From b2aa3fd0e0f0cfbc7ed4387ffaea0f1ed663c59f Mon Sep 17 00:00:00 2001
From: Jared Burce <jaredr@gmail.com>
Date: Sat, 6 Mar 2021 04:18:48 -0800
Subject: [PATCH] emu: MOV generic. Drop Reg16 register wrapper type

---
 src/emu/i8088.rs | 54 ++++++++++++++++++++++++------------------------
 1 file changed, 27 insertions(+), 27 deletions(-)

diff --git a/src/emu/i8088.rs b/src/emu/i8088.rs
index d5d2646..3e42c8d 100644
--- a/src/emu/i8088.rs
+++ b/src/emu/i8088.rs
@@ -8,10 +8,10 @@ use emu::pc::Bus;
 #[derive(Clone, Copy, Debug, Default)]
 pub struct i8088 {
   // Data Registers
-  pub a: Reg16,
-  pub b: Reg16,
-  pub c: Reg16,
-  pub d: Reg16,
+  pub a: u16,
+  pub b: u16,
+  pub c: u16,
+  pub d: u16,
 
   // Index Registers
   pub si: u16,  // Source Index
@@ -50,18 +50,17 @@ pub struct Flags {
 }
 
 mod ops {
-  use emu::i8088::segoff_to_addr;
+  use emu::i8088::{LValue, RValue, segoff_to_addr};
   use emu::byteorder::{ByteOrder, LittleEndian};
 
   pub fn call(ip: &mut u16, ss: u16, sp: &mut u16, mem: &mut [u8], addr: i16) {
     let target = ip.wrapping_add(addr as u16);
-    trace!("CALL 0x{:04X}", target);
     push16(ss, sp, mem, *ip);
     *ip = target;
   }
 
-  pub fn mov(reg: &mut super::Reg16, val: u16) {
-    reg.x = val;
+  pub fn mov<T>(dst: &mut impl LValue<T>, src: &impl RValue<T>) {
+    dst.write(src.read());
   }
 
   pub fn pop16(ss: u16, sp: &mut u16, mem: &[u8]) -> u16 {
@@ -77,10 +76,28 @@ mod ops {
   }
 
   pub fn ret(ip: &mut u16, ss: u16, sp: &mut u16, mem: &[u8]) {
-    trace!("RET");
     *ip = pop16(ss, sp, mem);
   }
+}
 
+pub trait LValue<T> {
+  fn write(&mut self, val: T);
+}
+
+pub trait RValue<T> {
+  fn read(&self) -> T;
+}
+
+impl LValue<u16> for u16 {
+  fn write(&mut self, val: u16) {
+    *self = val;
+  }
+}
+
+impl RValue<u16> for u16 {
+  fn read(&self) -> u16 {
+    *self
+  }
 }
 
 macro_rules! step {
@@ -110,7 +127,7 @@ macro_rules! step {
     let mut buf = [0; 2];
     buf[0] = $cpu.next_ip($bus);
     buf[1] = $cpu.next_ip($bus);
-    step!(@arg $cookie, LittleEndian::read_u16(&buf))
+    step!(@arg $cookie, &LittleEndian::read_u16(&buf))
   } };
 
   (@mem $cookie:tt, $cpu:ident, $bus:ident) => {
@@ -222,20 +239,3 @@ impl Debug for Flags {
     Ok(())
   }
 }
-
-#[repr(C)]
-#[derive(Clone, Copy)]
-pub union Reg16 {
-  x: u16,
-  lh: [u8; 2],
-}
-
-impl Debug for Reg16 {
-  fn fmt(&self, fmt: &mut Formatter) -> Result<(), std::fmt::Error> {
-    unsafe { self.x.fmt(fmt) }
-  }
-}
-
-impl Default for Reg16 {
-  fn default() -> Self { Self { x: 0u16 } }
-}