1 | /* |
2 | * Copyright (c) 2015-2017, Intel Corporation |
3 | * |
4 | * Redistribution and use in source and binary forms, with or without |
5 | * modification, are permitted provided that the following conditions are met: |
6 | * |
7 | * * Redistributions of source code must retain the above copyright notice, |
8 | * this list of conditions and the following disclaimer. |
9 | * * Redistributions in binary form must reproduce the above copyright |
10 | * notice, this list of conditions and the following disclaimer in the |
11 | * documentation and/or other materials provided with the distribution. |
12 | * * Neither the name of Intel Corporation nor the names of its contributors |
13 | * may be used to endorse or promote products derived from this software |
14 | * without specific prior written permission. |
15 | * |
16 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
17 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
18 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
19 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
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21 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
22 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
23 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
24 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
25 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
26 | * POSSIBILITY OF SUCH DAMAGE. |
27 | */ |
28 | |
29 | /** \file |
30 | * \brief Platform specific popcount functions |
31 | */ |
32 | |
33 | #ifndef UTIL_POPCOUNT_H_ |
34 | #define UTIL_POPCOUNT_H_ |
35 | |
36 | #include "ue2common.h" |
37 | #include "util/arch.h" |
38 | |
39 | static really_inline |
40 | u32 popcount32(u32 x) { |
41 | #if defined(HAVE_POPCOUNT_INSTR) |
42 | // Single-instruction builtin. |
43 | return _mm_popcnt_u32(x); |
44 | #else |
45 | // Fast branch-free version from bit-twiddling hacks as older Intel |
46 | // processors do not have a POPCNT instruction. |
47 | x -= (x >> 1) & 0x55555555; |
48 | x = (x & 0x33333333) + ((x >> 2) & 0x33333333); |
49 | return (((x + (x >> 4)) & 0xf0f0f0f) * 0x1010101) >> 24; |
50 | #endif |
51 | } |
52 | |
53 | static really_inline |
54 | u32 popcount64(u64a x) { |
55 | #if defined(ARCH_X86_64) |
56 | # if defined(HAVE_POPCOUNT_INSTR) |
57 | // Single-instruction builtin. |
58 | return (u32)_mm_popcnt_u64(x); |
59 | # else |
60 | // Fast branch-free version from bit-twiddling hacks as older Intel |
61 | // processors do not have a POPCNT instruction. |
62 | x -= (x >> 1) & 0x5555555555555555; |
63 | x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333); |
64 | x = (x + (x >> 4)) & 0x0f0f0f0f0f0f0f0f; |
65 | return (x * 0x0101010101010101) >> 56; |
66 | # endif |
67 | #else |
68 | // Synthesise from two 32-bit cases. |
69 | return popcount32(x >> 32) + popcount32(x); |
70 | #endif |
71 | } |
72 | |
73 | #endif /* UTIL_POPCOUNT_H_ */ |
74 | |
75 | |