From 2722041c9299976ab5a4ffd40ebe7341bb830507 Mon Sep 17 00:00:00 2001
From: Thomas <thomas@thomasw.dev>
Date: Sun, 24 Dec 2023 20:56:39 +0100
Subject: [PATCH] Add configurable, PAL/NTSC-aware framerate limiter
---
src/bin/siena/main.rs | 21 ++++++++++++++++++---
src/frontend/channel.rs | 18 ------------------
src/frontend/sdl.rs | 14 +-------------
src/snes/bus/mainbus.rs | 4 +++-
src/snes/cartridge.rs | 2 +-
src/snes/ppu/ppu.rs | 34 +++++++++++++++++++++++++++++++++-
src/snes/ppu/tests.rs | 2 +-
src/test/mod.rs | 2 +-
8 files changed, 58 insertions(+), 39 deletions(-)
diff --git a/src/bin/siena/main.rs b/src/bin/siena/main.rs
index 5b7261f..7d6d71d 100644
--- a/src/bin/siena/main.rs
+++ b/src/bin/siena/main.rs
@@ -16,7 +16,7 @@ use siena::frontend::sdl::{SDLEventPump, SDLRenderer};
use siena::frontend::Renderer;
use siena::snes::bus::mainbus::{BusTrace, Mainbus};
use siena::snes::bus::Bus;
-use siena::snes::cartridge::Cartridge;
+use siena::snes::cartridge::{Cartridge, VideoFormat};
use siena::snes::cpu_65816::cpu::Cpu65816;
use siena::snes::joypad::{Button, Joypad, JoypadEvent};
use siena::snes::ppu::ppu::{SCREEN_HEIGHT, SCREEN_WIDTH};
@@ -99,6 +99,10 @@ struct Args {
/// Skip cartridge header detection, load as HiROM (mostly for test ROMs)
#[arg(long)]
no_header_hirom: bool,
+
+ /// Override frame rate limit (0 = unlimited)
+ #[arg(long)]
+ fps: Option<u64>,
}
fn main() -> Result<()> {
@@ -118,7 +122,7 @@ fn main() -> Result<()> {
// Initialize cartridge
let f = fs::read(args.filename)?;
- let cart = if !args.no_header && !args.no_header_hirom {
+ let cartridge = if !args.no_header && !args.no_header_hirom {
let c = Cartridge::load(&f);
println!("Cartridge: {}", &c);
c
@@ -126,13 +130,24 @@ fn main() -> Result<()> {
Cartridge::load_nohdr(&f, args.no_header_hirom)
};
+ // Determine frame rate limit, either based on the video format
+ // or what the user specified.
+ let fps = match args.fps {
+ None => match cartridge.get_video_format() {
+ VideoFormat::NTSC => 60,
+ VideoFormat::PAL => 50,
+ },
+ Some(fps) => fps,
+ };
+
// Initialize S-CPU bus
let mut bus = Mainbus::<ChannelRenderer>::new(
- cart,
+ cartridge,
args.trace_bus,
displaychannel,
joypads,
args.verbose,
+ fps,
);
bus.apu.verbose = args.spc_verbose;
bus.apu.ports.write().unwrap().trace = args.trace_apu_comm;
diff --git a/src/frontend/channel.rs b/src/frontend/channel.rs
index eee5257..46ca8e2 100644
--- a/src/frontend/channel.rs
+++ b/src/frontend/channel.rs
@@ -1,5 +1,4 @@
use std::sync::Arc;
-use std::time::Instant;
use anyhow::Result;
use crossbeam_channel::{Receiver, Sender, TrySendError};
@@ -13,9 +12,6 @@ pub struct ChannelRenderer {
receiver: Receiver<DisplayBuffer>,
width: usize,
height: usize,
-
- fps_count: u64,
- fps_time: Instant,
}
impl ChannelRenderer {
@@ -34,9 +30,6 @@ impl Renderer for ChannelRenderer {
receiver,
width,
height,
-
- fps_count: 0,
- fps_time: Instant::now(),
})
}
@@ -46,17 +39,6 @@ impl Renderer for ChannelRenderer {
/// Renders changes to screen
fn update(&mut self) -> Result<()> {
- self.fps_count += 1;
-
- if self.fps_time.elapsed().as_secs() >= 2 {
- println!(
- "PPU Frame rate: {:0.2} frames/second",
- self.fps_count as f32 / self.fps_time.elapsed().as_secs_f32()
