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authorC.J. Collier <cjcollier@linuxfoundation.org>2016-06-14 07:54:47 -0700
committerC.J. Collier <cjcollier@linuxfoundation.org>2016-06-14 07:55:43 -0700
commit5129044dce1f85ce4950f31bcf90f3886466f06a (patch)
tree1c6269614c0c15ffef8451c58ae8f8b30a1bc804 /lib/librte_sched/rte_reciprocal.c
parente04be89c2409570e0055b2cda60bd11395bb93b0 (diff)
Imported upstream release 16.04
* gbp import-orig ../dpdk-16.04.tar.xz Change-Id: Iac2196db782ba322f6974d8a752acc34ce5024c3 Signed-off-by: C.J. Collier <cjcollier@linuxfoundation.org>
Diffstat (limited to 'lib/librte_sched/rte_reciprocal.c')
-rw-r--r--lib/librte_sched/rte_reciprocal.c72
1 files changed, 72 insertions, 0 deletions
diff --git a/lib/librte_sched/rte_reciprocal.c b/lib/librte_sched/rte_reciprocal.c
new file mode 100644
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--- /dev/null
+++ b/lib/librte_sched/rte_reciprocal.c
@@ -0,0 +1,72 @@
+/*-
+ * BSD LICENSE
+ *
+ * Copyright(c) Hannes Frederic Sowa
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ * * Neither the name of Intel Corporation nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+
+#include <rte_common.h>
+
+#include "rte_reciprocal.h"
+
+/* find largest set bit.
+ * portable and slow but does not matter for this usage.
+ */
+static inline int fls(uint32_t x)
+{
+ int b;
+
+ for (b = 31; b >= 0; --b) {
+ if (x & (1u << b))
+ return b + 1;
+ }
+
+ return 0;
+}
+
+struct rte_reciprocal rte_reciprocal_value(uint32_t d)
+{
+ struct rte_reciprocal R;
+ uint64_t m;
+ int l;
+
+ l = fls(d - 1);
+ m = ((1ULL << 32) * ((1ULL << l) - d));
+ m /= d;
+
+ ++m;
+ R.m = m;
+ R.sh1 = RTE_MIN(l, 1);
+ R.sh2 = RTE_MAX(l - 1, 0);
+
+ return R;
+}