[RFC 1/7] eal: extend bit manipulation functions

[Mattias Rönnblom]

On 2024-03-02 18:05, Stephen Hemminger wrote:
> On Sat, 2 Mar 2024 14:53:22 +0100
> Mattias Rönnblom <mattias.ronnblom at ericsson.com> wrote:
> 
>> diff --git a/lib/eal/include/rte_bitops.h b/lib/eal/include/rte_bitops.h
>> index 449565eeae..9a368724d5 100644
>> --- a/lib/eal/include/rte_bitops.h
>> +++ b/lib/eal/include/rte_bitops.h
>> @@ -2,6 +2,7 @@
>>    * Copyright(c) 2020 Arm Limited
>>    * Copyright(c) 2010-2019 Intel Corporation
>>    * Copyright(c) 2023 Microsoft Corporation
>> + * Copyright(c) 2024 Ericsson AB
>>    */
>>   
> 
> Unless this is coming from another project code base, the common
> practice is not to add copyright for each contributor in later versions.
> 

Unless it's a large contribution (compared to the rest of the file)?

I guess that's why the 916c50d commit adds the Microsoft copyright notice.

>> +/**
>> + * Test if a particular bit in a 32-bit word is set.
>> + *
>> + * This function does not give any guarantees in regards to memory
>> + * ordering or atomicity.
>> + *
>> + * @param addr
>> + *   A pointer to the 32-bit word to query.
>> + * @param nr
>> + *   The index of the bit (0-31).
>> + * @return
>> + *   Returns true if the bit is set, and false otherwise.
>> + */
>> +static inline bool
>> +rte_bit_test32(const uint32_t *addr, unsigned int nr);
> 
> Is it possible to reorder these inlines to avoid having
> forward declarations?
> 

Yes, but I'm not sure it's a net gain.

A statement expression macro seems like a perfect tool for the job, but 
then MSVC doesn't support statement expressions. You could also have a 
macro that just generate the function body, as oppose to the whole function.

I'll consider if I should just bite the bullet and expand all the 
macros. 4x duplication.

> Also, new functions should be marked __rte_experimental
> for a release or two.

Yes, thanks.