From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavan Nikhilesh Subject: [PATCH v2 1/2] eal: add API to align integer to previous power of 2 Date: Mon, 19 Feb 2018 17:06:42 +0530 Message-ID: <20180219113643.10337-1-pbhagavatula@caviumnetworks.com> References: <20180217104934.17291-1-pbhagavatula@caviumnetworks.com> Mime-Version: 1.0 Content-Type: text/plain Cc: dev@dpdk.org, Pavan Nikhilesh To: jerin.jacob@caviumnetworks.com, matan@mellanox.com, keith.wiles@intel.com, thomas@monjalon.net Return-path: Received: from NAM02-CY1-obe.outbound.protection.outlook.com (mail-cys01nam02on0053.outbound.protection.outlook.com [104.47.37.53]) by dpdk.org (Postfix) with ESMTP id A4EFEA48F for ; Mon, 19 Feb 2018 12:37:29 +0100 (CET) In-Reply-To: <20180217104934.17291-1-pbhagavatula@caviumnetworks.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Add 32b and 64b API's to align the given integer to the previous power of 2. Signed-off-by: Pavan Nikhilesh --- 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 | 43 ++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h index c7803e41c..b2017ee5c 100644 --- a/lib/librte_eal/common/include/rte_common.h +++ b/lib/librte_eal/common/include/rte_common.h @@ -259,6 +259,27 @@ rte_align32pow2(uint32_t 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 |= x >> 1; + x |= x >> 2; + x |= x >> 4; + x |= x >> 8; + x |= x >> 16; + + return x - (x >> 1); +} + /** * Aligns 64b input parameter to the next power of 2 * @@ -282,6 +303,28 @@ rte_align64pow2(uint64_t 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 |= v >> 1; + v |= v >> 2; + v |= v >> 4; + v |= v >> 8; + v |= v >> 16; + v |= v >> 32; + + return v - (v >> 1); +} + /*********** Macros for calculating min and max **********/ /** -- 2.16.1