[dpdk-dev] [PATCH v3 2/5] bitmap: rename rte_bsf64 and move to common header

[Anatoly Burakov <anatoly.burakov@intel.com>]

Rename rte_bsf64 to rte_bsf64_safe (this is a "safe" version in
that it prevents undefined behavior by checking if incoming
parameter is zero) and move it to common header.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
---

Notes:
    v3:
    - Added clarification that pos is not checked

 doc/guides/rel_notes/deprecation.rst       |  5 +++++
 lib/librte_eal/common/include/rte_bitmap.h | 14 ++++---------
 lib/librte_eal/common/include/rte_common.h | 23 ++++++++++++++++++++++
 3 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index 34b28234c..5d447e8eb 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -22,6 +22,11 @@ Deprecation Notices
 
     + ``rte_eal_devargs_type_count``
 
+* eal: function ``rte_bsf64`` in ``rte_bitmap.h`` has been renamed to
+  ``rte_bsf64_safe`` and moved to ``rte_common.h``. A new ``rte_bsf64`` function
+  will be added in release 19.05 in ``rte_common.h`` that follows convention set
+  by existing ``rte_bsf32`` function.
+
 * pci: Several exposed functions are misnamed.
   The following functions are deprecated starting from v17.11 and are replaced:
 
diff --git a/lib/librte_eal/common/include/rte_bitmap.h b/lib/librte_eal/common/include/rte_bitmap.h
index d2ed6204c..77727c828 100644
--- a/lib/librte_eal/common/include/rte_bitmap.h
+++ b/lib/librte_eal/common/include/rte_bitmap.h
@@ -93,14 +93,10 @@ __rte_bitmap_index2_set(struct rte_bitmap *bmp)
 	bmp->index2 = (((bmp->index1 << RTE_BITMAP_SLAB_BIT_SIZE_LOG2) + bmp->offset1) << RTE_BITMAP_CL_SLAB_SIZE_LOG2);
 }
 
-static inline int
+static inline int __rte_deprecated
 rte_bsf64(uint64_t slab, uint32_t *pos)
 {
-	if (slab == 0)
-		return 0;
-
-	*pos = __builtin_ctzll(slab);
-	return 1;
+	return rte_bsf64_safe(slab, pos);
 }
 
 static inline uint32_t
@@ -408,9 +404,8 @@ __rte_bitmap_scan_search(struct rte_bitmap *bmp)
 	value1 = bmp->array1[bmp->index1];
 	value1 &= __rte_bitmap_mask1_get(bmp);
 
-	if (rte_bsf64(value1, &bmp->offset1)) {
+	if (rte_bsf64_safe(value1, &bmp->offset1))
 		return 1;
-	}
 
 	__rte_bitmap_index1_inc(bmp);
 	bmp->offset1 = 0;
@@ -419,9 +414,8 @@ __rte_bitmap_scan_search(struct rte_bitmap *bmp)
 	for (i = 0; i < bmp->array1_size; i ++, __rte_bitmap_index1_inc(bmp)) {
 		value1 = bmp->array1[bmp->index1];
 
-		if (rte_bsf64(value1, &bmp->offset1)) {
+		if (rte_bsf64_safe(value1, &bmp->offset1))
 			return 1;
-		}
 	}
 
 	return 0;
diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
index 87f0f6302..d115b175c 100644
--- a/lib/librte_eal/common/include/rte_common.h
+++ b/lib/librte_eal/common/include/rte_common.h
@@ -491,6 +491,29 @@ rte_fls_u32(uint32_t x)
 	return (x == 0) ? 0 : 32 - __builtin_clz(x);
 }
 
+/**
+ * Searches the input parameter for the least significant set bit
+ * (starting from zero). Safe version (checks for input parameter being zero).
+ *
+ * @warning ``pos`` must be a valid pointer. It is not checked!
+ *
+ * @param v
+ *     The input parameter.
+ * @param pos
+ *     If ``v`` was not 0, this value will contain position of least significant
+ *     bit within the input parameter.
+ * @return
+ *     Returns 0 if ``v`` was 0, otherwise returns 1.
+ */
+static inline int
+rte_bsf64_safe(uint64_t v, uint32_t *pos)
+{
+	if (v == 0)
+		return 0;
+
+	*pos = __builtin_ctzll(v);
+	return 1;
+}
 
 #ifndef offsetof
 /** Return the offset of a field in a structure. */
-- 
2.17.1