3 files changed, 119 insertions, 5 deletions

diff --git a/tools/xor_compress.c b/tools/xor_compress.c
index f186f05..48e5167 100644
--- a/tools/xor_compress.c
+++ b/tools/xor_compress.c
@@ -90,7 +90,7 @@ int write_compressed(const char *filename, unsigned char *data, size_t n, bool v
         }
     }
 
-    if (verbose) fprintf(stderr, PROGRAM_NAME ": %s: ld bc, $%x\n", filename, runs);
+    if (verbose) printf(PROGRAM_NAME ": %s: ld bc, $%x\n", filename, runs);
 
     fflush(f);
     fclose(f);
diff --git a/tools/xor_compress.py b/tools/xor_compress.py
index b3bf317..015c80e 100644
--- a/tools/xor_compress.py
+++ b/tools/xor_compress.py
@@ -1,11 +1,22 @@
 #!/usr/bin/env python3
 
-# Usage: ./xor_compress.py sources.bin... > dest.bin.xor
-
 import sys
 
+sys.argv.pop(0)
+
+verbose = False
+if sys.argv and sys.argv[0] == '-v':
+    verbose = True
+    sys.argv.pop(0)
+
+if len(sys.argv) < 2:
+    print('Usage: xor_compress.py [-v] file... files.xor', file=sys.stderr)
+    exit(1)
+
+out_filename = sys.argv.pop()
+
 data = bytearray()
-for filename in sys.argv[1:]:
+for filename in sys.argv:
     with open(filename, 'rb') as f:
         data.extend(f.read())
 
@@ -13,10 +24,12 @@ n = len(data)
 output = bytearray()
 v = 0x00
 i = 0
+runs = 0
 
 while i < n:
     byte = data[i]
     i += 1
+    runs += 1
 
     if data[i] == v:
         # Alternating (>= 0x80)
@@ -44,4 +57,8 @@ while i < n:
         output.append(len(buffer) - 1)
         output.extend(buffer)
 
-sys.stdout.buffer.write(output)
+with open(out_filename, 'wb') as f:
+    f.write(output)
+
+if verbose:
+    print('%s: ld bc, $%x' % (out_filename, runs))
diff --git a/tools/xor_compress.rs b/tools/xor_compress.rs
new file mode 100644
index 0000000..0d912ba
--- /dev/null
+++ b/tools/xor_compress.rs
@@ -0,0 +1,97 @@
+const PROGRAM_NAME: &str = "xor_compress";
+
+fn read_files(filenames: &[String]) -> Result<Vec<u8>, (&String, std::io::Error)> {
+    let mut data = Vec::new();
+    for filename in filenames.iter() {
+        match std::fs::read(filename) {
+            Ok(bytes) => data.extend(&bytes),
+            Err(err)  => return Err((filename, err)),
+        }
+    }
+    Ok(data)
+}
+
+fn write_compressed(filename: &String, data: Vec<u8>) -> Result<u32, std::io::Error> {
+    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 data[i] == v {
+            // 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;
+            }
+        } else {
+            // 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);
+        }
+    }
+
+    match std::fs::write(filename, &output[..]) {
+        Ok(()) => Ok(runs),
+        Err(err) => Err(err),
+    }
+}
+
+fn main() {
+    let mut args: Vec<String> = std::env::args().skip(1).collect();
+
+    let mut verbose = false;
+    if !args.is_empty() && args[0] == "-v" {
+        verbose = true;
+        args.remove(0);
+    }
+
+    if args.len() < 2 {
+        eprintln!("Usage: {} [-v] file... files.xor", PROGRAM_NAME);
+        std::process::exit(1);
+    }
+
+    let out_filename = args.pop().unwrap();
+    let data = match read_files(&args[..]) {
+        Ok(data) => data,
+        Err((filename, err)) => {
+            eprintln!("{}: {}: {}", PROGRAM_NAME, filename, err);
+            std::process::exit(err.raw_os_error().unwrap_or(1));
+        }
+    };
+    if !data.is_empty() {
+        match write_compressed(&out_filename, data) {
+            Ok(runs) => if verbose {
+                println!("{}: {}: ld bc, ${:x}", PROGRAM_NAME, out_filename, runs);
+            },
+            Err(err) => {
+                eprintln!("{}: {}: {}", PROGRAM_NAME, out_filename, err);
+                std::process::exit(err.raw_os_error().unwrap_or(1));
+            },
+        }
+    }
+}