Align bytes by 8

include_dir/src/lib.rs

@@ -106,6 +106,32 @@ pub use crate::metadata::Metadata;
 pub use crate::{dir::Dir, dir_entry::DirEntry, file::File};
 pub use include_dir_macros::include_dir;
 
+/// A simple macro that embeds the bytes of an external file into the executable and
+/// guarantees that they are aligned.
+///
+/// # Usage
+///
+/// `include_bytes_aligned!(ALIGNMENT, PATH)`
+///
+/// Where `ALIGNMENT` is any integer literal (must be a power of 2), and PATH is a string literal path
+/// to the file to include, just as in [`include_bytes!`](std::include_bytes).
+///
+/// # Efficiency
+///
+/// This macro does not copy the bytes or duplicate them. Takes up the same amount of space in memory
+/// as the usual [`include_bytes!`](std::include_bytes).
+#[macro_export]
+macro_rules! include_bytes_aligned {
+    ($align_to:expr, $path:expr) => {{
+        #[repr(C, align($align_to))]
+        struct __Aligned<T: ?Sized>(T);
+
+        const __DATA: &'static __Aligned<[u8]> = &__Aligned(*include_bytes!($path));
+
+        &__DATA.0
+    }};
+}
+
 #[doc = include_str!("../README.md")]
 #[allow(dead_code)]
 fn check_readme_examples() {}

macros/src/lib.rs

@@ -82,7 +82,7 @@ fn expand_file(root: &Path, path: &Path) -> proc_macro2::TokenStream {
         .canonicalize()
         .unwrap_or_else(|e| panic!("failed to resolve \"{}\": {}", path.display(), e));
     let literal = match abs.to_str() {
-        Some(abs) => quote!(include_bytes!(#abs)),
+        Some(abs) => quote!(::include_dir::include_bytes_aligned!(8, #abs)),
         None => {
             let contents = read_file(path);
             let literal = Literal::byte_string(&contents);