1 #ifndef strings_h 2 #define strings_h 3 4 /* MSVC doesn't define ffs/ffsl. This dummy strings.h header is provided 5 * for both */ 6 #ifdef _MSC_VER 7 # include <intrin.h> 8 # pragma intrinsic(_BitScanForward) 9 static __forceinline int ffsl(long x) 10 { 11 unsigned long i; 12 13 if (_BitScanForward(&i, x)) 14 return (i + 1); 15 return (0); 16 } 17 18 static __forceinline int ffs(int x) 19 { 20 21 return (ffsl(x)); 22 } 23 24 # ifdef _M_X64 25 # pragma intrinsic(_BitScanForward64) 26 # endif 27 28 static __forceinline int ffsll(unsigned __int64 x) 29 { 30 unsigned long i; 31 #ifdef _M_X64 32 if (_BitScanForward64(&i, x)) 33 return (i + 1); 34 return (0); 35 #else 36 // Fallback for 32-bit build where 64-bit version not available 37 // assuming little endian 38 union { 39 unsigned __int64 ll; 40 unsigned long l[2]; 41 } s; 42 43 s.ll = x; 44 45 if (_BitScanForward(&i, s.l[0])) 46 return (i + 1); 47 else if(_BitScanForward(&i, s.l[1])) 48 return (i + 33); 49 return (0); 50 #endif 51 } 52 53 #else 54 # define ffsll(x) __builtin_ffsll(x) 55 # define ffsl(x) __builtin_ffsl(x) 56 # define ffs(x) __builtin_ffs(x) 57 #endif 58 59 #endif /* strings_h */ 60
