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
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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. */
44 always_inline uword count_set_bits (uword x)
47 const uword c1 = 0x5555555555555555;
48 const uword c2 = 0x3333333333333333;
49 const uword c3 = 0x0f0f0f0f0f0f0f0f;
51 const uword c1 = 0x55555555;
52 const uword c2 = 0x33333333;
53 const uword c3 = 0x0f0f0f0f;
56 /* Sum 1 bit at a time. */
57 x = x - ((x >> (uword) 1) & c1);
59 /* 2 bits at a time. */
60 x = (x & c2) + ((x >> (uword) 2) & c2);
62 /* 4 bits at a time. */
63 x = (x + (x >> (uword) 4)) & c3;
65 /* 8, 16, 32 bits at a time. */
66 x = x + (x >> (uword) 8);
67 x = x + (x >> (uword) 16);
69 x = x + (x >> (uword) 32);
72 return x & (2*BITS (uword) - 1);
75 /* Based on "Hacker's Delight" code from GLS. */
77 uword masks[1 + log2_uword_bits];
81 compress_init (compress_main_t * cm, uword mask)
89 for (i = 0; i < log2_uword_bits; i++)
100 cm->masks[1 + i] = n = (m << 1) & zm;
103 zm = zm ^ q ^ (q >> (1 << i));
108 compress_bits (compress_main_t * cm, uword x)
112 r = x & cm->masks[0];
113 q = r & cm->masks[1]; r ^= q ^ (q >> 1);
114 q = r & cm->masks[2]; r ^= q ^ (q >> 2);
115 q = r & cm->masks[3]; r ^= q ^ (q >> 4);
116 q = r & cm->masks[4]; r ^= q ^ (q >> 8);
117 q = r & cm->masks[5]; r ^= q ^ (q >> 16);
119 q = r & cm->masks[6]; r ^= q ^ (q >> (uword) 32);
126 rotate_left (uword x, uword i)
127 { return (x << i) | (x >> (BITS (i) - i)); }
130 rotate_right (uword x, uword i)
131 { return (x >> i) | (x << (BITS (i) - i)); }
133 /* Returns snoob from Hacker's Delight. Next highest number
134 with same number of set bits. */
136 next_with_same_number_of_set_bits (uword x)
138 uword smallest, ripple, ones;
140 ripple = x + smallest;
142 ones = ones >> (2 + log2_first_set (x));
143 return ripple | ones;
146 #define foreach_set_bit(var,mask,body) \
148 uword _foreach_set_bit_m_##var = (mask); \
149 uword _foreach_set_bit_f_##var; \
150 while (_foreach_set_bit_m_##var != 0) \
152 _foreach_set_bit_f_##var = first_set (_foreach_set_bit_m_##var); \
153 _foreach_set_bit_m_##var ^= _foreach_set_bit_f_##var; \
154 (var) = min_log2 (_foreach_set_bit_f_##var); \
155 do { body; } while (0); \
159 #endif /* included_clib_bitops_h */