src/jemalloc/include/msvc_compat/strings.h

   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 */