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use std::env::args;
use std::process::exit;
use std::fs::{File, write};
use std::io::{Read, Error};
fn compress_files<'a>(in_filenames: &'a [String], out_filename: &'a String) -> Result<u32, (&'a String, Error)> {
let mut data = Vec::new();
for filename in in_filenames {
(|| {
Ok(File::open(filename)?.read_to_end(&mut data)?)
})().map_err(|err| (filename, err))?;
}
let n = data.len();
let mut output = Vec::new();
let mut v = 0x00;
let mut i = 0;
let mut runs = 0;
while i < n {
let mut byte = data[i];
i += 1;
runs += 1;
if i == n || data[i] != v {
// Sequential (< 0x80)
// Run stops at 0x80 bytes or when the value two ahead is equal to v
let mut buffer = vec![v ^ byte];
while i < n {
v = byte;
if buffer.len() > 0x7f || (i + 1 < n && data[i + 1] == v) {
break;
}
byte = data[i];
buffer.push(v ^ byte);
i += 1;
}
output.push((buffer.len() - 1) as u8);
output.extend(buffer);
} else {
// Alternating (>= 0x80)
// Run stops at 0x80 bytes or when the values stop alternating
let mut size = 0;
while i < n && size < 0x80 && data[i] == (if size % 2 == 0 { v } else { byte }) {
size += 1;
i += 1;
}
output.push(size + 0x7f);
output.push(v ^ byte);
if size % 2 == 0 {
v = byte;
}
}
}
match write(out_filename, &output[..]) {
Ok(()) => Ok(runs),
Err(err) => Err((out_filename, err)),
}
}
fn main() {
let mut argv_iter = args();
let program_name = argv_iter.next().expect("xor-compress");
let mut argv: Vec<String> = argv_iter.collect();
let verbose = !argv.is_empty() && argv[0] == "-v";
if verbose {
argv.remove(0);
}
if argv.len() < 2 {
eprintln!("Usage: {} [-v] file... files.xor", program_name);
exit(1);
}
let out_filename = argv.pop().unwrap();
match compress_files(&argv[..], &out_filename) {
Ok(runs) => if verbose {
println!("{}: {}: ld bc, ${:x}", program_name, out_filename, runs);
},
Err((filename, err)) => {
eprintln!("{}: {}: {}", program_name, filename, err);
exit(err.raw_os_error().unwrap_or(1));
}
}
}
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