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# Floating point precision checks
#
# This file contains floating point precision checks
#
# This file is released under public domain - or - in countries where this is
# not possible under the following license:
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software, to deal in the software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the software,
# and to permit persons to whom the software is furnished to do so, subject
# to no condition whatsoever.
#
# This software is provided AS IS, without warranty of any kind, express or
# implied.
# FIXME:
# This file was only built for x86 and x86_64 platforms but it does not check
# for the platform since CMake does not provide a viable variable.
include(CheckCSourceRuns)
macro(check_float_precision)
check_c_source_runs("
#include <stdio.h>
#include <string.h>
#include <fpu_control.h>
double div (double a, double b) {
fpu_control_t fpu_oldcw, fpu_cw;
volatile double result;
_FPU_GETCW(fpu_oldcw);
fpu_cw = (fpu_oldcw & ~_FPU_EXTENDED & ~_FPU_SINGLE) | _FPU_DOUBLE;
_FPU_SETCW(fpu_cw);
result = a / b;
_FPU_SETCW(fpu_oldcw);
return result;
}
int main (int argc, char **argv) {
double d = div (2877.0, 1000000.0);
char buf[255];
sprintf(buf, \"%.30f\", d);
// see if the result is actually in double precision
return strncmp(buf, \"0.00287699\", 10) == 0 ? 0 : 1;
}
" HAVE__FPU_SETCW)
endmacro(check_float_precision)
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