base94-simd

SIMD-accelerated base94 codec: encodes arbitrary binary data into the printable ASCII range 0x20..=0x7E (94 symbols), with an optional key-mixing step (kf) and a base94 digit encoding for integers.

Bytes are key-mixed ((b - kf) mod 256); mixed values >= 93 escape into two chars (0x7D/0x7E leader + follower), so output is at most twice the input size. With kf = 0 the mixing is the identity.

Backends

• x86_64: SSSE3 kernels over 16-byte blocks (runtime-detected; SSE2 helpers for the validity scan and length computation).
• aarch64: baseline NEON kernels over 16-byte blocks (vqtbl1 shares the compaction LUT with the pshufb backend; no runtime detection needed).
• other targets: portable scalar path (the reference definition).

All backends are bit-exact, pinned by fuzzing against the scalar reference.

let mut encoded = Vec::new();
base94_simd::encode_into(&mut encoded, b"hello", 0);
assert!(encoded.iter().all(|&c| (0x20..=0x7e).contains(&c)));
let mut decoded = Vec::new();
base94_simd::decode_into(&mut decoded, &encoded, 0).unwrap();
assert_eq!(decoded, b"hello");