1. A method of generating a generator output value in response to a generator input value, comprising: a plurality of sub-functions each sub-function receiving a respective sub-function input value responsive to the generator input value and providing a respective sub-function output value responsive to the respective sub-function input value; identifying an input case responsive to the generator input value; selecting at least one sub-function generator in response to the input case; inhibiting at least one sub-function generator in response to the input case; applying a value responsive to the generator input value to an input of the selected sub-function generator; blocking the value responsive to the generator input value from being applied to an input of the inhibited sub-function generator; outputting a value from the selected sub-function generator; and providing a generator output value responsive to the value from the selected sub-function generator.