/**********
Copyright 1990 Regents of the University of California.  All rights reserved.
Author: 1985 Thomas L. Quarles
Modified: 2000  AlansFixes
Modified: 2023 XSPICE breakpoint fix for shared ngspice by Vyacheslav Shevchuk
**********/

/* subroutine to do DC TRANSIENT analysis
        --- ONLY, unlike spice2 routine with the same name! */

#include "ngspice/ngspice.h"
#include "ngspice/cktdefs.h"
#include "cktaccept.h"
#include "ngspice/trandefs.h"
#include "ngspice/sperror.h"
#include "ngspice/fteext.h"
#include "ngspice/missing_math.h"

/* for setting breakpoints required by dbs data base */
extern struct dbcomm *dbs;
#include "ngspice/ftedebug.h"

#ifdef XSPICE
/* gtri - add - wbk - Add headers */
#include "ngspice/miftypes.h"

#include "ngspice/evt.h"
#include "ngspice/enh.h"
#include "ngspice/mif.h"
#include "ngspice/evtproto.h"
#include "ngspice/ipctiein.h"
/* gtri - end - wbk - Add headers */
#endif

#ifdef CLUSTER
#include "ngspice/cluster.h"
#endif

#ifdef SHARED_MODULE
extern int add_bkpt(void);
extern int sharedsync(double*, double*, double, double, double, int, int*, int);
extern int ng_ident;      /* for debugging */
#endif

#define INIT_STATS() \
do { \
    startTime = SPfrontEnd->IFseconds();        \
    startIters = ckt->CKTstat->STATnumIter;     \
    startdTime = ckt->CKTstat->STATdecompTime;  \
    startsTime = ckt->CKTstat->STATsolveTime;   \
    startlTime = ckt->CKTstat->STATloadTime;    \
    startkTime = ckt->CKTstat->STATsyncTime;    \
} while(0)

#define UPDATE_STATS(analysis) \
do { \
    ckt->CKTcurrentAnalysis = analysis; \
    ckt->CKTstat->STATtranTime += SPfrontEnd->IFseconds() - startTime; \
    ckt->CKTstat->STATtranIter += ckt->CKTstat->STATnumIter - startIters; \
    ckt->CKTstat->STATtranDecompTime += ckt->CKTstat->STATdecompTime - startdTime; \
    ckt->CKTstat->STATtranSolveTime += ckt->CKTstat->STATsolveTime - startsTime; \
    ckt->CKTstat->STATtranLoadTime += ckt->CKTstat->STATloadTime - startlTime; \
    ckt->CKTstat->STATtranSyncTime += ckt->CKTstat->STATsyncTime - startkTime; \
} while(0)


int
DCtran(CKTcircuit *ckt,
       int restart)   /* forced restart flag */
{
    TRANan *job = (TRANan *) ckt->CKTcurJob;

    int i;
    double olddelta;
    double delta;
    double newdelta;
    double *temp;
    double startdTime;
    double startsTime;
    double startlTime;
    double startkTime;
    double startTime;
    int startIters;
    int converged;
    int firsttime;
    int error;
#ifdef WANT_SENSE2
    int save, save2, size;
    long save1;
#endif
    int save_order;
    long save_mode;
    IFuid timeUid;
    IFuid *nameList;
    int numNames;
    double maxstepsize = 0.0;

    bool have_autostop = FALSE, flag_autostop = FALSE;

    int ltra_num;
    CKTnode *node;
#ifdef XSPICE
/* gtri - add - wbk - 12/19/90 - Add IPC stuff */
    Ipc_Boolean_t  ipc_firsttime = IPC_TRUE;
    Ipc_Boolean_t  ipc_secondtime = IPC_FALSE;
    Ipc_Boolean_t  ipc_delta_cut = IPC_FALSE;
    double         ipc_last_time = 0.0;
    double         ipc_last_delta = 0.0;
/* gtri - end - wbk - 12/19/90 - Add IPC stuff */

    // Fix for sharedsync olddelta: When DCTran processes
    // either analog or XSPICE breakpoint, then it subtracts delta from
    // ckt->CKTtime. It sends 0 as olddelta after analog breakpoint
    // processing. Still, for XSPICE breakpoints it subtracts delta (see code
    // 'else if(g_mif_info.breakpoint.current < ckt->CKTtime)' branch) and
    // then sends non zero olddelta to sharedsync at the end of the function
    // (see chkStep: label). Thus olddelta is subtracted twice. Then
    // ckt->CKTtime becomes less than last_accepted_time.
    // xspice_breakpoints_processed 0:
    // XSPICE models didn't have breakpoints in [last_accepted_time, CKTtime].
    // xspice_breakpoints_processed 1:
    // convergence criteria are satisfied but XSPICE breakpoint(s) is in the
    // time interval [last_accepted_time, CKTtime].
    int xspice_breakpoints_processed = 0;

#ifdef SHARED_MODULE
    double olddelta_for_shared_sync = 0.0;
#endif // SHARED_MODULE
#endif
#if defined CLUSTER || defined SHARED_MODULE
    int redostep;
#endif
    if(restart || ckt->CKTtime == 0) {
        delta=MIN(ckt->CKTfinalTime/100,ckt->CKTstep)/10;

