DPDK  16.11.11
rte_sched_common.h
1 /*-
2  * BSD LICENSE
3  *
4  * Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * * Redistributions of source code must retain the above copyright
12  * notice, this list of conditions and the following disclaimer.
13  * * Redistributions in binary form must reproduce the above copyright
14  * notice, this list of conditions and the following disclaimer in
15  * the documentation and/or other materials provided with the
16  * distribution.
17  * * Neither the name of Intel Corporation nor the names of its
18  * contributors may be used to endorse or promote products derived
19  * from this software without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
24  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
25  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
27  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
31  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32  */
33 
34 #ifndef __INCLUDE_RTE_SCHED_COMMON_H__
35 #define __INCLUDE_RTE_SCHED_COMMON_H__
36 
37 #ifdef __cplusplus
38 extern "C" {
39 #endif
40 
41 #include <stdint.h>
42 #include <sys/types.h>
43 
44 #define __rte_aligned_16 __attribute__((__aligned__(16)))
45 
46 static inline uint32_t
47 rte_sched_min_val_2_u32(uint32_t x, uint32_t y)
48 {
49  return (x < y)? x : y;
50 }
51 
52 #if 0
53 static inline uint32_t
54 rte_min_pos_4_u16(uint16_t *x)
55 {
56  uint32_t pos0, pos1;
57 
58  pos0 = (x[0] <= x[1])? 0 : 1;
59  pos1 = (x[2] <= x[3])? 2 : 3;
60 
61  return (x[pos0] <= x[pos1])? pos0 : pos1;
62 }
63 
64 #else
65 
66 /* simplified version to remove branches with CMOV instruction */
67 static inline uint32_t
68 rte_min_pos_4_u16(uint16_t *x)
69 {
70  uint32_t pos0 = 0;
71  uint32_t pos1 = 2;
72 
73  if (x[1] <= x[0]) pos0 = 1;
74  if (x[3] <= x[2]) pos1 = 3;
75  if (x[pos1] <= x[pos0]) pos0 = pos1;
76 
77  return pos0;
78 }
79 
80 #endif
81 
82 /*
83  * Compute the Greatest Common Divisor (GCD) of two numbers.
84  * This implementation uses Euclid's algorithm:
85  * gcd(a, 0) = a
86  * gcd(a, b) = gcd(b, a mod b)
87  *
88  */
89 static inline uint32_t
90 rte_get_gcd(uint32_t a, uint32_t b)
91 {
92  uint32_t c;
93 
94  if (a == 0)
95  return b;
96  if (b == 0)
97  return a;
98 
99  if (a < b) {
100  c = a;
101  a = b;
102  b = c;
103  }
104 
105  while (b != 0) {
106  c = a % b;
107  a = b;
108  b = c;
109  }
110 
111  return a;
112 }
113 
114 /*
115  * Compute the Lowest Common Denominator (LCD) of two numbers.
116  * This implementation computes GCD first:
117  * LCD(a, b) = (a * b) / GCD(a, b)
118  *
119  */
120 static inline uint32_t
121 rte_get_lcd(uint32_t a, uint32_t b)
122 {
123  return (a * b) / rte_get_gcd(a, b);
124 }
125 
126 #ifdef __cplusplus
127 }
128 #endif
129 
130 #endif /* __INCLUDE_RTE_SCHED_COMMON_H__ */