initial

src/debug.rs

@@ -0,0 +1,26 @@
+#[cfg(feature = "debug-trace")]
+macro_rules! trace {
+    ($($arg:tt)*) => {
+        eprintln!("[TRACE] {}", format!($($arg)*));
+    };
+}
+
+#[cfg(not(feature = "debug-trace"))]
+macro_rules! trace {
+    ($($arg:tt)*) => {};
+}
+
+pub(crate) use trace;
+
+pub fn hex_preview(data: &[u8], len: usize) -> String {
+    let preview: Vec<String> = data
+        .iter()
+        .take(len)
+        .map(|b| format!("{:02x}", b))
+        .collect();
+    if data.len() > len {
+        format!("{}... ({} bytes)", preview.join(""), data.len())
+    } else {
+        preview.join("")
+    }
+}