powMod2k

fnBigInt powMod2k(BigInt base, BigInt exp, size_t k) pure @safe

Computes modular exponentiation modulo a power of 2: base^exp mod 2^k.

Uses optimized binary exponentiation with bit masking for efficiency.

Parameters

baseThe base value
expThe exponent
kThe power of 2 for the modulus (result is mod 2^k)

Returns

base^exp mod 2^k