readrom: Print addresses for vectors

Signed-off-by: Miquel Sabaté Solà <[email protected]>

crates/readrom/src/main.rs

@@ -1,4 +1,4 @@
-use clap::{Arg, Command};
+use clap::{arg, Arg, Command};
 use header::{Header, Kind};
 use std::fs::File;
 use std::io::{ErrorKind, Read};
@@ -24,6 +24,22 @@ fn print_header(header: &Header) {
     println!("  Mapper:\t{}", header.mapper);
 }
 
+fn print_vectors(addrs: &[u8]) {
+    println!("Vectors:");
+    println!(
+        "  NMI:\t\t{:#04x}",
+        u16::from_le_bytes([addrs[0], addrs[1]])
+    );
+    println!(
+        "  Reset:\t{:#04x}",
+        u16::from_le_bytes([addrs[2], addrs[3]])
+    );
+    println!(
+        "  IRQ:\t\t{:#04x}",
+        u16::from_le_bytes([addrs[4], addrs[5]])
+    );
+}
+
 // Print the given `message` and exit(1).
 fn die(message: String) {
     println!("error: {}", message);
@@ -35,6 +51,7 @@ fn main() {
         .version("0.1.0")
         .about("Display information about NES/Famicom ROM files.")
         .arg(Arg::new("FILE").required(true).help("ROM file to be read"))
+        .arg(arg!(-H --header "Just print the ROM header and quit"))
         .get_matches();
     let file = match args.get_one::<String>("FILE") {
         Some(file) => file,
@@ -49,6 +66,8 @@ fn main() {
         return;
     };
 
+    // Header.
+
     let mut buf = vec![0u8; 0x10];
     if let Err(e) = input.read_exact(&mut buf) {
         match e.kind() {
@@ -65,4 +84,23 @@ fn main() {
         }
     };
     print_header(&header);
+
+    if *args.get_one::<bool>("header").unwrap() {
+        std::process::exit(0);
+    }
+
+    // PRG ROM.
+
+    buf = vec![0u8; header.prg_rom_size * 16 * 1024];
+    if let Err(e) = input.read_exact(&mut buf) {
+        match e.kind() {
+            ErrorKind::UnexpectedEof => die("could not read advertised PRG ROM space".to_string()),
+            _ => die(e.to_string()),
+        }
+    }
+
+    // Vectors.
+
+    let vectors = &buf.as_slice()[buf.len() - 6..];
+    print_vectors(vectors);
 }