Add support for value lists

[martonmiklos]

Hi Richard,

This PR add support for parsing the VAL_ elements. Vector uses these fields for assigning textual representation to to signals values.

I think it would be useful to generate enums for the C output. To perform that generation we will need to implement sanitization on the strings to make sure that all enum items are C compilant. To make it easier to review I have separated my patch at this point.

[howerj]

Looks good, shall I merge it, or are you still making changes?

[howerj]

It might be best to signal an error if the strings are not a valid C identifier ('' in the grammar could be used to reject invalid strings). At the very least a warning and that entire enumeration should be skipped if any one enumeration is invalid.

I generally keep my enumerations in the following format (although I have not done it in this project):

typedef enum {
TYPE_VALUE_1_E,
TYPE_VALUE_2_E,
} type_e;

It might be worth generating functions for encoding/decoding and validating that specific enumeration, and then using those functions in the pack/print/unpack/encode/decode routines.

Thanks for the work!
Richard

[martonmiklos]

I do not expect big changes regarding to this topic (the enum code generation to the C source will be an another PR). If something left out I can always submit an another PR.

What I have been thinking about now: it would be useful to add a VAL to the end of the example dbc files to be able to have minimal test coverage. I do not have Vector tools at hand at the moment, but I can add this tomorrow.

[howerj]

That sounds good, I'll merge this, and you can add examples if/when you have the time.