From 0f4e52697abe67a19ecd316a8dd5d8702de58cf1 Mon Sep 17 00:00:00 2001
From: Jared Burce <jaredr@gmail.com>
Date: Sat, 6 Mar 2021 04:52:09 -0800
Subject: [PATCH] emu: reghi & d8 address modes. make next_ip assoc instead of
 member

next_ip would borrow all of the cpu, now we just need IP and CS.
---
 src/emu/i8088.rs | 56 ++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 47 insertions(+), 9 deletions(-)

diff --git a/src/emu/i8088.rs b/src/emu/i8088.rs
index 3e42c8d..353238d 100644
--- a/src/emu/i8088.rs
+++ b/src/emu/i8088.rs
@@ -88,6 +88,12 @@ pub trait RValue<T> {
   fn read(&self) -> T;
 }
 
+impl RValue<u8> for u8 {
+  fn read(&self) -> u8 {
+    *self
+  }
+}
+
 impl LValue<u16> for u16 {
   fn write(&mut self, val: u16) {
     *self = val;
@@ -100,6 +106,27 @@ impl RValue<u16> for u16 {
   }
 }
 
+struct RegHi<'a> {
+  reg: &'a mut u16
+}
+
+impl<'a> LValue<u8> for RegHi<'a> {
+  fn write(&mut self, val: u8) {
+    let mut buf = [0; 2];
+    LittleEndian::write_u16(&mut buf, *self.reg);
+    buf[1] = val;
+    *self.reg = LittleEndian::read_u16(&buf);
+  }
+}
+
+impl<'a> RValue<u8> for RegHi<'a> {
+  fn read(&self) -> u8 {
+    let mut buf = [0; 2];
+    LittleEndian::write_u16(&mut buf, *self.reg);
+    buf[1] as u8
+  }
+}
+
 macro_rules! step {
   // Base case: all args processed and ready to call op
   (@code ( $($args:tt)* ),
@@ -112,7 +139,9 @@ macro_rules! step {
   (@code ( $($args:tt)* ),
          $cpu:ident, $bus:ident, $name:ident, $cycles:literal,
          ($next:ident $(= $nextrhs:ident)? $($rest:ident $(= $restrhs:ident)?)*)) => {
-    step!(@$next$(= $nextrhs)? ( ($($args)*), $cpu, $bus, $name, $cycles, ($($rest $(= $restrhs)?)*) ), $cpu, $bus)
+    step!(@$next$(= $nextrhs)?
+          ( ($($args)*), $cpu, $bus, $name, $cycles, ($($rest $(= $restrhs)?)*) ),
+          $cpu, $bus)
   };
 
   // accept an argument from a decoder and recur to look for next arg
@@ -123,10 +152,14 @@ macro_rules! step {
 
   // Argument Decoders
 
+  (@d8 $cookie:tt, $cpu:ident, $bus:ident) => { {
+    step!(@arg $cookie, &i8088::next_ip($cpu.cs, &mut $cpu.ip, $bus))
+  } };
+
   (@d16 $cookie:tt, $cpu:ident, $bus:ident) => { {
     let mut buf = [0; 2];
-    buf[0] = $cpu.next_ip($bus);
-    buf[1] = $cpu.next_ip($bus);
+    buf[0] = i8088::next_ip($cpu.cs, &mut $cpu.ip, $bus);
+    buf[1] = i8088::next_ip($cpu.cs, &mut $cpu.ip, $bus);
     step!(@arg $cookie, &LittleEndian::read_u16(&buf))
   } };
 
@@ -138,21 +171,25 @@ macro_rules! step {
     step!(@arg $cookie, &mut $cpu.$reg);
   };
 
+  (@reghi=$reg:ident $cookie:tt, $cpu:ident, $bus:ident) => {
+    step!(@arg $cookie, &mut RegHi { reg: &mut $cpu.$reg });
+  };
+
   (@regval=$reg:ident $cookie:tt, $cpu:ident, $bus:ident) => {
     step!(@arg $cookie, $cpu.$reg);
   };
 
   (@rel16 $cookie:tt, $cpu:ident, $bus:ident) => { {
     let mut buf = [0; 2];
-    buf[0] = $cpu.next_ip($bus);
-    buf[1] = $cpu.next_ip($bus);
+    buf[0] = i8088::next_ip($cpu.cs, &mut $cpu.ip, $bus);
+    buf[1] = i8088::next_ip($cpu.cs, &mut $cpu.ip, $bus);
     step!(@arg $cookie, LittleEndian::read_i16(&buf))
   } };
 
   // Entry Point
   (($cpu:ident, $bus:ident) => { $( $code:literal => $name:ident[$($args:ident $(= $argrhs:ident)?),*] / $cycles:literal ),*$(,)? } )  => {
     {
-      let opcode = $cpu.next_ip($bus);
+      let opcode = i8088::next_ip($cpu.cs, &mut $cpu.ip, $bus);
       match(opcode) {
         $( $code => step!(@code (), $cpu, $bus, $name, $cycles, ($($args $(= $argrhs)?)*)) ),*,
         _ => unimplemented!("opcode: {:02X}\ncpu: {:#X?}", opcode, $cpu)
@@ -170,6 +207,7 @@ impl i8088 {
   pub fn run(&mut self, bus: &mut Bus) {
     loop {
       step!((self, bus) => {
+        0xB4 => mov[reghi=a, d8] / 4,
         0xBA => mov[reg=d, d16] / 4,
         0xC3 => ret[reg=ip, regval=ss, reg=sp, mem] / 20,
         0xE8 => call[reg=ip, regval=ss, reg=sp, mem, rel16] / 23,
@@ -177,9 +215,9 @@ impl i8088 {
     }
   }
 
-  fn next_ip<'a>(&mut self, bus: &Bus) -> u8 {
-    let eip = segoff_to_addr(self.cs, self.ip);
-    self.ip += 1;
+  fn next_ip<'a>(cs: u16, ip: &mut u16, bus: &Bus) -> u8 {
+    let eip = segoff_to_addr(cs, *ip);
+    *ip += 1;
 
     // We'll assume cpu is always executing in RAM. Also assume the
     // IP doesn't reach the end of the segment (My guess is that it