CircularShift.cs

public static void CircularShiftLeft(ref uint value, int shift, int sizeInBits = BitsInInt32) {
    Contract.Requires(sizeInBits > 0 && sizeInBits <= BitsInInt32);
    Contract.Requires(shift <= sizeInBits && shift >= 0);
    uint mask = UInt32.MaxValue >> (BitsInInt32 - sizeInBits);
    uint masked = value & mask;
    uint shifted = (masked << shift) | (masked >> (sizeInBits - shift));
    value = (value & ~mask) | (shifted & mask);
}

public static void CircularShiftRight(ref uint value, int shift, int sizeInBits = BitsInInt32) {
    Contract.Requires(0 < sizeInBits && sizeInBits <= BitsInInt32);
    Contract.Requires(0 <= shift && shift <= sizeInBits);
    uint mask = UInt32.MaxValue >> (BitsInInt32 - sizeInBits);
    uint masked = value & mask;
    uint shifted = (masked >> shift) | (masked << (sizeInBits - shift));
    value = (value & ~mask) | (shifted & mask);
}