diff --git a/Components/9918/Implementation/9918.cpp b/Components/9918/Implementation/9918.cpp
index 98089e847..dd8a0ec85 100644
--- a/Components/9918/Implementation/9918.cpp
+++ b/Components/9918/Implementation/9918.cpp
@@ -44,11 +44,10 @@ Base<personality>::Base() :
}
if constexpr (is_yamaha_vdp(personality)) {
- // TODO: start of sync, or end of sync? Or elsewhere.
- // Note that there's a bug elsewhere if the proper value of this is zero in the
- // "if started before but reached this count" logic — that is boxed into considering
- // a single line only so never sees starts before 0.
- mode_timing_.line_interrupt_position = LineLayout<personality>::EndOfSync;
+ // TODO: this is used for interrupt _prediction_ but won't handle text modes correctly, and indeed
+ // can't be just a single value where the programmer has changed into or out of text modes during the
+ // middle of a line, since screen mode is latched (so it'll be one value for that line, another from then onwards).a
+ mode_timing_.line_interrupt_position = LineLayout<personality>::EndOfPixels;
}
// Establish that output is delayed after reading by `output_lag` cycles,
@@ -275,11 +274,14 @@ void TMS9918<personality>::run_for(const HalfCycles cycles) {
// -------------------------------
// Check for interrupt conditions.
// -------------------------------
- if(this->fetch_pointer_.column < this->mode_timing_.line_interrupt_position && end_column >= this->mode_timing_.line_interrupt_position) {
+ if constexpr (is_sega_vdp(personality)) {
// The Sega VDP offers a decrementing counter for triggering line interrupts;
// it is reloaded either when it overflows or upon every non-pixel line after the first.
// It is otherwise decremented.
- if constexpr (is_sega_vdp(personality)) {
+ if(
+ this->fetch_pointer_.column < this->mode_timing_.line_interrupt_position &&
+ end_column >= this->mode_timing_.line_interrupt_position
+ ) {
if(this->fetch_pointer_.row >= 0 && this->fetch_pointer_.row <= this->mode_timing_.pixel_lines) {
if(!this->line_interrupt_counter_) {
this->line_interrupt_pending_ = true;
@@ -291,14 +293,27 @@ void TMS9918<personality>::run_for(const HalfCycles cycles) {
this->line_interrupt_counter_ = this->line_interrupt_target_;
}
}
+ }
- if constexpr (is_yamaha_vdp(personality)) {
- if(
- this->vertical_active_ &&
- this->fetch_pointer_.row == ((this->line_interrupt_target_ - Storage<personality>::vertical_offset_) & 0xff)
- ) {
- this->line_interrupt_pending_ = true;
- }
+ if constexpr (is_yamaha_vdp(personality)) {
+ // The Yamaha VDPs allow the user to specify which line an interrupt should occur on,
+ // which is relative to the current vertical base. Such an interrupt will occur immediately
+ // after pixels have ended.
+ if(
+ this->vertical_active_ &&
+ this->fetch_pointer_.column < Storage<personality>::mode_description_.end_cycle &&
+ end_column >= Storage<personality>::mode_description_.end_cycle &&
+ this->fetch_pointer_.row == ((this->line_interrupt_target_ - Storage<personality>::vertical_offset_) & 0xff)
+ ) {
+ this->line_interrupt_pending_ = true;
+ Storage<personality>::line_matches_ = true;
+ }
+
+ if(
+ this->fetch_pointer_.column < Storage<personality>::mode_description_.start_cycle &&
+ end_column >= Storage<personality>::mode_description_.start_cycle
+ ) {
+ Storage<personality>::line_matches_ = false;
}
}
@@ -369,6 +384,13 @@ void TMS9918<personality>::run_for(const HalfCycles cycles) {
desc.pixels_per_byte = pixels_per_byte(this->underlying_mode_);
desc.width = width(this->underlying_mode_);
desc.rotate_address = interleaves_banks(this->underlying_mode_);
+ if(is_text(this->underlying_mode_)) {
+ desc.start_cycle = LineLayout<personality>::TextModeEndOfLeftBorder;
+ desc.end_cycle = LineLayout<personality>::TextModeEndOfPixels;
+ } else {
+ desc.start_cycle = LineLayout<personality>::EndOfLeftBorder;
+ desc.end_cycle = LineLayout<personality>::EndOfPixels;
+ }
}
// Based on the output mode, pick a line mode.
@@ -1256,6 +1278,7 @@ HalfCycles TMS9918<personality>::get_next_sequence_point() const {
// Calculate when the next line interrupt will occur.
int next_line_interrupt_row = -1;
+ int line_interrupt_position = this->mode_timing_.line_interrupt_position;
int cycles_to_next_interrupt_threshold = this->mode_timing_.line_interrupt_position - this->fetch_pointer_.column;
int line_of_next_interrupt_threshold = this->fetch_pointer_.row;
diff --git a/Components/9918/Implementation/AccessEnums.hpp b/Components/9918/Implementation/AccessEnums.hpp
index 531264ebf..ea6b5e1a2 100644
--- a/Components/9918/Implementation/AccessEnums.hpp
+++ b/Components/9918/Implementation/AccessEnums.hpp
@@ -78,6 +78,10 @@ constexpr bool interleaves_banks(ScreenMode mode) {
return mode == ScreenMode::YamahaGraphics6 || mode == ScreenMode::YamahaGraphics7;
}
+constexpr bool is_text(ScreenMode mode) {
+ return mode == ScreenMode::Text || mode == ScreenMode::YamahaText80;
+}
+
enum class FetchMode {
Text,
Character,
diff --git a/Components/9918/Implementation/Storage.hpp b/Components/9918/Implementation/Storage.hpp
index 4dce4261d..f0a0611b3 100644
--- a/Components/9918/Implementation/Storage.hpp
+++ b/Components/9918/Implementation/Storage.hpp
@@ -402,6 +402,7 @@ template <Personality personality> struct Storage<personality, std::enable_if_t<
uint8_t colour_status_ = 0;
uint16_t colour_location_ = 0;
uint16_t collision_location_[2]{};
+ bool line_matches_ = false;
Storage() noexcept {
// Seed to something valid.
diff --git a/Components/9918/Implementation/YamahaCommands.hpp b/Components/9918/Implementation/YamahaCommands.hpp
index 6254950bf..72cbd08d3 100644
--- a/Components/9918/Implementation/YamahaCommands.hpp
+++ b/Components/9918/Implementation/YamahaCommands.hpp
@@ -89,6 +89,8 @@ struct ModeDescription {
int width = 256;
int pixels_per_byte = 4;
bool rotate_address = false;
+ int start_cycle = 0;
+ int end_cycle = 0;
};
struct Command {