DPDK  2.2.0
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 <sys/types.h>
42 
43 #define __rte_aligned_16 __attribute__((__aligned__(16)))
44 
45 static inline uint32_t
46 rte_sched_min_val_2_u32(uint32_t x, uint32_t y)
47 {
48  return (x < y)? x : y;
49 }
50 
51 #if 0
52 static inline uint32_t
53 rte_min_pos_4_u16(uint16_t *x)
54 {
55  uint32_t pos0, pos1;
56 
57  pos0 = (x[0] <= x[1])? 0 : 1;
58  pos1 = (x[2] <= x[3])? 2 : 3;
59 
60  return (x[pos0] <= x[pos1])? pos0 : pos1;
61 }
62 
63 #else
64 
65 /* simplified version to remove branches with CMOV instruction */
66 static inline uint32_t
67 rte_min_pos_4_u16(uint16_t *x)
68 {
69  uint32_t pos0 = 0;
70  uint32_t pos1 = 2;
71 
72  if (x[1] <= x[0]) pos0 = 1;
73  if (x[3] <= x[2]) pos1 = 3;
74  if (x[pos1] <= x[pos0]) pos0 = pos1;
75 
76  return pos0;
77 }
78 
79 #endif
80 
81 /*
82  * Compute the Greatest Common Divisor (GCD) of two numbers.
83  * This implementation uses Euclid's algorithm:
84  * gcd(a, 0) = a
85  * gcd(a, b) = gcd(b, a mod b)
86  *
87  */
88 static inline uint32_t
89 rte_get_gcd(uint32_t a, uint32_t b)
90 {
91  uint32_t c;
92 
93  if (a == 0)
94  return b;
95  if (b == 0)
96  return a;
97 
98  if (a < b) {
99  c = a;
100  a = b;
101  b = c;
102  }
103 
104  while (b != 0) {
105  c = a % b;
106  a = b;
107  b = c;
108  }
109 
110  return a;
111 }
112 
113 /*
114  * Compute the Lowest Common Denominator (LCD) of two numbers.
115  * This implementation computes GCD first:
116  * LCD(a, b) = (a * b) / GCD(a, b)
117  *
118  */
119 static inline uint32_t
120 rte_get_lcd(uint32_t a, uint32_t b)
121 {
122  return (a * b) / rte_get_gcd(a, b);
123 }
124 
125 #ifdef __cplusplus
126 }
127 #endif
128 
129 #endif /* __INCLUDE_RTE_SCHED_COMMON_H__ */