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|
use header::Header;
use std::fs::File;
use std::io::{ErrorKind, Read, Seek, SeekFrom};
use vnf::{Machine, MemoryInitialValue, MemoryPolicy};
/// Version for this program.
const VERSION: &str = "0.1.0";
#[derive(Default)]
struct Args {
file: String,
start: Option<u16>,
assume_function: bool,
dump_memory: bool,
}
fn print_help() {
println!("Run an NES/Famicom ROM to test its code under a set of conditions.\n");
println!("usage: runrom [OPTIONS] <FILE>\n");
println!("Options:");
println!(" -d, --dump-memory\tShow the memory that has changed after a run.");
println!(" -f, --function\tRun the code by assuming it's a function.");
println!(" -h, --help\t\tPrint this message and quit.");
println!(" -s, --start\t\tAddress from where to start (default: reset vector).");
println!(" -v, --version\t\tPrint version information.");
std::process::exit(0);
}
// Print the given `message` and exit(1).
fn die(message: String) -> ! {
eprintln!("error: {message}");
std::process::exit(1);
}
fn parse_hex_digit(c: char) -> Result<u16, String> {
match c.to_digit(16) {
Some(val) => Ok(val as u16),
None => Err("cannot convert digit to hexadecimal".to_string()),
}
}
fn parse_hex_argument(given: &str) -> Result<u16, String> {
// Skip a leading '$' character.
let arg = if given.starts_with('$') {
given.get(1..).unwrap_or("")
} else {
given
};
let mut chars = arg.chars();
match arg.len() {
0 => Err("you need to provide an address".to_string()),
1 => Ok(parse_hex_digit(chars.next().unwrap())?),
2 => Ok((parse_hex_digit(chars.next().unwrap())? << 4)
+ (parse_hex_digit(chars.next().unwrap())?)),
3 => Ok((parse_hex_digit(chars.next().unwrap())? << 8)
+ (parse_hex_digit(chars.next().unwrap())? << 4)
+ (parse_hex_digit(chars.next().unwrap())?)),
4 => Ok((parse_hex_digit(chars.next().unwrap())? << 12)
+ (parse_hex_digit(chars.next().unwrap())? << 8)
+ (parse_hex_digit(chars.next().unwrap())? << 4)
+ (parse_hex_digit(chars.next().unwrap())?)),
_ => Err("hex literal is too big".to_string()),
}
}
fn parse_arguments() -> Args {
let mut args = std::env::args();
let mut res = Args::default();
// Skip command name.
args.next();
while let Some(arg) = args.next() {
match arg.as_str() {
"-h" | "--help" => print_help(),
"-s" | "--start" => {
if res.start.is_some() {
die("do not specify the '-s/--start' flag twice".to_string());
}
let Some(val) = args.next() else {
die("you need to specify a value for the -s/--start flag!".to_string());
return res;
};
match parse_hex_argument(&val) {
Ok(n) => res.start = Some(n),
Err(e) => die(e),
}
}
"-d" | "--dump-memory" => {
res.dump_memory = true;
}
"-f" | "--function" => {
res.assume_function = true;
}
"-v" | "--version" => {
println!("runrom {VERSION}");
std::process::exit(0);
}
_ => {
if arg.starts_with('-') {
die(format!("don't know how to handle the '{arg}' flag"));
}
if !res.file.is_empty() {
die("cannot have multiple source files".to_string());
}
res.file = arg;
}
}
}
if res.file.is_empty() {
die("you need to specify the file to be run".to_string());
}
res
}
// Given a ROM file identified by the `file` parameter, fetch the 16-bit address
// as pointed out by the reset vector.
fn start_from_reset_vector(file: &String) -> u16 {
// 1. Read the ROM header so we fetch the size of PRG ROM.
let Ok(mut input) = File::open(file) else {
die(format!("failed to open the given file '{file}'"));
};
let mut buf = vec![0u8; 0x10];
if let Err(e) = input.read_exact(&mut buf) {
match e.kind() {
ErrorKind::UnexpectedEof => die("malformed ROM file".to_string()),
_ => die(e.to_string()),
}
}
let header = match Header::try_from(buf.as_slice()) {
Ok(h) => h,
Err(e) => die(e.to_string()),
};
// 2. With a known PRG ROM size, fetch the two bytes pertaining to the reset
// vector.
// The two bytes of the reset address are located as follows:
// 1. Skip the ROM header, guaranteed to be exactly 0x10 bytes long.
// 2. Go to the end of PRG ROM.
// 3. -6: NMI addres; -4: reset addres; -2: IRQ address.
let offset: u64 = (0x10 + (header.prg_rom_size * 16 * 1024) - 4)
.try_into()
.unwrap();
if input.seek(SeekFrom::Start(offset)).is_err() {
die("cannot peek into the ROM's reset address".to_string());
};
let mut buf = [0u8; 0x02];
if let Err(e) = input.read_exact(&mut buf) {
match e.kind() {
ErrorKind::UnexpectedEof => die("malformed ROM file".to_string()),
_ => die(e.to_string()),
}
}
((buf[1] as u16) << 8) + buf[0] as u16
}
fn run(file: &String, start: u16, assume_function: bool, dump_memory: bool) -> Result<(), String> {
let mut machine = Machine::from(
file,
start,
#[allow(clippy::single_range_in_vec_init)]
MemoryPolicy {
initial_value: MemoryInitialValue::Fixed(0),
allowed_reads: vec![(0..0x800)],
allowed_writes: vec![(0..0x800)],
minimum_stack_value: 0,
},
)?;
machine.verbose = true;
if assume_function {
machine.run_function()?;
} else {
machine.until_address(0xFFFF)?;
}
if dump_memory {
let mut title = false;
for (idx, cell) in machine.ram.iter().enumerate() {
if cell.reads > 0 || cell.writes > 0 {
if !title {
println!("\n== Memory dump ==\n");
title = true;
}
println!(
"[${:X}] = ${:02X} [reads={}, writes={}]",
idx, cell.value, cell.reads, cell.writes
);
}
}
}
Ok(())
}
fn main() {
let args = parse_arguments();
let start = match args.start {
Some(s) => s,
None => start_from_reset_vector(&args.file),
};
match run(&args.file, start, args.assume_function, args.dump_memory) {
Ok(m) => m,
Err(e) => {
die(e);
}
}
}
|
