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Merge pull request #1366 from TomHarte/VIDCDelays 

Add various VIDC output latencies.
This commit is contained in:
Thomas Harte 2024-04-28 22:39:29 -04:00 committed by GitHub
parent 0bff2089c4 fa7fff86eb
commit f4da417c3a
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GPG Key ID: B5690EEEBB952194
1 changed files with 225 additions and 169 deletions
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394
Machines/Acorn/Archimedes/Video.hpp
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@ -12,6 +12,7 @@
#include "../../../Outputs/CRT/CRT.hpp"
#include <array>
#include <cassert>
#include <cstdint>
#include <cstring>
@ -26,7 +27,7 @@ struct Video {
ram_(ram),
crt_(Outputs::Display::InputDataType::Red4Green4Blue4) {
set_clock_divider(3);
crt_.set_visible_area(Outputs::Display::Rect(0.06f, 0.07f, 0.9f, 0.9f));
crt_.set_visible_area(Outputs::Display::Rect(0.041f, 0.04f, 0.95f, 0.95f));
crt_.set_display_type(Outputs::Display::DisplayType::RGB);
}
@ -92,8 +93,6 @@ struct Video {
case 0xbc: vertical_timing_.cursor_end = timing_value(value); break;
case 0xe0:
logger.error().append("TODO: video control: %08x", value);
// Set pixel rate. This is the value that a 24Mhz clock should be divided
// by to get half the pixel rate.
switch(value & 0b11) {
@ -131,15 +130,15 @@ struct Video {
horizontal_state_.increment_position(horizontal_timing_);
if(horizontal_state_.did_restart()) {
end_horizontal();
const auto old_phase = vertical_state_.phase();
vertical_state_.increment_position(vertical_timing_);
pixel_count_ = 0;
const auto phase = vertical_state_.phase();
if(phase != old_phase) {
// I don't have good information on this; first guess: copy frame and
// cursor start addresses into counters at the start of the first vertical
// display line.
// Copy frame and cursor start addresses into counters at the
// start of the first vertical display line.
if(phase == Phase::Display) {
address_ = frame_start_;
cursor_address_ = cursor_start_;
@ -167,57 +166,9 @@ struct Video {
cursor_pixel_ = 32;
}
// Accumulate total phase.
++time_in_phase_;
// Determine current output phase.
Phase new_phase;
switch(vertical_state_.phase()) {
case Phase::Sync: new_phase = Phase::Sync; break;
case Phase::Blank: new_phase = Phase::Blank; break;
case Phase::Border:
new_phase = horizontal_state_.phase() == Phase::Display ? Phase::Border : horizontal_state_.phase();
break;
case Phase::Display:
new_phase = horizontal_state_.phase();
break;
}
const auto flush_pixels = [&]() {
const auto duration = static_cast<int>(time_in_phase_);
crt_.output_data(duration, static_cast<size_t>(time_in_phase_) * 2);
time_in_phase_ = 0;
pixels_ = nullptr;
};
// Possibly output something.
if(new_phase != phase_) {
if(time_in_phase_) {
const auto duration = static_cast<int>(time_in_phase_);
switch(phase_) {
case Phase::Sync: crt_.output_sync(duration); break;
case Phase::Blank: crt_.output_blank(duration); break;
case Phase::Display: flush_pixels(); break;
case Phase::Border: crt_.output_level<uint16_t>(duration, border_colour_); break;
}
time_in_phase_ = 0;
}
phase_ = new_phase;
}
// Update cursor pixel counter if applicable; this might mean triggering it
// and it might just mean advancing it if it has already been triggered.
if(vertical_state_.cursor_active) {
const auto pixel_position = horizontal_state_.position << 1;
if(pixel_position <= horizontal_timing_.cursor_start && (pixel_position + 2) > horizontal_timing_.cursor_start) {
cursor_pixel_ = int(horizontal_timing_.cursor_start) - int(pixel_position);
}
}
// Grab some more pixels if appropriate.
