128-bit array memset fill #594

what - examples

pub fn new_array_zero_fill_u128() -> [u128; 4] {
    return [0; 4];
}

or for signed (i128) array:

pub fn new_array_zero_fill_i128() -> [i128; 4] {
    return [0; 4];
}

why

As an experiment I have been able to build a "shader" that imports & uses chacha20 from RustCrypto, with many (many) local workarounds that I would like to discuss in the near future. The first build issue that I encountered was this:

   Compiling cipher v0.5.1
error: memset on integer width 128 not implemented yet
   --> /Users/brody-dev/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/crypto-common-0.2.1/src/hazmat.rs:347:1
    |
347 | / impl_serializable_state_u128_array! {
348 | |     U1,
349 | |     U2,
350 | |     U3,
...   |
362 | |     U512
363 | | }
    | |_^

While it would be possible for me to continue building by removing or feature-gating the impl_serializable_state_u128! usage in crypto-common, I think it would be much easier if I could continue building without this kind of hackage.

While I would love to see this resolved for both signed & unsigned 128-bit arrays, the unsigned case is more important for me at this point.

related issues

• 64 bit and 128 bit integers are not supported at all #359
• Integer polyfills #307

potential workaround

• support memset on 128-bit integers #595