HelenOS sources
fpclassify 120 uspace/lib/c/include/math.h #define isfinite(x) (fpclassify(x) > FP_INFINITE)
fpclassify 121 uspace/lib/c/include/math.h #define isinf(x) (fpclassify(x) == FP_INFINITE)
fpclassify 122 uspace/lib/c/include/math.h #define isnan(x) (fpclassify(x) == FP_NAN)
fpclassify 123 uspace/lib/c/include/math.h #define isnormal(x) (fpclassify(x) == FP_NORMAL)
fpclassify 45 uspace/lib/math/generic/__fpclassify.c result = fpclassify((float) va_arg(ap, double));
fpclassify 48 uspace/lib/math/generic/__fpclassify.c result = fpclassify(va_arg(ap, double));
fpclassify 51 uspace/lib/math/generic/__fpclassify.c result = fpclassify(va_arg(ap, long double));
fpclassify 120 uspace/lib/posix/include/libc/math.h #define isfinite(x) (fpclassify(x) > FP_INFINITE)
fpclassify 121 uspace/lib/posix/include/libc/math.h #define isinf(x) (fpclassify(x) == FP_INFINITE)
fpclassify 122 uspace/lib/posix/include/libc/math.h #define isnan(x) (fpclassify(x) == FP_NAN)
fpclassify 123 uspace/lib/posix/include/libc/math.h #define isnormal(x) (fpclassify(x) == FP_NORMAL)
HelenOS homepage, sources at GitHub