[vlc-devel] [PATCH 1/3] vlc_common.h: add helpers to get the upper rounded value of integer divisions

[Steve Lhomme]

On Fri, Mar 17, 2017 at 9:46 AM, Rémi Denis-Courmont <remi at remlab.net> wrote:
> On March 17, 2017 4:36:08 PM GMT+08:00, Steve Lhomme <robux4 at videolabs.io> wrote:
>>---
>> include/vlc_common.h | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>>diff --git a/include/vlc_common.h b/include/vlc_common.h
>>index 6a75753dbf..b72dbfe689 100644
>>--- a/include/vlc_common.h
>>+++ b/include/vlc_common.h
>>@@ -507,6 +507,11 @@ struct vlc_common_members
>> /* clip v in [min, max] */
>> #define VLC_CLIP(v, min, max)    __MIN(__MAX((v), (min)), (max))
>>
>>+/* upper rounded value of the integer division */
>>+#define VLC_UPPER_DIV(v, div)     (((v) + (div) - 1) / (div))
>>+/* upper modulo value of the integer */
>>+#define VLC_UPPER_MODULO(v, mod)  (VLC_UPPER_DIV(v, mod) * mod)
>>+
>> VLC_USED
>> static inline int64_t GCD ( int64_t a, int64_t b )
>> {
>>--
>>2.11.1
>>
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>
> I don't like expansion-unsafe functional macros, TBH. They've bitten too many asses too many times, so to speak.

Reading on the subject, it seems the position of the parenthesis
matters (!). Would this be ok ?
#define VLC_UPPER_MODULO(v, mod)  ((mod) * VLC_UPPER_DIV(v, mod))

or probably better

#define VLC_UPPER_MODULO(v, mod)  ((v) + (v)%(mod))

> --
> Rémi Denis-Courmont
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