#ifdef STEPDEBUG
        printf("delta = %g    finalTime/100: %g    CKTstep: %g\n",delta,ckt->CKTfinalTime/100,ckt->CKTstep);
#endif
        /* begin LTRA code addition */
        if (ckt->CKTtimePoints != NULL)
            FREE(ckt->CKTtimePoints);

        if (ckt->CKTstep >= ckt->CKTmaxStep)
            maxstepsize = ckt->CKTstep;
        else
            maxstepsize = ckt->CKTmaxStep;

        ckt->CKTsizeIncr = 100;
        ckt->CKTtimeIndex = -1; /* before the DC soln has been stored */
        ckt->CKTtimeListSize = (int) ceil( ckt->CKTfinalTime / maxstepsize );
        ltra_num = CKTtypelook("LTRA");
        if (ltra_num >= 0 && ckt->CKThead[ltra_num] != NULL)
            ckt->CKTtimePoints = TMALLOC(double, ckt->CKTtimeListSize);
        /* end LTRA code addition */

        if(ckt->CKTbreaks) FREE(ckt->CKTbreaks);
        ckt->CKTbreaks = TMALLOC(double, 2);
        if(ckt->CKTbreaks == NULL) return(E_NOMEM);
        ckt->CKTbreaks[0] = 0;
        ckt->CKTbreaks[1] = ckt->CKTfinalTime;
        ckt->CKTbreakSize = 2;

#ifdef SHARED_MODULE
        add_bkpt();
#endif

#ifdef XSPICE
/* gtri - begin - wbk - 12/19/90 - Modify setting of CKTminBreak */
        /* Set to 10 times delmin for ATESSE 1 compatibity */
        if(ckt->CKTminBreak==0) ckt->CKTminBreak = 10.0 * ckt->CKTdelmin;
/* gtri - end - wbk - 12/19/90 - Modify setting of CKTminBreak */
#else
        if(ckt->CKTminBreak==0) ckt->CKTminBreak=ckt->CKTmaxStep*5e-5;
#endif

#ifdef XSPICE
/* gtri - add - wbk - 12/19/90 - Add IPC stuff and set anal_init and anal_type */
        /* Tell the beginPlot routine what mode we're in */
        g_ipc.anal_type = IPC_ANAL_TRAN;

        /* Tell the code models what mode we're in */
        g_mif_info.circuit.anal_type = MIF_DC;

        g_mif_info.circuit.anal_init = MIF_TRUE;
/* gtri - end - wbk */
#endif
        error = CKTnames(ckt,&numNames,&nameList);
        if(error) return(error);
        SPfrontEnd->IFnewUid (ckt, &timeUid, NULL, "time", UID_OTHER, NULL);
        error = SPfrontEnd->OUTpBeginPlot (ckt, ckt->CKTcurJob,
                                           ckt->CKTcurJob->JOBname,
                                           timeUid, IF_REAL,
                                           numNames, nameList, IF_REAL,
                                           &(job->TRANplot));
        tfree(nameList);
        if(error) return(error);

        /* initialize CKTsoaCheck `warn' counters */
        if (ckt->CKTsoaCheck)
            error = CKTsoaInit();

        ckt->CKTtime = 0;
        ckt->CKTdelta = 0;
        ckt->CKTbreak = 1;
        firsttime = 1;
        save_mode = (ckt->CKTmode&MODEUIC) | MODETRANOP | MODEINITJCT;
        save_order = ckt->CKTorder;

        have_autostop = cp_getvar("autostop", CP_BOOL, NULL, 0);

/* Add breakpoints here which have been requested by the user setting the
   stop command as 'stop when time = xx'.
   Get data from the global dbs data base.
*/
        if (dbs) {
            struct dbcomm *d;
            for (d = dbs; d; d = d->db_next)
                if ((d->db_type == DB_STOPWHEN) && cieq(d->db_nodename1,"time")
                    && (d->db_value2 > 0)) {
                    CKTsetBreak(ckt, d->db_value2);
                    if (ft_ngdebug)
                        printf("breakpoint set to time = %g\n", d->db_value2);
                }
        }

#ifdef XSPICE
/* gtri - begin - wbk - set a breakpoint at end of supply ramping time */
        /* must do this after CKTtime set to 0 above */
        if(ckt->enh->ramp.ramptime > 0.0)
            CKTsetBreak(ckt, ckt->enh->ramp.ramptime);
/* gtri - end - wbk - set a breakpoint at end of supply ramping time */

/* gtri - begin - wbk - Call EVTop if event-driven instances exist */
        if(ckt->evt->counts.num_insts != 0) {
            /* use new DCOP algorithm */
            converged = EVTop(ckt,
                        (ckt->CKTmode & MODEUIC) | MODETRANOP | MODEINITJCT,
                        (ckt->CKTmode & MODEUIC) | MODETRANOP | MODEINITFLOAT,
                        ckt->CKTdcMaxIter,
                        MIF_TRUE);
            EVTdump(ckt, IPC_ANAL_DCOP, 0.0);

            EVTop_save(ckt, MIF_FALSE, 0.0);

