Re: [PATCH 4/7] bitops: Support 32 and 64 bit mask macro

[Philippe Mathieu-Daudé]

On 9/8/21 10:19 AM, Yang Zhong wrote:
> The Qemu should enable bit mask macro like Linux did in the
> kernel, the GENMASK(h, l) and GENMASK_ULL(h, l) will set the
> bit to 1 from l to h bit in the 32 bit or 64 bit long type.
> 
> Signed-off-by: Yang Zhong <yang.zhong@intel.com>
> ---
>  include/qemu/bitops.h | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
> index 03213ce952..04dec60670 100644
> --- a/include/qemu/bitops.h
> +++ b/include/qemu/bitops.h
> @@ -18,6 +18,7 @@
>  
>  #define BITS_PER_BYTE           CHAR_BIT
>  #define BITS_PER_LONG           (sizeof (unsigned long) * BITS_PER_BYTE)
> +#define BITS_PER_LONG_LONG       64
>  
>  #define BIT(nr)                 (1UL << (nr))
>  #define BIT_ULL(nr)             (1ULL << (nr))
> @@ -28,6 +29,12 @@
>  #define MAKE_64BIT_MASK(shift, length) \
>      (((~0ULL) >> (64 - (length))) << (shift))
>  
> +#define GENMASK(h, l) \
> +    (((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
> +
> +#define GENMASK_ULL(h, l) \
> +    (((~0ULL) << (l)) & (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h))))

What is the difference with MAKE_64BIT_MASK()??