This probably still isn't correct, but restores text.
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Thomas Harte committed
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-126
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@@ -116,7 +116,7 @@ void MC6847Base::pixel_line(const int line, const int line_begin, const int line
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// TODO: obey graphics mode here, use proper colours, more.
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if(pixels_) {
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const int row = line % 12;
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const int row = address_.row();
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for(int c = line_begin; c < line_end; c++) {
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const int column = c - LineLayout::EndOfLeftBorder;
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const int pixels = font[line_.data[column] & 63][row];
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@@ -134,6 +134,8 @@ void MC6847Base::pixel_line(const int line, const int line_begin, const int line
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if(end == LineLayout::EndOfPixels) {
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crt_.output_data(32 * CRTMultiplier, 256);
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address_.apply_hsync();
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printf("\n");
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}
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}
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);
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@@ -160,3 +162,7 @@ void MC6847Base::sync_line(const int, const int end) {
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crt_.output_sync((LineLayout::EndOfLine) * CRTMultiplier);
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}
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}
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void MC6847Base::reset() {
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address_.apply_vertical_preload();
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}
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+143
-125
@@ -14,129 +14,9 @@
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namespace Motorola::MC6847 {
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enum class FrameTiming {
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/// Official frame timing, as implemented by the chip.
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NTSC,
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/// Standard PAL adaptation of adding 25 lines before vsync and 25 aftter, as used independently by
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/// the Acorn Atom and Dragon 32.
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PALPaddedVsync,
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};
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constexpr bool is_ntsc(const FrameTiming timing) {
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return timing == FrameTiming::NTSC;
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}
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template <FrameTiming timing> struct FrameLayout {
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static constexpr int BorderLength = timing == FrameTiming::NTSC ? 27 : 52;
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static constexpr int EndOfPixels = 192;
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static constexpr int EndOfBottomBorder = EndOfPixels + BorderLength;
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static constexpr int EndOfFrontPorch = EndOfBottomBorder + 2;
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static constexpr int EndOfSync = EndOfFrontPorch + 2;
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static constexpr int EndOfBackPorch = EndOfSync + 12;
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static constexpr int EndOfField = EndOfBackPorch + BorderLength;
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};
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static_assert(FrameLayout<FrameTiming::NTSC>::EndOfField == 262, "NTSC frames should be 262 lines long");
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static_assert(FrameLayout<FrameTiming::PALPaddedVsync>::EndOfField == 312, "PAL-padded frames should be 312 lines long");
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struct MC6847Base {
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MC6847Base(Outputs::Display::Type);
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void pixel_line(int line, int begin, int end);
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void border_line(int begin, int end);
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void porch_line(int begin, int end);
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void sync_line(int begin, int end);
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struct LineLayout {
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// Complete guesses. Who knows?
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static const int EndOfSync = 4;
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static const int EndOfLeftBorder = 18;
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static const int EndOfPixels = 50;
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static const int EndOfLine = 64;
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};
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Outputs::CRT::CRT crt_;
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uint16_t *pixels_ = nullptr;
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struct LineCapture {
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// TODO: capture mode here.
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uint8_t data[32];
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} line_;
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};
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template <FrameTiming timing, typename MemoryAccessT>
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class MC6847: private MC6847Base {
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public:
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MC6847(MemoryAccessT &memory) :
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MC6847Base(is_ntsc(timing) ? Outputs::Display::Type::NTSC60 : Outputs::Display::Type::PAL50),
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memory_(memory) {
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crt_.set_fixed_framing([&] {
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run_for(Cycles(10'000));
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});
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}
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//
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// Expected input clock: NTSC-style 3.58 Mhz.
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//
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void run_for(const Cycles cycles) {
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// This template binds the drawing logic to whatever was supplied
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// as MemoryAccessT; a consequence of that is that frame layout logic is here.
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cycles_ += cycles;
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position_.advance(
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cycles_.divide(2).template as<int>(),
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[&] (const int line, const int begin, const int end) {
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if(line < FrameLayout<timing>::EndOfPixels) {
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const int line_start = (line / 12) * 32;
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Numeric::clamp<LineLayout::EndOfLeftBorder, LineLayout::EndOfPixels>(
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begin,
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end,
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[&](const int fetch_begin, const int fetch_end) {
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for(int c = fetch_begin; c < fetch_end; c++) {
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const int column = c - LineLayout::EndOfLeftBorder;
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line_.data[column] = memory_[0x400 + size_t(line_start + column)];
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}
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}
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);
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pixel_line(line, begin, end);
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} else if(line < FrameLayout<timing>::EndOfBottomBorder) {
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border_line(begin, end);
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} else if(line < FrameLayout<timing>::EndOfFrontPorch) {
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porch_line(begin, end);
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} else if(line < FrameLayout<timing>::EndOfSync) {
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sync_line(begin, end);
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} else if(line < FrameLayout<timing>::EndOfBackPorch) {
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porch_line(begin, end);
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} else {
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border_line(begin, end);
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}
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},
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[&] {
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// TODO: reset counters, etc.
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}
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);
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}
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void set_scan_target(Outputs::Display::ScanTarget *const target) {
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crt_.set_scan_target(target);
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}
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Outputs::Display::ScanStatus get_scaled_scan_status() const {
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return crt_.get_scaled_scan_status() * 2;
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}
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void set_display_type(const Outputs::Display::DisplayType display_type) {
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crt_.set_display_type(display_type);
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}
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Outputs::Display::DisplayType get_display_type() const {
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return crt_.get_display_type();
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}
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private:
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MemoryAccessT &memory_;
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Cycles cycles_;
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Numeric::DividingAccumulator<64, FrameLayout<timing>::EndOfField> position_;
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};
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/*!
