ref: c11957a7915d355d80ff7e6a21721ba05441ca29
dir: /libkern/nan-spim.c/
#include <lib9.h> #define NANEXP (2047<<20) #define NANMASK (2047<<20) #define NANSIGN (1<<31) double NaN(void) { union { double d; long x[2]; } a; a.x[1] = NANEXP; a.x[0] = 1; return a.d; } int isNaN(double d) { union { double d; long x[2]; } a; a.d = d; if((a.x[1] & NANMASK) != NANEXP) return 0; return !isInf(d, 0); } double Inf(int sign) { union { double d; long x[2]; } a; a.x[1] = NANEXP; a.x[0] = 0; if(sign < 0) a.x[1] |= NANSIGN; return a.d; } int isInf(double d, int sign) { union { double d; long x[2]; } a; a.d = d; if(a.x[0] != 0) return 0; if(a.x[1] == NANEXP) return sign >= 0; if(a.x[1] == (NANEXP|NANSIGN)) return sign <= 0; return 0; }