Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 167 insertions, 0 deletions

diff --git a/src/spdk/dpdk/lib/librte_sched/rte_approx.c b/src/spdk/dpdk/lib/librte_sched/rte_approx.c
new file mode 100644
index 00000000..30620b83
--- /dev/null
+++ b/src/spdk/dpdk/lib/librte_sched/rte_approx.c
@@ -0,0 +1,167 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2010-2014 Intel Corporation
+ */
+
+#include <stdlib.h>
+
+#include "rte_approx.h"
+
+/*
+ * 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
+ * is to find positive integers p, q such that alpha - d < p/q < alpha + d, and
+ * q is minimal.
+ *
+ * http://people.ksp.sk/~misof/publications/2007approx.pdf
+ */
+
+/* fraction comparison: compare (a/b) and (c/d) */
+static inline uint32_t
+less(uint32_t a, uint32_t b, uint32_t c, uint32_t d)
+{
+	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;
+}
+
+/* check whether a/b is a valid approximation */
+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))
+		return 0;
+
+	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,
+	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 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
+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;
+	p_b = 1;
+	q_b = 1;
+
+	while (1) {
+		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);
+		if (aa || bb) {
+			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;
+		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 ;
+		q_b = new_q_b;
+
+		/* compute the number of steps to the right */
+		x_num = alpha_num * q_b - denum * p_b;
+		x_denum = - alpha_num * q_a + denum * p_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);
+		if (aa || bb) {
+			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;
+		q_b = new_q_b;
+	}
+}
+
+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) {
+		alpha *= 10;
+		d *= 10;
+		denum *= 10;
+	}
+	alpha_num = (uint32_t) alpha;
+	d_num = (uint32_t) d;
+
+	/* Perform approximation */
+	return find_best_rational_approximation(alpha_num, d_num, denum, p, q);
+}