[PATCH 02/27] Input: Add round_towards_zero helper

[walter harms]

Hello daniel,
C99 defines FE_TOWARDZERO, so any compiler that support c99 should work
with the example below.

re,
 wh
ntl: i guess you code will work also with older compilers

#include <stdio.h>
#include <fenv.h>
#include <math.h>

/* gcc fesetround.c -lm -std=c99 */
int main()
{
  double ii;

  fesetround(FE_TOWARDZERO);

  for(ii=-2.0;ii<2.0;ii+=0.2)
       printf("%f,nextint=%f\n",ii,nearbyint(ii));

  return 0;
}



Am 03.06.2011 16:59, schrieb Daniel Stone:
> lrint() exists to round _away_ from zero, but there's no equivalent for
> rounding towards zero, aside from tediously calling fesetenv(), which
> isn't hugely portable anyway, then lround().  Great.
> 
> Signed-off-by: Daniel Stone <daniel at fooishbar.org>
> ---
>  dix/inpututils.c |    9 +++++++++
>  include/input.h  |    2 ++
>  2 files changed, 11 insertions(+), 0 deletions(-)
> 
> diff --git a/dix/inpututils.c b/dix/inpututils.c
> index 49e1758..bf8d093 100644
> --- a/dix/inpututils.c
> +++ b/dix/inpututils.c
> @@ -584,3 +584,12 @@ void verify_internal_event(const InternalEvent *ev)
>          FatalError("Wrong event type %d. Aborting server\n", ev->any.header);
>      }
>  }
> +
> +double
> +round_towards_zero(double val)
> +{
> +    if (val >= 0.0)
> +        return floor(val);
> +    else
> +        return ceil(val);
> +}
> diff --git a/include/input.h b/include/input.h
> index 56847ed..a15623a 100644
> --- a/include/input.h
> +++ b/include/input.h
> @@ -594,4 +594,6 @@ extern _X_EXPORT void valuator_mask_copy(ValuatorMask *dest,
>                                           const ValuatorMask *src);
>  extern _X_EXPORT int valuator_mask_get(const ValuatorMask *mask, int valnum);
>  
> +extern _X_EXPORT double round_towards_zero(double val);
> +
>  #endif /* INPUT_H */