public MaskedLong negate() {
		if (!isFullyDefined()) {
			throw new UnsupportedOperationException("Cannot negate unknown values, yet.");
			// TODO: Work this using a ripple-carry method, if needed.
		}
		return fromMaskAndValue(-1, -val);
	}
Negate the value

@return the result.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/assembler/sleigh/expr/MaskedLong.java