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/*
* Copyright (c) 2015 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
Copyright (c) 2005 Eliot Dresselhaus
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef included_clib_bitops_h
#define included_clib_bitops_h
static_always_inline uword
clear_lowest_set_bit (uword x)
{
#ifdef __BMI__
return uword_bits > 32 ? _blsr_u64 (x) : _blsr_u32 (x);
#else
return x & (x - 1);
#endif
}
static_always_inline uword
get_lowest_set_bit (uword x)
{
#ifdef __BMI__
return uword_bits > 32 ? _blsi_u64 (x) : _blsi_u32 (x);
#else
return x & -x;
#endif
}
static_always_inline u8
get_lowest_set_bit_index (uword x)
{
return uword_bits > 32 ? __builtin_ctzll (x) : __builtin_ctz (x);
}
/* Population count from Hacker's Delight. */
always_inline uword
count_set_bits (uword x)
{
#ifdef __POPCNT__
return uword_bits > 32 ? __builtin_popcountll (x) : __builtin_popcount (x);
#else
#if uword_bits == 64
const uword c1 = 0x5555555555555555;
const uword c2 = 0x3333333333333333;
const uword c3 = 0x0f0f0f0f0f0f0f0f;
#else
const uword c1 = 0x55555555;
const uword c2 = 0x33333333;
const uword c3 = 0x0f0f0f0f;
#endif
/* Sum 1 bit at a time. */
x = x - ((x >> (uword) 1) & c1);
/* 2 bits at a time. */
x = (x & c2) + ((x >> (uword) 2) & c2);
/* 4 bits at a time. */
x = (x + (x >> (uword) 4)) & c3;
/* 8, 16, 32 bits at a time. */
x = x + (x >> (uword) 8);
x = x + (x >> (uword) 16);
#if uword_bits == 64
x = x + (x >> (uword) 32);
#endif
return x & (2 * BITS (uword) - 1);
#endif
}
#if uword_bits == 64
#define count_leading_zeros(x) __builtin_clzll (x)
#else
#define count_leading_zeros(x) __builtin_clzll (x)
#endif
#define count_trailing_zeros(x) get_lowest_set_bit_index (x)
#define log2_first_set(x) get_lowest_set_bit_index (x)
/* Based on "Hacker's Delight" code from GLS. */
typedef struct
{
uword masks[1 + log2_uword_bits];
} compress_main_t;
always_inline void
compress_init (compress_main_t * cm, uword mask)
{
uword q, m, zm, n, i;
m = ~mask;
zm = mask;
cm->masks[0] = mask;
for (i = 0; i < log2_uword_bits; i++)
{
q = m;
m ^= m << 1;
m ^= m << 2;
m ^= m << 4;
m ^= m << 8;
m ^= m << 16;
#if uword_bits > 32
m ^= m << (uword) 32;
#endif
cm->masks[1 + i] = n = (m << 1) & zm;
m = q & ~m;
q = zm & n;
zm = zm ^ q ^ (q >> (1 << i));
}
}
always_inline uword
compress_bits (compress_main_t * cm, uword x)
{
uword q, r;
r = x & cm->masks[0];
q = r & cm->masks[1];
r ^= q ^ (q >> 1);
q = r & cm->masks[2];
r ^= q ^ (q >> 2);
q = r & cm->masks[3];
r ^= q ^ (q >> 4);
q = r & cm->masks[4];
r ^= q ^ (q >> 8);
q = r & cm->masks[5];
r ^= q ^ (q >> 16);
#if uword_bits > 32
q = r & cm->masks[6];
r ^= q ^ (q >> (uword) 32);
#endif
return r;
}
always_inline uword
rotate_left (uword x, uword i)
{
return (x << i) | (x >> (BITS (i) - i));
}
always_inline uword
rotate_right (uword x, uword i)
{
return (x >> i) | (x << (BITS (i) - i));
}
/* Returns snoob from Hacker's Delight. Next highest number
with same number of set bits. */
always_inline uword
next_with_same_number_of_set_bits (uword x)
{
uword smallest, ripple, ones;
smallest = x & -x;
ripple = x + smallest;
ones = x ^ ripple;
ones = ones >> (2 + log2_first_set (x));
return ripple | ones;
}
#define foreach_set_bit_index(i, v) \
for (uword _tmp = (v) + 0 * (uword) (i = get_lowest_set_bit_index (v)); \
_tmp; \
i = get_lowest_set_bit_index (_tmp = clear_lowest_set_bit (_tmp)))
#else
#warning "already included"
#endif /* included_clib_bitops_h */
/*
* fd.io coding-style-patch-verification: ON
*
* Local Variables:
* eval: (c-set-style "gnu")
* End:
*/
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