X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;f=lib%2Flibrte_sched%2Frte_approx.c;h=30620b83d0da2eb6e0edb78f0c6f2b49d59eb39a;hb=cda94419964ff5874f84b2564cb904f2d16d58c6;hp=575df910f75d57542841f8fd5ea0d395fac0bd57;hpb=1c1d4d7a923d4804f1926fc5264f9ecdd8977b04;p=dpdk.git diff --git a/lib/librte_sched/rte_approx.c b/lib/librte_sched/rte_approx.c index 575df910f7..30620b83d0 100644 --- a/lib/librte_sched/rte_approx.c +++ b/lib/librte_sched/rte_approx.c @@ -1,42 +1,13 @@ -/*- - * BSD LICENSE - * - * Copyright(c) 2010-2013 Intel Corporation. All rights reserved. - * 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. +/* SPDX-License-Identifier: BSD-3-Clause + * Copyright(c) 2010-2014 Intel Corporation */ #include #include "rte_approx.h" -/* - * Based on paper "Approximating Rational Numbers by Fractions" by Michal +/* + * Based on paper "Approximating Rational Numbers by Fractions" by Michal * Forisek forisek@dcs.fmph.uniba.sk * * Given a rational number alpha with 0 < alpha < 1 and a precision d, the goal @@ -47,21 +18,21 @@ */ /* fraction comparison: compare (a/b) and (c/d) */ -static inline uint32_t +static inline uint32_t less(uint32_t a, uint32_t b, uint32_t c, uint32_t d) { - return (a*d < b*c); + return a*d < b*c; } static inline uint32_t less_or_equal(uint32_t a, uint32_t b, uint32_t c, uint32_t d) { - return (a*d <= b*c); + return a*d <= b*c; } /* check whether a/b is a valid approximation */ -static inline uint32_t -matches(uint32_t a, uint32_t b, +static inline uint32_t +matches(uint32_t a, uint32_t b, uint32_t alpha_num, uint32_t d_num, uint32_t denum) { if (less_or_equal(a, b, alpha_num - d_num, denum)) @@ -69,44 +40,44 @@ matches(uint32_t a, uint32_t b, if (less(a ,b, alpha_num + d_num, denum)) return 1; - + return 0; } -static inline void -find_exact_solution_left(uint32_t p_a, uint32_t q_a, uint32_t p_b, uint32_t q_b, +static inline void +find_exact_solution_left(uint32_t p_a, uint32_t q_a, uint32_t p_b, uint32_t q_b, uint32_t alpha_num, uint32_t d_num, uint32_t denum, uint32_t *p, uint32_t *q) { uint32_t k_num = denum * p_b - (alpha_num + d_num) * q_b; uint32_t k_denum = (alpha_num + d_num) * q_a - denum * p_a; uint32_t k = (k_num / k_denum) + 1; - + *p = p_b + k * p_a; *q = q_b + k * q_a; } static inline void find_exact_solution_right(uint32_t p_a, uint32_t q_a, uint32_t p_b, uint32_t q_b, - uint32_t alpha_num, uint32_t d_num, uint32_t denum, uint32_t *p, uint32_t *q) + uint32_t alpha_num, uint32_t d_num, uint32_t denum, uint32_t *p, uint32_t *q) { uint32_t k_num = - denum * p_b + (alpha_num - d_num) * q_b; uint32_t k_denum = - (alpha_num - d_num) * q_a + denum * p_a; uint32_t k = (k_num / k_denum) + 1; - + *p = p_b + k * p_a; *q = q_b + k * q_a; } -static int +static int find_best_rational_approximation(uint32_t alpha_num, uint32_t d_num, uint32_t denum, uint32_t *p, uint32_t *q) { uint32_t p_a, q_a, p_b, q_b; - + /* check assumptions on the inputs */ if (!((0 < d_num) && (d_num < alpha_num) && (alpha_num < denum) && (d_num + alpha_num < denum))) { return -1; } - + /* set initial bounds for the search */ p_a = 0; q_a = 1; @@ -117,12 +88,12 @@ find_best_rational_approximation(uint32_t alpha_num, uint32_t d_num, uint32_t de uint32_t new_p_a, new_q_a, new_p_b, new_q_b; uint32_t x_num, x_denum, x; int aa, bb; - + /* compute the number of steps to the left */ x_num = denum * p_b - alpha_num * q_b; x_denum = - denum * p_a + alpha_num * q_a; x = (x_num + x_denum - 1) / x_denum; /* x = ceil(x_num / x_denum) */ - + /* check whether we have a valid approximation */ aa = matches(p_b + x * p_a, q_b + x * q_a, alpha_num, d_num, denum); bb = matches(p_b + (x-1) * p_a, q_b + (x - 1) * q_a, alpha_num, d_num, denum); @@ -130,7 +101,7 @@ find_best_rational_approximation(uint32_t alpha_num, uint32_t d_num, uint32_t de find_exact_solution_left(p_a, q_a, p_b, q_b, alpha_num, d_num, denum, p, q); return 0; } - + /* update the interval */ new_p_a = p_b + (x - 1) * p_a ; new_q_a = q_b + (x - 1) * q_a; @@ -154,13 +125,13 @@ find_best_rational_approximation(uint32_t alpha_num, uint32_t d_num, uint32_t de find_exact_solution_right(p_a, q_a, p_b, q_b, alpha_num, d_num, denum, p, q); return 0; } - + /* update the interval */ new_p_a = p_b + (x - 1) * p_a; new_q_a = q_b + (x - 1) * q_a; new_p_b = p_b + x * p_a; new_q_b = q_b + x * q_a; - + p_a = new_p_a; q_a = new_q_a; p_b = new_p_b; @@ -171,16 +142,16 @@ find_best_rational_approximation(uint32_t alpha_num, uint32_t d_num, uint32_t de int rte_approx(double alpha, double d, uint32_t *p, uint32_t *q) { uint32_t alpha_num, d_num, denum; - + /* Check input arguments */ if (!((0.0 < d) && (d < alpha) && (alpha < 1.0))) { return -1; } - + if ((p == NULL) || (q == NULL)) { return -2; } - + /* Compute alpha_num, d_num and denum */ denum = 1; while (d < 1) { @@ -190,7 +161,7 @@ int rte_approx(double alpha, double d, uint32_t *p, uint32_t *q) } alpha_num = (uint32_t) alpha; d_num = (uint32_t) d; - + /* Perform approximation */ - return find_best_rational_approximation(alpha_num, d_num, denum, p, q); + return find_best_rational_approximation(alpha_num, d_num, denum, p, q); }