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emu: PUSH/POP opcodes, reimpl RET as just "POP IP"

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This also promotes CALL/RET to actually using the bus for
addressing (because it goes through the generic PUSH/POP code), which
is probably more correct anyway.
This commit is contained in:
Jared Burce
2021-03-18 00:32:08 -07:00
parent dcf96ec5b3
commit 3b746b75ec
2 changed files with 33 additions and 16 deletions
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27
src/emu/i8088.rs
View File

@@ -352,6 +352,13 @@ impl i8088 {
loop {
step!((self, bus) =>
opcodes: {
0x06 => push[bus, regval=ss, reg=sp, regval=es] / 14,
0x07 => pop[bus, regval=ss, reg=sp, reg=es] / 12,
0x0E => push[bus, regval=ss, reg=sp, regval=cs] / 14,
0x16 => push[bus, regval=ss, reg=sp, regval=ss] / 14,
0x17 => pop[bus, regval=ss, reg=sp, reg=ss] / 12,
0x1E => push[bus, regval=ss, reg=sp, regval=ds] / 14,
0x1F => pop[bus, regval=ss, reg=sp, reg=ds] / 12,
0x26 => nop[seg=es, prefix] / 2,
0x2E => nop[seg=cs, prefix] / 2,
0x36 => nop[seg=ss, prefix] / 2,
@@ -362,6 +369,22 @@ impl i8088 {
0x3C => cmp[flags, reglo=a, d8] / "3/24+",
0x3D => cmp[flags, reg=a, d16] / "3/24+",
0x3E => nop[seg=ds, prefix] / 2,
0x50 => push[bus, regval=ss, reg=sp, regval=a] / 15,
0x51 => push[bus, regval=ss, reg=sp, regval=c] / 15,
0x52 => push[bus, regval=ss, reg=sp, regval=d] / 15,
0x53 => push[bus, regval=ss, reg=sp, regval=b] / 15,
0x54 => push[bus, regval=ss, reg=sp, regval=sp] / 15,
0x55 => push[bus, regval=ss, reg=sp, regval=bp] / 15,
0x56 => push[bus, regval=ss, reg=sp, regval=si] / 15,
0x57 => push[bus, regval=ss, reg=sp, regval=di] / 15,
0x58 => pop[bus, regval=ss, reg=sp, reg=a] / 12,
0x59 => pop[bus, regval=ss, reg=sp, reg=c] / 12,
0x5A => pop[bus, regval=ss, reg=sp, reg=d] / 12,
0x5B => pop[bus, regval=ss, reg=sp, reg=b] / 12,
0x5C => pop[bus, regval=ss, reg=sp, reg=sp] / 12,
0x5D => pop[bus, regval=ss, reg=sp, reg=bp] / 12,
0x5E => pop[bus, regval=ss, reg=sp, reg=si] / 12,
0x5F => pop[bus, regval=ss, reg=sp, reg=di] / 12,
0x60 => show[cpu] / 0, // Fake opcode for debugging
0x61 => peek[seg=ds, addr] / 0, // Fake opcode for debugging
0x62 _ => assert[modrm8, d8] / 0, // Fake opcode for debugging
@@ -413,9 +436,9 @@ impl i8088 {
0xBD => mov[reg=bp, d16] / 4,
0xBE => mov[reg=si, d16] / 4,
0xBF => mov[reg=di, d16] / 4,
0xC3 => ret[reg=ip, regval=ss, reg=sp, mem] / 20,
0xC3 => pop[bus, regval=ss, reg=sp, reg=ip] / 20, // RET
0xCD => int[cpu, bus, d8] / 71,
0xE8 => call[reg=ip, regval=ss, reg=sp, mem, rel16] / 23,
0xE8 => call[reg=ip, bus, regval=ss, reg=sp, rel16] / 23,
0xF2 => nop[rep=NotEqual, prefix] / 0, // REPNE/REPNZ
0xF3 => nop[rep=Equal, prefix] / 0, // REP/REPE/REPZ
},

22
src/emu/operations.rs
View File

@@ -1,12 +1,9 @@
use std::fmt::Debug;
use emu::byteorder::{ByteOrder, LittleEndian};
use emu::dos;
use emu::i8088::{Flags, RepPrefix, i8088};
use emu::operands::{Addr, Address, LValue, Operand, Reg, RValue};
use emu::pc::Bus;
use emu::util::segoff_to_addr;
macro_rules! string_op {
( ($type:ty,
@@ -92,9 +89,9 @@ pub fn peek(addr: &(impl Address + RValue<u8>)) {
println!("PEEK: @{:#X} = {:#X} ({})", addr.addr(), addr.read(), addr.read());
}
pub fn call(ip: &mut Reg, ss: u16, sp: &mut Reg, mem: &mut [u8], addr: i16) {
pub fn call(ip: &mut Reg, bus: &mut Bus, ss: u16, sp: &mut Reg, addr: i16) {
let target = ip.read().wrapping_add(addr as u16);
push16(ss, sp, mem, ip.read());
push(bus, ss, sp, ip.read());
ip.write(target);
}
@@ -209,20 +206,17 @@ pub fn movsw(flags: &Flags,
pub fn nop() {}
pub fn pop16(ss: u16, sp: &mut Reg, mem: &[u8]) -> u16 {
let val = LittleEndian::read_u16(&mem[segoff_to_addr(ss.read(), sp.read())..]);
pub fn pop(bus: &mut Bus, ss: u16, sp: &mut Reg, dst: &mut Reg) {
let ptr = Addr { bus: bus, segment: ss, offset: sp.read() };
dst.write(ptr.read());
sp.write(sp.read() + 2);
val
}
pub fn push16(ss: u16, sp: &mut Reg, mem: &mut [u8], val: u16) {
pub fn push(bus: &mut Bus, ss: u16, sp: &mut Reg, val: u16) {
// XXX: Not checking for stack faults or anything
sp.write(sp.read() - 2);
LittleEndian::write_u16(&mut mem[segoff_to_addr(ss.read(), sp.read())..], val);
}
pub fn ret(ip: &mut Reg, ss: u16, sp: &mut Reg, mem: &[u8]) {
ip.write(pop16(ss, sp, mem));
let mut ptr = Addr { bus: bus, segment: ss, offset: sp.read() };
ptr.write(val);
}
pub fn scasb(flags: &mut Flags,