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Fetch pixels earlier for a mostly-working high-resolution output.

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This commit is contained in:
Thomas Harte 2025-01-02 14:42:49 -05:00
parent dbe733524c
commit 09bd5503b4
1 changed files with 37 additions and 33 deletions
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70
Machines/Commodore/Plus4/Video.hpp
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@ -314,53 +314,58 @@ public:
if(video_shift_ || wide_screen_) {
next_attribute_.advance();
next_character_.advance();
next_cursor_.advance();
next_pixels_.advance();
// TODO: calculation here depends on graphics mode.
switch(video_mode_) {
case VideoMode::Blank:
break;
case VideoMode::Text: {
const auto character = next_character_.read();
const uint8_t pixels = pager_.read(uint16_t(
character_base_ + (character << 3) + vertical_sub_count_
)) ^ next_cursor_.read();
output_.load_pixels(pixels, x_scroll_);
} break;
case VideoMode::BitmapMulticolour:
case VideoMode::BitmapHighRes: {
const uint8_t pixels = pager_.read(uint16_t(
bitmap_base_ + (video_counter_ << 3) + vertical_sub_count_
));
output_.load_pixels(pixels, x_scroll_);
} break;
}
} else {
output_.reset();
output_.load_pixels(next_pixels_.read(), x_scroll_);
}
if(increment_video_counter_) {
//
// If this is one of the relevant bad lines then obtain a new character index and attributes,
// placing them into the delaying shift registers.
//
const auto address = [&] { return uint16_t(video_matrix_base_ + video_counter_); };
uint8_t character = 0;
if(bad_line2_) {
shifter_.write<1>(pager_.read(address()));
} else if(bad_line()) {
next_character_.write(shifter_.read<0>());
next_character_.write(character = shifter_.read<0>());
shifter_.write<0>(pager_.read(address() + 0x400));
}
if(!bad_line()) next_character_.write(shifter_.read<0>());
if(!bad_line()) next_character_.write(character = shifter_.read<0>());
next_attribute_.write(shifter_.read<1>());
next_cursor_.write(
const uint8_t cursor =
(flash_count_ & 0x10) &&
(
(!cursor_position_ && !character_position_) ||
((character_position_ == cursor_position_) && vertical_sub_active_)
)
? 0xff : 0x00
);
? 0xff : 0x00;
//
// Also obtain pixel data, which is a function of current character in text modes but not
// in bitmap modes.
//
uint8_t pixels = 0;
switch(video_mode_) {
case VideoMode::Blank:
break;
case VideoMode::Text:
pixels = pager_.read(uint16_t(
character_base_ + (character << 3) + vertical_sub_count_
)) ^ cursor;
break;
case VideoMode::BitmapMulticolour:
case VideoMode::BitmapHighRes:
pixels = pager_.read(uint16_t(
bitmap_base_ + (video_counter_ << 3) + vertical_sub_count_
));
break;
}
next_pixels_.write(pixels);
shifter_.advance();
++video_counter_;
}
@ -525,7 +530,7 @@ public:
if(enable_display_) {
character_window_ = video_shift_ = true;
}
next_pixels_ = 0;
output_.reset();
break;
}
@ -642,7 +647,6 @@ private:
uint16_t video_counter_ = 0;
uint16_t video_counter_reload_ = 0;
uint16_t next_pixels_ = 0;
enum class OutputState {
Blank,
@ -726,7 +730,7 @@ private:
};
ShiftRegister<3> next_attribute_;
ShiftRegister<3> next_character_;
ShiftRegister<3> next_cursor_;
ShiftRegister<3> next_pixels_;
/// Maintains a 16-bit pixel shift register along with a hard-switchover
/// set of attributes.