Re: Why tvb_get_bits() assumes Big Endian?

[Tomasz Moń <desowin () gmail com>]

On Thu, Jul 30, 2020 at 8:30 AM Jaap Keuter <jaap.keuter () xs4all nl> wrote:
> Let’s put a hypothetical here, a 7 bit value spanning 2 octets:
>
>  15 14 13 12 11 10  9  8| 7  6  5  4  3  2  1  0
> +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
> |  |  |  |  |  |  | 6| 5| 4| 3| 2| 1| 0|  |  |  |
> +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
>
> This would be the typical interpretation, as seen in network protocols.
>
> Your suggestion is that the interpretation can also be:
>
>  15 14 13 12 11 10  9  8| 7  6  5  4  3  2  1  0
> +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
> |  |  |  |  |  |  | 1| 0| 6| 5| 4| 3| 2|  |  |  |
> +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

This is not what I wanted to write. Assuming you meant two octets, and
the bitmask on the 16-bit value is 0x1FC0 then the alternative
interpretation would be:
  15 14 13 12 11 10  9  8| 7  6  5  4  3  2  1  0
 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |  |  |  |  |  |  | 4| 3| 2| 1| 0| 6| 5|  |  |  |
 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

> Here the first interpretation is a simple matter of mask and shift, the second interpretation is somewhat more 
> involved. Since the first interpretation is common in network protocols (and efficient to handle) the code was made 
> with that in mind.

Is the complexity the only reason? I prefer the complex things to be
in the common code and not in individual dissectors.
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