add: configuration for throttling

src/args.rs

@@ -13,6 +13,7 @@ pub struct Porcel8ProgramArgs {
         help = "Emulate new behaviour of instructions (As seen in Chip-48 and SuperChip8)",
         default_value_t = true
     )]
+    /// Use updated CHIP-8 behaviours.
     pub new_chip8_behaviour: bool,
     #[arg(
         short='i',
@@ -20,5 +21,12 @@ pub struct Porcel8ProgramArgs {
         help = "Halt on invalid instruction",
         default_value_t = false
     )]
+    /// Halt on finding invalid instruction
     pub halt_on_invalid: bool,
+    /// Enable Instruction Throttling 
+    #[arg(short, default_value_t=true)]
+    pub do_instruction_throttling: bool,
+    /// Target Instructions per second, if throttling is enabled
+    #[arg(short='t',long,default_value_t=5_000u64)]
+    pub ips_throttling_rate: u64
 }

src/device/device.rs

@@ -1,7 +1,7 @@
 use crate::{device::instruction::Instruction, util::EmulatorError};
 use crate::device::keyboard::Keyboard;
 use crate::device::timer::DeviceTimerManager;
-use crate::util::EmulatorResult;
+use crate::util::{DeviceConfig, EmulatorResult};
 use rand::random;
 use rand::seq::IteratorRandom;
 use std::sync::{Arc, Mutex};
@@ -14,9 +14,8 @@ pub struct Device {
     pub timer: DeviceTimerManager,
     pub stack: Vec<u16>,
     pub frame_buffer: Arc<Mutex<Box<[bool; 64 * 32]>>>,
-    pub new_chip8_mode: bool,
-    pub halt_on_invalid: bool,
     pub device_keyboard: Keyboard,
+    pub device_config: DeviceConfig
 }
 
 impl Device {
@@ -28,8 +27,7 @@ impl Device {
         timer: DeviceTimerManager,
         fb: Arc<Mutex<Box<[bool; Device::FRAME_BUFFER_SIZE]>>>,
         device_keyboard: Keyboard,
-        new_chip8_mode: bool,
+        device_config: DeviceConfig
-        halt_on_invalid: bool
     ) -> Device {
         let memory = vec![0u8; Self::DEVICE_MEMORY_SIZE]
             .into_boxed_slice()
@@ -41,10 +39,9 @@ impl Device {
             memory,
             frame_buffer: fb,
             stack: Vec::with_capacity(16),
-            halt_on_invalid,
             timer,
-            new_chip8_mode,
             device_keyboard,
+            device_config
         }
     }
 }
@@ -55,11 +52,6 @@ impl Device {
     const FONT_DEFAULT_MEM_LOCATION_END: usize = 0x9F;
     const ROM_START: usize = 0x200;
 
-    // Throttling configuration for cpu
-    const DO_CHIP_CPU_THROTTLING:bool = false;
-    const TARGET_CPU_SPEED_INSTRUCTIONS_PER_SECOND: u64 = 10000;
-    const TARGET_CPU_INSTRUCTION_TIME: Duration = Duration::from_micros(1_000_000/Self::TARGET_CPU_SPEED_INSTRUCTIONS_PER_SECOND);
-
     pub fn cycle(&mut self) -> EmulatorResult<()> {
         let time_start = std::time::Instant::now();
         self.device_keyboard.update_keyboard_registers()?;
@@ -71,9 +63,9 @@ impl Device {
         let instruction = Instruction::decode_instruction(instr_slice);
         self.execute_instruction(instruction)?;
 
