CPU constructor overhaul

src/cpu.rs

@@ -81,14 +81,61 @@ impl CPU {
     ///
     /// [CPU Registers]: https://gbdev.io/pandocs/Power_Up_Sequence.html#cpu-registers
     pub fn new() -> Self {
-        let mut out = Self::default();
-        out.af.wide_mut().0 = 0x1100 | Flags::new().with_z(true).into_bits() as u16;
-        out.bc.wide_mut().0 = 0x0100;
-        out.de.wide_mut().0 = 0xff56;
-        out.hl.wide_mut().0 = 0x000d;
-        out.pc.0 = 0x0100;
-        out.sp.0 = 0xfffe;
-        out
+        Self::new_mgb()
+    }
+
+    pub fn new_dmg() -> Self {
+        Self::default()
+            .with_af(0x0100 | Flags::new().with_z(true).into_bits() as u16)
+            .with_bc(0x0013)
+            .with_de(0x00d8)
+            .with_hl(0x014d)
+            .with_pc(0x0100)
+            .with_sp(0xfffe)
+    }
+
+    pub fn new_mgb() -> Self {
+        Self::default()
+            .with_af(0xff00 | Flags::new().with_z(true).into_bits() as u16)
+            .with_bc(0x0013)
+            .with_de(0x00d8)
+            .with_hl(0x014d)
+            .with_pc(0x0100)
+            .with_sp(0xfffe)
+    }
+
+    pub fn new_cgb() -> Self {
+        Self::default()
+            .with_af(0x1100 | Flags::new().with_z(true).into_bits() as u16)
+            .with_bc(0x0100)
+            .with_de(0xff56)
+            .with_hl(0x000d)
+            .with_pc(0x0100)
+            .with_sp(0xfffe)
+    }
+
+    pub fn with_pc(self, value: u16) -> Self {
+        Self { pc: Wrapping(value), ..self }
+    }
+
+    pub fn with_sp(self, value: u16) -> Self {
+        Self { sp: Wrapping(value), ..self }
+    }
+
+    pub fn with_af(self, value: u16) -> Self {
+        Self { af: SplitRegister::from(value), ..self }
+    }
+
+    pub fn with_bc(self, value: u16) -> Self {
+        Self { bc: SplitRegister::from(value), ..self }
+    }
+
+    pub fn with_de(self, value: u16) -> Self {
+        Self { de: SplitRegister::from(value), ..self }
+    }
+
+    pub fn with_hl(self, value: u16) -> Self {
+        Self { hl: SplitRegister::from(value), ..self }
     }
 }