emu: show/peek debug instructions

src/emu/i8088.rs

@@ -54,6 +54,16 @@ mod ops {
   use emu::dos;
   use emu::i8088::{Bus, LValue, RValue, i8088, segoff_to_addr};
 
+  pub fn show(cpu: &mut i8088) {
+    println!("{:#X?}", cpu);
+  }
+
+  pub fn peek(cpu: &mut i8088, bus: &mut Bus, addr: &u16) {
+    let addr = segoff_to_addr(cpu.ds, *addr);
+    let val = bus.ram[addr];
+    println!("PEEK: @{:#X} = {:#X} ({})", addr, val, val);
+  }
+
   pub fn call(ip: &mut u16, ss: u16, sp: &mut u16, mem: &mut [u8], addr: i16) {
     let target = ip.wrapping_add(addr as u16);
     push16(ss, sp, mem, *ip);
@@ -211,6 +221,7 @@ macro_rules! step {
    } };
 
   (@r16 $cookie:tt, $cpu:expr, $bus:expr, ($modrm:ident, $modrm16:tt, $modrm8:tt)) => { {
+    // TODO: Should these also be passed into the macro like the modrm specs?
     let reg = match $modrm >> 3 & 0x7 {
       0 => &mut $cpu.a,
       1 => &mut $cpu.c,
@@ -226,6 +237,7 @@ macro_rules! step {
   } };
 
   (@r8 $cookie:tt, $cpu:expr, $bus:expr, ($modrm:ident, $modrm16:tt, $modrm8:tt)) => {
+    // TODO: Should these also be passed into the macro like the modrm specs?
     match $modrm >> 3 & 0x7 {
       0 => step!(@arg $cookie, &mut RegHi { reg: &mut $cpu.a } ),
       1 => step!(@arg $cookie, &mut RegHi { reg: &mut $cpu.c } ),
@@ -348,6 +360,8 @@ impl i8088 {
     loop {
       step!((self, bus) =>
         opcodes: {
+          0x60 => show[cpu] / 0,  // Fake opcode for debugging
+          0x61 => peek[cpu, bus, d16] / 0,  // Fake opcode for debugging
           //0x8B _ => mov[r16, modrm16] / "2/12+",
           0x8C: { 0x08 => mov[modrm16, reg=cs] / "2/13+", },
           0x8E: { 0x18 => mov[reg=ds, modrm16] / "2/12+", },