Re: [Qemu-devel] [PATCH v3 4/7] range: add some more functions

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 23 Oct 2018 17:23:03 +0200
David Hildenbrand <david@redhat.com> wrote:

> Add some more functions that will be used in memory-device context.
> 
> range_init(): Init using lower bound and size, check for validity
> range_init_nofail(): Init using lower bound and size, validity asserted
> range_size(): Extract the size of a range
> range_overlaps_range(): Check for overlaps of two ranges
> range_contains_range(): Check if one range is contained in the other
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  include/qemu/range.h | 62 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 62 insertions(+)
> 
> diff --git a/include/qemu/range.h b/include/qemu/range.h
> index 7e75f4e655..ba606c6bc0 100644
> --- a/include/qemu/range.h
> +++ b/include/qemu/range.h
> @@ -112,6 +112,68 @@ static inline uint64_t range_upb(Range *range)
>      return range->upb;
>  }
>  
> +/*
> + * Initialize @range to span the interval [@lob,@lob + @size - 1].
> + * @size may be 0. If the range would overflow, returns -ERANGE, otherwise
> + * 0.
> + */
> +static inline int QEMU_WARN_UNUSED_RESULT range_init(Range *range, uint64_t lob,
> +                                                     uint64_t size)
> +{
> +    if (lob + size < lob) {
> +        return -ERANGE;
> +    }
> +    range->lob = lob;
> +    range->upb = lob + size - 1;
> +    range_invariant(range);
> +    return 0;
> +}
> +
> +/*
> + * Initialize @range to span the interval [@lob,@lob + @size - 1].
> + * @size may be 0. Range must not overflow.
> + */
> +static inline void range_init_nofail(Range *range, uint64_t lob, uint64_t size)
> +{
> +    range->lob = lob;
> +    range->upb = lob + size - 1;
> +    range_invariant(range);
> +}
> +
> +/*
> + * Get the size of @range.
> + */
> +static inline uint64_t range_size(const Range *range)
> +{
> +    return range->upb - range->lob + 1;
> +}
> +
> +/*
> + * Check if @range1 overlaps with @range2. If one of the ranges is empty,
> + * the result is always "false".
> + */
> +static inline bool range_overlaps_range(const Range *range1,
> +                                        const Range *range2)
> +{
> +    if (range_is_empty(range1) || range_is_empty(range2)) {
compilation fails with:
 "error: passing argument 1 of ‘range_is_empty’ discards ‘const’ qualifier from pointer target type [-Werror]"

the same for range_invariant,
following should fix issues:

diff --git a/include/qemu/range.h b/include/qemu/range.h
index 3586eb1..4b05bd1 100644
--- a/include/qemu/range.h
+++ b/include/qemu/range.h
@@ -39,7 +39,7 @@ struct Range {
     uint64_t upb;        /* inclusive upper bound */
 };
 
-static inline void range_invariant(Range *range)
+static inline void range_invariant(const Range *range)
 {
     assert(range->lob <= range->upb || range->lob == range->upb + 1);
 }
@@ -48,7 +48,7 @@ static inline void range_invariant(Range *range)
 #define range_empty ((Range){ .lob = 1, .upb = 0 })
 
 /* Is @range empty? */
-static inline bool range_is_empty(Range *range)
+static inline bool range_is_empty(const Range *range)
 {
     range_invariant(range);
     return range->lob > range->upb;



> +        return false;
> +    }
> +    return !(range2->upb < range1->lob || range1->upb < range2->lob);
> +}
> +
> +/*
> + * Check if @range1 contains @range2. If one of the ranges is empty,
> + * the result is always "false".
> + */
> +static inline bool range_contains_range(const Range *range1,
> +                                        const Range *range2)
> +{
> +    if (range_is_empty(range1) || range_is_empty(range2)) {
> +        return false;
> +    }
> +    return range1->lob <= range2->lob && range1->upb >= range2->upb;
> +}
> +
>  /*
>   * Extend @range to the smallest interval that includes @extend_by, too.
>   */