blob: d92fd297a1b4985003d7a3c0458a8fbc2b592ef7 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
/* SPDX-License-Identifier: GPL-3.0-or-later */
/* Copyright 2021 - 2022, Kim Kuparinen < kimi.h.kuparinen@gmail.com > */
/**
* @file bits.c
* Bit manipulation helper implementations, currently just byte swaps.
*/
#include <apos/types.h>
#include <apos/attrs.h>
#include <apos/bits.h>
#include <apos/builtin.h>
#undef __bswap16
__weak uint16_t __bswap16(const uint16_t u)
{
return (u & 0xff00) >> 8 | (u & 0x00ff) << 8;
}
#undef __bswap32
__weak uint32_t __bswap32(const uint32_t u)
{
return (u & 0xff000000) >> 24 | (u & 0x00ff0000) >> 8 |
(u & 0x0000ff00) << 8 | (u & 0x000000ff) << 24;
}
#undef __bswap64
__weak uint64_t __bswap64(const uint64_t u)
{
return (u & 0xff00000000000000ULL) >> 56 |
(u & 0x00ff000000000000ULL) >> 40 |
(u & 0x0000ff0000000000ULL) >> 24 |
(u & 0x000000ff00000000ULL) >> 8 |
(u & 0x00000000ff000000ULL) << 8 |
(u & 0x0000000000ff0000ULL) << 24 |
(u & 0x000000000000ff00ULL) << 40 |
(u & 0x00000000000000ffULL) << 56;
}
#undef ffs
__weak int ffs(int v)
{
/* http://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightParallel */
if (v == 0)
return 0;
/* silence ubsan warning */
if (v == INT_MIN)
return 32;
int c = 32;
v &= -v;
if (v) c--;
if (v & 0x0000FFFF) c -= 16;
if (v & 0x00FF00FF) c -= 8;
if (v & 0x0F0F0F0F) c -= 4;
if (v & 0x33333333) c -= 2;
if (v & 0x55555555) c -= 1;
return c + 1;
}
|
