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Quick and dirty startup display stabilization
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This simulates the display hw not being ready on startup until the mirror oscillation stabilizes. This is an attempt to fix Space Squash not starting, but doesn't seem to be very effective. I need to debug some more, but it would probably be a good idea to emulate this with a command line option for how long this period should last.

Also, this implementation doesn't correctly output dummy frames during this period, so it looks like the emu hangs. This should be fixed if this feature becomes more mature.
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@yupferris
yupferris committed Feb 12, 2017
1 parent cdf028a commit 5cfed9e
Showing 1 changed file with 82 additions and 61 deletions.
143 changes: 82 additions & 61 deletions rustual-boy-core/src/vip/mod.rs
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Expand Up @@ -14,6 +14,12 @@ pub const DISPLAY_PIXELS: usize = DISPLAY_RESOLUTION_X * DISPLAY_RESOLUTION_Y;
const DRAWING_BLOCK_HEIGHT: usize = 8;
const DRAWING_BLOCK_COUNT: usize = DISPLAY_RESOLUTION_Y / DRAWING_BLOCK_HEIGHT;

// It seems it can take quite a long time before the display stabilizes from a
// cold start, sometimes in excess of 5 seconds, so we'll use that time here
// in order to be conservative.
// 5s / 50ns = 100000000 clocks
const DISPLAY_STABILIZATION_PERIOD: usize = 100000000;

// 20mhz / (1s / 5ms) = 100000 clocks
const DISPLAY_FRAME_QUARTER_PERIOD: usize = 100000;

Expand Down Expand Up @@ -64,6 +70,7 @@ pub struct Vip {

drawing_state: DrawingState,

reg_interrupt_pending_display_not_ready: bool,
reg_interrupt_pending_left_display_finished: bool,
reg_interrupt_pending_right_display_finished: bool,
reg_interrupt_pending_start_of_game_frame: bool,
Expand Down Expand Up @@ -108,6 +115,9 @@ pub struct Vip {

reg_clear_color: u8,

is_display_stable: bool,
display_stabilization_clock_counter: usize,

display_frame_quarter_clock_counter: usize,
display_frame_quarter_counter: usize,

Expand All @@ -133,6 +143,7 @@ impl Vip {

drawing_state: DrawingState::Idle,

reg_interrupt_pending_display_not_ready: false,
reg_interrupt_pending_left_display_finished: false,
reg_interrupt_pending_right_display_finished: false,
reg_interrupt_pending_start_of_game_frame: false,
Expand Down Expand Up @@ -177,6 +188,9 @@ impl Vip {

reg_clear_color: 0,

is_display_stable: false,
display_stabilization_clock_counter: 0,

display_frame_quarter_clock_counter: 0,
display_frame_quarter_counter: 0,

Expand Down Expand Up @@ -243,6 +257,7 @@ impl Vip {
VRAM_START ... VRAM_END => self.read_vram_halfword(addr - VRAM_START),
INTERRUPT_PENDING_REG => {
//logln!(Log::Vip, "WARNING: Read halfword from Interrupt Pending Reg not fully implemented");
(if self.reg_interrupt_pending_display_not_ready { 1 } else { 0 } << 0) |
(if self.reg_interrupt_pending_left_display_finished { 1 } else { 0 } << 1) |
(if self.reg_interrupt_pending_right_display_finished { 1 } else { 0 } << 2) |
(if self.reg_interrupt_pending_start_of_game_frame { 1 } else { 0 } << 3) |
Expand All @@ -264,7 +279,6 @@ impl Vip {
0
}
DISPLAY_CONTROL_READ_REG => {
let scan_ready = true; // TODO
// TODO: Not entirely sure this is correct
let frame_clock = match self.display_state {
DisplayState::Idle => true,
Expand All @@ -279,7 +293,7 @@ impl Vip {
DisplayState::LeftFramebuffer => if self.display_first_framebuffers { 0b0001 } else { 0b0100 },
DisplayState::RightFramebuffer => if self.display_first_framebuffers { 0b0010 } else { 0b1000 },
} << 2) |
(if scan_ready { 1 } else { 0 } << 6) |
(if self.is_display_stable { 1 } else { 0 } << 6) |
(if frame_clock { 1 } else { 0 } << 7) |
(if mem_refresh { 1 } else { 0 } << 8) |
(if self.reg_display_control_sync_enable { 1 } else { 0 } << 9) |
Expand Down Expand Up @@ -499,86 +513,93 @@ impl Vip {
let mut raise_interrupt = false;

for _ in 0..cycles {
self.display_frame_quarter_clock_counter += 1;
if self.display_frame_quarter_clock_counter >= DISPLAY_FRAME_QUARTER_PERIOD {
self.display_frame_quarter_clock_counter = 0;

