Function with_scratch

src/pack_ints.rs:237–246

Scratch space to bridge gap between pack_ints and pack_bytes. In theory, we could avoid this intermediate step, but it would result in a lot of generated code.

(f: impl FnOnce(&mut Vec<u8>) -> T)

// Scratch space to bridge gap between pack_ints and pack_bytes.
// In theory, we could avoid this intermediate step, but it would result in a lot of generated code.
fn with_scratch<T>(f: impl FnOnce(&mut Vec<u8>) -> T) -> T {
    thread_local! {
        static SCRATCH: std::cell::RefCell<Vec<u8>> = Default::default();
    }
    SCRATCH.with(|s| {
        let s = &mut s.borrow_mut();
        s.clear();
        f(s)
    })
}
macro_rules! impl_u8 {
    () => {
        fn pack8(v: &mut [Self], out: &mut Vec<u8>) {