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:
7 * http://www.apache.org/licenses/LICENSE-2.0
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.
16 Copyright (c) 2005 Eliot Dresselhaus
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:
26 The above copyright notice and this permission notice shall be
27 included in all copies or substantial portions of the Software.
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.
38 #ifndef included_clib_bitops_h
39 #define included_clib_bitops_h
41 #include <vppinfra/clib.h>
43 /* Population count from Hacker's Delight. */
45 count_set_bits (uword x)
48 const uword c1 = 0x5555555555555555;
49 const uword c2 = 0x3333333333333333;
50 const uword c3 = 0x0f0f0f0f0f0f0f0f;
52 const uword c1 = 0x55555555;
53 const uword c2 = 0x33333333;
54 const uword c3 = 0x0f0f0f0f;
57 /* Sum 1 bit at a time. */
58 x = x - ((x >> (uword) 1) & c1);
60 /* 2 bits at a time. */
61 x = (x & c2) + ((x >> (uword) 2) & c2);
63 /* 4 bits at a time. */
64 x = (x + (x >> (uword) 4)) & c3;
66 /* 8, 16, 32 bits at a time. */
67 x = x + (x >> (uword) 8);
68 x = x + (x >> (uword) 16);
70 x = x + (x >> (uword) 32);
73 return x & (2 * BITS (uword) - 1);
76 /* Based on "Hacker's Delight" code from GLS. */
79 uword masks[1 + log2_uword_bits];
83 compress_init (compress_main_t * cm, uword mask)
91 for (i = 0; i < log2_uword_bits; i++)
100 m ^= m << (uword) 32;
102 cm->masks[1 + i] = n = (m << 1) & zm;
105 zm = zm ^ q ^ (q >> (1 << i));
110 compress_bits (compress_main_t * cm, uword x)
114 r = x & cm->masks[0];
115 q = r & cm->masks[1];
117 q = r & cm->masks[2];
119 q = r & cm->masks[3];
121 q = r & cm->masks[4];
123 q = r & cm->masks[5];
126 q = r & cm->masks[6];
127 r ^= q ^ (q >> (uword) 32);
134 rotate_left (uword x, uword i)
136 return (x << i) | (x >> (BITS (i) - i));
140 rotate_right (uword x, uword i)
142 return (x >> i) | (x << (BITS (i) - i));
145 /* Returns snoob from Hacker's Delight. Next highest number
146 with same number of set bits. */
148 next_with_same_number_of_set_bits (uword x)
150 uword smallest, ripple, ones;
152 ripple = x + smallest;
154 ones = ones >> (2 + log2_first_set (x));
155 return ripple | ones;
158 #define foreach_set_bit(var,mask,body) \
160 uword _foreach_set_bit_m_##var = (mask); \
161 uword _foreach_set_bit_f_##var; \
162 while (_foreach_set_bit_m_##var != 0) \
164 _foreach_set_bit_f_##var = first_set (_foreach_set_bit_m_##var); \
165 _foreach_set_bit_m_##var ^= _foreach_set_bit_f_##var; \
166 (var) = min_log2 (_foreach_set_bit_f_##var); \
167 do { body; } while (0); \
171 #endif /* included_clib_bitops_h */
174 * fd.io coding-style-patch-verification: ON
177 * eval: (c-set-style "gnu")