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Fix faulty centring.

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This commit is contained in:
Thomas Harte 2024-09-08 21:06:59 -04:00
parent 0efe649ca5
commit 51c8396e32
1 changed files with 20 additions and 15 deletions
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35
Machines/Acorn/Electron/Video.cpp
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@ -23,7 +23,7 @@ VideoOutput::VideoOutput(const uint8_t *memory) :
crt_.set_visible_area(crt_.get_rect_for_area( crt_.set_visible_area(crt_.get_rect_for_area(
312 - vsync_end, 312 - vsync_end,
256, 256,
h_total - hsync_end, h_total - hsync_start,
80 * 8, 80 * 8,
4.0f / 3.0f 4.0f / 3.0f
)); ));
@ -56,18 +56,10 @@ uint8_t VideoOutput::run_for(const Cycles cycles) {
// reverse-engineering of the Electron ULA. It should therefore be as accurate to the // reverse-engineering of the Electron ULA. It should therefore be as accurate to the
// original hardware as my comprehension of VHDL and adaptation into sequential code allows. // original hardware as my comprehension of VHDL and adaptation into sequential code allows.
// Horizontal and vertical counter updates; code below should act // In this, the sequential world of C++, all tests below should assume that the position
const bool is_v_end = this->is_v_end(); // named by (h_count_, v_count_) is the one that was active **prior to this cycle**.
h_count_ += 8; //
if(h_count_ == h_total) { // So this cycle spans the period from (h_count_, v_count_) to (h_count_, v_count_)+1.
h_count_ = 0;
++v_count_;
if(is_v_end) {
v_count_ = 0;
field_ = !field_;
}
}
// Test for interrupts. // Test for interrupts.
if(v_count_ == v_rtc && ((!field_ && !h_count_) || (field_ && h_count_ == h_half))) { if(v_count_ == v_rtc && ((!field_ && !h_count_) || (field_ && h_count_ == h_half))) {
@ -100,7 +92,7 @@ uint8_t VideoOutput::run_for(const Cycles cycles) {
// Update character row on the trailing edge of hsync. // Update character row on the trailing edge of hsync.
if(h_count_ == hsync_end) { if(h_count_ == hsync_end) {
if(is_v_end) { if(is_v_end()) {
char_row_ = 0; char_row_ = 0;
} else { } else {
char_row_ = last_line() ? 0 : char_row_ + 1; char_row_ = last_line() ? 0 : char_row_ + 1;
@ -113,7 +105,7 @@ uint8_t VideoOutput::run_for(const Cycles cycles) {
} }
// Latch video address at frame start. // Latch video address at frame start.
if(h_count_ == h_reset_addr && is_v_end) { if(h_count_ == h_reset_addr && is_v_end()) {
row_addr_ = byte_addr_ = screen_base_; row_addr_ = byte_addr_ = screen_base_;
} }
@ -206,6 +198,19 @@ uint8_t VideoOutput::run_for(const Cycles cycles) {
} }
} }
} }
// Horizontal and vertical counter updates; code below should act
h_count_ += 8;
if(h_count_ == h_total) {
h_count_ = 0;
if(is_v_end()) {
v_count_ = 0;
field_ = !field_;
} else {
++v_count_;
}
}
} }
return interrupts; return interrupts;