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 */ 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 */ 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 */ 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 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 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