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
|
/* SPDX-License-Identifier: GPL-2.0-only */
#include <types.h>
/*
* Provide platform-independent backend implementation for __builtin_clz() in
* <lib.h> in case GCC does not have an assembly version for this arch.
*/
#if !CONFIG(ARCH_X86) /* work around lack of --gc-sections on x86 */ \
&& !CONFIG(ARCH_RISCV_RV32) /* defined in rv32 libgcc.a */
int __clzsi2(u32 a);
int __clzsi2(u32 a)
{
static const u8 four_bit_table[] = {
[0x0] = 4, [0x1] = 3, [0x2] = 2, [0x3] = 2,
[0x4] = 1, [0x5] = 1, [0x6] = 1, [0x7] = 1,
[0x8] = 0, [0x9] = 0, [0xa] = 0, [0xb] = 0,
[0xc] = 0, [0xd] = 0, [0xe] = 0, [0xf] = 0,
};
int r = 0;
if (!(a & (0xffffU << 16))) {
r += 16;
a <<= 16;
}
if (!(a & (0xffU << 24))) {
r += 8;
a <<= 8;
}
if (!(a & (0xfU << 28))) {
r += 4;
a <<= 4;
}
return r + four_bit_table[a >> 28];
}
#endif
|
