] = character_patterns[0] & 0x04;
+		target[5] = character_patterns[0] & 0x02;
+		target[6] = character_patterns[0] & 0x01;
+		target[7] = character_patterns[1] & 0x40;
+		target[8] = character_patterns[1] & 0x20;
+		target[9] = character_patterns[1] & 0x10;
+		target[10] = character_patterns[1] & 0x08;
+		target[11] = character_patterns[1] & 0x04;
+		target[12] = character_patterns[1] & 0x02;
+		target[13] = character_patterns[1] & 0x01;
+		graphics_carry_ = character_patterns[1] & 0x01;
+		target += 14;
+	}
+
+	return target;
+}
+
+uint8_t *VideoBase::output_low_resolution(uint8_t *target, uint8_t *source, size_t length, int row) {
+	const int row_shift = row&4;
+	for(size_t c = 0; c < length; ++c) {
+		// Low-resolution graphics mode shifts the colour code on a loop, but has to account for whether this
+		// 14-sample output window is starting at the beginning of a colour cycle or halfway through.
+		if(c&1) {
+			target[0] = target[4] = target[8] = target[12] = (source[c] >> row_shift) & 4;
+			target[1] = target[5] = target[9] = target[13] = (source[c] >> row_shift) & 8;
+			target[2] = target[6] = target[10] = (source[c] >> row_shift) & 1;
+			target[3] = target[7] = target[11] = (source[c] >> row_shift) & 2;
+			graphics_carry_ = (source[c] >> row_shift) & 8;
+		} else {
+			target[0] = target[4] = target[8] = target[12] = (source[c] >> row_shift) & 1;
+			target[1] = target[5] = target[9] = target[13] = (source[c] >> row_shift) & 2;
+			target[2] = target[6] = target[10] = (source[c] >> row_shift) & 4;
+			target[3] = target[7] = target[11] = (source[c] >> row_shift) & 8;
+			graphics_carry_ = (source[c] >> row_shift) & 2;
+		}
+		target += 14;
+	}
+
+	return target;
+}
+
+uint8_t *VideoBase::output_double_low_resolution(uint8_t *target, uint8_t *source, uint8_t *auxiliary_source, size_t length, int row) {
+	const int row_shift = row&4;
+	for(size_t c = 0; c < length; ++c) {
+		if(c&1) {
+			target[0] = target[4] = (auxiliary_source[c] >> row_shift) & 2;
+			target[1] = target[5] = (auxiliary_source[c] >> row_shift) & 4;
+			target[2] = target[6] = (auxiliary_source[c] >> row_shift) & 8;
+			target[3] = (auxiliary_source[c] >> row_shift) & 1;
+
+			target[8] = target[12] = (source[c] >> row_shift) & 4;
+			target[9] = target[13] = (source[c] >> row_shift) & 8;
+			target[10] = (source[c] >> row_shift) & 1;
+			target[7] = target[11] = (source[c] >> row_shift) & 2;
+			graphics_carry_ = (source[c] >> row_shift) & 8;
+		} else {
+			target[0] = target[4] = (auxiliary_source[c] >> row_shift) & 8;
+			target[1] = target[5] = (auxiliary_source[c] >> row_shift) & 1;
+			target[2] = target[6] = (auxiliary_source[c] >> row_shift) & 2;
+			target[3] = (auxiliary_source[c] >> row_shift) & 4;
+
+			target[8] = target[12] = (source[c] >> row_shift) & 1;
+			target[9] = target[13] = (source[c] >> row_shift) & 2;
+			target[10] = (source[c] >> row_shift) & 4;
+			target[7] = target[11] = (source[c] >> row_shift) & 8;
+			graphics_carry_ = (source[c] >> row_shift) & 2;
+		}
+		target += 14;
+	}
+
+	return target;
+}
+
+uint8_t *VideoBase::output_high_resolution(uint8_t *target, uint8_t *source, size_t length) {
+	for(size_t c = 0; c < length; ++c) {
+		// High resolution graphics shift out LSB to MSB, optionally with a delay of half a pixel.
+		// If there is a delay, the previous output level is held to bridge the gap.
+		if(base_stream_[c] & 0x80) {
+			target[0] = graphics_carry_;
+			target[1] = target[2] = source[c] & 0x01;
+			target[3] = target[4] = source[c] & 0x02;
+			target[5] = target[6] = source[c] & 0x04;
+			target[7] = target[8] = source[c] & 0x08;
+			target[9] = target[10] = source[c] & 0x10;
+			target[11] = target[12] = source[c] & 0x20;
+			target[13] = source[c] & 0x40;
+		} else {
+			target[0] = target[1] = source[c] & 0x01;
+			target[2] = target[3] = source[c] & 0x02;
+			target[4] = target[5] = source[c] & 0x04;
+			target[6] = target[7] = source[c] & 0x08;
+			target[8] = target[9] = source[c] & 0x10;
+			target[10] = target[11] = source[c] & 0x20;
+			target[12] = target[13] = source[c] & 0x40;
+		}
+		graphics_carry_ = source[c] & 0x40;
+		target += 14;
+	}
+	return target;
+}
+
+uint8_t *VideoBase::output_double_high_resolution(uint8_t *target, uint8_t *source, uint8_t *auxiliary_source, size_t length) {
+	for(size_t c = 0; c < length; ++c) {
+		target[0] = graphics_carry_;
+		target[1] = auxiliary_source[c] & 0x01;
+		target[2] = auxiliary_source[c] & 0x02;
+		target[3] = auxiliary_source[c] & 0x04;
+		target[4] = auxiliary_source[c] & 0x08;
+		target[5] = auxiliary_source[c] & 0x10;
+		target[6] = auxiliary_source[c] & 0x20;
+		target[7] = auxiliary_source[c] & 0x40;
+		target[8] = auxiliary_source[c] & 0x01;
+		target[9] = auxiliary_source[c] & 0x02;
+		target[10] = auxiliary_source[c] & 0x04;
+		target[11] = auxiliary_source[c] & 0x08;
+		target[12] = auxiliary_source[c] & 0x10;
+		target[13] = auxiliary_source[c] & 0x20;
+		graphics_carry_ = auxiliary_source[c] & 0x40;
+		pixel_pointer_ += 14;
+	}
+
+	return target;
+}