示例#1
0
static void drv_generic(FILE *ptfile, ptype_list *pttype)
{
struct logen *ptgen;

   if ( (pttype=getptype(pttype,LOGEN)) ) {
      fprintf (ptfile,"   generic (\n");
      for (ptgen=pttype->DATA;ptgen;ptgen=ptgen->NEXT) {
         fprintf (ptfile,"      CONSTANT %s : ",ptgen->NAME);
         switch(ptgen->TYPE) {
            case GENTYPE_BIT:
               fputs("bit     := ", ptfile);
               break;
            case GENTYPE_VAL:
               fputs("natural := ", ptfile);
               break;
            case GENTYPE_ARG:
               fputs("arg     := ", ptfile);
               break;
            case GENTYPE_TEXT:
               fputs("string  := ", ptfile);
               break;
            case GENTYPE_LIST:
               fputs("list    := ", ptfile);
               break;
         }
         drv_genvalue(ptfile, ptgen);
         if (ptgen->NEXT)
            fputs(";\n",ptfile);
      }
      fputs("\n   );\n",ptfile);
   }
}
示例#2
0
extern void improve_capa_critical_path(lofig_list* lofig, int optim_level)
{
   ptype_list* ptype, *ptype2;
   loins_list* loins;
   locon_list* locon;
   chain_list *lofigchain;
   losig_list* losig;
   ptype_list* long_path;
   int change=1;

   
   /*relaxation algorithm*/
   while (change) {
      change=0;
      long_path=critical_path(lofig);
      long_path=sort_capa(long_path);
      
      /* on all signals of the critical path, improve capa*/
      for (ptype=long_path; ptype; ptype=ptype->NEXT) {
         losig=(losig_list*) ptype->DATA;
         if (!losig->NAMECHAIN) {
            fprintf(stderr,"improve_capa_critical_path: no name on signal\n");
            autexit(1);
         }
         /*seek latest driver*/
         ptype2=getptype(losig->USER,LOFIGCHAIN);
         if (!ptype2) {
            fprintf(stderr,
            "improve_capa_critical_path: no lofigchain on losig '%s'\n",
            (char*) losig->NAMECHAIN->DATA);
            autexit(1);
         }
         loins=NULL;
         for (lofigchain=ptype2->DATA; lofigchain; lofigchain=lofigchain->NEXT){
            locon= (locon_list*) lofigchain->DATA;
            if (locon->DIRECTION==UNKNOWN) {
               fprintf(stderr,"BEH: 'linkage %s' isn't accepted\n",
               locon->NAME);
               autexit(1);
            }
            if (locon->TYPE==EXTERNAL || locon->DIRECTION==IN) continue;
            loins=locon->ROOT;
            if (loins_delay(loins,losig->NAMECHAIN->DATA)>ptype->TYPE) break;
         }

         /*instance has changed, re-evaluate critical path*/
         if (loins && change_instance(loins, losig, lofig, optim_level)) {
            change=1;
            break;
         }   
      }

      freeptype(long_path);
   }

}
extern void final_eval_delay(befig_list *befig)
{
   bereg_list *bereg;
   bebus_list *bebus;
   beout_list *beout;
   biabl_list *biabl;
   bepor_list* bepor;
   float delay;
   
   if (!befig) {
      fprintf(stderr,"eval_delay: NULL pointer\n");
      exit(1);
   }   
   

   /*constants*/
   putdelay(getablatomone(),0);
   putdelay(getablatomzero(),0);

   for (bepor=befig->BEPOR; bepor; bepor=bepor->NEXT) {
      /*only input*/
      if (bepor->DIRECTION!=IN && bepor->DIRECTION!=INOUT 
       && bepor->DIRECTION!=TRANSCV) continue;
      if (isvdd(bepor->NAME) || isvss(bepor->NAME)) continue;
      /*  T + RC  */
      delay=getdelaylax(bepor->NAME) + getimpedancelax(bepor->NAME)
                  * getcapacitance(bepor->NAME);
      putdelay(bepor->NAME,delay);
   }

