Paul Eggert wrote:
> * lib/timespec.h (dtotimespec): New decl.
> * lib/dtotimespec.c, modules/dtotimespec: New files.
> ---
> ChangeLog | 4 +++
> lib/dtotimespec.c | 69
> +++++++++++++++++++++++++++++++++++++++++++++++++++
> lib/timespec.h | 2 +
> modules/dtotimespec | 25 ++++++++++++++++++
> 4 files changed, 100 insertions(+), 0 deletions(-)
> create mode 100644 lib/dtotimespec.c
> create mode 100644 modules/dtotimespec
>
> diff --git a/ChangeLog b/ChangeLog
> index 0f37252..d20588f 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,5 +1,9 @@
> 2011-06-30 Paul Eggert <egg...@cs.ucla.edu>
>
> + dtotimespec: new module
> + * lib/timespec.h (dtotimespec): New decl.
> + * lib/dtotimespec.c, modules/dtotimespec: New files.
> +
> * lib/timespec.h (timespec_sign, timespectod): New inline functions.
>
> pselect: new module
> diff --git a/lib/dtotimespec.c b/lib/dtotimespec.c
...
> +struct timespec
> +dtotimespec (double sec)
> +{
> + enum { BILLION = 1000 * 1000 * 1000 };
> + double min_representable = TYPE_MINIMUM (time_t);
> + double max_representable =
> + ((TYPE_MAXIMUM (time_t) * (double) BILLION + (BILLION - 1))
> + / BILLION);
> + struct timespec r;
Nice work.
Not surprisingly, I found no way to make it misbehave.
> + if (! (min_representable < sec))
> + {
> + r.tv_sec = TYPE_MINIMUM (time_t);
> + r.tv_nsec = 0;
> + }
> + else if (! (sec < max_representable))
> + {
> + r.tv_sec = TYPE_MAXIMUM (time_t);
> + r.tv_nsec = BILLION - 1;
> + }
> + else
> + {
> + time_t s = sec;
> + double frac = BILLION * (sec - s);
> + long ns = frac;
> + ns += ns < frac;
> + s += ns / BILLION;
> + ns %= BILLION;
> +
> + if (ns < 0)
> + {
> + s--;
> + ns += BILLION;
> + }
> +
> + r.tv_sec = s;
> + r.tv_nsec = ns;
> + }
> +
> + return r;
> +}
