ref: c1d40df49550393f3afe53fb6e6d500dfa8eb7a8
dir: /sys/src/ape/lib/ap/plan9/nan.c/
#include <float.h> #include <math.h> #define NANEXP (2047<<20) #define NANMASK (2047<<20) #define NANSIGN (1<<31) double NaN(void) { FPdbleword a; a.hi = NANEXP; a.lo = 1; return a.x; } int isNaN(double d) { FPdbleword a; a.x = d; if((a.hi & NANMASK) != NANEXP) return 0; return !isInf(d, 0); } double Inf(int sign) { FPdbleword a; a.hi = NANEXP; a.lo = 0; if(sign < 0) a.hi |= NANSIGN; return a.x; } int isInf(double d, int sign) { FPdbleword a; a.x = d; if(a.lo != 0) return 0; if(a.hi == NANEXP) return sign >= 0; if(a.hi == (NANEXP|NANSIGN)) return sign <= 0; return 0; }