// Fetch if relevant display signals are active.
if(vertical_state_.display_active() && horizontal_state_.display_active()) {
const auto next_byte = [&]() -> uint8_t {
const auto next_byte = [&]() {
const auto next = ram_[address_];
++address_;
@ -226,98 +177,26 @@ struct Video {
if(address_ == buffer_end_ + 16) {
address_ = buffer_start_;
}
return next;
bitmap_queue_[bitmap_queue_pointer_ & 7] = next;
++bitmap_queue_pointer_;
};
switch(colour_depth_) {
case Depth::EightBPP:
pixel_data_[0] = next_byte();
pixel_data_[1] = next_byte();
break;
case Depth::FourBPP:
pixel_data_[0] = next_byte();
break;
case Depth::TwoBPP:
if(!(pixel_count_&1)) {
pixel_data_[0] = next_byte();
}
break;
case Depth::OneBPP:
if(!(pixel_count_&3)) {
pixel_data_[0] = next_byte();
}
break;
}
++pixel_count_;
}
if(phase_ == Phase::Display) {
if(pixels_ && time_in_phase_ == PixelBufferSize/2) {
flush_pixels();
}
if(!pixels_) {
if(time_in_phase_) {
flush_pixels();
}
pixels_ = reinterpret_cast<uint16_t *>(crt_.begin_data(PixelBufferSize));
}
if(pixels_) {
// Each tick in here is two ticks of the pixel clock, so:
//
// 8bpp mode: output two bytes;
// 4bpp mode: output one byte;
// 2bpp mode: output one byte every second tick;
// 1bpp mode: output one byte every fourth tick.
switch(colour_depth_) {
case Depth::EightBPP:
pixels_[0] = (colours_[pixel_data_[0] & 0xf] & colour(0b0111'0011'0111)) | high_spread[pixel_data_[0] >> 4];
pixels_[1] = (colours_[pixel_data_[1] & 0xf] & colour(0b0111'0011'0111)) | high_spread[pixel_data_[1] >> 4];
break;
case Depth::FourBPP:
pixels_[0] = colours_[pixel_data_[0] & 0xf];
pixels_[1] = colours_[pixel_data_[0] >> 4];
break;
case Depth::TwoBPP:
pixels_[0] = colours_[pixel_data_[0] & 3];
pixels_[1] = colours_[(pixel_data_[0] >> 2) & 3];
pixel_data_[0] >>= 4;
break;
case Depth::OneBPP:
pixels_[0] = colours_[pixel_data_[0] & 1];
pixels_[1] = colours_[(pixel_data_[0] >> 1) & 1];
pixel_data_[0] >>= 2;
break;
}
// Overlay cursor if applicable.
// TODO: pull this so far out that the cursor can display over the border, too.
if(cursor_pixel_ < 32) {
if(cursor_pixel_ >= 0) {
const auto pixel = cursor_image_[static_cast<size_t>(cursor_pixel_)];
if(pixel) {
pixels_[0] = cursor_colours_[pixel];
}
}
if(cursor_pixel_ < 31) {
const auto pixel = cursor_image_[static_cast<size_t>(cursor_pixel_ + 1)];
if(pixel) {
pixels_[1] = cursor_colours_[pixel];
}
}
}
pixels_ += 2;
case Depth::EightBPP: next_byte(); next_byte(); break;
case Depth::FourBPP: next_byte(); break;
case Depth::TwoBPP: if(!(pixel_count_&3)) next_byte(); break;
case Depth::OneBPP: if(!(pixel_count_&7)) next_byte(); break;
}
}
// Advance cursor position.
if(cursor_pixel_ < 32) cursor_pixel_ += 2;
// Move along line.
switch(vertical_state_.phase()) {
case Phase::Sync: tick_horizontal<Phase::Sync>(); break;
case Phase::Blank: tick_horizontal<Phase::Blank>(); break;
case Phase::Border: tick_horizontal<Phase::Border>(); break;
case Phase::Display: tick_horizontal<Phase::Display>(); break;
}
++time_in_phase_;
}
/// @returns @c true if a vertical retrace interrupt has been signalled since the last call to @c interrupt(); @c false otherwise.
@ -369,32 +248,61 @@ private:
uint32_t cursor_shift_ = 0;
Timing horizontal_timing_, vertical_timing_;
enum class Depth {
OneBPP = 0b00,
TwoBPP = 0b01,
FourBPP = 0b10,
EightBPP = 0b11,
};
// Current video state.
enum class Phase {
Sync, Blank, Border, Display,
};
template <bool is_vertical>
struct State {
uint32_t position = 0;
uint32_t display_start = 0;
uint32_t display_end = 0;
void increment_position(const Timing &timing) {
++position;
if(position == 1024) position = 0;
if(position == timing.period) {
state = DidRestart;
position = 0;
}
if(position == timing.sync_width) state |= SyncEnded;
if(position == timing.display_start) state |= DisplayStarted;
if(position == timing.display_end) state |= DisplayEnded;
if(position == timing.display_start) { state |= DisplayStarted; display_start = position; }
if(position == timing.display_end) { state |= DisplayEnded; display_end = position; }
if(position == timing.border_start) state |= BorderStarted;
if(position == timing.border_end) state |= BorderEnded;
cursor_active |= position == timing.cursor_start;
cursor_active &= position != timing.cursor_end;
if(position == timing.period) {
state = DidRestart;
position = 0;
// Both display start and end need to be seeded as bigger than can be reached,
// while having some overhead for addition.
