Fixed Width Interchange

Fixed Width Interchange, FWI, is a language similar to Google's Protobuf, but designed for applications where the buffer is a fixed, compile-time set width, and can be used in-place without building messages.

A few use-cases include:

• Shared Memory
• Websockets
• Network Data Transfer

FWI files can be compiled down to the language of your choice, such as C++ or JavaScript.

FWI data sets use exactly how much memory they need, i.e. all indexes and mapping is done at compile-time and is not packaged with the payload. If your block contains 4 bytes worth of data, the entire payload size will be 4 bytes.

Note that booleans are stored in as little space as possible, and are encoded as a single bit in a byte, rather than taking up the whole byte. 8 boolean values will take up only 1 byte.

Install the FWI compiler with

gem install fwi

To compile a .fwi file, use the fwi command. Use fwi -h for usage instructions.

To include the generated sources in your language of choice, you must also grab the FWI Standard Library, available under stdlib/ on this project. We have made every effort to make the standard library as small as possible for each language.

namespace MyNamespace

enum MyEnum {
    VAL_1,
    VAL_2
}

namespace MySubNS {
    block MyBlock {
        bool bool_array[8]
    }
}

block MyBlock {
    bool bool_1, bool_2

    u16 my_unsigned_16
    i32 my_signed_32
    int my_other_signed_32
    long my_signed_64

    float my_float
    double my_double

    MyEnum my_enum_array[12]
    MySubNS::MyBlock my_sub_block
}