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
63
64
65
66
67
68
69
70
|
/*
* Copyright (C) 2024 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL )
/** @file
*
* Byte swapping
*
*/
.section ".note.GNU-stack", "", @progbits
.text
/**
* Find first (i.e. least significant) set bit
*
* @v value Value
* @ret lsb Least significant bit set in value (LSB=1), or zero
*/
.section ".text.riscv_ffs"
.globl riscv_ffs
riscv_ffs:
beqz a0, 2f
mv t0, a0
li a0, ( __riscv_xlen + 1 )
1: slli t0, t0, 1
addi a0, a0, -1
bnez t0, 1b
2: ret
.size riscv_ffs, . - riscv_ffs
/**
* Find last (i.e. most significant) set bit
*
* @v value Value
* @ret msb Most significant bit set in value (LSB=1), or zero
*/
.section ".text.riscv_fls"
.globl riscv_fls
riscv_fls:
beqz a0, 2f
mv t0, a0
li a0, __riscv_xlen
bltz t0, 2f
1: slli t0, t0, 1
addi a0, a0, -1
bgez t0, 1b
2: ret
.size riscv_fls, . - riscv_fls
|
