The instruction is the mixed type one, which can be generated when disassembling a node of a multinode model that has positive length of the look-ahead signal segment.
That length is specified when creating the multinode model and can be retrieved using the function
The instruction has syntax
The instruction sets the outcome to a look-ahead signal at given zero-based position.
When the length of the look-ahead signal segment of a multinode model is positive, assembler programs cannot be loaded into nodes of the multinode model.
Therefore, if you need to assemble a program that contains
lookup instructions (e.g. generated by the disassembler), you have to create a model with the zero-length look-ahead signal segment.
You have to define instruction meta-class ‘lookup’ that fetches signals at given positions from an array used as a substitute for the look-ahead signal segment.
You also need to register necessary instruction classes derived from instruction meta-class ‘lookup’, the number of which is equal to the number of possible values of position.