83 lines
2.9 KiB
Rust
83 lines
2.9 KiB
Rust
use crate::nes::cpu::instructions::*;
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use failure::Error;
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use std::fmt;
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use crate::nes::bus::*;
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use crate::nes::types::*;
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use std::fmt::Debug;
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// Disassemble code around the pc of the cpu
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pub struct Disasm {
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pub start: Addr,
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pub stop: Addr,
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pub instructions: Vec<String>,
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pub addresses: Vec<Addr>
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}
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impl BusDevice for Disasm {}
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impl Disasm {
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// Disassemble given code region
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pub fn disassemble(mem: &MemoryBus, start: Addr, stop: Addr) -> Result<Self, Error> {
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let mut instructions = Vec::new();
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let mut addresses = Vec::new();
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let mut mem_iter = ((start as usize) .. (stop as usize)+1).map({|a| a as Addr});
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while let Some(addr) = mem_iter.next() {
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let opcode = mem.readb(addr);
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// Decode opcode, default to NOP/IMP to "skip" the byte
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let i = Instruction::decode_op(opcode)
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.unwrap_or(Instruction::decode_op(0xeau8).unwrap());
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// debug!("{:?}", i);
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let args = match i.addr_mode {
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AddrMode::IMM => format!("#{0:02x} ({0})", mem.readb(mem_iter.next().unwrap())),
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AddrMode::ZP0 | AddrMode::ZPX | AddrMode::ZPY => {
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let rel_addr = mem.readb(mem_iter.next().unwrap());
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format!("{:#04x}", rel_addr)
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},
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AddrMode::ABS | AddrMode::ABX | AddrMode::ABY => {
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let val = mem.readw(mem_iter.next().unwrap());
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mem_iter.next().unwrap();
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format!("{:#06x}", val)
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},
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AddrMode::REL => {
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let rel_addr = mem.readb(mem_iter.next().unwrap()) as Word;
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let jmp_addr = Disasm::get_rel_addr(rel_addr, addr+2);
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format!("#{:02x} => {:#06x}", rel_addr, jmp_addr)
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},
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AddrMode::IND => {
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let addr = mem.readw(mem_iter.next().unwrap());
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mem_iter.next().unwrap();
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format!("{:#06x}", addr)
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},
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AddrMode::IZX | AddrMode::IZY => {
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let addr = mem.readb(mem_iter.next().unwrap());
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format!("{:#06x}", addr)
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}
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AddrMode::IMP => String::from(""),
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_ => bail!("Disassembly of {} not implemented", i.addr_mode),
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};
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let s = format!("{:#06x}: {} {} ({})", addr, i.operation, args, i.addr_mode);
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// debug!("{:#06x} {}", addr, &s);
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instructions.push(s);
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addresses.push(addr);
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}
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Ok(Disasm { start, stop, instructions, addresses })
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}
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fn get_rel_addr(rel_addr: Addr, curr_addr: Addr) -> Addr {
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if rel_addr < 0x80 {
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curr_addr + rel_addr
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} else {
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curr_addr + (rel_addr) - 256
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}
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}
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}
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impl Debug for Disasm {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(f, "{:?}", self)
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}
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} |