missing/isinf.c

   1 /* public domain rewrite of isinf(3) */
   2
   3 #ifdef __osf__
   4
   5 #define _IEEE 1
   6 #include <nan.h>
   7
   8 int
   9 isinf(double n)
  10 {
  11     if (IsNANorINF(n) && IsINF(n)) {
  12         return 1;
  13     }
  14     else {
  15         return 0;
  16     }
  17 }
  18
  19 #else
  20
  21 #include "ruby/config.h"
  22
  23 #if defined(HAVE_FINITE) && defined(HAVE_ISNAN)
  24
  25 #include <math.h>
  26 #ifdef HAVE_IEEEFP_H
  27 #include <ieeefp.h>
  28 #endif
  29
  30 /*
  31  * isinf may be provided only as a macro.
  32  * ex. HP-UX, Solaris 10
  33  * http://www.gnu.org/software/automake/manual/autoconf/Function-Portability.html
  34  */
  35 #ifndef isinf
  36 int
  37 isinf(double n)
  38 {
  39     return (!finite(n) && !isnan(n));
  40 }
  41 #endif
  42
  43 #else
  44
  45 #ifdef HAVE_STRING_H
  46 # include <string.h>
  47 #else
  48 # include <strings.h>
  49 #endif
  50
  51 static double zero(void) { return 0.0; }
  52 static double one (void) { return 1.0; }
  53 static double inf (void) { return one() / zero(); }
  54
  55 int
  56 isinf(double n)
  57 {
  58     static double pinf = 0.0;
  59     static double ninf = 0.0;
  60
  61     if (pinf == 0.0) {
  62         pinf = inf();
  63         ninf = -pinf;
  64     }
  65     return memcmp(&n, &pinf, sizeof n) == 0
  66         || memcmp(&n, &ninf, sizeof n) == 0;
  67 }
  68 #endif
  69 #endif