diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/c99_math.h | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/include/c99_math.h b/include/c99_math.h index 0a49950cfc0..bd35d1b32ed 100644 --- a/include/c99_math.h +++ b/include/c99_math.h @@ -161,4 +161,48 @@ llrintf(float f) #endif +#if defined(fpclassify) +/* ISO C99 says that fpclassify is a macro. Assume that any implementation + * of fpclassify, whether it's in a C99 compiler or not, will be a macro. + */ +#elif defined(__cplusplus) +/* For C++, fpclassify() should be defined in <cmath> */ +#elif defined(_MSC_VER) +/* Not required on VS2013 and above. Oddly, the fpclassify() function + * doesn't exist in such a form on MSVC. This is an implementation using + * slightly different lower-level Windows functions. + */ +#include <float.h> + +static inline enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL} +fpclassify(double x) +{ + switch(_fpclass(x)) { + case _FPCLASS_SNAN: /* signaling NaN */ + case _FPCLASS_QNAN: /* quiet NaN */ + return FP_NAN; + case _FPCLASS_NINF: /* negative infinity */ + case _FPCLASS_PINF: /* positive infinity */ + return FP_INFINITE; + case _FPCLASS_NN: /* negative normal */ + case _FPCLASS_PN: /* positive normal */ + return FP_NORMAL; + case _FPCLASS_ND: /* negative denormalized */ + case _FPCLASS_PD: /* positive denormalized */ + return FP_SUBNORMAL; + case _FPCLASS_NZ: /* negative zero */ + case _FPCLASS_PZ: /* positive zero */ + return FP_ZERO; + default: + /* Should never get here; but if we do, this will guarantee + * that the pattern is not treated like a number. + */ + return FP_NAN; + } +} +#else +#error "Need to include or define an fpclassify function" +#endif + + #endif /* #define _C99_MATH_H_ */ |