cmake/TestFloatFormat.cpp

   1 /*
   2  * This file is part of the GROMACS molecular simulation package.
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   4  * Copyright (c) 2014, by the GROMACS development team, led by
   5  * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
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  35 #include <stdio.h>
  36
  37 volatile const double abc [10] = {
  38     /* Zero-terminated strings encoded as floating-point numbers */
  39     /* "GROMACSX" in ascii    */
  40     (double)  3.80279098314984902657e+35, (double) 0.0,
  41     /* "GROMACSX" in ebcdic   */
  42     (double) -1.37384666579378297437e+38, (double) 0.0,
  43     /* "D__float" (vax)       */
  44     (double)  3.53802595280598432000e+18, (double) 0.0,
  45     /* "IBMHEXFP" s390/ascii  */
  46     (double)  1.77977764695171661377e+10, (double) 0.0,
  47     /* "IBMHEXFP" s390/ebcdic */
  48     (double) -5.22995989424860458374e+10, (double) 0.0,
  49 };
  50
  51 /* Check that a double is 8 bytes - compilation dies if it isnt */
  52 extern char xyz [sizeof(double) == 8 ? 1 : -1];
  53
  54 int
  55 main()
  56 {
  57     int         i;
  58     double      d;
  59
  60     /* Make sure some compilers do not optimize away the entire structure
  61      * with floating-point data by using it to produce a return value.
  62      */
  63     for (i = 0, d = 0; i < 10; i++)
  64     {
  65         d += abc[i];
  66     }
  67     return (d == 12345.0);
  68 }