/* gtri - end - wbk - Call EVTop if event-driven instances exist */
        } else
#endif
            converged = CKTop(ckt,
                (ckt->CKTmode & MODEUIC) | MODETRANOP | MODEINITJCT,
                (ckt->CKTmode & MODEUIC) | MODETRANOP | MODEINITFLOAT,
                ckt->CKTdcMaxIter);

        if(converged != 0) {
            fprintf(stdout,"\nTransient solution failed -\n");
            CKTncDump(ckt);
            fprintf(stdout,"\n");
            fflush(stdout);
        } else if (ckt->CKTmode & MODEUIC && !ft_ngdebug) {
            fprintf(stdout,"Operating point simulation skipped by 'uic',\n");
            fprintf(stdout,"  now using transient initial conditions.\n");
            fflush(stdout);
        } else if (!ft_noacctprint && !ft_noinitprint) {
            fprintf(stdout,"\nInitial Transient Solution\n");
            fprintf(stdout,"--------------------------\n\n");
            fprintf(stdout,"%-30s %15s\n", "Node", "Voltage");
            fprintf(stdout,"%-30s %15s\n", "----", "-------");
            for(node=ckt->CKTnodes->next;node;node=node->next) {
                if (strstr(node->name, "#branch") || !strchr(node->name, '#'))
                    fprintf(stdout,"%-30s %15g\n", node->name,
                                              ckt->CKTrhsOld[node->number]);
            }
            fprintf(stdout,"\n");
            fflush(stdout);
        }

        if (converged != 0) {
            SPfrontEnd->OUTendPlot(job->TRANplot);
            return(converged);
        }
#ifdef XSPICE
/* gtri - add - wbk - 12/19/90 - Add IPC stuff */

        /* Send the operating point results for Mspice compatibility */
        if(g_ipc.enabled) {
            ipc_send_dcop_prefix();
            CKTdump(ckt, 0.0, job->TRANplot);
            ipc_send_dcop_suffix();
        }

/* gtri - end - wbk */

/* gtri - add - wbk - 12/19/90 - set anal_init and anal_type */

        g_mif_info.circuit.anal_init = MIF_TRUE;

        /* Tell the code models what mode we're in */
        g_mif_info.circuit.anal_type = MIF_TRAN;

/* gtri - end - wbk */

/* gtri - begin - wbk - Add Breakpoint stuff */

        /* Initialize the temporary breakpoint variables to infinity */
        g_mif_info.breakpoint.current = 1.0e30;
        g_mif_info.breakpoint.last    = 1.0e30;

/* gtri - end - wbk - Add Breakpoint stuff */
#endif
        ckt->CKTstat->STATtimePts ++;
        ckt->CKTorder = 1;
        for(i=0;i<7;i++) {
            ckt->CKTdeltaOld[i]=ckt->CKTmaxStep;
        }
        ckt->CKTdelta = delta;
#ifdef STEPDEBUG
        (void)printf("delta initialized to %g\n",ckt->CKTdelta);
#endif
        ckt->CKTsaveDelta = ckt->CKTfinalTime/50;

#ifdef WANT_SENSE2
        if(ckt->CKTsenInfo && (ckt->CKTsenInfo->SENmode & TRANSEN)){
#ifdef SENSDEBUG
            printf("\nTransient Sensitivity Results\n\n");
            CKTsenPrint(ckt);
#endif /* SENSDEBUG */
            save = ckt->CKTsenInfo->SENmode;
            ckt->CKTsenInfo->SENmode = TRANSEN;
            save1 = ckt->CKTmode;
            save2 = ckt->CKTorder;
            ckt->CKTmode = save_mode;
            ckt->CKTorder = save_order;
            error = CKTsenDCtran(ckt);
            if (error)
                return(error);

            ckt->CKTmode = save1;
            ckt->CKTorder = save2;
        }
#endif

        ckt->CKTmode = (ckt->CKTmode&MODEUIC) | MODETRAN | MODEINITTRAN;
        /* modeinittran set here */
        ckt->CKTag[0]=ckt->CKTag[1]=0;
        if (ckt->CKTstate1 && ckt->CKTstate0) {
            memcpy(ckt->CKTstate1, ckt->CKTstate0,
                  (size_t) ckt->CKTnumStates * sizeof(double));
        }

#ifdef WANT_SENSE2
        if(ckt->CKTsenInfo && (ckt->CKTsenInfo->SENmode & TRANSEN)){
            size = SMPmatSize(ckt->CKTmatrix);
            for(i = 1; i<=size ; i++)
                ckt->CKTrhsOp[i] = ckt->CKTrhsOld[i];
        }
#endif

        INIT_STATS();
#ifdef CLUSTER
        CLUsetup(ckt);
#endif
    } else {
        /* saj As traninit resets CKTmode */
        ckt->CKTmode = (ckt->CKTmode&MODEUIC) | MODETRAN | MODEINITPRED;
        /* saj */
        INIT_STATS();
        if(ckt->CKTminBreak==0) ckt->CKTminBreak=ckt->CKTmaxStep*5e-5;
        firsttime=0;
        /* To get rawfile working saj*/
        error = SPfrontEnd->OUTpBeginPlot (NULL, NULL,
                                           NULL,
                                           NULL, 0,
                                           666, NULL, 666,
                                           &(job->TRANplot));
        if(error) {
            fprintf(stderr, "Couldn't relink rawfile\n");
            return error;
        }
        /* end saj*/
        goto resume;
    }

/* 650 */
    nextTime:

    /* begin LTRA code addition */
    if (ckt->CKTtimePoints) {
    ckt->CKTtimeIndex++;
        if (ckt->CKTtimeIndex >= ckt->CKTtimeListSize) {
            /* need more space */
            int need;
            need = (int) ceil( (ckt->CKTfinalTime - ckt->CKTtime) / maxstepsize );
            if (need < ckt->CKTsizeIncr)
                need = ckt->CKTsizeIncr;
            ckt->CKTtimeListSize += need;
            ckt->CKTtimePoints = TREALLOC(double, ckt->CKTtimePoints, ckt->CKTtimeListSize);
            ckt->CKTsizeIncr = (int) ceil(1.4 * ckt->CKTsizeIncr);
        }
        ckt->CKTtimePoints[ckt->CKTtimeIndex] = ckt->CKTtime;
    }
    /* end LTRA code addition */

    error = CKTaccept(ckt);
    /* check if current breakpoint is outdated; if so, clear */
    if (ckt->CKTtime > ckt->CKTbreaks[0]) CKTclrBreak(ckt);

    if (ckt->CKTsoaCheck)
        error = CKTsoaCheck(ckt);