   /*separ value from condition for flip-flop to avoid cycle*/
   for (bereg=befig->BEREG; bereg; bereg=bereg->NEXT) {
      for (biabl=bereg->BIABL; biabl; biabl=biabl->NEXT) {
         if (getptype(biabl->USER,ABL_STABLE)) { /*only flip-flop*/
            search_abl(biabl->VALABL,befig);
         }
      }
   }
   
   for (beout=befig->BEOUT; beout; beout=beout->NEXT) {
      search_abl(beout->ABL,befig);
      /*do not define delay now*/
   }
   
   for (bebus=befig->BEBUS; bebus; bebus=bebus->NEXT) {
      for (biabl=bebus->BIABL; biabl; biabl=biabl->NEXT) {
         search_abl(biabl->CNDABL,befig);
         search_abl(biabl->VALABL,befig);
         /*do not define delay now*/
      }
   }   
   
}
static void search_name(char* name, befig_list* befig)
{
   bereg_list* bereg;
   beaux_list* beaux;
   bebux_list* bebux;
   biabl_list* biabl;

   
   for (beaux=befig->BEAUX; beaux; beaux=beaux->NEXT) {
      if (beaux->NAME!=name) continue;
      search_abl(beaux->ABL,befig);
      eval_delay(beaux->NAME,beaux->ABL);
      return;      
   }
   
   for (bebux=befig->BEBUX; bebux; bebux=bebux->NEXT) {
      if (bebux->NAME!=name) continue;
      for (biabl=bebux->BIABL; biabl; biabl=biabl->NEXT) {
         search_abl(biabl->CNDABL,befig);
         search_abl(biabl->VALABL,befig);
      }
      eval_bus(bebux->NAME,bebux->BIABL);
      return;      
   }
   
   for (bereg=befig->BEREG; bereg; bereg=bereg->NEXT) {
      if (bereg->NAME!=name) continue;
      for (biabl=bereg->BIABL; biabl; biabl=biabl->NEXT) {
         search_abl(biabl->CNDABL,befig);             /*only condition*/
         if (!getptype(biabl->USER,ABL_STABLE)) { /*only latch*/
            search_abl(biabl->VALABL,befig);
         }
      }
      /*calculate delay on clock setup for flip-flop and on all entries */
      /*for latch*/
      eval_reg(bereg->NAME,bereg->BIABL);
      return;
   }         
   

   fprintf(stderr,"search_name: %s unknown\n",name);
   exit(1);
}
示例#5
0
extern void save_xsch(FILE* xsch_stream, lofig_list* lofig, ptype_list* long_path, int color_mode)
{
   long color;
   ptype_list* ptype, *ptype2=NULL;
   float delay=0, delay_out=0;
   char mes[1024];
   char* signame = NULL;
   locon_list* locon;
   losig_list* losig;
   float gradient=1;
   int count;
   loins_list* loins;
   char *source, *dest=NULL, *last_sig;
   chain_list* chain, *loinschain=NULL;
   chain_list* lofigchain;
   losig_list* losig_aux;

   /*build gradient*/
   if (long_path && color_mode==XSCH_GRADIENT) {
      /*get time of last entry*/
      count=1;
      for (ptype=long_path; ptype->NEXT; ptype=ptype->NEXT) count++;
      
      if (!ptype->DATA) {
         fprintf(stderr,"save_xsch: compute error\n");
         exit(1);
      }
      delay=ptype->TYPE;
      gradient=delay/((float)XSCH_COLOR_MAX);
   }
   