display_end = display_start = std::numeric_limits<uint32_t>::max() >> 1;
} else {
++position;
if(position == 1024) position = 0;
}
}
bool is_outputting(Depth depth) const {
return position >= display_start + output_latencies[static_cast<uint32_t>(depth)] && position < display_end + output_latencies[static_cast<uint32_t>(depth)];
}
uint32_t output_cycle(Depth depth) const {
return position - display_start - output_latencies[static_cast<uint32_t>(depth)];
}
static constexpr uint32_t output_latencies[] = {
19 >> 1, // 1 bpp.
11 >> 1, // 2 bpp.
7 >> 1, // 4 bpp.
5 >> 1 // 8 bpp.
};
static constexpr uint8_t SyncEnded = 0x1;
static constexpr uint8_t BorderStarted = 0x2;
static constexpr uint8_t BorderEnded = 0x4;
@ -415,28 +323,37 @@ private:
return (state & DisplayStarted) && !(state & DisplayEnded);
}
Phase phase() const {
// TODO: turn the following logic into a 32-entry lookup table.
Phase phase(Phase horizontal_fallback = Phase::Border) const {
// TODO: turn the following logic into a lookup table.
if(!(state & SyncEnded)) {
return Phase::Sync;
}
if(!(state & BorderStarted) || (state & BorderEnded)) {
return Phase::Blank;
}
if constexpr (!is_vertical) {
return horizontal_fallback;
}
if(!(state & DisplayStarted) || (state & DisplayEnded)) {
return Phase::Border;
}
return Phase::Display;
}
};
State horizontal_state_, vertical_state_;
Phase phase_ = Phase::Sync;
uint32_t time_in_phase_ = 0;
uint32_t pixel_count_ = 0;
State<false> horizontal_state_;
State<true> vertical_state_;
int time_in_phase_ = 0;
Phase phase_;
uint16_t phased_border_colour_;
int pixel_count_ = 0;
int display_area_start_ = 0;
uint16_t *pixels_ = nullptr;
// It is elsewhere assumed that this size is a multiple of 8.
static constexpr size_t PixelBufferSize = 320;
static constexpr size_t PixelBufferSize = 256;
// Programmer-set addresses.
uint32_t buffer_start_ = 0;
@ -452,9 +369,6 @@ private:
int cursor_pixel_ = 0;
std::array<uint8_t, 32> cursor_image_;
// Ephemeral graphics data.
uint8_t pixel_data_[2]{};
// Colour palette, converted to internal format.
uint16_t border_colour_;
std::array<uint16_t, 16> colours_{};
@ -470,13 +384,12 @@ private:
// the pixel clock because that's the fidelity at which the programmer
// places horizontal events — display start, end, sync period, etc.
uint32_t clock_divider_ = 0;
Depth colour_depth_;
enum class Depth {
OneBPP = 0b00,
TwoBPP = 0b01,
FourBPP = 0b10,
EightBPP = 0b11,
} colour_depth_;
// A temporary buffer that holds video contents during the latency
// period between their generation and their output.
uint8_t bitmap_queue_[8];
int bitmap_queue_pointer_ = 0;
void set_clock_divider(uint32_t divider) {
if(divider == clock_divider_) {
@ -495,6 +408,149 @@ private:
Outputs::CRT::PAL::AlternatesPhase);
clock_rate_observer_.update_clock_rates();
}
void flush_pixels() {
crt_.output_data(time_in_phase_, static_cast<size_t>(pixel_count_));
time_in_phase_ = 0;
pixel_count_ = 0;
pixels_ = nullptr;
}
void set_phase(Phase phase) {
if(time_in_phase_) {
switch(phase_) {
case Phase::Sync: crt_.output_sync(time_in_phase_); break;
case Phase::Blank: crt_.output_blank(time_in_phase_); break;
case Phase::Border: crt_.output_level<uint16_t>(time_in_phase_, phased_border_colour_); break;
case Phase::Display: flush_pixels(); break;
}
}
phase_ = phase;
time_in_phase_ = 0;
phased_border_colour_ = border_colour_;
pixel_count_ = 0;
}
void end_horizontal() {
set_phase(Phase::Sync);
display_area_start_ = -1;
bitmap_queue_pointer_ = 0;
}
template <Phase vertical_phase> void tick_horizontal() {
// Sync lines: obey nothing. All sync, all the time.
