[dpdk-dev] [PATCH 1/2] eal: add API to align integer to previous power of 2

[Pavan Nikhilesh <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>
---
 lib/librte_eal/common/include/rte_common.h | 36 ++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
index c7803e41c..126914f07 100644
--- a/lib/librte_eal/common/include/rte_common.h
+++ b/lib/librte_eal/common/include/rte_common.h
@@ -259,6 +259,24 @@ 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_align32lowpow2(uint32_t x)
+{
+	x = rte_align32pow2(x);
+	x--;
+
+	return x - (x >> 1);
+}
+
 /**
  * Aligns 64b input parameter to the next power of 2
  *
@@ -282,6 +300,24 @@ 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_align64lowpow2(uint64_t v)
+{
+	v = rte_align64pow2(v);
+	v--;
+
+	return v - (v >> 1);
+}
+
 /*********** Macros for calculating min and max **********/
 
 /**
-- 
2.16.1