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Install more realistic pixel pipeline.

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This commit is contained in:
Thomas Harte
2025-09-18 17:46:09 -04:00
parent 4efe3a333d
commit 7a59f94f3d
1 changed files with 24 additions and 20 deletions
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Machines/Acorn/BBCMicro/BBCMicro.cpp
+24 -20
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@@ -256,16 +256,17 @@ public:
void set_palette(const uint8_t value) {
const auto index = value >> 4;
Logger::info().append("Palette entry %d set to %x", index, value & 0xf);
palette_[index] = value & 0xf;
}
void set_control(const uint8_t value) {
Logger::info().append("Video control set to %x", value);
cycle_length_ = (value & 0x10) ? 8 : 16;
crtc_clock_multiplier_ = (value & 0x10) ? 1 : 2;
Logger::info().append("TODO: video control => flash %d", bool(value & 0x01));
Logger::info().append("TODO: video control => teletext %d", bool(value & 0x02));
Logger::info().append("TODO: video control => columns %d", (value >> 2) & 0x03);
Logger::info().append("TODO: video control => cursor segment %d%d%d", bool(value & 0x80), bool(value & 0x40), bool(value & 0x20));
pixels_per_clock_ = 1 << ((value >> 2) & 0x03);
Logger::info().append("TODO: video control => columns %d", (value >> 2) & 0x03);
}
/*!
@@ -335,7 +336,7 @@ public:
}
// Increment cycles since state changed.
cycles_ += cycle_length_;
cycles_ += crtc_clock_multiplier_ << 3;
// Collect some more pixels if output is ongoing.
if(previous_output_mode_ == OutputMode::Pixels) {
@@ -352,7 +353,7 @@ public:
((state.refresh_address & 0x800) << 3) |
(state.refresh_address & 0x3ff)
);
// TODO: wraparound?
// TODO: wraparound? Does that happen on Mode 7?
} else {
address = uint16_t((state.refresh_address << 3) | (state.row_address & 7));
if(address & 0x8000) {
@@ -360,19 +361,18 @@ public:
}
}
// Hard coded from here for Mode 0!
const auto source = ram_[address];
pixel_pointer_[0] = (source & 0x80) ? 0xff : 0x00;
pixel_pointer_[1] = (source & 0x40) ? 0xff : 0x00;
pixel_pointer_[2] = (source & 0x20) ? 0xff : 0x00;
pixel_pointer_[3] = (source & 0x10) ? 0xff : 0x00;
pixel_pointer_[4] = (source & 0x08) ? 0xff : 0x00;
pixel_pointer_[5] = (source & 0x04) ? 0xff : 0x00;
pixel_pointer_[6] = (source & 0x02) ? 0xff : 0x00;
pixel_pointer_[7] = (source & 0x01) ? 0xff : 0x00;
pixel_pointer_ += 8;
pixels_ += 8;
// Hard coded: pixel mode!
pixel_shifter_ = ram_[address];
for(int c = 0; c < crtc_clock_multiplier_ * pixels_per_clock_; c++) {
const uint8_t colour =
((pixel_shifter_ & 0x80) >> 4) |
((pixel_shifter_ & 0x20) >> 3) |
((pixel_shifter_ & 0x08) >> 2) |
((pixel_shifter_ & 0x02) >> 1);
pixel_shifter_ <<= 1;
*pixel_pointer_++ = palette_[colour];
++pixels_;
}
// Flush the current buffer pixel if full; the CRTC allows many different display
// widths so it's not necessarily possible to predict the correct number in advance
@@ -418,12 +418,16 @@ private:
} previous_output_mode_ = OutputMode::Sync;
int cycles_ = 0;
int cycles_into_hsync_ = 0;
int cycle_length_ = 8;
Outputs::CRT::CRT crt_;
uint8_t *pixel_data_ = nullptr, *pixel_pointer_ = nullptr;
size_t pixels_ = 0;
uint8_t palette_[16];
int crtc_clock_multiplier_ = 1;
int pixels_per_clock_ = 1;
uint8_t pixel_shifter_ = 0;
const uint8_t *const ram_ = nullptr;
SystemVIA &system_via_;