/* sce2t.f -- translated by f2c (version 19980913).
   You must link the resulting object file with the libraries:
	-lf2c -lm   (in that order)
*/

#include "f2c.h"

/* $Procedure      SCE2T ( ET to discrete SCLK ticks ) */
/* Subroutine */ int sce2t_(integer *sc, doublereal *et, doublereal *sclkdp)
{
    /* System generated locals */
    integer i__1;

    /* Local variables */
    extern /* Subroutine */ int chkin_(char *, ftnlen), scet01_(integer *, 
	    doublereal *, doublereal *), sigerr_(char *, ftnlen), chkout_(
	    char *, ftnlen), setmsg_(char *, ftnlen), errint_(char *, integer 
	    *, ftnlen);
    extern integer sctype_(integer *);
    extern logical return_(void);

/* $ Abstract */

/*     Convert ephemeris seconds past J2000 (ET) to integral */
/*     encoded spacecraft clock (`ticks'). For conversion to */
/*     fractional ticks, (required for C-kernel production), see */
/*     the routine SCE2C. */

/* $ Disclaimer */

/*     THIS SOFTWARE AND ANY RELATED MATERIALS WERE CREATED BY THE */
/*     CALIFORNIA INSTITUTE OF TECHNOLOGY (CALTECH) UNDER A U.S. */
/*     GOVERNMENT CONTRACT WITH THE NATIONAL AERONAUTICS AND SPACE */
/*     ADMINISTRATION (NASA). THE SOFTWARE IS TECHNOLOGY AND SOFTWARE */
/*     PUBLICLY AVAILABLE UNDER U.S. EXPORT LAWS AND IS PROVIDED "AS-IS" */
/*     TO THE RECIPIENT WITHOUT WARRANTY OF ANY KIND, INCLUDING ANY */
/*     WARRANTIES OF PERFORMANCE OR MERCHANTABILITY OR FITNESS FOR A */
/*     PARTICULAR USE OR PURPOSE (AS SET FORTH IN UNITED STATES UCC */
/*     SECTIONS 2312-2313) OR FOR ANY PURPOSE WHATSOEVER, FOR THE */
/*     SOFTWARE AND RELATED MATERIALS, HOWEVER USED. */

/*     IN NO EVENT SHALL CALTECH, ITS JET PROPULSION LABORATORY, OR NASA */
/*     BE LIABLE FOR ANY DAMAGES AND/OR COSTS, INCLUDING, BUT NOT */
/*     LIMITED TO, INCIDENTAL OR CONSEQUENTIAL DAMAGES OF ANY KIND, */
/*     INCLUDING ECONOMIC DAMAGE OR INJURY TO PROPERTY AND LOST PROFITS, */
/*     REGARDLESS OF WHETHER CALTECH, JPL, OR NASA BE ADVISED, HAVE */
/*     REASON TO KNOW, OR, IN FACT, SHALL KNOW OF THE POSSIBILITY. */

/*     RECIPIENT BEARS ALL RISK RELATING TO QUALITY AND PERFORMANCE OF */
/*     THE SOFTWARE AND ANY RELATED MATERIALS, AND AGREES TO INDEMNIFY */
/*     CALTECH AND NASA FOR ALL THIRD-PARTY CLAIMS RESULTING FROM THE */
/*     ACTIONS OF RECIPIENT IN THE USE OF THE SOFTWARE. */

/* $ Required_Reading */

/*     SCLK */
/*     TIME */

/* $ Keywords */

/*     CONVERSION */
/*     TIME */

/* $ Declarations */
/* $ Brief_I/O */

/*     Variable  I/O  Description */
/*     --------  ---  -------------------------------------------------- */
/*     SC         I   NAIF spacecraft ID code. */
/*     ET         I   Ephemeris time, seconds past J2000. */
/*     SCLKDP     O   SCLK, encoded as ticks since spacecraft clock */
/*                    start. */

/* $ Detailed_Input */

/*     SC             is a NAIF integer code for a spacecraft whose */
/*                    encoded SCLK value at the epoch specified by ET is */
/*                    desired. */

/*     ET             is an epoch, specified as ephemeris seconds past */
/*                    J2000. */