if constexpr (vertical_phase == Phase::Sync) {
return;
}
// Blank lines: obey only the transition from sync to non-sync.
if constexpr (vertical_phase == Phase::Blank) {
if(phase_ == Phase::Sync && horizontal_state_.phase() != Phase::Sync) {
set_phase(Phase::Blank);
}
return;
}
// Border lines: ignore display phases; also reset the border phase if the colour changes.
if constexpr (vertical_phase == Phase::Border) {
const auto phase = horizontal_state_.phase(Phase::Border);
if(phase != phase_ || (phase_ == Phase::Border && border_colour_ != phased_border_colour_)) {
set_phase(phase);
}
return;
}
if constexpr (vertical_phase != Phase::Display) {
// Should be impossible.
assert(false);
}
// Some timing facts, to explain what would otherwise be magic constants.
static constexpr int CursorDelay = 5; // The cursor will appear six pixels after its programmed trigger point.
// ... BUT! Border and display are currently a pixel early. So move the
// cursor for alignment.
// Deal with sync and blank via set_phase(); collapse display and border into Phase::Display.
const auto phase = horizontal_state_.phase(Phase::Display);
if(phase != phase_) set_phase(phase);
// Update cursor pixel counter if applicable; this might mean triggering it
// and it might just mean advancing it if it has already been triggered.
cursor_pixel_ += 2;
if(vertical_state_.cursor_active) {
const auto pixel_position = horizontal_state_.position << 1;
if(pixel_position <= horizontal_timing_.cursor_start && (pixel_position + 2) > horizontal_timing_.cursor_start) {
cursor_pixel_ = int(horizontal_timing_.cursor_start) - int(pixel_position) - CursorDelay;
}
}
// If this is not [collapsed] Phase::Display, just stop here.
if(phase_ != Phase::Display) return;
// Display phase: maintain an output buffer (if available).
if(pixel_count_ == PixelBufferSize) flush_pixels();
if(!pixel_count_) pixels_ = reinterpret_cast<uint16_t *>(crt_.begin_data(PixelBufferSize));
// Output.
if(pixels_) {
// Paint the border colour for potential painting over.
if(horizontal_state_.is_outputting(colour_depth_)) {
const auto source = horizontal_state_.output_cycle(colour_depth_);
// TODO: all below should be delayed an extra pixel. As should the border, actually. Fix up externally?
switch(colour_depth_) {
case Depth::EightBPP: {
const uint8_t *bitmap = &bitmap_queue_[(source << 1) & 7];
pixels_[0] = (colours_[bitmap[0] & 0xf] & colour(0b0111'0011'0111)) | high_spread[bitmap[0] >> 4];
pixels_[1] = (colours_[bitmap[1] & 0xf] & colour(0b0111'0011'0111)) | high_spread[bitmap[1] >> 4];
} break;
case Depth::FourBPP:
pixels_[0] = colours_[bitmap_queue_[source & 7] & 0xf];
pixels_[1] = colours_[bitmap_queue_[source & 7] >> 4];
break;
case Depth::TwoBPP: {
uint8_t &bitmap = bitmap_queue_[(source >> 1) & 7];
pixels_[0] = colours_[bitmap & 3];
pixels_[1] = colours_[(bitmap >> 2) & 3];
bitmap >>= 4;
} break;
case Depth::OneBPP: {
uint8_t &bitmap = bitmap_queue_[(source >> 2) & 7];
pixels_[0] = colours_[bitmap & 1];
pixels_[1] = colours_[(bitmap >> 1) & 1];
bitmap >>= 2;
} break;
}
} else {
pixels_[0] = pixels_[1] = border_colour_;
}
// Overlay cursor if applicable.
if(cursor_pixel_ < 32) {
if(cursor_pixel_ >= 0) {
const auto pixel = cursor_image_[static_cast<size_t>(cursor_pixel_)];
if(pixel) {
pixels_[0] = cursor_colours_[pixel];
}
}
if(cursor_pixel_ >= -1 && cursor_pixel_ < 31) {
const auto pixel = cursor_image_[static_cast<size_t>(cursor_pixel_ + 1)];
if(pixel) {
pixels_[1] = cursor_colours_[pixel];
}
}
}
pixels_ += 2;
}
pixel_count_ += 2;
}
};
}