glibc的幾個有用的處理二進制位的內置函數
2019-11-11 00:28:00
供稿：網友
— Built-in Function: int __builtin_ffs (unsigned int x)Returns one plus the index of the least significant 1-bit of x, or if x is zero, returns zero.返回右起第一個‘1’的位置?！?Built-in Function: int __builtin_clz (unsigned int x)Returns the number of leading 0-bits in x, starting at the most significant bit position. If x is 0, the result is undefined.返回左起第一個‘1’之前0的個數?！?Built-in Function: int __builtin_ctz (unsigned int x)Returns the number of trailing 0-bits in x, starting at the least significant bit position. If x is 0, the result is undefined.返回右起第一個‘1’之后的0的個數。— Built-in Function: int __builtin_popcount (unsigned int x)Returns the number of 1-bits in x.返回‘1’的個數?！?Built-in Function: int __builtin_parity (unsigned int x)Returns the parity of x, i.e. the number of 1-bits in x modulo 2.返回‘1’的個數的奇偶性?！?Built-in Function: int __builtin_ffsl (unsigned long)Similar to __builtin_ffs, except the argument type is unsigned long. — Built-in Function: int __builtin_clzl (unsigned long)Similar to __builtin_clz, except the argument type is unsigned long. — Built-in Function: int __builtin_ctzl (unsigned long)Similar to __builtin_ctz, except the argument type is unsigned long. — Built-in Function: int __builtin_popcountl (unsigned long)Similar to __builtin_popcount, except the argument type is unsigned long. — Built-in Function: int __builtin_parityl (unsigned long)Similar to __builtin_parity, except the argument type is unsigned long. — Built-in Function: int __builtin_ffsll (unsigned long long)Similar to __builtin_ffs, except the argument type is unsigned long long. — Built-in Function: int __builtin_clzll (unsigned long long)Similar to __builtin_clz, except the argument type is unsigned long long. — Built-in Function: int __builtin_ctzll (unsigned long long)Similar to __builtin_ctz, except the argument type is unsigned long long. — Built-in Function: int __builtin_popcountll (unsigned long long)Similar to __builtin_popcount, except the argument type is unsigned long long. — Built-in Function: int __builtin_parityll (unsigned long long)Similar to __builtin_parity, except the argument type is unsigned long long.來源：點擊打開鏈接