-        let instruction_time = time_start.elapsed();
+        if let Some(throttling_duration) = self.device_config.get_throttling_config() {
-        let time_left_to_sleep_for_instruction = Self::TARGET_CPU_INSTRUCTION_TIME.checked_sub(instruction_time).unwrap_or(Duration::ZERO);
+            let instruction_time = time_start.elapsed();
-        if Self::DO_CHIP_CPU_THROTTLING {
+            let time_left_to_sleep_for_instruction = throttling_duration.checked_sub(instruction_time).unwrap_or(Duration::ZERO);
             log::trace!("Instruction took {:?}, left with {:?}",instruction_time,time_left_to_sleep_for_instruction);
             sleep(time_left_to_sleep_for_instruction);
         }
@@ -89,7 +81,7 @@ impl Device {
         match instruction {
             Instruction::InvalidInstruction => {
                 log::info!("Executing passthrough");
-                if self.halt_on_invalid {
+                if self.device_config.should_halt_on_invalid() {
                     return Err(EmulatorError::IOError("Caught Invalid Instruction".to_string()));
                 }
             },
@@ -152,7 +144,7 @@ impl Device {
                 }
             }
             Instruction::JumpWithOffset(x, num) => {
-                let regnum = if self.new_chip8_mode { x } else { 0 };
+                let regnum = if self.device_config.is_new_chip8() { x } else { 0 };
                 let new_pc = self.registers.v[regnum] as u16 + num;
                 self.registers.pc = new_pc;
             }
@@ -205,7 +197,7 @@ impl Device {
                 self.set_flag_register(!is_overflow);
             }
             Instruction::RShift(x, y) => {
-                if !self.new_chip8_mode {
+                if !self.device_config.is_new_chip8() {
                     self.registers.v[x] = self.registers.v[y];
                 }
                 let val = self.registers.v[x];
@@ -214,7 +206,7 @@ impl Device {
                 self.set_flag_register(bit_carry);
             }
             Instruction::LShift(x, y) => {
-                if !self.new_chip8_mode {
+                if !self.device_config.is_new_chip8() {
                     self.registers.v[x] = self.registers.v[y];
                 }
                 let left = self.registers.v[x];
@@ -239,7 +231,7 @@ impl Device {
                 let reg_value = self.registers.v[x];
                 let index_original = self.registers.i;
                 // newer instruction set requires wrapping on 12 bit overflow, and setting vf
-                let addn_res = if self.new_chip8_mode {
+                let addn_res = if self.device_config.is_new_chip8() {
                     let overflowing = (reg_value as u16 + index_original) >= 0x1000;
                     self.set_flag_register(overflowing);
                     (reg_value as u16 + index_original) % 0x1000
@@ -290,7 +282,7 @@ impl Device {
                 let index = self.registers.i as usize;
                 self.memory[index..=(index + last_reg_to_store)].copy_from_slice(reg_slice);
                 // Old Chip8 used to use i as a incrementing index
-                if !self.new_chip8_mode {
+                if !self.device_config.is_new_chip8() {
                     self.registers.i += last_reg_to_store as u16 + 1;
                 }
             }
@@ -299,7 +291,7 @@ impl Device {
                 let mem_slice = &self.memory[index..=(index + last_reg_to_load)];
                 self.registers.v[0..=last_reg_to_load].copy_from_slice(mem_slice);
                 // Old Chip8 used to use i as a incrementing index
-                if !self.new_chip8_mode {
+                if !self.device_config.is_new_chip8() {
                     self.registers.i += last_reg_to_load as u16 + 1;
                 }
             }

src/main.rs

@@ -14,6 +14,7 @@ use sdl2::render::BlendMode;
 
 use sdl2::render::WindowCanvas;
 use simple_logger::SimpleLogger;
+use util::DeviceConfig;
 
 use crate::args::Porcel8ProgramArgs;
 use crate::device::Device;
@@ -33,7 +34,7 @@ const WINDOW_TITLE: &str = "porcel8";
 
 fn main() -> EmulatorResult<()> {
     SimpleLogger::new().with_level(LevelFilter::Info).env().init().unwrap();
-    let Porcel8ProgramArgs { filename, new_chip8_behaviour, draw_scale, halt_on_invalid } = Porcel8ProgramArgs::parse();
+    let Porcel8ProgramArgs { filename, new_chip8_behaviour, draw_scale, halt_on_invalid, do_instruction_throttling, ips_throttling_rate: ipms_throttling_rate } = Porcel8ProgramArgs::parse();
 
     log::info!("Started emulator");
 
@@ -45,8 +46,8 @@ fn main() -> EmulatorResult<()> {
     let (sdl_kb_adapter, device_keyboard) = SdlKeyboardAdapter::new_keyboard();
 
     timer.start();
-
+    let device_config = DeviceConfig::new(new_chip8_behaviour, halt_on_invalid, do_instruction_throttling, ipms_throttling_rate);
-    let device = Device::new(timer, frame_buffer_for_device, device_keyboard, new_chip8_behaviour, halt_on_invalid);
+    let device = Device::new(timer, frame_buffer_for_device, device_keyboard, device_config);
 
     let (device_termination_signal_sender, compute_handle) = start_compute_thread(filename, device)?;
 
