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Corrects test and implementation to pass the exhaustive VDP interrupt prediction test.

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This commit is contained in:
Thomas Harte
2018-10-21 18:42:49 -04:00
parent 616777517d
commit c07f9fed99
2 changed files with 15 additions and 13 deletions
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Components/9918/9918.cpp
+13 -11
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@@ -638,23 +638,31 @@ HalfCycles TMS9918::get_time_until_interrupt() {
// Calculate the amount of time until the next end-of-frame interrupt.
const int frame_length = 342 * mode_timing_.total_lines;
const int time_until_frame_interrupt =
int time_until_frame_interrupt =
(
((mode_timing_.end_of_frame_interrupt_position.row * 342) + mode_timing_.end_of_frame_interrupt_position.column + frame_length) -
((write_pointer_.row * 342) + write_pointer_.column)
) % frame_length;
if(!time_until_frame_interrupt) time_until_frame_interrupt = frame_length;
if(!enable_line_interrupts_) return half_cycles_before_internal_cycles(time_until_frame_interrupt);
// Calculate the row upon which the next line interrupt will occur.
// Calculate when the next line interrupt will occur.
int next_line_interrupt_row = -1;
int cycles_to_next_interrupt_threshold = mode_timing_.line_interrupt_position - write_pointer_.column;
int line_of_next_interrupt_threshold = write_pointer_.row;
if(cycles_to_next_interrupt_threshold <= 0) {
cycles_to_next_interrupt_threshold += 342;
++line_of_next_interrupt_threshold;
}
if(is_sega_vdp(personality_)) {
// If there is still time for a line interrupt this frame, that'll be it;
// otherwise it'll be on the next frame, supposing there's ever time for
// it at all.
if(write_pointer_.row+line_interrupt_counter <= mode_timing_.pixel_lines) {
next_line_interrupt_row = write_pointer_.row+line_interrupt_counter;
if(line_of_next_interrupt_threshold + line_interrupt_counter <= mode_timing_.pixel_lines) {
next_line_interrupt_row = line_of_next_interrupt_threshold + line_interrupt_counter;
} else {
if(line_interrupt_target <= mode_timing_.pixel_lines)
next_line_interrupt_row = mode_timing_.total_lines + line_interrupt_target;
@@ -671,10 +679,7 @@ HalfCycles TMS9918::get_time_until_interrupt() {
// Figure out the number of internal cycles until the next line interrupt, which is the amount
// of time to the next tick over and then next_line_interrupt_row - row_ lines further.
int local_cycles_until_next_tick = (mode_timing_.line_interrupt_position - write_pointer_.column + 342) % 342;
if(!local_cycles_until_next_tick) local_cycles_until_next_tick += 342;
const int local_cycles_until_line_interrupt = local_cycles_until_next_tick + (next_line_interrupt_row - write_pointer_.row) * 342;
const int local_cycles_until_line_interrupt = cycles_to_next_interrupt_threshold + (next_line_interrupt_row - line_of_next_interrupt_threshold) * 342;
if(!generate_interrupts_) return half_cycles_before_internal_cycles(local_cycles_until_line_interrupt);
// Return whichever interrupt is closer.
@@ -687,9 +692,6 @@ bool TMS9918::get_interrupt_line() {
// MARK: -
// if(sprite.shift_position > 0 && !sprites_magnified_)
// sprite.shift_position *= 2;
void Base::draw_tms_character(int start, int end) {
LineBuffer &line_buffer = line_buffers_[read_pointer_.row];