- );
- self.fps_count = 0;
- self.fps_time = Instant::now();
- }
-
let buffer = std::mem::replace(
&mut self.displaybuffer,
new_displaybuffer(self.width, self.height),
diff --git a/src/frontend/sdl.rs b/src/frontend/sdl.rs
index ee1e2f8..0ccd525 100644
--- a/src/frontend/sdl.rs
+++ b/src/frontend/sdl.rs
@@ -1,8 +1,7 @@
use std::cell::RefCell;
use std::sync::atomic::AtomicU8;
use std::sync::Arc;
-use std::thread::sleep;
-use std::time::{Duration, Instant};
+use std::time::Instant;
use anyhow::{anyhow, Result};
use sdl2::event::Event;
@@ -38,8 +37,6 @@ pub struct SDLRenderer {
#[allow(dead_code)]
height: usize,
- last_frame: Instant,
- frametime: u64,
fps_count: u64,
fps_time: Instant,
}
@@ -70,13 +67,6 @@ impl SDLRenderer {
self.fps_time = Instant::now();
}
- // Limit the framerate
- let framelen = self.last_frame.elapsed().as_micros() as u64;
- if framelen < self.frametime {
- //sleep(Duration::from_micros(self.frametime - framelen));
- }
- self.last_frame = Instant::now();
-
Ok(())
}
}
@@ -111,8 +101,6 @@ impl Renderer for SDLRenderer {
displaybuffer: new_displaybuffer(width, height),
width,
height,
- last_frame: Instant::now(),
- frametime: 1000000 / 50,
fps_count: 0,
fps_time: Instant::now(),
})
diff --git a/src/snes/bus/mainbus.rs b/src/snes/bus/mainbus.rs
index 4840b32..b539dac 100644
--- a/src/snes/bus/mainbus.rs
+++ b/src/snes/bus/mainbus.rs
@@ -235,6 +235,7 @@ where
renderer: TRenderer,
joypads: [Joypad; JOYPAD_COUNT],
apu_verbose: bool,
+ fps: u64,
) -> Self {
Self {
cartridge,
@@ -244,7 +245,7 @@ where
hdmaen: 0,
joypads: Some(joypads),
- ppu: PPU::<TRenderer>::new(renderer),
+ ppu: PPU::<TRenderer>::new(renderer, fps),
apu: Apu::new(apu_verbose),
memsel: 0,
@@ -857,6 +858,7 @@ mod tests {
NullRenderer::new(0, 0).unwrap(),
joypads,
false,
+ 0,
)
}
diff --git a/src/snes/cartridge.rs b/src/snes/cartridge.rs
index 7bb884f..d95007c 100644
--- a/src/snes/cartridge.rs
+++ b/src/snes/cartridge.rs
@@ -93,7 +93,7 @@ impl Cartridge {
(1 << self.rom[self.header_offset + HDR_RAMSIZE_OFFSET]) * 1024
}
- fn get_video_format(&self) -> VideoFormat {
+ pub fn get_video_format(&self) -> VideoFormat {
match self.rom[self.header_offset + HDR_DESTINATION_OFFSET] {
0 // Japan
| 1 // North-America
diff --git a/src/snes/ppu/ppu.rs b/src/snes/ppu/ppu.rs
index a629811..4ac2f37 100644
--- a/src/snes/ppu/ppu.rs
+++ b/src/snes/ppu/ppu.rs
@@ -11,6 +11,8 @@ use crate::tickable::{Tickable, Ticks};
use std::cell::Cell;
use std::sync::atomic::Ordering;
use std::sync::Arc;
+use std::thread::sleep;
+use std::time::{Duration, Instant};
pub const SCREEN_WIDTH: usize = 8 * 32;
pub const SCREEN_HEIGHT: usize = 8 * 28;
@@ -38,6 +40,10 @@ fn _default_none<T>() -> Option<T> {
None
}
+fn _default_now() -> Instant {
+ Instant::now()
+}
+
#[derive(Serialize, Deserialize)]
pub struct PPU<TRenderer: Renderer> {
pub(super) vram: InnerVram,
@@ -45,6 +51,14 @@ pub struct PPU<TRenderer: Renderer> {
#[serde(skip, default = "_default_none")]
pub renderer: Option<TRenderer>,
+ /// Timestamp when the last frame was completed
+ #[serde(skip, default = "_default_now")]
+ last_frame: Instant,
+
+ /// The desired speed at which to run the PPU (and with that the emulator)
+ /// in microseconds per frame.