    /*
 * Breakpoint handling scheme:
 * When a timepoint t is accepted (by CKTaccept), clear all previous
 * breakpoints, because they will never be needed again.
 *
 * t may itself be a breakpoint, or indistinguishably close. DON'T
 * clear t itself; recognise it as a breakpoint and act accordingly
 *
 * if t is not a breakpoint, limit the timestep so that the next
 * breakpoint is not crossed
 */

#ifdef STEPDEBUG
    printf("Delta %g accepted at time %g (finaltime: %g)\n",ckt->CKTdelta,ckt->CKTtime,ckt->CKTfinalTime);
    fflush(stdout);
#endif /* STEPDEBUG */
    ckt->CKTstat->STATaccepted ++;
    ckt->CKTbreak = 0;
    /* XXX Error will cause single process to bail. */
    if(error)  {
        UPDATE_STATS(DOING_TRAN);
        return(error);
    }
#ifdef XSPICE
/* gtri - modify - wbk - 12/19/90 - Send IPC stuff */

    if ((g_ipc.enabled) || wantevtdata) {

        /* Send event-driven results */
        EVTdump(ckt, IPC_ANAL_TRAN, 0.0);

        /* Then follow with analog results... */

        /* Test to see if delta was cut by a breakpoint, */
        /* a non-convergence, or a too large truncation error */
        if(ipc_firsttime)
            ipc_delta_cut = IPC_FALSE;
        else if(ckt->CKTtime < (ipc_last_time + (0.999 * ipc_last_delta)))
            ipc_delta_cut = IPC_TRUE;
        else
            ipc_delta_cut = IPC_FALSE;

        /* Record the data required to check for delta cuts */
        ipc_last_time = ckt->CKTtime;
        ipc_last_delta = MIN(ckt->CKTdelta, ckt->CKTmaxStep);

        /* Send results data if time since last dump is greater */
        /* than 'mintime', or if first or second timepoints, */
        /* or if delta was cut */
        if( (ckt->CKTtime >= (g_ipc.mintime + g_ipc.last_time)) ||
            ipc_firsttime || ipc_secondtime || ipc_delta_cut ) {

            if (wantevtdata)
                CKTdump(ckt, ckt->CKTtime, job->TRANplot);
            else {
                ipc_send_data_prefix(ckt->CKTtime);
                CKTdump(ckt, ckt->CKTtime, job->TRANplot);
                ipc_send_data_suffix();
            }

            if(ipc_firsttime) {
                ipc_firsttime = IPC_FALSE;
                ipc_secondtime = IPC_TRUE;
            } else if(ipc_secondtime) {
                ipc_secondtime = IPC_FALSE;
            }

            g_ipc.last_time = ckt->CKTtime;
        }
    } else
/* gtri - modify - wbk - 12/19/90 - Send IPC stuff */
#endif
#ifdef CLUSTER
        CLUoutput(ckt);
#endif
        if((ckt->CKTmode&MODEUIC && ckt->CKTtime > 0 && ckt->CKTtime >= ckt->CKTinitTime) 
                || (!(ckt->CKTmode&MODEUIC) && ckt->CKTtime >= ckt->CKTinitTime))
            CKTdump(ckt, ckt->CKTtime, job->TRANplot);
#ifdef XSPICE
/* gtri - begin - wbk - Update event queues/data for accepted timepoint */
    /* Note: this must be done AFTER sending results to SI so it can't */
    /* go next to CKTaccept() above */
    if(ckt->evt->counts.num_insts > 0)
        EVTaccept(ckt, ckt->CKTtime);
/* gtri - end - wbk - Update event queues/data for accepted timepoint */
#endif
    ckt->CKTstat->STAToldIter = ckt->CKTstat->STATnumIter;
    /* check for the end of the tran simulation, either by< stop time given,
       or final time has been reached. */
    if (have_autostop)
    /* time consuming autostop check only, when variable 'autostop' has been set
       before tran is started.*/
        flag_autostop = check_autostop("tran");
    /* If CKTtime and CKTfinalTime are almost equal, then finish */
    if (flag_autostop || AlmostEqualUlps(ckt->CKTtime, ckt->CKTfinalTime, 100)) {
#ifdef STEPDEBUG
        printf(" done:  time is %g, final time is %g, and tol is %g\n",
        ckt->CKTtime, ckt->CKTfinalTime, ckt->CKTminBreak);
#endif
        SPfrontEnd->OUTendPlot (job->TRANplot);
        job->TRANplot = NULL;
        UPDATE_STATS(0);
#ifdef WANT_SENSE2
        if(ckt->CKTsenInfo && (ckt->CKTsenInfo->SENmode & TRANSEN)){
            ckt->CKTsenInfo->SENmode = save;
        }
#endif
        if (flag_autostop)
            fprintf(stdout, "\nNote: Autostop after %e s, all measurement conditions are fulfilled.\n", ckt->CKTtime);

