ISRC: update to trnoise source, same as in VSRC

src/spicelib/devices/isrc/isrcacct.c

@@ -201,7 +201,7 @@ ISRCaccept(CKTcircuit *ckt, GENmodel *inModel)
                         /* FIXME, dont' want this here, over to aof_get or somesuch */
                         if (ckt->CKTtime == 0.0) {
                             if (ft_ngdebug)
-                                printf("VSRC: free fft tables\n");
+                                printf("ISRC: free fft tables\n");
                             fftFree();
                         }
 #endif

src/spicelib/devices/isrc/isrcdel.c

@@ -7,6 +7,7 @@ Author: 1985 Thomas L. Quarles
 #include "isrcdefs.h"
 #include "ngspice/sperror.h"
 #include "ngspice/suffix.h"
+#include "ngspice/1-f-code.h"
 
 
 int
@@ -15,6 +16,8 @@ ISRCdelete(GENinstance *gen_inst)
     ISRCinstance *inst = (ISRCinstance *) gen_inst;
 
     FREE(inst->ISRCcoeffs);
+    trnoise_state_free(inst->ISRCtrnoise_state);
+    FREE(inst->ISRCtrrandom_state);
 
     return OK;
 }

src/spicelib/devices/isrc/isrcload.c

@@ -334,19 +334,27 @@ INoi1 1 0  DC 0 TRNOISE(0n 0.5n 1 10n) : generate 1/f noise
                         double TS = state -> TS;
                         double RTSAM = state->RTSAM;
 
-                        /* reset top (hack for repeated tran commands) */
-                        if (time == 0)
-                            state->top = 0;
+                        /* reset top (hack for repeated tran commands)
+                        when there is the jump from time=0 to time>0 */
+                        if (time == 0.0)
+                            state->timezero = TRUE;
+                        else
+                            if (state->timezero) {
+                                state->top = 0;
+                                state->timezero = FALSE;
+                            }
 
-                        /* no noise */
-                        if(TS == 0.0) {
+                        /* no noise or time == 0 */
+                        if (TS == 0.0 || time == 0.0) {
                             value = 0.0;
-                        } else {
+                        }
+                        else {
+
                             /* 1/f and white noise */
-                            size_t n1 = (size_t) floor(time / TS);
+                            size_t n1 = (size_t)floor(time / TS);
 
                             double V1 = trnoise_state_get(state, ckt, n1);
-                            double V2 = trnoise_state_get(state, ckt, n1+1);
+                            double V2 = trnoise_state_get(state, ckt, n1 + 1);
 
                             value = V1 + (V2 - V1) * (time / TS - (double)n1);
                         }

src/spicelib/devices/isrc/isrcpar.c

@@ -206,7 +206,9 @@ ISRCparam(int param, IFvalue *value, GENinstance *inst, IFvalue *select)
 
             if (here->ISRCfunctionOrder > 6 && RTSAM != 0.0)
                 RTSEMT = here->ISRCcoeffs[6]; // RTS trap emission time
-
+            /* after an 'alter' command to the TRNOISE voltage source the state gets re-written
+               with the new parameters. So free the old state first. */
+            trnoise_state_free(here->ISRCtrnoise_state);
             here->ISRCtrnoise_state =
                 trnoise_state_init(NA, TS, NALPHA, NAMP, RTSAM, RTSCAPT, RTSEMT);
         }
@@ -233,6 +235,9 @@ ISRCparam(int param, IFvalue *value, GENinstance *inst, IFvalue *select)
             if (here->ISRCfunctionOrder > 4)
                 PARAM2 = here->ISRCcoeffs[4]; // second parameter
 
+            /* after an 'alter' command to the TRRANDOM voltage source the state gets re-written
+               with the new parameters. So free the old state first. */
+            tfree(here->ISRCtrrandom_state);
             here->ISRCtrrandom_state =
                 trrandom_state_init(rndtype, TS, TD, PARAM1, PARAM2);
         }