From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavan Nikhilesh Subject: Re: [PATCH v3 1/2] eal: add API to align integer to previous power of 2 Date: Wed, 4 Apr 2018 22:12:08 +0530 Message-ID: <20180404164207.GA21153@ltp-pvn> References: <20180217104934.17291-1-pbhagavatula@caviumnetworks.com> <20180404101606.5156-1-pbhagavatula@caviumnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: dev@dpdk.org To: Matan Azrad , "jerin.jacob@caviumnetworks.com" , "keith.wiles@intel.com" , Thomas Monjalon Return-path: Received: from NAM03-CO1-obe.outbound.protection.outlook.com (mail-co1nam03on0048.outbound.protection.outlook.com [104.47.40.48]) by dpdk.org (Postfix) with ESMTP id F3B5C1BC41 for ; Wed, 4 Apr 2018 18:42:38 +0200 (CEST) Content-Disposition: inline In-Reply-To: List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi Matan, On Wed, Apr 04, 2018 at 04:10:36PM +0000, Matan Azrad wrote: > Hi Pavan > > Shouldn't the new APIs be tagged with the experimental tag as agreed? Can't tag it experimental as it causes cyclic dependency (need to include rte_compact.h). Besides it's a simple proven math API I don't think it will change anytime soon. Thanks, Pavan > > Besides that, > Acked-by: Matan Azrad > > From: Pavan Nikhilesh, Wednesday, April 4, 2018 1:16 PM > > Add 32b and 64b API's to align the given integer to the previous power of 2. > > > > Signed-off-by: Pavan Nikhilesh > > --- > > v3 Changes: > > - Move commonly used code to rte_combine(32/64)ms1b so that it can be > > reused. > > > > v2 Changes: > > - Modified api name to `rte_align(32/64)prevpow2` from > > `rte_align(32/64)lowpow2`. > > - corrected fuction to return if the integer is already aligned to power of 2. > > > > lib/librte_eal/common/include/rte_common.h | 92 > > ++++++++++++++++++++++++++---- > > 1 file changed, 81 insertions(+), 11 deletions(-) > > > > diff --git a/lib/librte_eal/common/include/rte_common.h > > b/lib/librte_eal/common/include/rte_common.h > > index c7803e41c..7e147dcf2 100644 > > --- a/lib/librte_eal/common/include/rte_common.h > > +++ b/lib/librte_eal/common/include/rte_common.h > > @@ -223,6 +223,51 @@ extern int RTE_BUILD_BUG_ON_detected_error; } > > while(0) #endif > > > > +/** > > + * Combines 32b inputs most significant set bits into the least > > + * significant bits to construct a value with the same MSBs as x > > + * but all 1's under it. > > + * > > + * @param x > > + * The integer whose MSBs need to be combined with its LSBs > > + * @return > > + * The combined value. > > + */ > > +static inline uint32_t > > +rte_combine32ms1b(register uint32_t x) > > +{ > > + x |= x >> 1; > > + x |= x >> 2; > > + x |= x >> 4; > > + x |= x >> 8; > > + x |= x >> 16; > > + > > + return x; > > +} > > + > > +/** > > + * Combines 64b inputs most significant set bits into the least > > + * significant bits to construct a value with the same MSBs as x > > + * but all 1's under it. > > + * > > + * @param v > > + * The integer whose MSBs need to be combined with its LSBs > > + * @return > > + * The combined value. > > + */ > > +static inline uint64_t > > +rte_combine64ms1b(register uint64_t v) > > +{ > > + v |= v >> 1; > > + v |= v >> 2; > > + v |= v >> 4; > > + v |= v >> 8; > > + v |= v >> 16; > > + v |= v >> 32; > > + > > + return v; > > +} > > + > > /*********** Macros to work with powers of 2 ********/ > > > > /** > > @@ -250,15 +295,28 @@ static inline uint32_t rte_align32pow2(uint32_t x) { > > x--; > > - x |= x >> 1; > > - x |= x >> 2; > > - x |= x >> 4; > > - x |= x >> 8; > > - x |= x >> 16; > > + x = rte_combine32ms1b(x); > > > > return x + 1; > > } > > > > +/** > > + * Aligns input parameter to the previous power of 2 > > + * > > + * @param x > > + * The integer value to algin > > + * > > + * @return > > + * Input parameter aligned to the previous power of 2 > > + */ > > +static inline uint32_t > > +rte_align32prevpow2(uint32_t x) > > +{ > > + x = rte_combine32ms1b(x); > > + > > + return x - (x >> 1); > > +} > > + > > /** > > * Aligns 64b input parameter to the next power of 2 > > * > > @@ -272,16 +330,28 @@ static inline uint64_t rte_align64pow2(uint64_t v) { > > v--; > > - v |= v >> 1; > > - v |= v >> 2; > > - v |= v >> 4; > > - v |= v >> 8; > > - v |= v >> 16; > > - v |= v >> 32; > > + v = rte_combine64ms1b(v); > > > > return v + 1; > > } > > > > +/** > > + * Aligns 64b input parameter to the previous power of 2 > > + * > > + * @param v > > + * The 64b value to align > > + * > > + * @return > > + * Input parameter aligned to the previous power of 2 > > + */ > > +static inline uint64_t > > +rte_align64prevpow2(uint64_t v) > > +{ > > + v = rte_combine64ms1b(v); > > + > > + return v - (v >> 1); > > +} > > + > > /*********** Macros for calculating min and max **********/ > > > > /** > > -- > > 2.16.3 >