int isinf(double d) { #if HAVE_FP_CLASS int fpclass = fp_class(d); #else int fpclass = fp_class_d(d); #endif if (fpclass == FP_POS_INF) return 1; if (fpclass == FP_NEG_INF) return -1; return 0; }
/************************************************************************* * trio_isinf */ TRIO_PUBLIC int trio_isinf(TRIO_VOLATILE double number) { #if defined(TRIO_COMPILER_DECC) /* * DECC has an isinf() macro, but it works differently than that * of C99, so we use the fp_class() function instead. */ return ((fp_class(number) == FP_POS_INF) ? 1 : ((fp_class(number) == FP_NEG_INF) ? -1 : 0)); #elif defined(isinf) /* * C99 defines isinf() as a macro. */ return isinf(number); #elif defined(TRIO_COMPILER_MSVC) /* * MSVC has an _fpclass() function that can be used to detect infinity. */ return ((_fpclass(number) == _FPCLASS_PINF) ? 1 : ((_fpclass(number) == _FPCLASS_NINF) ? -1 : 0)); #elif defined(USE_IEEE_754) /* * Examine IEEE 754 bit-pattern. Infinity must have a special exponent * pattern, and an empty mantissa. */ int has_mantissa; int is_special_quantity; is_special_quantity = trio_is_special_quantity(number, &has_mantissa); return (is_special_quantity && !has_mantissa) ? ((number < 0.0) ? -1 : 1) : 0; #else /* * Fallback solution. */ int status; # if defined(TRIO_PLATFORM_UNIX) void (*signal_handler)(int) = signal(SIGFPE, SIG_IGN); # endif double infinity = trio_pinf(); status = ((number == infinity) ? 1 : ((number == -infinity) ? -1 : 0)); # if defined(TRIO_PLATFORM_UNIX) signal(SIGFPE, signal_handler); # endif return status; #endif }