Re: [XEN PATCH][for-4.19 v3 1/8] xen/include: add macro LOWEST_BIT

[Nicola Vetrini <nicola.vetrini@bugseng.com>]

On 20/10/2023 19:03, Julien Grall wrote:
> Hi Nicola,
> 
> On 20/10/2023 16:28, Nicola Vetrini wrote:
>> diff --git a/xen/include/xen/macros.h b/xen/include/xen/macros.h
>> index d0caae7db298..49f3ebf848e9 100644
>> --- a/xen/include/xen/macros.h
>> +++ b/xen/include/xen/macros.h
>> @@ -8,8 +8,11 @@
>>   #define DIV_ROUND(n, d) (((n) + (d) / 2) / (d))
>>   #define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
>>   -#define MASK_EXTR(v, m) (((v) & (m)) / ((m) & -(m)))
>> -#define MASK_INSR(v, m) (((v) * ((m) & -(m))) & (m))
>> +/* Returns the 2^ffs(x) or 0, where ffs(x) is the index of the lowest 
>> set bit */
>> +#define LOWEST_BIT(x) ((x) & -(x))
>> +
>> +#define MASK_EXTR(v, m) (((v) & (m)) / LOWEST_BIT(m))
>> +#define MASK_INSR(v, m) (((v) * LOWEST_BIT(m)) & (m))
>>     #define count_args_(dot, a1, a2, a3, a4, a5, a6, a7, a8, x, ...) x
>>   #define count_args(args...) \
>> diff --git a/xen/include/xen/types.h b/xen/include/xen/types.h
>> index aea259db1ef2..23cad71c8a47 100644
>> --- a/xen/include/xen/types.h
>> +++ b/xen/include/xen/types.h
> 
> I don't understand how the changes in this file are related to the
> commit. Did you intend to create a separate commit?
> 
> The rest LGTM.
> 

Oh, I made a mistake. This hunk should have been part of patch 7 as a 
cleanup.
I can resubmit with this removed, or it could be ignored altogether.

>> @@ -31,9 +31,9 @@ typedef __PTRDIFF_TYPE__ ptrdiff_t;
>>   #define NULL ((void*)0)
>>   #endif
>>   -#define INT8_MIN        (-127-1)
>> -#define INT16_MIN       (-32767-1)
>> -#define INT32_MIN       (-2147483647-1)
>> +#define INT8_MIN        (-127 - 1)
>> +#define INT16_MIN       (-32767 - 1)
>> +#define INT32_MIN       (-2147483647 - 1)
>>     #define INT8_MAX        (127)
>>   #define INT16_MAX       (32767)
>> @@ -43,10 +43,10 @@ typedef __PTRDIFF_TYPE__ ptrdiff_t;
>>   #define UINT16_MAX      (65535)
>>   #define UINT32_MAX      (4294967295U)
>>   -#define INT_MAX         ((int)(~0U>>1))
>> +#define INT_MAX         ((int)(~0U >> 1))
>>   #define INT_MIN         (-INT_MAX - 1)
>>   #define UINT_MAX        (~0U)
>> -#define LONG_MAX        ((long)(~0UL>>1))
>> +#define LONG_MAX        ((long)(~0UL >> 1))
>>   #define LONG_MIN        (-LONG_MAX - 1)
>>   #define ULONG_MAX       (~0UL)
>> 
> 
> Cheers,

-- 
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)