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Encapsulates the 6847's address-generation logic;
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*/
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struct AddressGenerator {
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// MARK: - Events.
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@@ -150,7 +30,7 @@ struct AddressGenerator {
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if(y_ == y_divider_ || y_ == 12) { // Complete guess: always wrap at 12 even if an in-frame mode switch
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// has occurred.
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y_ = 0;
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return;
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++counter_;
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}
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// Clear either four or five bits.
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@@ -167,15 +47,22 @@ struct AddressGenerator {
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counter_ = preload_;
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}
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uint16_t advance() {
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void advance() {
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++x_;
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if(x_ == x_divider_ || x_ == 3) {
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++counter_;
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x_ = 0;
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}
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}
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uint16_t address() const {
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return counter_;
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}
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int row() const {
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return y_;
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}
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// MARK: - Inputs.
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void set_hsync(const bool active) {
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@@ -237,4 +124,135 @@ private:
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int y_ = 0;
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};
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enum class FrameTiming {
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/// Official frame timing, as implemented by the chip.
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NTSC,
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/// Standard PAL adaptation of adding 25 lines before vsync and 25 aftter, as used independently by
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/// the Acorn Atom and Dragon 32.
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PALPaddedVsync,
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};
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constexpr bool is_ntsc(const FrameTiming timing) {
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return timing == FrameTiming::NTSC;
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}
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template <FrameTiming timing> struct FrameLayout {
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static constexpr int BorderLength = timing == FrameTiming::NTSC ? 27 : 52;
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static constexpr int EndOfPixels = 192;
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static constexpr int EndOfBottomBorder = EndOfPixels + BorderLength;
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static constexpr int EndOfFrontPorch = EndOfBottomBorder + 2;
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static constexpr int EndOfSync = EndOfFrontPorch + 2;
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static constexpr int EndOfBackPorch = EndOfSync + 12;
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static constexpr int EndOfField = EndOfBackPorch + BorderLength;
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};
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static_assert(FrameLayout<FrameTiming::NTSC>::EndOfField == 262, "NTSC frames should be 262 lines long");
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static_assert(FrameLayout<FrameTiming::PALPaddedVsync>::EndOfField == 312, "PAL-padded frames should be 312 lines long");
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struct MC6847Base {
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MC6847Base(Outputs::Display::Type);
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void pixel_line(int line, int begin, int end);
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void border_line(int begin, int end);
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void porch_line(int begin, int end);
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void sync_line(int begin, int end);
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void reset();
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struct LineLayout {
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// Complete guesses. Who knows?
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static const int EndOfSync = 4;
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static const int EndOfLeftBorder = 18;
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static const int EndOfPixels = 50;
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static const int EndOfLine = 64;
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};
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Outputs::CRT::CRT crt_;
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uint16_t *pixels_ = nullptr;
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struct LineCapture {
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// TODO: capture mode here.
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uint8_t data[32];
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} line_;
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AddressGenerator address_;
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};
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template <FrameTiming timing, typename MemoryAccessT>
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class MC6847: private MC6847Base {
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public:
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MC6847(MemoryAccessT &memory) :
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MC6847Base(is_ntsc(timing) ? Outputs::Display::Type::NTSC60 : Outputs::Display::Type::PAL50),
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memory_(memory) {
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// HACK. Allows me to test the address generator locally, prior to integrating it into the SAM.
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address_.set_preload(0x400);
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address_.set_mode(0);
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crt_.set_fixed_framing([&] {
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run_for(Cycles(10'000));
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});
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}
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//
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// Expected input clock: NTSC-style 3.58 Mhz.
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//
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void run_for(const Cycles cycles) {
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// This template binds the drawing logic to whatever was supplied
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// as MemoryAccessT; a consequence of that is that frame layout logic is here.
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cycles_ += cycles;
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position_.advance(
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cycles_.divide(2).template as<int>(),
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[&] (const int line, const int begin, const int end) {
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if(line < FrameLayout<timing>::EndOfPixels) {
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Numeric::clamp<LineLayout::EndOfLeftBorder, LineLayout::EndOfPixels>(
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begin,
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end,
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[&](const int fetch_begin, const int fetch_end) {
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for(int c = fetch_begin; c < fetch_end; c++) {
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if(c > LineLayout::EndOfLeftBorder) address_.advance();
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const int column = c - LineLayout::EndOfLeftBorder;
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const auto source = address_.address();
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line_.data[column] = memory_[source];
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}
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}
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);
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pixel_line(line, begin, end);
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} else if(line < FrameLayout<timing>::EndOfBottomBorder) {
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border_line(begin, end);
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} else if(line < FrameLayout<timing>::EndOfFrontPorch) {
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porch_line(begin, end);
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} else if(line < FrameLayout<timing>::EndOfSync) {
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sync_line(begin, end);
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} else if(line < FrameLayout<timing>::EndOfBackPorch) {
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porch_line(begin, end);
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} else {
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border_line(begin, end);
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}
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},
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[&] {
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reset();
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}
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);
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}
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void set_scan_target(Outputs::Display::ScanTarget *const target) {
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crt_.set_scan_target(target);
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}
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Outputs::Display::ScanStatus get_scaled_scan_status() const {
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return crt_.get_scaled_scan_status() * 2;
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}
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void set_display_type(const Outputs::Display::DisplayType display_type) {
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crt_.set_display_type(display_type);
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}
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Outputs::Display::DisplayType get_display_type() const {
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return crt_.get_display_type();
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}
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private:
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MemoryAccessT &memory_;
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Cycles cycles_;
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Numeric::DividingAccumulator<64, FrameLayout<timing>::EndOfField> position_;
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};
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}
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