eal: add 64-bit fls function

Add missing implementation for 64-bit fls function, and extend
unit test to test the new function as well.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>

diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
index d102f2c..7b50b84 100644 (file)
--- a/lib/librte_eal/common/include/rte_common.h
+++ b/lib/librte_eal/common/include/rte_common.h
@@ -547,6 +547,24 @@ rte_bsf64_safe(uint64_t v, uint32_t *pos)
        return 1;
 }
 
+/**
+ * Return the last (most-significant) bit set.
+ *
+ * @note The last (most significant) bit is at position 64.
+ * @note rte_fls_u64(0) = 0, rte_fls_u64(1) = 1,
+ *       rte_fls_u64(0x8000000000000000) = 64
+ *
+ * @param x
+ *     The input parameter.
+ * @return
+ *     The last (most-significant) bit set, or 0 if the input is 0.
+ */
+static inline int
+rte_fls_u64(uint64_t x)
+{
+       return (x == 0) ? 0 : 64 - __builtin_clzll(x);
+}
+
 #ifndef offsetof
 /** Return the offset of a field in a structure. */
 #define offsetof(TYPE, MEMBER)  __builtin_offsetof (TYPE, MEMBER)

diff --git a/test/test/test_common.c b/test/test/test_common.c
index 4a42aae..f6dd4c1 100644 (file)
--- a/test/test/test_common.c
+++ b/test/test/test_common.c
@@ -242,6 +242,8 @@ test_fls(void)
        };
 
        for (i = 0; i < RTE_DIM(test); i++) {
+               uint64_t arg64;
+
                arg = test[i].arg;
                rc = rte_fls_u32(arg);
                expected = test[i].rc;
@@ -250,6 +252,25 @@ test_fls(void)
                                arg, rc, expected);
                        return TEST_FAILED;
                }
+               /* 64-bit version */
+               arg = test[i].arg;
+               rc = rte_fls_u64(arg);
+               expected = test[i].rc;
+               if (rc != expected) {
+                       printf("Wrong rte_fls_u64(0x%x) rc=%d, expected=%d\n",
+                               arg, rc, expected);
+                       return TEST_FAILED;
+               }
+               /* 64-bit version shifted by 32 bits */
+               arg64 = (uint64_t)test[i].arg << 32;
+               rc = rte_fls_u64(arg64);
+               /* don't shift zero */
+               expected = test[i].rc == 0 ? 0 : test[i].rc + 32;
+               if (rc != expected) {
+                       printf("Wrong rte_fls_u64(0x%" PRIx64 ") rc=%d, expected=%d\n",
+                               arg64, rc, expected);
+                       return TEST_FAILED;
+               }
        }
 
        return 0;