        /* Final return from tran*/
        return(OK);
    }
    if(SPfrontEnd->IFpauseTest()) {
        /* user requested pause... */
        UPDATE_STATS(DOING_TRAN);
        return(E_PAUSE);
    }
resume:
#ifdef STEPDEBUG
    if( (ckt->CKTdelta <= ckt->CKTfinalTime/50) &&
        (ckt->CKTdelta <= ckt->CKTmaxStep)) {
        ;
    } else {
        if(ckt->CKTfinalTime/50<ckt->CKTmaxStep) {
            (void)printf("limited by Tstop/50\n");
        } else {
            (void)printf("limited by Tmax == %g\n",ckt->CKTmaxStep);
        }
    }
#endif
#ifdef HAS_PROGREP
    if (ckt->CKTtime == 0.)
        SetAnalyse( "tran init", 0);
    else
        SetAnalyse( "tran", (int)((ckt->CKTtime * 1000.) / ckt->CKTfinalTime + 0.5));
#endif
    ckt->CKTdelta =
            MIN(ckt->CKTdelta,ckt->CKTmaxStep);
#ifdef XSPICE
/* gtri - begin - wbk - Cut integration order if first timepoint after breakpoint */
    /* if(ckt->CKTtime == g_mif_info.breakpoint.last) */
    if ( AlmostEqualUlps( ckt->CKTtime, g_mif_info.breakpoint.last, 100 ) )
        ckt->CKTorder = 1;
/* gtri - end   - wbk - Cut integration order if first timepoint after breakpoint */

#endif

  /* are we at a breakpoint, or indistinguishably close? */
    /* if ((ckt->CKTtime == ckt->CKTbreaks[0]) || (ckt->CKTbreaks[0] - */
    if ( AlmostEqualUlps( ckt->CKTtime, ckt->CKTbreaks[0], 100 ) ||
         ckt->CKTbreaks[0] - ckt->CKTtime <= ckt->CKTdelmin) {
        /* first timepoint after a breakpoint - cut integration order */
        /* and limit timestep to .1 times minimum of time to next breakpoint,
         * and previous timestep
         */
        ckt->CKTorder = 1;
#ifdef STEPDEBUG
        if( (ckt->CKTdelta > .1*ckt->CKTsaveDelta) ||
            (ckt->CKTdelta > .1*(ckt->CKTbreaks[1] - ckt->CKTbreaks[0])) ) {
            if(ckt->CKTsaveDelta < (ckt->CKTbreaks[1] - ckt->CKTbreaks[0]))  {
                (void)printf("limited by pre-breakpoint delta (saveDelta: %g, nxt_breakpt: %g, curr_breakpt: %g\n",
                  ckt->CKTsaveDelta, ckt->CKTbreaks[1], ckt->CKTbreaks[0]);
            } else {
                (void)printf("limited by next breakpoint\n");
            }
        }
#endif

        ckt->CKTdelta = MIN(ckt->CKTdelta, .1 * MIN(ckt->CKTsaveDelta,
            ckt->CKTbreaks[1] - ckt->CKTbreaks[0]));

        if(firsttime) {
            /* set a breakpoint to reduce ringing of current in devices */
            if (ckt->CKTmode & MODEUIC)
                CKTsetBreak(ckt, ckt->CKTstep);

            ckt->CKTdelta /= 10;
#ifdef STEPDEBUG
            (void)printf("delta cut for initial timepoint\n");
#endif
        }

#ifndef XSPICE
        /* don't want to get below delmin for no reason */
        ckt->CKTdelta = MAX(ckt->CKTdelta, ckt->CKTdelmin*2.0);
#endif

    }

#ifndef XSPICE
    else if(ckt->CKTtime + ckt->CKTdelta >= ckt->CKTbreaks[0]) {
        ckt->CKTsaveDelta = ckt->CKTdelta;
        ckt->CKTdelta = ckt->CKTbreaks[0] - ckt->CKTtime;
#ifdef STEPDEBUG
        (void)printf("delta cut to %g to hit breakpoint\n",ckt->CKTdelta);
        fflush(stdout);
#endif
        ckt->CKTbreak = 1; /* why? the current pt. is not a bkpt. */
    }
#endif /* !XSPICE */


#ifdef XSPICE
/* gtri - begin - wbk - Add Breakpoint stuff */

    if(ckt->CKTtime + ckt->CKTdelta >= g_mif_info.breakpoint.current) {
        /* If next time > temporary breakpoint, force it to the breakpoint */
        /* And mark that timestep was set by temporary breakpoint */
        ckt->CKTsaveDelta = ckt->CKTdelta;
        ckt->CKTdelta = g_mif_info.breakpoint.current - ckt->CKTtime;
        g_mif_info.breakpoint.last = ckt->CKTtime + ckt->CKTdelta;
    } else {
        /* Else, mark that timestep was not set by temporary breakpoint */
        g_mif_info.breakpoint.last = 1.0e30;
    }

/* gtri - end - wbk - Add Breakpoint stuff */

/* gtri - begin - wbk - Modify Breakpoint stuff */
    /* Throw out any permanent breakpoint with time <= current time or in the
     * very near future, unless it the final stop break.
     */
#ifdef STEPDEBUG
    printf("    brk_pt: %g    ckt_time: %g    ckt_min_break: %g\n",
           ckt->CKTbreaks[0], ckt->CKTtime, ckt->CKTminBreak);
#endif
    while ((ckt->CKTbreaks[0] <= ckt->CKTtime + ckt->CKTminBreak ||
            AlmostEqualUlps(ckt->CKTbreaks[0], ckt->CKTtime, 100)) &&
           ckt->CKTbreaks[0] < ckt->CKTfinalTime) {
#ifdef STEPDEBUG
        printf("throwing out permanent breakpoint times <= current time "
               "(brk pt: %g)\n",
               ckt->CKTbreaks[0]);
        printf("    ckt_time: %g    ckt_min_break: %g\n",
               ckt->CKTtime, ckt->CKTminBreak);
#endif
        CKTclrBreak(ckt);
    }
    /* Force the breakpoint if appropriate */
    if(ckt->CKTtime + ckt->CKTdelta > ckt->CKTbreaks[0]) {
        ckt->CKTbreak = 1;
        ckt->CKTsaveDelta = ckt->CKTdelta;
        ckt->CKTdelta = ckt->CKTbreaks[0] - ckt->CKTtime;
    }

