@Override
	public int getParameterOffset() {
		synchronized (function) {
			// if paramStart hasn't been specified, try to find the first parameter
			if (paramStart == 0 && !variables.isEmpty()) {

				// find the first stack variable defined at or after 0
				loadStackVariables();
				Object key = Integer.valueOf(0);
				int loc = Collections.binarySearch(variables, key, StackVariableComparator.get());
				loc = (loc < 0 ? -1 - loc : loc);
				if (loc < variables.size()) {
					Variable var = variables.get(loc);
					if (var != null) {
						return var.getStackOffset();
					}
				}
			}
			return paramStart;
		}
	}
Get the offset to the start of the parameters.

@return offset
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/oldfunction/OldStackFrameDB.java