nanopb - how to specify encoding of integer in proto file

Question

How do I set a int32 to use a fixed size for encoding?

In the API, it says

PB_LTYPE_FIXED32    0x04    32-bit integer or floating point.

But what option do I set in the .proto file to encode a int32 as a PB_LTYPE_FIXED32 as opposed to a PB_LTYPE_VARINT?

In the function encode_basic_field the fields structure, which is autogenerated, stores the field type which means that this information is set in .proto file somehow.

Answer 1

I think you should try "int32_t" instead of int32.

please check the "nanopb" project, in the file "nanopb_generator.py", there is a dictionary called "datatypes", here is some code:

    FieldD.TYPE_FIXED32:    ('uint32_t', 'FIXED32',     4,  4),
    FieldD.TYPE_SFIXED32:   ('int32_t',  'SFIXED32',    4,  4),

because it's my first time to see the "nanopb" project, I'm not 100% sure whether it will work or not.