/* $ Detailed_Output */

/*     SCLKDP         is an encoded integral spacecraft clock value. */
/*                    SCLKDP is an encoded representation of the total */
/*                    count of spacecraft clock ticks measured from the */
/*                    time the spacecraft clock started to the epoch ET: */
/*                    partition information IS reflected in the encoded */
/*                    value.  SCLKDP is rounded to the nearest integral */
/*                    double precision number. */

/* $ Parameters */

/*     None. */

/* $ Exceptions */

/*     1)  This routine assumes that that an SCLK kernel appropriate */
/*         to the spacecraft clock identified by the input argument SC */
/*         has been loaded.  If an SCLK kernel has not been loaded, */
/*         does not contain all of the required data, or contains */
/*         invalid data, error diagnoses will be performed by routines */
/*         called by this routine.  The output argument SCLKDP will not */
/*         be modified. */

/*     2)  When using SCLK kernels that map SCLK to a time system other */
/*         than ET (also called barycentric dynamical time---`TDB'), it */
/*         is necessary to have a leapseconds kernel loaded at the time */
/*         this routine is called.  If a leapseconds kernel is required */
/*         for conversion between SCLK and ET but is not loaded, the */
/*         error will be diagnosed by routines called by this routine. */
/*         The output argument SCLKDP will not be modified. */

/*         The time system that an SCLK kernel maps SCLK to is indicated */
/*         by the variable SCLK_TIME_SYSTEM_nn in the kernel, where nn */
/*         is the negative of the NAIF integer code for the spacecraft. */
/*         The time system used in a kernel is TDB if and only if the */
/*         variable is assigned the value 1. */


/*     3)  If the clock type for the spacecraft clock identified by */
/*         SC is not supported by this routine, the error */
/*         SPICE(NOTSUPPORTED) is signaled.  The output argument SCLKDP */
/*         will not be modified. */

/*     4)  If the input ET value is not representable as an encoded */
/*         spacecraft clock value for the spacecraft clock identified by */
/*         SC, the error will be diagnosed by routines called by this */
/*         routine.  The output argument SCLKDP will not be modified. */

/* $ Files */

/*     None. */

/* $ Particulars */

/*     This routine outputs discrete, encoded SCLK values.  Since */
/*     continuous SCLK values are generally more useful, the newer */
/*     routine SCE2C (ET to continuous ticks) should normally be used */
/*     in place of this one.  However, the functionality of this */
/*     routine is needed for converting ET to SCLK strings, and the */
/*     routine SCE2S calls this routine for that purpose. */

/*     The advantage of encoded SCLK, as opposed to character string */
/*     representations of SCLK, is that encoded SCLK values are easy to */
/*     perform arithmetic operations on.  Also, working with encoded SCLK */
/*     reduces the overhead of repeated conversion of  character strings */
/*     to integers or double precision numbers. */

/*     To convert ET to a string representation of an SCLK value, use */
/*     the SPICELIB routine SCE2S. */

/*     See the SCLK Required Reading for a list of the entire set of */
/*     SCLK conversion routines. */

/* $ Examples */

/*     1)  Convert ET directly to an encoded SCLK value; use both of */
/*         these time values to look up both C-kernel (pointing) and */
/*         SPK (position and velocity) data for an epoch specified by an */
/*         ephemeris time. */

/*            During program initialization, load the leapseconds and */
/*            SCLK kernels.  We will pretend that these files are named */
/*            "LEAPSECONDS.KER" and "GLLSCLK.KER".  To use this code */
/*            fragment, you must substitute the actual names of these */
/*            kernel files for the names used here. */

/*               C */
/*               C     Load leapseconds and SCLK kernels: */
/*               C */
/*                     CALL FURNSH ( 'LEAPSECONDS.KER' ) */
/*                     CALL FURNSH ( 'GLLSCLK.KER'     ) */

/*            The mission is Galileo, which has spacecraft ID -77. */
/*            Let ET be the epoch, specified in ephemeris seconds */
/*            past J2000, at which both position and pointing data */
/*            is desired. */

/*            Find the encoded SCLK value corresponding to ET. */

/*                     CALL SCE2T  ( -77,  ET,  SCLKDP ) */

/*            Now you're ready to call both CKGP, which expects the input */
/*            epoch to be specified by an encoded SCLK string, and */
/*            SPKEZ, which expects the epoch to be specified as an */
/*            ephemeris time. */