/* gtri - end - wbk - Modify Breakpoint stuff */

#ifdef SHARED_MODULE
        /* Either directly go to next time step, or modify ckt->CKTdelta depending on
           synchronization requirements. sharedsync() returns 0. */
    sharedsync(&ckt->CKTtime, &ckt->CKTdelta, 0, ckt->CKTfinalTime,
        ckt->CKTdelmin, 0, &ckt->CKTstat->STATrejected, 0);
#endif

/* gtri - begin - wbk - Do event solution */

    if(ckt->evt->counts.num_insts > 0) {

        /* if time = 0 and op_alternate was specified as false during */
        /* dcop analysis, call any changed instances to let them */
        /* post their outputs with their associated delays */
        if((ckt->CKTtime == 0.0) && (! ckt->evt->options.op_alternate))
            EVTiter(ckt);

        /* while there are events on the queue with event time <= next */
        /* projected analog time, process them */
        while((g_mif_info.circuit.evt_step = EVTnext_time(ckt))
               <= (ckt->CKTtime + ckt->CKTdelta)) {

            /* Initialize temp analog bkpt to infinity */
            g_mif_info.breakpoint.current = 1e30;

            /* Pull items off queue and process them */
            EVTdequeue(ckt, g_mif_info.circuit.evt_step);
            EVTiter(ckt);

            /* If any instances have forced an earlier */
            /* next analog time, cut the delta */
            if(ckt->CKTbreaks[0] < g_mif_info.breakpoint.current)
                if(ckt->CKTbreaks[0] > ckt->CKTtime + ckt->CKTminBreak)
                    g_mif_info.breakpoint.current = ckt->CKTbreaks[0];
            if(g_mif_info.breakpoint.current < ckt->CKTtime + ckt->CKTdelta) {
                /* Breakpoint must be > last accepted timepoint */
                /* and >= current event time */
                if(g_mif_info.breakpoint.current >  ckt->CKTtime + ckt->CKTminBreak  &&
                   g_mif_info.breakpoint.current >= g_mif_info.circuit.evt_step) {
                    ckt->CKTsaveDelta = ckt->CKTdelta;
                    ckt->CKTdelta = g_mif_info.breakpoint.current - ckt->CKTtime;
                    g_mif_info.breakpoint.last = ckt->CKTtime + ckt->CKTdelta;
                }
            }

        } /* end while next event time <= next analog time */
    } /* end if there are event instances */

/* gtri - end - wbk - Do event solution */
#else /* no XSPICE */

#ifdef CLUSTER
    if(!CLUsync(ckt->CKTtime,&ckt->CKTdelta,0)) {
      printf("Sync error!\n");
      exit(0);
    }
#endif /* CLUSTER */

#ifdef SHARED_MODULE
    /* Either directly go to next time step, or modify ckt->CKTdelta depending on
       synchronization requirements. sharedsync() returns 0.
    */
    sharedsync(&ckt->CKTtime, &ckt->CKTdelta, 0, ckt->CKTfinalTime,
        ckt->CKTdelmin, 0, &ckt->CKTstat->STATrejected, 0);
#endif

#endif  /* no XSPICE */
    for(i=5; i>=0; i--)
        ckt->CKTdeltaOld[i+1] = ckt->CKTdeltaOld[i];
    ckt->CKTdeltaOld[0] = ckt->CKTdelta;

    temp = ckt->CKTstates[ckt->CKTmaxOrder+1];
    for(i=ckt->CKTmaxOrder;i>=0;i--) {
        ckt->CKTstates[i+1] = ckt->CKTstates[i];
    }
    ckt->CKTstates[0] = temp;

/* 600 */
    for (;;) {
#if defined CLUSTER || defined SHARED_MODULE
        redostep = 1;
#endif
#ifdef XSPICE
/* gtri - add - wbk - 4/17/91 - Fix Berkeley bug */
/* This is needed here to allow CAPask to output currents */
/* during Transient analysis.  A grep for CKTcurrentAnalysis */
/* indicates that it should not hurt anything else ... */

        ckt->CKTcurrentAnalysis = DOING_TRAN;

/* gtri - end - wbk - 4/17/91 - Fix Berkeley bug */
        xspice_breakpoints_processed = 0;
#endif
        olddelta=ckt->CKTdelta;
        /* time abort? */
        ckt->CKTtime += ckt->CKTdelta;
#ifdef CLUSTER
        CLUinput(ckt);
#endif
        ckt->CKTdeltaOld[0]=ckt->CKTdelta;
        NIcomCof(ckt);
#ifdef PREDICTOR
        error = NIpred(ckt);
#endif /* PREDICTOR */
        save_mode = ckt->CKTmode;
        save_order = ckt->CKTorder;
#ifdef XSPICE
/* gtri - begin - wbk - Add Breakpoint stuff */

        /* Initialize temporary breakpoint to infinity */
        g_mif_info.breakpoint.current = 1.0e30;