match self.display_frame_quarter_counter {
0 => {
self.frame_clock(&mut raise_interrupt);
}
1 => {
self.display(video_frame_sink);
if self.is_display_stable {
self.display_frame_quarter_clock_counter += 1;
if self.display_frame_quarter_clock_counter >= DISPLAY_FRAME_QUARTER_PERIOD {
self.display_frame_quarter_clock_counter = 0;

match self.display_frame_quarter_counter {
0 => {
self.frame_clock(&mut raise_interrupt);
}
1 => {
self.display(video_frame_sink);

if self.reg_display_control_display_enable && self.reg_display_control_sync_enable {
self.begin_left_framebuffer_display_process();
if self.reg_display_control_display_enable && self.reg_display_control_sync_enable {
self.begin_left_framebuffer_display_process();
}
}
}
2 => {
if self.reg_display_control_display_enable {
if let DisplayState::LeftFramebuffer = self.display_state {
self.reg_interrupt_pending_left_display_finished = true;
if self.reg_interrupt_enable_left_display_finished {
raise_interrupt = true;
2 => {
if self.reg_display_control_display_enable {
if let DisplayState::LeftFramebuffer = self.display_state {
self.reg_interrupt_pending_left_display_finished = true;
if self.reg_interrupt_enable_left_display_finished {
raise_interrupt = true;
}
}
}

if self.reg_display_control_sync_enable {
self.begin_right_framebuffer_display_process();
if self.reg_display_control_sync_enable {
self.begin_right_framebuffer_display_process();
}
}
}
}
_ => {
if self.reg_display_control_display_enable {
if let DisplayState::RightFramebuffer = self.display_state {
self.reg_interrupt_pending_right_display_finished = true;
if self.reg_interrupt_enable_right_display_finished {
raise_interrupt = true;
_ => {
if self.reg_display_control_display_enable {
if let DisplayState::RightFramebuffer = self.display_state {
self.reg_interrupt_pending_right_display_finished = true;
if self.reg_interrupt_enable_right_display_finished {
raise_interrupt = true;
}
}
}

self.end_display_process();
self.end_display_process();
}
}
}
}

self.display_frame_quarter_counter = match self.display_frame_quarter_counter {
3 => 0,
_ => self.display_frame_quarter_counter + 1
};
}
self.display_frame_quarter_counter = match self.display_frame_quarter_counter {
3 => 0,
_ => self.display_frame_quarter_counter + 1
};
}

if let DrawingState::Drawing = self.drawing_state {
self.drawing_block_counter += 1;
if self.drawing_block_counter >= DRAWING_BLOCK_PERIOD {
self.drawing_block_counter = 0;
if let DrawingState::Drawing = self.drawing_state {
self.drawing_block_counter += 1;
if self.drawing_block_counter >= DRAWING_BLOCK_PERIOD {
self.drawing_block_counter = 0;

if self.reg_drawing_control_sbcount < DRAWING_BLOCK_COUNT {
self.end_drawing_block(&mut raise_interrupt);
if self.reg_drawing_control_sbcount < DRAWING_BLOCK_COUNT {
self.end_drawing_block(&mut raise_interrupt);

if self.reg_drawing_control_sbcount < DRAWING_BLOCK_COUNT - 1 {
self.reg_drawing_control_sbcount += 1;
if self.reg_drawing_control_drawing_enable {
self.begin_drawing_block();
}
} else {
self.reg_drawing_control_sbcount = 0;
if self.reg_drawing_control_sbcount < DRAWING_BLOCK_COUNT - 1 {
self.reg_drawing_control_sbcount += 1;
if self.reg_drawing_control_drawing_enable {
self.begin_drawing_block();
}
} else {
self.reg_drawing_control_sbcount = 0;

self.end_drawing_process();
self.reg_interrupt_pending_drawing_finished = true;
if self.reg_interrupt_enable_drawing_finished {
raise_interrupt = true;
self.end_drawing_process();
self.reg_interrupt_pending_drawing_finished = true;
if self.reg_interrupt_enable_drawing_finished {
raise_interrupt = true;
}
}
}
}
}

if self.reg_drawing_control_sbout {
self.drawing_sbout_counter += 1;
if self.drawing_sbout_counter >= DRAWING_SBOUT_PERIOD {
self.reg_drawing_control_sbout = false;
if self.reg_drawing_control_sbout {
self.drawing_sbout_counter += 1;
if self.drawing_sbout_counter >= DRAWING_SBOUT_PERIOD {
self.reg_drawing_control_sbout = false;
}
}
}
} else {
self.display_stabilization_clock_counter += 1;
if self.display_stabilization_clock_counter >= DISPLAY_STABILIZATION_PERIOD {
self.is_display_stable = true;
}
}
}

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