[PD] [epochtime] - my first external

[David Sabine]

Hello Frank,

I've implemented the changes you suggested.  Note that I make two
corrections -- "time()" produces errors, the argument must be "time( NULL )"

In any case, this isn't quite the behavior I'm looking for.  In essense,
this object now outputs a number of seconds since the patch was opened. (or
since the object was created in the patch).   In other words, it produces a
number representing "epoch" as the PD patch understand it...but I'd like to
produce "epoch" as UNIX understands it: i.e. Jan 1, 1970.

In any case, perhaps this whole project has lead me away from my original
goal - which was to create a difftime object.  Ultimately, I'd like to send
a message to an object (a list representing a date) and compare it to a
second date.  Perhaps like below:

"2002 11 20 12 24 00"   (as in Nov 20, 2002 12:24 P.M.)
-
"2002 11 19 12 24 00"  (as in 'yesterday'!)
=
86400 seconds.

This would be the same output as "difftime()" in C or C++.

It was only after some initial research that I realized that the difftime()
function actually uses "seconds since epoch" as represented by "time_t
time()" to determine the number of seconds between the two compared dates.
Hence, when I started writing the new external, I found it easier to START
with epoch (as a mental excersize and to familiarize myself with the process
of writing/creating externals).

SO, at this point, I've completed a partially useless object called
"epochtime" and I'm no closer to understanding how I could really build a
"difftime" object.  I'm currently stuck trying to understand how I'll take
the "list" in through the inlet and parse it so that it corresponds with the
"tm" structure.

Many thanks,
Dave S




----- Original Message -----
From: "Frank Barknecht" <fbar at footils.org>
To: <pd-list at iem.kug.ac.at>
Sent: Wednesday, November 20, 2002 4:41 AM
Subject: Re: [PD] [epochtime] - my first external


> Hi,
> David Sabine hat gesagt: // David Sabine wrote:
>
> > In any case, I don't think this object will be of any use to anybody
because
> > PD returns the following number: 1.03777e+009 (or something like it)
which
> > can't be used very reliably.  I mean it works, but I can't see the
seconds
> > pass -- i can only observe the passage of time every 64 seconds or so.
> > (What I mean is that the object will output the same number for about 64
> > seconds, then it outputs another number which is slightly higher.)
>
> This has to do with the exponential display of large numbers.
> Depending on what you want you could make an object with outlets for
> the 'real' time, like outlets for
> struct tm
> {
>   int tm_sec; /* Seconds. [0-60] (1 leap second) */
>   int tm_min; /* Minutes. [0-59] */
>   int tm_hour; /* Hours. [0-23] */
>   int tm_mday; /* Day. [1-31] */
>   int tm_mon; /* Month. [0-11] */
>   int tm_year; /* Year - 1900.  */
>   int tm_wday; /* Day of week. [0-6] */
>   int tm_yday; /* Days in year.[0-365] */
>   int tm_isdst; /* DST. [-1/0/1]*/
>   ...
>
> I didn't follow your problems with difftime, but I think difftime
> should work as well, if you for example would start the 'clock' at
> creation time:
>
> typedef struct _epochtime {
>   t_object  x_obj;
>   time_t t, starttime;
> } t_epochtime;
>
>
> void *epochtime_new(void)
> {
>   t_epochtime *x = (t_epochtime *)pd_new(epochtime_class);
>   x->starttime=time();
>   outlet_new(&x->x_obj, &s_float);
>
>   return (x);
> }
>
> and on a bang you'd take the current time and do a diff:
>
> x->t=time();
> outlet_float(x->x_obj.ob_outlet,
>   (t_float) (difftime(x->starttime, x->t)));
>
> This should work, but I didn't test it. I use a [bang~] and a counter
> for timing.
>
> ciao
> --
>  Frank Barknecht                               _ ______footils.org__
>
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