/* gtri - end - wbk - Add Breakpoint stuff */


/* gtri - begin - wbk - add convergence problem reporting flags */
        /* delta is forced to equal delmin on last attempt near line 650 */
        if(ckt->CKTdelta <= ckt->CKTdelmin)
            ckt->enh->conv_debug.last_NIiter_call = MIF_TRUE;
        else
            ckt->enh->conv_debug.last_NIiter_call = MIF_FALSE;
/* gtri - begin - wbk - add convergence problem reporting flags */


/* gtri - begin - wbk - Call all hybrids */

/* gtri - begin - wbk - Set evt_step */

        if(ckt->evt->counts.num_insts > 0) {
            g_mif_info.circuit.evt_step = ckt->CKTtime;
        }
/* gtri - end - wbk - Set evt_step */
#endif

        converged = NIiter(ckt,ckt->CKTtranMaxIter);

        ckt->CKTstat->STATtimePts ++;
        ckt->CKTmode = (ckt->CKTmode&MODEUIC)|MODETRAN | MODEINITPRED;
        if(firsttime && ckt->CKTstate1 && ckt->CKTstate2 && ckt->CKTstate3) {
            memcpy(ckt->CKTstate2, ckt->CKTstate1,
                   (size_t) ckt->CKTnumStates * sizeof(double));
            memcpy(ckt->CKTstate3, ckt->CKTstate1,
                   (size_t) ckt->CKTnumStates * sizeof(double));
        }
        /* txl, cpl addition */
        if (converged == 1111) {
                return(converged);
        }

        if(converged != 0) {
#ifndef CLUSTER
#ifndef SHARED_MODULE
            ckt->CKTtime = ckt->CKTtime -ckt->CKTdelta;
            ckt->CKTstat->STATrejected ++;
#else
            redostep = 1;
#endif
#endif
            ckt->CKTdelta = ckt->CKTdelta/8;
#ifdef STEPDEBUG
            (void)printf("delta cut to %g for non-convergence\n",ckt->CKTdelta);
            fflush(stdout);
#endif
            if(firsttime) {
                ckt->CKTmode = (ckt->CKTmode&MODEUIC) | MODETRAN | MODEINITTRAN;
            }
            ckt->CKTorder = 1;

#ifdef XSPICE
/* gtri - begin - wbk - Add Breakpoint stuff */

        } else if(g_mif_info.breakpoint.current < ckt->CKTtime) {
            /* Force backup if temporary breakpoint is < current time */

        past_breakpoint:
            ckt->CKTsaveDelta = ckt->CKTdelta;
            ckt->CKTtime -= ckt->CKTdelta;
            ckt->CKTdelta = g_mif_info.breakpoint.current - ckt->CKTtime;
            g_mif_info.breakpoint.last = ckt->CKTtime + ckt->CKTdelta;
            xspice_breakpoints_processed = 1;

            if(firsttime) {
                ckt->CKTmode = (ckt->CKTmode&MODEUIC)|MODETRAN | MODEINITTRAN;
            }
            ckt->CKTorder = 1;

/* gtri - end - wbk - Add Breakpoint stuff */
#endif

        } else {
            if (firsttime) {
#ifdef WANT_SENSE2
                if(ckt->CKTsenInfo && (ckt->CKTsenInfo->SENmode & TRANSEN)){
                    save1 = ckt->CKTmode;
                    save2 = ckt->CKTorder;
                    ckt->CKTmode = save_mode;
                    ckt->CKTorder = save_order;
                    error = CKTsenDCtran (ckt);
                    if (error)
                        return(error);

                    ckt->CKTmode = save1;
                    ckt->CKTorder = save2;
                }
#endif
                firsttime = 0;
#if !defined CLUSTER && !defined SHARED_MODULE
                goto nextTime;  /* no check on
                                 * first time point
                                 */
#else
                redostep = 0;
                goto chkStep;
#endif
            }
            newdelta = ckt->CKTdelta;
            error = CKTtrunc(ckt,&newdelta);
            if(error) {
                UPDATE_STATS(DOING_TRAN);
                return(error);
            }
            if (newdelta > .9 * ckt->CKTdelta) {
#if defined(XSPICE)
                /* The timestep has succeeded.  XSPICE instances with
                 * both analog and event ports ("hybrids") and others
                 * that have called cm_irreversible() receive an EVENT
                 * call here that allows them to capture their final
                 * port values and advance co-simulations.  As this is an EVENT
                 * call, they are not expected to do any integrations,
                 * so there is no need for a further convergence test.
                 */

                if (ckt->evt->counts.num_hybrids > 0) {
                    g_mif_info.circuit.evt_step = ckt->CKTtime;
                    EVTcall_hybrids(ckt);
                    if (g_mif_info.breakpoint.current < ckt->CKTtime) {
                        /* A hybrid requested a breakpoint in the past. */

                        goto past_breakpoint;
                    }
                }
#endif

                if ((ckt->CKTorder == 1) && (ckt->CKTmaxOrder > 1)) { /* don't rise the order for backward Euler */
                    newdelta = ckt->CKTdelta;
                    ckt->CKTorder = 2;
                    error = CKTtrunc(ckt, &newdelta);
                    if (error) {
                        UPDATE_STATS(DOING_TRAN);
                        return(error);
                    }
                    if (newdelta <= 1.05 * ckt->CKTdelta) {
                        ckt->CKTorder = 1;
                    }
                }
                /* time point OK  - 630 */
                ckt->CKTdelta = newdelta;

