From 97f17497d162afdb82c8704bf097f0fee3724b2e Mon Sep 17 00:00:00 2001 From: "C.J. Collier" Date: Tue, 14 Jun 2016 07:50:17 -0700 Subject: Imported Upstream version 16.04 Change-Id: I77eadcd8538a9122e4773cbe55b24033dc451757 Signed-off-by: C.J. Collier --- lib/librte_sched/rte_reciprocal.c | 72 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 lib/librte_sched/rte_reciprocal.c (limited to 'lib/librte_sched/rte_reciprocal.c') diff --git a/lib/librte_sched/rte_reciprocal.c b/lib/librte_sched/rte_reciprocal.c new file mode 100644 index 00000000..652f0237 --- /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 +#include + +#include + +#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; +} -- cgit 1.2.3-korg