def partial

bend-collections-laws-crypto@1.0.0.0 · src/crypto/blake/blake3/blake3.bend:95

import Base

95# The block truncated to its first `len` bytes: the word at byte offset pos
96# keeps its low len - pos bytes (all four when at least four remain).
97def partial(w: U32, delta: Nat) -> U32:
98  match delta:
99    case 0n: 0
100    case 1n: U32.and(w,255)
101    case 2n: U32.and(w,65535)
102    case 3n: U32.and(w,16777215)
103    case 4n+q: w