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Simplify control flow, half-obey 256-character flag.

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This commit is contained in:
Thomas Harte 2025-01-02 22:39:23 -05:00
parent aed8b65e2b
commit 5c31104d0e
1 changed files with 25 additions and 18 deletions
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43
Machines/Commodore/Plus4/Video.hpp
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@ -117,7 +117,7 @@ public:
break;
case 0xff12:
bitmap_base_ = uint16_t((value & 0x3c) << 10);
bitmap_base_ = uint16_t((value & 0x38) << 10);
break;
case 0xff13:
character_base_ = uint16_t((value & 0xfc) << 8);
@ -152,7 +152,7 @@ public:
// Cycles(EndCharacterFetchWindow - horizontal_counter_ + EndOfLine) * is_ntsc_ ? Cycles(4) : Cycles(5) / 2;
}
const bool is_long_cycle = single_clock_ || refresh_ || external_fetch_;
const bool is_long_cycle = single_clock_ || refresh_ || (external_fetch_ && enable_display_);
if(is_ntsc_) {
return is_long_cycle ? Cycles(16) : Cycles(8);
@ -324,24 +324,27 @@ public:
// 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 uint8_t character = shifter_.read<0>();
next_character_.write(character);
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(character = shifter_.read<0>());
shifter_.write<0>(pager_.read(address() + 0x400));
}
if(!bad_line()) next_character_.write(character = shifter_.read<0>());
next_attribute_.write(shifter_.read<1>());
const uint8_t cursor =
(flash_count_ & 0x10) &&
(
(!cursor_position_ && !character_position_) ||
((character_position_ == cursor_position_) && vertical_sub_active_)
)
? 0xff : 0x00;
const auto cursor = [&]() -> uint8_t {
return
(flash_count_ & 0x10) &&
(
(!cursor_position_ && !character_position_) ||
((character_position_ == cursor_position_) && vertical_sub_active_)
)
? 0xff : 0x00;
};
//
// Also obtain pixel data, which is a function of current character in text modes but not
@ -353,16 +356,18 @@ public:
break;
case VideoMode::Text:
case VideoMode::MulticolourText:
pixels = pager_.read(uint16_t(
character_base_ + (character << 3) + vertical_sub_count_
)) ^ cursor;
break;
case VideoMode::MulticolourText: {
const uint16_t address_top =
characters_256_ ?
uint16_t((character_base_ & 0xf800) + (character << 3)) :
uint16_t(character_base_ + ((character & 0x7f) << 3));
pixels = pager_.read(uint16_t(address_top + vertical_sub_count_)) ^ cursor();
} break;
case VideoMode::ExtendedColourText:
pixels = pager_.read(uint16_t(
character_base_ + ((character & 0x3f) << 3) + vertical_sub_count_
)) ^ cursor;
)) ^ cursor();
break;
case VideoMode::MulticolourBitmap:
@ -863,6 +868,8 @@ private:
const auto target = pixels_;
if(target) pixels_ += length;
// TODO: check character top bit for potential flash if characters_256_ is false.
switch(mode) {
case VideoMode::Text: {
const auto attributes = output_.attributes<0>();