def ghash_field_shift_right

qasim-bend-kit@0.1.0.2 · libs/AES256GCMCore.bend:359

import Base

359def ghash_field_shift_right(value: GhashField) -> GhashField:
360    match value:
361        case GhashField{+w0, +w1, +w2, +w3}:
362            GhashField{
363                ghash_field_shift_top(w0, U32.is_ne(U32.and(1, w3), 0)),
364                U32.or(U32.shrn(w1, 1n), U32.shln(U32.and(1, w0), 31n)),
365                U32.or(U32.shrn(w2, 1n), U32.shln(U32.and(1, w1), 31n)),
366                U32.or(U32.shrn(w3, 1n), U32.shln(U32.and(1, w2), 31n))}