[U-Boot] [PATCH 06/51] cmd: Add command for calculating binary operations

[Simon Glass]

Hi Mario,

On 19 July 2017 at 01:53, Mario Six <mario.six at gdsys.cc> wrote:
> Hi Simon,
>
> On Tue, Jul 18, 2017 at 4:01 PM, Simon Glass <sjg at chromium.org> wrote:
>> Hi Mario,
>>
>> On 14 July 2017 at 05:54, Mario Six <mario.six at gdsys.cc> wrote:
>>> This patch adds a command that enables the calculation of bit operations
>>> (AND, OR, XOR) on binary data from the command line. Memory locations as
>>> well as the contents of environment variables are eligible as sources
>>> and destination of the binary data used in the operations.
>>>
>>> The possible applications are manifold: Setting specific bits in
>>> registers using the regular read-OR-write pattern, masking out bits in
>>> bit values, implementation of simple OTP encryption using the XOR
>>> operation, etc.
>>>
>>> Signed-off-by: Mario Six <mario.six at gdsys.cc>
>>
>> Is this very different from setexpr? It looks like it supports and / or.
>>
>> Regards,
>> Simon
>
> It is quite similar, but it lacks the support to write the result directly back
> to memory, and, the more important point, it also only operates on bytes, words
> and longs, whereas binop operates on arbitrarily long byte arrays.
>
> I thought about somehow fixing up setexpr to add support for these two
> features, but couldn't think of a good way to do so. Do you have an idea how to
> do that? I'd also rather not add an additional command if somehow possible.

Not really. It makes sense to me now. Perhaps add in the help that you
can use byte arrays.

Also can you add a test for this? See for example ut_cmd.

Regards,
Simon