@@ -111,8 +112,6 @@ fn start_compute_thread(filename: String, mut device: Device) -> EmulatorResult<
                 panic!("Disconnected");
             }
             device.cycle().expect("Failed to execute");
-            // Put a bit of delay to slow down execution
-            thread::sleep(Duration::from_millis(2))
         }
     })?;
     Ok((device_termination_signal_sender, compute_handle))

src/util.rs

@@ -1,17 +1,54 @@
+use crate::device::keyboard::KeyboardEvent;
+use sdl2::video::WindowBuildError;
+use sdl2::IntegerOrSdlError;
 use std::sync::mpsc::SendError;
 use std::sync::PoisonError;
-use sdl2::IntegerOrSdlError;
+use std::time::Duration;
-use sdl2::video::WindowBuildError;
-use crate::device::keyboard::KeyboardEvent;
 
 pub type EmulatorResult<T> = Result<T, EmulatorError>;
 
+/// CHIP-8 Device configuration
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub struct DeviceConfig {
+    is_new_chip8: bool,
+    halt_on_invalid: bool,
+    /// None if disabled, target instruction time otherwise
+    throttling_time: Option<Duration>,
+}
+
+impl DeviceConfig {
+    pub fn new(
+        is_new_chip8: bool,
+        halt_on_invalid: bool,
+        do_instruction_throttling: bool,
+        ips_throttling_rate: u64,
+    ) -> DeviceConfig {
+        DeviceConfig {
+            is_new_chip8,
+            halt_on_invalid,
+            throttling_time: if do_instruction_throttling {
+                Some(Duration::from_micros(1_000_000 / ips_throttling_rate))
+            } else {
+                None
+            },
+        }
+    }
+    pub fn is_new_chip8(&self) -> bool {
+        self.is_new_chip8
+    }
+    pub fn should_halt_on_invalid(&self) -> bool {
+        self.halt_on_invalid
+    }
+    pub fn get_throttling_config(&self) -> Option<Duration> {
+        self.throttling_time
+    }
+}
 
 #[derive(Clone, Debug)]
 pub enum EmulatorError {
     SdlError(String),
     IOError(String),
-    MutexInvalidState(String)
+    MutexInvalidState(String),
 }
 
 impl From<String> for EmulatorError {
@@ -29,24 +66,50 @@ impl From<WindowBuildError> for EmulatorError {
 impl From<IntegerOrSdlError> for EmulatorError {
     fn from(value: IntegerOrSdlError) -> Self {
         match value {
-            IntegerOrSdlError::IntegerOverflows(x, y) => { Self::SdlError(format!("{} - {}", x, y)) }
+            IntegerOrSdlError::IntegerOverflows(x, y) => Self::SdlError(format!("{} - {}", x, y)),
-            IntegerOrSdlError::SdlError(str) => { Self::SdlError(str) }
+            IntegerOrSdlError::SdlError(str) => Self::SdlError(str),
         }
     }
 }
-impl From<std::io::Error> for EmulatorError{
+impl From<std::io::Error> for EmulatorError {
     fn from(value: std::io::Error) -> Self {
         Self::IOError(value.to_string())
     }
 }
-impl<T> From<PoisonError<T>> for EmulatorError{
+impl<T> From<PoisonError<T>> for EmulatorError {
     fn from(value: PoisonError<T>) -> Self {
         Self::MutexInvalidState(value.to_string())
     }
 }
 
-impl From<SendError<KeyboardEvent>> for EmulatorError{
+impl From<SendError<KeyboardEvent>> for EmulatorError {
     fn from(value: SendError<KeyboardEvent>) -> Self {
-        Self::IOError(format!("Failed to communicate keyboard event to main thread: {}",value))
+        Self::IOError(format!(
+            "Failed to communicate keyboard event to main thread: {}",
+            value
+        ))
+    }
+}
+
+#[cfg(test)]
+mod tests{
+    use std::time::Duration;
+
+    use super::DeviceConfig;
+
+    #[test]
+    fn test_device_config_all_false(){
+        let device_config = DeviceConfig::new(false, false, false, 800);
+        assert_eq!(false,device_config.is_new_chip8());
+        assert_eq!(false,device_config.should_halt_on_invalid());
+        assert!(device_config.get_throttling_config().is_none());
+    }
+    #[test]
+    fn test_device_config_throttling_enabled_and_new_chip8(){
+        let device_config = DeviceConfig::new(true, false, true, 100);
+        const EXPECTED_INSTRUCTION_TIME_MS:u64 = 10;
+        assert_eq!(true,device_config.is_new_chip8());
+        assert_eq!(false,device_config.should_halt_on_invalid());
+        assert_eq!(Some(Duration::from_millis(EXPECTED_INSTRUCTION_TIME_MS)),device_config.get_throttling_config());
     }
 }