ref: 74e47cdeb4f9b8d81766c24391bac05f87922115
dir: /libc/nan64.c/
/* * 64-bit IEEE not-a-number routines. * This is big/little-endian portable assuming that * the 64-bit doubles and 64-bit integers have the * same byte ordering. */ #include <u.h> #include <libc.h> #include "fmtdef.h" #if defined (__APPLE__) || (__powerpc__) #define _NEEDLL #endif static uvlong uvnan = ((uvlong)0x7FF00000<<32)|0x00000001; static uvlong uvinf = ((uvlong)0x7FF00000<<32)|0x00000000; static uvlong uvneginf = ((uvlong)0xFFF00000<<32)|0x00000000; double __NaN(void) { uvlong *p; /* gcc complains about "return *(double*)&uvnan;" */ p = &uvnan; return *(double*)p; } int __isNaN(double d) { uvlong x; double *p; p = &d; x = *(uvlong*)p; return (ulong)(x>>32)==0x7FF00000 && !__isInf(d, 0); } double __Inf(int sign) { uvlong *p; if(sign < 0) p = &uvinf; else p = &uvneginf; return *(double*)p; } int __isInf(double d, int sign) { uvlong x; double *p; p = &d; x = *(uvlong*)p; if(sign == 0) return x==uvinf || x==uvneginf; else if(sign > 0) return x==uvinf; else return x==uvneginf; }