FD.io VPP  v18.07.1-19-g511ce25
Vector Packet Processing
bitops.h
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1 /*
2  * Copyright (c) 2015 Cisco and/or its affiliates.
3  * Licensed under the Apache License, Version 2.0 (the "License");
4  * you may not use this file except in compliance with the License.
5  * You may obtain a copy of the License at:
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software
10  * distributed under the License is distributed on an "AS IS" BASIS,
11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  * See the License for the specific language governing permissions and
13  * limitations under the License.
14  */
15 /*
16  Copyright (c) 2005 Eliot Dresselhaus
17 
18  Permission is hereby granted, free of charge, to any person obtaining
19  a copy of this software and associated documentation files (the
20  "Software"), to deal in the Software without restriction, including
21  without limitation the rights to use, copy, modify, merge, publish,
22  distribute, sublicense, and/or sell copies of the Software, and to
23  permit persons to whom the Software is furnished to do so, subject to
24  the following conditions:
25 
26  The above copyright notice and this permission notice shall be
27  included in all copies or substantial portions of the Software.
28 
29  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
30  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
31  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
32  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
33  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
34  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
35  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
36 */
37 
38 #ifndef included_clib_bitops_h
39 #define included_clib_bitops_h
40 
41 #include <vppinfra/clib.h>
42 
43 /* Population count from Hacker's Delight. */
46 {
47 #ifdef __POPCNT__
48 #if uword_bits == 64
49  return __builtin_popcountll (x);
50 #else
51  return __builtin_popcount (x);
52 #endif
53 #else
54 #if uword_bits == 64
55  const uword c1 = 0x5555555555555555;
56  const uword c2 = 0x3333333333333333;
57  const uword c3 = 0x0f0f0f0f0f0f0f0f;
58 #else
59  const uword c1 = 0x55555555;
60  const uword c2 = 0x33333333;
61  const uword c3 = 0x0f0f0f0f;
62 #endif
63 
64  /* Sum 1 bit at a time. */
65  x = x - ((x >> (uword) 1) & c1);
66 
67  /* 2 bits at a time. */
68  x = (x & c2) + ((x >> (uword) 2) & c2);
69 
70  /* 4 bits at a time. */
71  x = (x + (x >> (uword) 4)) & c3;
72 
73  /* 8, 16, 32 bits at a time. */
74  x = x + (x >> (uword) 8);
75  x = x + (x >> (uword) 16);
76 #if uword_bits == 64
77  x = x + (x >> (uword) 32);
78 #endif
79 
80  return x & (2 * BITS (uword) - 1);
81 #endif
82 }
83 
84 /* Based on "Hacker's Delight" code from GLS. */
85 typedef struct
86 {
87  uword masks[1 + log2_uword_bits];
89 
90 always_inline void
92 {
93  uword q, m, zm, n, i;
94 
95  m = ~mask;
96  zm = mask;
97 
98  cm->masks[0] = mask;
99  for (i = 0; i < log2_uword_bits; i++)
100  {
101  q = m;
102  m ^= m << 1;
103  m ^= m << 2;
104  m ^= m << 4;
105  m ^= m << 8;
106  m ^= m << 16;
107 #if uword_bits > 32
108  m ^= m << (uword) 32;
109 #endif
110  cm->masks[1 + i] = n = (m << 1) & zm;
111  m = q & ~m;
112  q = zm & n;
113  zm = zm ^ q ^ (q >> (1 << i));
114  }
115 }
116 
119 {
120  uword q, r;
121 
122  r = x & cm->masks[0];
123  q = r & cm->masks[1];
124  r ^= q ^ (q >> 1);
125  q = r & cm->masks[2];
126  r ^= q ^ (q >> 2);
127  q = r & cm->masks[3];
128  r ^= q ^ (q >> 4);
129  q = r & cm->masks[4];
130  r ^= q ^ (q >> 8);
131  q = r & cm->masks[5];
132  r ^= q ^ (q >> 16);
133 #if uword_bits > 32
134  q = r & cm->masks[6];
135  r ^= q ^ (q >> (uword) 32);
136 #endif
137 
138  return r;
139 }
140 
143 {
144  return (x << i) | (x >> (BITS (i) - i));
145 }
146 
149 {
150  return (x >> i) | (x << (BITS (i) - i));
151 }
152 
153 /* Returns snoob from Hacker's Delight. Next highest number
154  with same number of set bits. */
157 {
158  uword smallest, ripple, ones;
159  smallest = x & -x;
160  ripple = x + smallest;
161  ones = x ^ ripple;
162  ones = ones >> (2 + log2_first_set (x));
163  return ripple | ones;
164 }
165 
166 #define foreach_set_bit(var,mask,body) \
167 do { \
168  uword _foreach_set_bit_m_##var = (mask); \
169  uword _foreach_set_bit_f_##var; \
170  while (_foreach_set_bit_m_##var != 0) \
171  { \
172  _foreach_set_bit_f_##var = first_set (_foreach_set_bit_m_##var); \
173  _foreach_set_bit_m_##var ^= _foreach_set_bit_f_##var; \
174  (var) = min_log2 (_foreach_set_bit_f_##var); \
175  do { body; } while (0); \
176  } \
177 } while (0)
178 
179 #endif /* included_clib_bitops_h */
180 
181 /*
182  * fd.io coding-style-patch-verification: ON
183  *
184  * Local Variables:
185  * eval: (c-set-style "gnu")
186  * End:
187  */
static uword log2_first_set(uword x)
Definition: clib.h:253
int i
static void compress_init(compress_main_t *cm, uword mask)
Definition: bitops.h:91
#define always_inline
Definition: clib.h:92
static uword rotate_right(uword x, uword i)
Definition: bitops.h:148
#define log2_uword_bits
Definition: types.h:84
u64 uword
Definition: types.h:112
static uword count_set_bits(uword x)
Definition: bitops.h:45
uword masks[1+log2_uword_bits]
Definition: bitops.h:87
#define BITS(x)
Definition: clib.h:58
static uword compress_bits(compress_main_t *cm, uword x)
Definition: bitops.h:118
static uword rotate_left(uword x, uword i)
Definition: bitops.h:142
static uword next_with_same_number_of_set_bits(uword x)
Definition: bitops.h:156