[OpenWrt-Devel] [RFC] libubox/binary.h design proposal

[Javier Domingo Cansino]

Hi Etienne,

Sorry if I didn't express myself correctly. I meant that I have to create
code to communicate through that protocol. I am not designing a protocol.
Anyway, I was more interested on feedback from similar libraries or about
the design of the library.

Cheers!

On Sun, Oct 4, 2015 at 10:38 PM Etienne Champetier <
champetier.etienne at gmail.com> wrote:

> Hi,
>
> 2015-10-04 22:47 GMT+02:00 Javier Domingo Cansino <javierdo1 at gmail.com>:
>
>> Hello,
>>
>> I asked Friday on IRC how to write blobs, I was suggested using
>> blob_raw_put from libubox/blob.h, but as I have to implement a binary
>> protocol that uses different endianess, non aligned data etc., I think the
>> best solution is creating a set of helper functions to write/read blobs.
>>
>
> I don't know what you really want to do, but have you looked at protobuf?
> https://en.wikipedia.org/wiki/Protocol_Buffers
>
>
>
>>
>> As this is quite generic library, there might already exist some work
>> done that I am missing (please link!). I would love to have feedback from
>> this design before typing code.
>>
>> I have started my work on github[1], which is basically a header file
>> with the following comment and some prototype ideas. The syntax I have
>> thought is described there, but it basically follows a printf syntax,
>> allowing raw chars to be written.
>>
>> Cheers!
>>
>> /*
>>  * Syntax for the function is as follows.
>>  *   %[n][a][lb][01r]{i,y,w,d,q,s}
>>  *
>>  *   All the characters that don't follow this will be treated as raw
>> chars
>>  *   to be written as they are.
>>  *
>>  * Data type
>>  *   * i - bit
>>  *   * y - byte
>>  *   * w - 2 byte word
>>  *   * d - 4 byte word
>>  *   * q - 8 byte word
>>  *   * s - string without termination (use strlen()+1 in quantity to null)
>>  *
>>  * Data value
>>  *   * 0 - fill the specified space with zeros
>>  *   * 1 - fill the specified space with ones
>>  *   * r - fill the specified space with random data
>>  *
>>  *   String data type is not valid in this case
>>  *
>>  * Endianess. No conversion by default
>>  *   * l - little endian
>>  *   * b - big endian
>>  *
>>  * Alignment. No alignment by default
>>  *   * a - align this to it's datatype
>>  *         bits are aligned to byte
>>  *
>>  * Quantity. One by default
>>  *   * n - number of same datatype (placed together)
>>  *         this denotes length of string, padded with 0
>>  *
>>  * Some examples:
>>  *   * %4lw - 4 little endian 2 byte word
>>  *   * %2i  - 2 bits 'ab' from value b'000000ab'
>>  *   * %2bi - 2 bits 'ab' from value b'000000ba'
>>  *   * %2li - 2 bits 'ab' from value b'ab000000'
>>  *
>>  */
>>
>>
>> [1] Github branch: https://github.com/txomon/libubox
>>
>> _______________________________________________
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>> openwrt-devel at lists.openwrt.org
>> https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
>>
>>
>
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