+ desired_frametime: u64,
+
pub(super) cycles: usize,
pub(super) last_scanline: usize,
pub(super) intreq_vblank: bool,
@@ -75,7 +89,9 @@ where
const VBLANK_START: usize = 0xE1;
const LINE_HBLANK_START: usize = 274 * 4;
- pub fn new(renderer: TRenderer) -> Self {
+ pub fn new(renderer: TRenderer, fps: u64) -> Self {
+ let desired_frametime = if fps == 0 { 0 } else { 1_000_000 / fps };
+
Self {
vram: vec![0; VRAM_WORDS],
@@ -96,6 +112,9 @@ where
vmadd: Cell::new(0),
vmain: 0,
vram_prefetch: Cell::new(0),
+
+ last_frame: Instant::now(),
+ desired_frametime,
}
}
@@ -217,16 +236,29 @@ where
// Reload OAMADD
self.state.oamadd_addr.set(self.state.oamadd_reload.get());
+ // Roll over the VRAM buffer so changes can be made for the
+ // next frame.
self.state.vram = Arc::new(self.vram.clone());
}
} else {
if self.vblank {
+ // VBlank period has ended
self.vblank = false;
// Send frame to the screen
+ // Wait for threadpool workers to finish all scanlines
self.pool.join();
+
+ // Present frame to the screen
let renderer = self.renderer.as_mut().unwrap();
renderer.update()?;
+
+ // Sync to desired framerate
+ let frametime = self.last_frame.elapsed().as_micros() as u64;
+ if frametime < self.desired_frametime {
+ sleep(Duration::from_micros(self.desired_frametime - frametime));
+ }
+ self.last_frame = Instant::now();
}
// Scanline 0 is discarded by the original hardware, so
diff --git a/src/snes/ppu/tests.rs b/src/snes/ppu/tests.rs
index 1dad23e..6c62eff 100644
--- a/src/snes/ppu/tests.rs
+++ b/src/snes/ppu/tests.rs
@@ -8,7 +8,7 @@ fn ppustate() -> PPUState {
PPUState::new()
}
fn ppu() -> PPU<NullRenderer> {
- PPU::new(NullRenderer {})
+ PPU::new(NullRenderer {}, 0)
}
#[test]
diff --git a/src/test/mod.rs b/src/test/mod.rs
index f558d5c..dfd868f 100644
--- a/src/test/mod.rs
+++ b/src/test/mod.rs
@@ -19,7 +19,7 @@ fn test_display(rom: &[u8], pass_hash: &[u8], time_limit: u128, stable: bool, hi
let (display, dispstatus) = TestRenderer::new_test(SCREEN_WIDTH, SCREEN_HEIGHT);
let (joypads, _) = Joypad::new_channel_all();
let cart = Cartridge::load_nohdr(rom, hirom);
- let bus = Mainbus::<TestRenderer>::new(cart, BusTrace::None, display, joypads, false);
+ let bus = Mainbus::<TestRenderer>::new(cart, BusTrace::None, display, joypads, false, 0);
let reset = bus.read16(0xFFFC);
let mut cpu = Cpu65816::<Mainbus<TestRenderer>>::new(bus, reset);