Re: [Qemu-block] [PATCH v10 2/9] include: Add a lookup table of sizes

[Eric Blake]

On 9/21/18 12:23 PM, Leonid Bloch wrote:
> Adding a lookup table for the powers of two, with the appropriate size
> prefixes. This is needed when a size has to be stringified, in which
> case something like '(1 * KiB)' would become a literal '(1 * (1L << 10))'
> string. Powers of two are used very often for sizes, so such a table
> will also make it easier and more intuitive to write them.

Would it be better to provide a generic util function that takes an 
arbitrary runtime value and converts it to a human-readable form?

> ---
>   include/qemu/units.h | 55 ++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 55 insertions(+)
>
> diff --git a/include/qemu/units.h b/include/qemu/units.h
> index 692db3fbb2..68a7758650 100644
> --- a/include/qemu/units.h
> +++ b/include/qemu/units.h
> @@ -17,4 +17,59 @@
>   #define PiB     (INT64_C(1) << 50)
>   #define EiB     (INT64_C(1) << 60)
>   
> +#define S_1KiB                  1024
> +#define S_2KiB                  2048

These look redundant with the earlier macros while still being limited 
to compile-time situations, whereas a human-readable converter form will 
be useful not only for printing compile-time constants, but also 
beneficial for arbitrary user-provided values.

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org