Signal Mapping

At runtime, R2U2 takes as input a vector of signals at each execution step. This vector represent the value of each signal at the corresponding timestamp. In order to associate those inputs to the variables defined in a C2PO file, we have to provide a mapping of variable names to indices in that signals vector.

All variable symbols in a C2PO file that are referenced in a specification must be mapped to an index, otherwise C2PO will report an error. C2PO provides two ways to provide a mapping: a map or a trace file.

Map File

A map file directly associates an index with a variable symbol and traditionally has a .map file extension. Each line of the input file is of the form

symbol : numeral 

If symbol corresponds to a variable symbol in the C2PO file, its signal index is set to the value of numeral. If symbol is not present in the C2PO file, the line is ignored. Repeat signal indices are allowed, if you want two variables to map to the same input. As an example:

p:0
q:1
i:2
j:3
k:2

At each step of R2U2, the value at index 0 will be interpreted as p and so on for each other symbol. Also, this file is such that i and k will have the same input signal. Importantly, the type of the value in the signals vector should match the type defined in the C2PO file. If i, j, and k are ints, then their values in the signal vector must also be of int type.

Remember that C2PO also supports input arrays, including things like Array: int[3];. To map these inputs, we provide a mapping for each index in the array:

Array[0]:0
Array[1]:1
Array[2]:2

Trace File

Alternatively, if you are using R2U2 in offline mode and using a .csv file as input to R2U2, it may be convenient to use that same file for signal mapping. For this we use the first line in the .csv file as a header to define which column corresponds to which variable. The first line must start with a # character then be followed by a comma-separated list of each variable in the C2PO file. For example

# p,q,i,j,k
  0,1,5,2,3
  0,0,4,2,3
  1,1,2,6,10