New upstream version 18.02upstream/18.02

Change-Id: I89ed24cb2a49b78fe5be6970b99dd46c1499fcc3
Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>

1 files changed, 164 insertions, 0 deletions

diff --git a/lib/librte_eal/common/rte_reciprocal.c b/lib/librte_eal/common/rte_reciprocal.c
new file mode 100644
index 00000000..d81b11db
--- /dev/null
+++ b/lib/librte_eal/common/rte_reciprocal.c
@@ -0,0 +1,164 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2017 Cavium, Inc
+ */
+/*-
+ *   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;
+}
+
+/*
+ * Code taken from Hacker's Delight:
+ * http://www.hackersdelight.org/hdcodetxt/divlu.c.txt
+ * License permits inclusion here per:
+ * http://www.hackersdelight.org/permissions.htm
+ */
+static uint64_t
+divide_128_div_64_to_64(uint64_t u1, uint64_t u0, uint64_t v, uint64_t *r)
+{
+	const uint64_t b = (1ULL << 32); /* Number base (16 bits). */
+	uint64_t un1, un0,           /* Norm. dividend LSD's. */
+		 vn1, vn0,           /* Norm. divisor digits. */
+		 q1, q0,             /* Quotient digits. */
+		 un64, un21, un10,   /* Dividend digit pairs. */
+		 rhat;               /* A remainder. */
+	int s;                       /* Shift amount for norm. */
+
+	/* If overflow, set rem. to an impossible value. */
+	if (u1 >= v) {
+		if (r != NULL)
+			*r = (uint64_t) -1;
+		return (uint64_t) -1;
+	}
+
+	/* Count leading zeros. */
+	s = __builtin_clzll(v);
+	if (s > 0) {
+		v = v << s;
+		un64 = (u1 << s) | ((u0 >> (64 - s)) & (-s >> 31));
+		un10 = u0 << s;
+	} else {
+
+		un64 = u1 | u0;
+		un10 = u0;
+	}
+
+	vn1 = v >> 32;
+	vn0 = v & 0xFFFFFFFF;
+
+	un1 = un10 >> 32;
+	un0 = un10 & 0xFFFFFFFF;
+
+	q1 = un64/vn1;
+	rhat = un64 - q1*vn1;
+again1:
+	if (q1 >= b || q1*vn0 > b*rhat + un1) {
+		q1 = q1 - 1;
+		rhat = rhat + vn1;
+		if (rhat < b)
+			goto again1;
+	}
+
+	un21 = un64*b + un1 - q1*v;
+
+	q0 = un21/vn1;
+	rhat = un21 - q0*vn1;
+again2:
+	if (q0 >= b || q0*vn0 > b*rhat + un0) {
+		q0 = q0 - 1;
+		rhat = rhat + vn1;
+		if (rhat < b)
+			goto again2;
+	}
+
+	if (r != NULL)
+		*r = (un21*b + un0 - q0*v) >> s;
+	return q1*b + q0;
+}
+
+struct rte_reciprocal_u64
+rte_reciprocal_value_u64(uint64_t d)
+{
+	struct rte_reciprocal_u64 R;
+	uint64_t m;
+	int l;
+
+	l = 63 - __builtin_clzll(d);
+
+	m = divide_128_div_64_to_64((1ULL << l), 0, d, NULL) << 1;
+	m = (1ULL << l) - d ? m + 2 : 1;
+	R.m = m;
+
+	R.sh1 = l > 1 ? 1 : l;
+	R.sh2 = (l > 0) ? l : 0;
+	R.sh2 -= R.sh2 && (m == 1) ? 1 : 0;
+
+	return R;
+}