sys/src/ape/lib/fmt/nan64.c

   1 /*
   2  * 64-bit IEEE not-a-number routines.
   3  * This is big/little-endian portable assuming that
   4  * the 64-bit doubles and 64-bit integers have the
   5  * same byte ordering.
   6  */
   7
   8 #include "nan.h"
   9
  10 #ifdef __APPLE__
  11 #define _NEEDLL
  12 #endif
  13
  14 typedef unsigned long long uvlong;
  15 typedef unsigned long ulong;
  16
  17 #ifdef _NEEDLL
  18 static uvlong uvnan    = 0x7FF0000000000001LL;
  19 static uvlong uvinf    = 0x7FF0000000000000LL;
  20 static uvlong uvneginf = 0xFFF0000000000000LL;
  21 #else
  22 static uvlong uvnan    = 0x7FF0000000000001;
  23 static uvlong uvinf    = 0x7FF0000000000000;
  24 static uvlong uvneginf = 0xFFF0000000000000;
  25 #endif
  26
  27 double
  28 __NaN(void)
  29 {
  30         uvlong *p;
  31
  32         /* gcc complains about "return *(double*)&uvnan;" */
  33         p = &uvnan;
  34         return *(double*)p;
  35 }
  36
  37 int
  38 __isNaN(double d)
  39 {
  40         uvlong x;
  41         double *p;
  42
  43         p = &d;
  44         x = *(uvlong*)p;
  45         return (ulong)(x>>32)==0x7FF00000 && !__isInf(d, 0);
  46 }
  47
  48 double
  49 __Inf(int sign)
  50 {
  51         uvlong *p;
  52
  53         if(sign < 0)
  54                 p = &uvinf;
  55         else
  56                 p = &uvneginf;
  57         return *(double*)p;
  58 }
  59
  60 int
  61 __isInf(double d, int sign)
  62 {
  63         uvlong x;
  64         double *p;
  65
  66         p = &d;
  67         x = *(uvlong*)p;
  68         if(sign == 0)
  69                 return x==uvinf || x==uvneginf;
  70         else if(sign > 0)
  71                 return x==uvinf;
  72         else
  73                 return x==uvneginf;
  74 }
  75
  76