/*               C */
/*               C     Find scan platform pointing CMAT and s/c--target */
/*               C     vector (first 3 components of STATE) at epoch. */
/*               C     We assume that CK and SPK kernels have been loaded */
/*               C     already, via CKLPF and SPKLEF respectively. */
/*               C */
/*                     CALL CKGP  ( SCANPL, */
/*                    .             SCLKDP, */
/*                    .             TOL, */
/*                    .             REFSYS, */
/*                    .             CMAT, */
/*                    .             CLKOUT, */
/*                    .             FOUND   ) */

/*                     CALL SPKEZ ( TARGET, */
/*                    .             ET, */
/*                    .             REFSYS, */
/*                    .             CORR, */
/*                    .             -77, */
/*                    .             STATE, */
/*                    .             LT      ) */


/*     2)  Convert UTC to an encoded Voyager 2 SCLK value. */

/*            Again, your initialization code must load the leapseconds */
/*            and SCLK kernels. */

/*               C */
/*               C     Load leapseconds and SCLK kernels: */
/*               C */
/*                     CALL FURNSH ( 'LEAPSECONDS.KER' ) */
/*                     CALL FURNSH ( 'VGR2SCLK.KER'    ) */


/*            To find the encoded Voyager 2 SCLK value SCLKDP */
/*            corresponding to a UTC time, you can use the code fragment */

/*                     CALL UTC2ET ( UTC,  ET          ) */
/*                     CALL SCE2T  ( -32,  ET,  SCLKDP ) */

/* $ Restrictions */

/*     1)  An SCLK kernel appropriate to the spacecraft clock identified */
/*         by SC must be loaded at the time this routine is called. */

/*     2)  If the SCLK kernel used with this routine does not map SCLK */
/*         directly to barycentric dynamical time, a leapseconds kernel */
/*         must be loaded at the time this routine is called. */

/* $ Literature_References */

/*     [1]  CK Required Reading */

/*     [2]  SPK Required Reading */

/* $ Author_and_Institution */

/*     N.J. Bachman   (JPL) */

/* $ Version */

/* -    SPICELIB Version 1.0.4, 27-JAN-2004 (NJB) */

/*        Header was updated to remove comments indicating this routine */
/*        was deprecated.  Minor changes were made to clarify both the */
/*        functionality of this routine and the difference between */
/*        this routine and SCE2C.  Examples were updated to use FURNSH. */

/* -    SPICELIB Version 1.0.3, 09-MAR-1999 (NJB) */

/*        Updated to reflect the introduction of continuous ticks and */
/*        the routine SCE2C. */

/* -    SPICELIB Version 1.0.2, 10-APR-1992 (NJB) (WLT) */

/*        Header was updated to reflect possibility of needing to load */
/*        a leapseconds kernel before calling this routine.  Comment */
/*        section for permuted index source lines was added following the */
/*        header. */

/* -    SPICELIB Version 1.0.1, 12-OCT-1990 (NJB) */

/*        Restrictions section no longer states that you must load the */
/*        leapseconds kernel prior to calling this routine. */

/*        The examples have been slightly re-written. */

/* -    SPICELIB Version 1.0.0, 03-SEP-1990 (NJB) */

/* -& */
/* $ Index_Entries */

/*     ephemeris time to spacecraft_clock ticks */

/* -& */
/* $ Revisions */

/* -    SPICELIB Version 1.0.1, 12-OCT-1990 (NJB) */

/*        Restrictions section no longer states that you must load the */
/*        leapseconds kernel prior to calling this routine. */

/*        The examples have been slightly re-written.  In particular, */
/*        they no longer use calls to CLPOOL. */

/* -& */

/*     SPICELIB functions */


/*     Standard SPICE error handling. */

    if (return_()) {
	return 0;
    } else {
	chkin_("SCE2T", (ftnlen)5);
    }

/*     Just hand off the conversion to the appropriate routine. */

    if (sctype_(sc) == 1) {
	scet01_(sc, et, sclkdp);
    } else {
	setmsg_("Clock type # is not supported.", (ftnlen)30);
	i__1 = sctype_(sc);
	errint_("#", &i__1, (ftnlen)1);
	sigerr_("SPICE(NOTSUPPORTED)", (ftnlen)19);
	chkout_("SCE2T", (ftnlen)5);
	return 0;
    }
    chkout_("SCE2T", (ftnlen)5);
    return 0;
} /* sce2t_ */