#ifdef NDEV
                if (!ft_norefprint) {
                    /* show a time process indicator, by Gong Ding, gdiso@ustc.edu */
                    if (ckt->CKTtime / ckt->CKTfinalTime * 100 < 10.0)
                        printf("%%%3.2lf\b\b\b\b\b", ckt->CKTtime / ckt->CKTfinalTime * 100);
                    else  if (ckt->CKTtime / ckt->CKTfinalTime * 100 < 100.0)
                        printf("%%%4.2lf\b\b\b\b\b\b", ckt->CKTtime / ckt->CKTfinalTime * 100);
                    else
                        printf("%%%5.2lf\b\b\b\b\b\b\b", ckt->CKTtime / ckt->CKTfinalTime * 100);
                    fflush(stdout);
                }
#endif

#ifdef STEPDEBUG
                (void)printf(
                  "delta set to truncation error result: %g. Point accepted at CKTtime: %g\n",
                  ckt->CKTdelta,ckt->CKTtime);
                fflush(stdout);
#endif

#ifdef WANT_SENSE2
                if(ckt->CKTsenInfo && (ckt->CKTsenInfo->SENmode & TRANSEN)){
                    save1 = ckt->CKTmode;
                    save2 = ckt->CKTorder;
                    ckt->CKTmode = save_mode;
                    ckt->CKTorder = save_order;
                    error = CKTsenDCtran(ckt);
                    if (error)
                        return (error);

                    ckt->CKTmode = save1;
                    ckt->CKTorder = save2;
                }
#endif

#if !defined CLUSTER && !defined SHARED_MODULE
                /* go to 650 - trapezoidal */
                goto nextTime;
#else
                redostep = 0;
                goto chkStep;
#endif
            } else {
#ifndef CLUSTER
#ifndef SHARED_MODULE
                ckt->CKTtime = ckt->CKTtime -ckt->CKTdelta;
                ckt->CKTstat->STATrejected ++;
#else
                redostep = 1;
#endif
#endif
                ckt->CKTdelta = newdelta;
#ifdef STEPDEBUG
                (void)printf(
                    "delta set to truncation error result:point rejected\n");
#endif
            }
        }

        if (ckt->CKTdelta <= ckt->CKTdelmin) {
            if (olddelta > ckt->CKTdelmin) {
                ckt->CKTdelta = ckt->CKTdelmin;
#ifdef STEPDEBUG
                (void)printf("delta at delmin\n");
#endif
            } else {
                UPDATE_STATS(DOING_TRAN);
                errMsg = CKTtrouble(ckt, "Timestep too small");
                SPfrontEnd->OUTendPlot(job->TRANplot);
                job->TRANplot = NULL;
                UPDATE_STATS(0);
                return(E_TIMESTEP);
            }
        }
#ifdef XSPICE
/* gtri - begin - wbk - Do event backup */

        if(ckt->evt->counts.num_insts > 0) {
#ifdef SHARED_MODULE
            double discard_start_time = ckt->CKTtime + ckt->CKTdelta;
            // ngspice in executable mode subtracts olddelta from the time
            // before new delta calculation, but it keeps delta in CKTtime and
            // postpones subtraction in library mode. Delayed subtraction leads
            // to incorrect points dropping because ckt->CKTdelta is almost always
            // less than olddelta if there are convergence issues, and EVTbackup
            // may drop valid events that need to be processed within
            // [last_accepted_time, last_accepted_time + ckt->CKTdelta] range
            // after delta adjustment.
            if (redostep && xspice_breakpoints_processed == 0)
                discard_start_time -= olddelta;
            EVTbackup(ckt, discard_start_time);
#else
            EVTbackup(ckt, ckt->CKTtime + ckt->CKTdelta);
#endif
        }

/* gtri - end - wbk - Do event backup */
#endif
#ifdef CLUSTER
        chkStep:
        if(CLUsync(ckt->CKTtime,&ckt->CKTdelta,redostep)){
            goto nextTime;
        } else {
            ckt->CKTtime -= olddelta;
            ckt->CKTstat->STATrejected ++;
        }
#endif

#ifdef SHARED_MODULE
        /* redostep == 0:
           Either directly go to next time step, or modify ckt->CKTdelta depending on
           synchronization requirements. sharedsync() returns 0.
           redostep == 1:
           No convergence, or too large truncation error.
           Redo the last time step by subtracting olddelta, and modify ckt->CKTdelta
           depending on synchronization requirements. sharedsync() returns 1.
           User-supplied redo request:
           sharedsync() may return 1 if the user has decided to do so in the callback
           function.
        */
chkStep:
#ifdef XSPICE
       // There is no need to subtract olddelta from ckt->CKTtime one more time
       // if it has been subtracted during XSPICE breakpoint processing.
       // olddelta will be reinitialized on
       // the new iteration, so it reassigning here should be safe. It can't be
       // zeroed during breakpoint processing because it takes part in the
       // "timestep too small" check.
        olddelta_for_shared_sync = olddelta;
        if (xspice_breakpoints_processed)
                 olddelta_for_shared_sync = 0.0;
        if(sharedsync(&ckt->CKTtime, &ckt->CKTdelta, olddelta_for_shared_sync, ckt->CKTfinalTime,
                 ckt->CKTdelmin, redostep, &ckt->CKTstat->STATrejected, 1) == 0)
            goto nextTime;
#else
        if(sharedsync(&ckt->CKTtime, &ckt->CKTdelta, olddelta, ckt->CKTfinalTime,
                 ckt->CKTdelmin, redostep, &ckt->CKTstat->STATrejected, 1) == 0)
            goto nextTime;
#endif // XSPICE
#endif // SHARED_MODULE

    }
    /* NOTREACHED */
}