Exponential filter in C++

ExponentialFilter.cpp

		int getSmooth6() {
			// ASSUMPTION: history has at least 6 entries
			auto a = (getOffset(0) + getOffset(-1)) / 2;
			auto b = (getOffset(0) + getOffset(-2)) / 2;
			auto c = (getOffset(0) + getOffset(-3)) / 2;
			auto d = (getOffset(-1) + getOffset(-2)) / 2;
			auto e = (getOffset(-1) + getOffset(-3)) / 2;
			auto f = (getOffset(-2) + getOffset(-3)) / 2;
			return (((((a + b * 2) / 3 + c * 2) / 3 + d * 2) / 3 + e * 2) / 3 + f * 2) / 3;
		}

		// Exponential filter
		int getSmooth3(int offset) {
			// ASSUMPTION: capacity is >= 3
			auto a = (getOffset(offset) + getOffset(offset - 1)) / 2;
			auto b = (getOffset(offset) + getOffset(offset - 2)) / 2;
			auto c = (getOffset(offset - 1) + getOffset(offset - 2)) / 2;
			return ((a + b * 2) / 3 + c * 2) / 3;
		}