1 /* SPDX-License-Identifier: GPL-2.0-only */
2
3 #include <types.h>
4
5 /*
6 * Provide platform-independent backend implementation for __builtin_clz() in
7 * <lib.h> in case GCC does not have an assembly version for this arch.
8 */
9
10 /*
11 * FIXME
12 * work around lack of --gc-sections on x86
13 * defined in rv32 libgcc.a
14 */
15
16 #if !ENV_X86 && !ENV_RISCV
17 int __clzsi2(u32 a);
__clzsi2(u32 a)18 int __clzsi2(u32 a)
19 {
20 static const u8 four_bit_table[] = {
21 [0x0] = 4, [0x1] = 3, [0x2] = 2, [0x3] = 2,
22 [0x4] = 1, [0x5] = 1, [0x6] = 1, [0x7] = 1,
23 [0x8] = 0, [0x9] = 0, [0xa] = 0, [0xb] = 0,
24 [0xc] = 0, [0xd] = 0, [0xe] = 0, [0xf] = 0,
25 };
26 int r = 0;
27
28 if (!(a & (0xffffU << 16))) {
29 r += 16;
30 a <<= 16;
31 }
32
33 if (!(a & (0xffU << 24))) {
34 r += 8;
35 a <<= 8;
36 }
37
38 if (!(a & (0xfU << 28))) {
39 r += 4;
40 a <<= 4;
41 }
42
43 return r + four_bit_table[a >> 28];
44 }
45 #endif
46