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Merge pull request #562 from TomHarte/TimingTweaks

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Corrects residual Master System interrupt timing issues.
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Thomas Harte 2018-10-21 18:47:25 -04:00 committed by GitHub
commit fb3171f366
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2 changed files with 56 additions and 13 deletions
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28
Components/9918/9918.cpp
View File

@ -66,7 +66,7 @@ Base::Base(Personality p) :
}
if(is_sega_vdp(personality_)) {
mode_timing_.line_interrupt_position = 65;
mode_timing_.line_interrupt_position = 64;
mode_timing_.end_of_frame_interrupt_position.column = 63;
mode_timing_.end_of_frame_interrupt_position.row = 193;
@ -564,7 +564,7 @@ void TMS9918::set_register(int address, uint8_t value) {
uint8_t TMS9918::get_current_line() {
// Determine the row to return.
static const int row_change_position = 62; // This is the proper Master System value; substitute if any other VDPs turn out to have this functionality.
static const int row_change_position = 63; // This is the proper Master System value; substitute if any other VDPs turn out to have this functionality.
int source_row =
(write_pointer_.column < row_change_position)
? (write_pointer_.row + mode_timing_.total_lines - 1)%mode_timing_.total_lines
@ -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];

41
OSBindings/Mac/Clock SignalTests/MasterSystemVDPTests.mm
View File

@ -116,4 +116,45 @@
NSAssert(vdp.get_interrupt_line(), @"Interrupt line wasn't set when promised");
}
- (void)testPrediction {
TI::TMS::TMS9918 vdp(TI::TMS::Personality::SMSVDP);
for(int c = 0; c < 256; ++c) {
for(int with_eof = (c < 192) ? 0 : 1; with_eof < 2; ++with_eof) {
// Enable or disable end-of-frame interrupts as required.
vdp.set_register(1, with_eof ? 0x20 : 0x00);
vdp.set_register(1, 0x81);
// Enable line interrupts.
vdp.set_register(1, 0x10);
vdp.set_register(1, 0x80);
// Set the line interrupt timing as desired.
vdp.set_register(1, c);
vdp.set_register(1, 0x8a);
// Now run through an entire frame...
int half_cycles = 262*224*2;
int last_time_until_interrupt = vdp.get_time_until_interrupt().as_int();
while(half_cycles--) {
// Validate that an interrupt happened if one was expected, and clear anything that's present.
NSAssert(vdp.get_interrupt_line() == (last_time_until_interrupt == 0), @"Unexpected interrupt state change; expected %d but got %d; position %d %d @ %d", (last_time_until_interrupt == 0), vdp.get_interrupt_line(), c, with_eof, half_cycles);
vdp.get_register(1);
vdp.run_for(HalfCycles(1));
// Get the time until interrupt.
int time_until_interrupt = vdp.get_time_until_interrupt().as_int();
NSAssert(time_until_interrupt != -1, @"No interrupt scheduled; position %d %d @ %d", c, with_eof, half_cycles);
NSAssert(time_until_interrupt >= 0, @"Interrupt is scheduled in the past; position %d %d @ %d", c, with_eof, half_cycles);
if(last_time_until_interrupt) {
NSAssert(time_until_interrupt == (last_time_until_interrupt - 1), @"Discontinuity found in interrupt prediction; from %d to %d; position %d %d @ %d", last_time_until_interrupt, time_until_interrupt, c, with_eof, half_cycles);
}
last_time_until_interrupt = time_until_interrupt;
}
}
}
}
@end