1 #include <common/stddef.h>
2
3 /**
4 * @brief 统计二进制数的前导0
5 *
6 * @param x 待统计的数
7 * @return int 结果
8 */
__clz(uint32_t x)9 static __always_inline int __clz(uint32_t x)
10 {
11 asm volatile("bsr %%eax, %%eax\n\t"
12 "xor $0x1f, %%eax\n\t"
13 : "=a"(x)
14 : "a"(x)
15 : "memory");
16 return x;
17 }
18
19 /**
20 * @brief 统计二进制数的前导0 (宽度为unsigned long)
21 *
22 * @param x 待统计的数
23 * @return int 结果
24 */
__clzl(unsigned long x)25 static __always_inline int __clzl(unsigned long x)
26 {
27 int res = 0;
28 asm volatile("cltq\n\t"
29 "bsr %%rax, %%rax\n\t"
30 "xor $0x3f, %%rax\n\t"
31 "mov %%eax,%0\n\t"
32 : "=m"(res)
33 : "a"(x)
34 : "memory");
35 return res;
36 }
37
38 /**
39 * @brief 统计二进制数的前导0（宽度为unsigned long long）
40 *
41 * @param x 待统计的数
42 * @return int 结果
43 */
__clzll(unsigned long long x)44 static __always_inline int __clzll(unsigned long long x)
45 {
46 int res = 0;
47 asm volatile("cltq\n\t"
48 "bsr %%rax, %%rax\n\t"
49 "xor $0x3f, %%rax\n\t"
50 "mov %%eax,%0\n\t"
51 : "=m"(res)
52 : "a"(x)
53 : "memory");
54 return res;
55 }
56
__ctz(uint32_t x)57 static __always_inline int __ctz(uint32_t x)
58 {
59 asm volatile("tzcnt %%eax, %%eax":"=a"(x):"a"(x):"memory");
60 return x;
61 }
62
__ctzl(unsigned long x)63 static __always_inline int __ctzl(unsigned long x)
64 {
65 asm volatile("tzcnt %%rax, %%rax":"=a"(x):"a"(x):"memory");
66 return x;
67 }
68
69 #define __ctzll __ctzl