[dmd-internals] Modifying the dmd compiler to add support for bitfields

[Andrei Alexandrescu]

Thanks! Sorry, forgot to ask one more detail so I know which list to put 
him in: is he a fee-only advisor?

Thanks,

Andrei

On 1/9/12 12:10 PM, Walter Bright wrote:
> I'm glad you're aware of it.
>
> Anyhow, the compiler (optimizer and back end) can already deal with bit
> fields as it is based on a C compiler. The bitfield ops are replaced by
> mask and shift in the cgelem.c code.
>
> dt_t is simply a way to represent static data.
>
> On 1/9/2012 3:35 AM, Sandeep Datta wrote:
>> Hi Walter,
>>
>> Thanks for the reply. I am aware of the mixin based solution but the
>> main motivation for me at this point is getting to know the D compiler
>> well. And IMHO native support for bitfields will be a welcome new
>> change. I am trying to write an OS/kernel
>> (https://github.com/SDX2000/Deimos) in D and as far as machine hugging
>> code is concerned bitfields and unions are a mainstay. The mixin
>> syntax looks jarring and alien. Please see
>> https://github.com/SDX2000/Deimos/issues/1 for what I am trying to
>> accomplish.
>>
>> I am particularly curious about the dt_t data structure you seem to be
>> using how does this work?
>>
>> Regards,
>> Sandeep Datta.
>>
>> On Mon, Jan 9, 2012 at 5:53 AM, Walter Bright <walter at digitalmars.com
>> <mailto:walter at digitalmars.com>> wrote:
>>
>>     Bit fields are already done in D using a library solution:
>>
>>     http://d.digitalmars.com/2.0/phobos/std_bitmanip.html
>>
>>
>>     On 1/8/2012 7:49 AM, Sandeep Datta wrote:
>>>     [Cross post from the D news group]
>>>
>>>     Hi All,
>>>
>>>     To gain a better understanding of how the D compiler works I am
>>>     trying to implement support for bit fields in structures. I have
>>>     modified the parser code to admit the following syntax (for now)...
>>>
>>>     struct A{
>>>     uint:8 a;
>>>     uint:5 b;
>>>     uint:* unused; //Takes up the remaining space.
>>>     //Raise an error when the computed size is zero.
>>>     }
>>>
>>>     You can see my changes here...https://github.com/SDX2000/dmd
>>>
>>>     I have been trying to work out a strategy for modifying the compiler
>>>     code generation for quite some time now but haven't been able to
>>>     make much headway in this direction.
>>>
>>>     I would appreciate any help at this point.
>>>
>>>     Regards,
>>>     Sandeep Datta.
>>>
>>>
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