From 35acf888472865e9fc57d7bb61a366a594fd6d56 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 3 Oct 2024 22:07:46 -0400
Subject: [PATCH] Take a swing at adding an adjustment period.
---
Components/6845/CRTC6845.hpp | 75 +++++++++++++++++++++---------------
1 file changed, 43 insertions(+), 32 deletions(-)
diff --git a/Components/6845/CRTC6845.hpp b/Components/6845/CRTC6845.hpp
index a52e464ee..cee1a3b52 100644
--- a/Components/6845/CRTC6845.hpp
+++ b/Components/6845/CRTC6845.hpp
@@ -232,12 +232,21 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
if(character_counter_ == layout_.horizontal.start_sync) {
hsync_counter_ = 0;
bus_state_.hsync = true;
+
+// printf("%d / %d [%d] + %d [v %d] => m:%d f:%d a:%d [sync: %d %d as %d]\n",
+// row_counter_, bus_state_.row_address, row_end_hit,
+// adjustment_counter_, layout_.vertical.adjust,
+// eom_latched_, eof_latched_, is_in_adjustment_period_,
+// bus_state_.hsync, bus_state_.vsync,
+// layout_.vertical.start_sync);
}
// Check for end-of-line.
+ character_reset_history_ <<= 1;
if(character_total_hit) {
character_counter_ = 0;
character_is_visible_ = true;
+ character_reset_history_ |= 1;
} else {
character_counter_++;
}
@@ -251,30 +260,46 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
// End-of-frame.
//
- if(new_frame) {
- is_in_adjustment_period_ = eom_latched_ = eof_latched_ = false;
- } else {
- eom_latched_ |= character_counter_ == 1 && row_end_hit && row_counter_ == layout_.vertical.total;
-
- if(eom_latched_ && character_counter_ == 2) {
- eof_latched_ |= adjustment_counter_ == layout_.vertical.adjust;
- is_in_adjustment_period_ |= eom_latched_ && !eof_latched_;
+ if(character_total_hit) {
+ if(eof_latched_) {
+ eof_latched_ = eom_latched_ = is_in_adjustment_period_ = false;
+ adjustment_counter_ = 0;
+ } else if(is_in_adjustment_period_) {
+ adjustment_counter_ = (adjustment_counter_ + 1) & 31;
}
}
- if(character_total_hit) {
- if(is_in_adjustment_period_) {
- adjustment_counter_ = (adjustment_counter_ + 1) & 31;
- } else if(eof_latched_) {
- is_in_adjustment_period_ = false;
- adjustment_counter_ = 0;
- }
+ if(character_reset_history_ & 2) {
+ eom_latched_ |= row_end_hit && row_counter_ == layout_.vertical.total;
+ }
+
+ if(character_reset_history_ & 4 && eom_latched_) {
+ is_in_adjustment_period_ |= adjustment_counter_ != layout_.vertical.adjust;
+ eof_latched_ |= adjustment_counter_ == layout_.vertical.adjust;
}
//
// Vertical.
//
+ // Sync.
+ const bool vsync_horizontal =
+ (!odd_field_ && !character_counter_) ||
+ (odd_field_ && character_counter_ == (layout_.horizontal.total >> 1));
+ if(vsync_horizontal) {
+ if((row_counter_ == layout_.vertical.start_sync && !bus_state_.row_address) || bus_state_.vsync) {
+ bus_state_.vsync = true;
+ vsync_counter_ = (vsync_counter_ + 1) & 0xf;
+ } else {
+ vsync_counter_ = 0;
+ }
+
+ if(vsync_counter_ == layout_.vertical.sync_lines) {
+ bus_state_.vsync = false;
+ }
+ }
+
+ // Row address.
if(character_total_hit) {
if(eof_latched_ ) {
bus_state_.row_address = 0;
@@ -288,6 +313,7 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
}
}
+ // Row counter.
row_counter_ = next_row_counter_;
if(new_frame) {
next_row_counter_ = 0;
@@ -297,23 +323,7 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
is_first_scanline_ &= !row_end_hit;
}
- // Sync.
- const bool vsync_horizontal =
- (!odd_field_ && !character_counter_) ||
- (odd_field_ && character_counter_ == (layout_.horizontal.total >> 1));
- if(vsync_horizontal) {
- if(row_counter_ == layout_.vertical.start_sync || bus_state_.vsync) {
- bus_state_.vsync = true;
- vsync_counter_ = (vsync_counter_ + 1) & 0xf;
- } else {
- vsync_counter_ = 0;
- }
-
- if(vsync_counter_ == layout_.vertical.sync_lines) {
- bus_state_.vsync = false;
- }
- }
-
+ // Vertical display enable.
if(is_first_scanline_) {
line_is_visible_ = true;
} else if(line_is_visible_ && row_counter_ == layout_.vertical.displayed) {
@@ -406,6 +416,7 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
int selected_register_ = 0;
uint8_t character_counter_ = 0;
+ uint32_t character_reset_history_ = 0;
uint8_t row_counter_ = 0, next_row_counter_ = 0;
uint8_t adjustment_counter_ = 0;