cpu: Change ST and DT back to u8

src/cpu.rs

@@ -51,8 +51,8 @@ pub struct CPU {
     pc: Adr,
     i: Adr,
     v: [u8; 16],
-    delay: f64,
+    delay: u8,
-    sound: f64,
+    sound: u8,
     // I/O
     keys: [bool; 16],
     /// Set to the last key that's been *released* after a keypause
@@ -257,7 +257,7 @@ impl CPU {
     /// assert_eq!(0, cpu.sound());
     /// ```
     pub fn sound(&self) -> u8 {
-        self.sound as u8
+        self.sound
     }
 
     /// Gets the value in the Delay Timer register
@@ -268,7 +268,7 @@ impl CPU {
     /// assert_eq!(0, cpu.delay());
     /// ```
     pub fn delay(&self) -> u8 {
-        self.delay as u8
+        self.delay
     }
 
     /// Gets the number of cycles the CPU has executed
@@ -332,8 +332,8 @@ impl CPU {
         // Zero the registers
         self.i = 0;
         self.v = [0; 16];
-        self.delay = 0.0;
+        self.delay = 0;
-        self.sound = 0.0;
+        self.sound = 0;
         // I/O
         self.keys = [false; 16];
         self.lastkey = None;
@@ -415,25 +415,22 @@ impl CPU {
     /// ```rust
     /// # use chirp::*;
     /// let mut cpu = CPU::default();
-    /// let mut bus = bus!{
+    /// let mut screen = bus!{
-    ///     Program [0x0200..0x0f00] = &[
+    ///     Screen  [0x000..0x100],
-    ///         0x00, 0xe0, // cls
-    ///         0x22, 0x02, // jump 0x202 (pc)
-    ///     ],
-    ///     Screen  [0x0f00..0x1000],
     /// };
-    /// cpu.multistep(&mut bus, 0x20)
+    /// cpu.load_program_bytes(&[0x00, 0xe0, 0x22, 0x02]);
+    /// cpu.multistep(&mut screen, 0x20)
     ///     .expect("The program should only have valid opcodes.");
     /// assert_eq!(0x202, cpu.pc());
     /// assert_eq!(0x20, cpu.cycle());
     /// ```
     pub fn multistep(&mut self, screen: &mut Bus, steps: usize) -> Result<&mut Self> {
+        //let speed = 1.0 / steps as f64;
         for _ in 0..steps {
             self.tick(screen)?;
-            let speed = 1.0 / steps as f64;
-            self.delay -= speed;
-            self.sound -= speed;
         }
+        self.delay = self.delay.saturating_sub(1);
+        self.sound = self.sound.saturating_sub(1);
         self.flags.draw_wait = false;
         Ok(self)
     }
@@ -613,8 +610,8 @@ impl Default for CPU {
             pc: 0x200,
             i: 0,
             v: [0; 16],
-            delay: 0.0,
+            delay: 0,
-            sound: 0.0,
+            sound: 0,
             cycle: 0,
             keys: [false; 16],
             lastkey: None,

src/cpu/behavior.rs

@@ -520,7 +520,7 @@ impl CPU {
     /// ```
     #[inline(always)]
     pub(super) fn load_delay_timer(&mut self, x: Reg) {
-        self.v[x] = self.delay as u8;
+        self.v[x] = self.delay;
     }
     /// |`Fx0A`| Wait for key, then vX = K
     #[inline(always)]
@@ -539,7 +539,7 @@ impl CPU {
     /// ```
     #[inline(always)]
     pub(super) fn store_delay_timer(&mut self, x: Reg) {
-        self.delay = self.v[x] as f64;
+        self.delay = self.v[x];
     }
     /// |`Fx18`| Load vX into ST
     /// ```py
@@ -547,7 +547,7 @@ impl CPU {
     /// ```
     #[inline(always)]
     pub(super) fn store_sound_timer(&mut self, x: Reg) {
-        self.sound = self.v[x] as f64;
+        self.sound = self.v[x];
     }
     /// |`Fx1e`| Add vX to I,
     /// ```py

src/cpu/tests.rs

@@ -875,8 +875,7 @@ mod io {
         for word in 0..=0xff {
             for x in 0..=0xf {
                 // set the register under test to `word`
-                cpu.delay = word as f64;
+                cpu.delay = word;
-
                 cpu.load_delay_timer(x);
 
                 assert_eq!(cpu.v[x], word);
@@ -895,7 +894,7 @@ mod io {
 
                 cpu.store_delay_timer(x);
 
-                assert_eq!(cpu.delay, word as f64);
+                assert_eq!(cpu.delay, word);
             }
         }
     }
@@ -911,7 +910,7 @@ mod io {
 
                 cpu.store_sound_timer(x);
 
-                assert_eq!(cpu.sound, word as f64);
+                assert_eq!(cpu.sound, word);
             }
         }
     }
@@ -1072,28 +1071,28 @@ mod behavior {
         #[test]
         fn delay() {
             let (mut cpu, mut bus) = setup_environment();
-            cpu.delay = 10.0;
             cpu.flags.monotonic = false;
+            cpu.delay = 10;
             for _ in 0..2 {
                 cpu.multistep(&mut bus, 8)
                     .expect("Running valid instructions should always succeed");
                 std::thread::sleep(Duration::from_secs_f64(1.0 / 60.0));
             }
             // time is within 1 frame deviance over a theoretical 2 frame pause
-            assert!(7.0 <= cpu.delay && cpu.delay <= 9.0);
+            assert_eq!(cpu.delay, 8);
         }
         #[test]
         fn sound() {
             let (mut cpu, mut bus) = setup_environment();
-            cpu.sound = 10.0;
             cpu.flags.monotonic = false; // disable monotonic timing
+            cpu.sound = 10;
             for _ in 0..2 {
                 cpu.multistep(&mut bus, 8)
                     .expect("Running valid instructions should always succeed");
                 std::thread::sleep(Duration::from_secs_f64(1.0 / 60.0));
             }
             // time is within 1 frame deviance over a theoretical 2 frame pause
-            assert!(7.0 <= cpu.sound && cpu.sound <= 9.0);
+            assert_eq!(cpu.sound, 8);
         }
         #[test]
         fn vbi_wait() {