From: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
To: jerin.jacob@caviumnetworks.com, matan@mellanox.com,
keith.wiles@intel.com, thomas@monjalon.net
Cc: dev@dpdk.org, Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
Subject: [dpdk-dev] [PATCH v3 1/2] eal: add API to align integer to previous power of 2
Date: Wed, 4 Apr 2018 15:46:05 +0530 [thread overview]
Message-ID: <20180404101606.5156-1-pbhagavatula@caviumnetworks.com> (raw)
In-Reply-To: <20180217104934.17291-1-pbhagavatula@caviumnetworks.com>
Add 32b and 64b API's to align the given integer to the previous power
of 2.
Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
---
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
next prev parent reply other threads:[~2018-04-04 10:16 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-17 10:49 [dpdk-dev] [PATCH " Pavan Nikhilesh
2018-02-17 10:49 ` [dpdk-dev] [PATCH 2/2] test: update common auto test Pavan Nikhilesh
2018-02-18 6:11 ` [dpdk-dev] [PATCH 1/2] eal: add API to align integer to previous power of 2 Matan Azrad
2018-02-18 15:39 ` Wiles, Keith
2018-02-19 6:03 ` Matan Azrad
2018-02-19 13:55 ` Wiles, Keith
2018-02-19 14:13 ` Matan Azrad
2018-02-19 14:21 ` Wiles, Keith
2018-02-19 16:18 ` Thomas Monjalon
2018-02-19 8:36 ` Pavan Nikhilesh
2018-02-19 11:36 ` [dpdk-dev] [PATCH v2 " Pavan Nikhilesh
2018-02-19 11:36 ` [dpdk-dev] [PATCH v2 2/2] test: update common auto test Pavan Nikhilesh
2018-02-19 12:09 ` [dpdk-dev] [PATCH v2 1/2] eal: add API to align integer to previous power of 2 Matan Azrad
2018-02-26 19:10 ` Pavan Nikhilesh
2018-02-27 19:30 ` Matan Azrad
2018-04-04 10:16 ` Pavan Nikhilesh [this message]
2018-04-04 10:16 ` [dpdk-dev] [PATCH v3 2/2] test: update common auto test Pavan Nikhilesh
2018-04-04 12:49 ` Thomas Monjalon
2018-04-04 12:54 ` Pavan Nikhilesh
2018-04-04 16:10 ` [dpdk-dev] [PATCH v3 1/2] eal: add API to align integer to previous power of 2 Matan Azrad
2018-04-04 16:42 ` Pavan Nikhilesh
2018-04-04 17:11 ` Matan Azrad
2018-04-04 17:51 ` Pavan Nikhilesh
2018-04-04 18:10 ` Matan Azrad
2018-04-04 18:15 ` Pavan Nikhilesh
2018-04-04 18:23 ` Matan Azrad
2018-04-04 18:36 ` Pavan Nikhilesh
2018-04-04 19:41 ` Matan Azrad
2018-04-04 13:20 ` [dpdk-dev] [PATCH v4] " Pavan Nikhilesh
2018-04-04 15:23 ` Thomas Monjalon
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