   /*color for signals*/
   for (losig=lofig->LOSIG; losig; losig=losig->NEXT) {

      if (!losig->NAMECHAIN || !losig->NAMECHAIN->DATA) {
         fprintf(stderr,"save_xsch: no name for signal\n");
         exit(1);
      }
      signame=losig->NAMECHAIN->DATA;
      
      if (isvdd(signame) || isvss(signame)) continue;
      
      if (losig->TYPE==EXTERNAL) {
         /*search external output*/
         ptype=getptype(losig->USER,LOFIGCHAIN);
         for (lofigchain=ptype->DATA; lofigchain; lofigchain=lofigchain->NEXT) {
            locon=lofigchain->DATA;
            if (locon->TYPE==EXTERNAL && locon->DIRECTION!=IN) break;
         }
         if (lofigchain) delay=getdelay(output_name(signame));
         else delay=getdelay(signame);
      }   
      else delay=getdelay(signame);
      
      switch (color_mode) {
      case XSCH_GRADIENT: color=gradient_color(delay,gradient); break;
      case XSCH_CRITICAL_PATH: default: color=XSCH_NEUTRAL_COLOR; break;
      }
      
      flush_losig(xsch_stream, signame, color, delay, losig->TYPE);
      
   }
   
   
   /*color for instances*/
   for (loins=lofig->LOINS; loins; loins=loins->NEXT) {
      /*search signal output*/
      for (locon=loins->LOCON; locon; locon=locon->NEXT) {
         if (locon->DIRECTION==UNKNOWN) {
            fprintf(stderr,"BEH: 'linkage %s' in figure '%s' isn't accepted\n",
            locon->NAME,loins->INSNAME);
            exit(1);
         }
         if (locon->DIRECTION==OUT || locon->DIRECTION==INOUT 
           || locon->DIRECTION==TRISTATE || locon->DIRECTION==TRANSCV) break;
      }
      if (!locon) {
         fprintf(stderr,"save_xsch: no output found for '%s'\n",loins->INSNAME);
         exit(1);
      }
      losig=locon->SIG;
      signame=losig->NAMECHAIN->DATA;
      
      delay=getdelay(loins->INSNAME);
     
      switch (color_mode) {
      case XSCH_GRADIENT: color=gradient_color(delay,gradient); break;
      case XSCH_CRITICAL_PATH: default:
         /*is instance in critical path?*/
         for (ptype=long_path; ptype; ptype=ptype->NEXT) {
            if ((char*)ptype->DATA!=signame) continue;
          /*if output and input signals belong to critical path, then instance belongs*/
            for (locon=loins->LOCON; locon; locon=locon->NEXT) {
               if (locon->DIRECTION==OUT || locon->DIRECTION==TRISTATE) continue;
               losig_aux=locon->SIG;
               /*is signal in critical path?*/
               for (ptype2=long_path; ptype2; ptype2=ptype2->NEXT) {
                  if ((char*)ptype2->DATA==losig_aux->NAMECHAIN->DATA) break;
               }
               if (ptype2) break;
            }
            ptype=ptype2;  /*found?*/
            break;
         }
         
         /*build critical path list*/
         if (ptype) loinschain=addchain(loinschain,loins);
     
         if (ptype) color=XSCH_RED_COLOR;
         else color=XSCH_NEUTRAL_COLOR;
      }
      flush_loins(xsch_stream, loins->INSNAME, color, delay);
      
   }
   

   /*color for connectors*/
   for (locon=lofig->LOCON; locon; locon=locon->NEXT) {

      if (isvdd(locon->NAME) || isvss(locon->NAME)) continue;
      
      switch (locon->DIRECTION) {
      case IN: 
         delay_out=getdelay(locon->NAME);
         sprintf(mes, "%d ps",(int)delay_out);
         break;
      case OUT: case TRISTATE: 
         delay_out=getdelay(output_name(locon->NAME));
         sprintf(mes, "%d ps",(int)delay_out);
         break;
      case INOUT: case TRANSCV: 
         delay=getdelay(locon->NAME);
         delay_out=getdelay(output_name(locon->NAME));
         sprintf(mes, "%d ps on input; %d ps on output",(int)delay,(int)delay_out);
         break;
      }

      switch (color_mode) {
      case XSCH_GRADIENT: color=gradient_color(delay_out,gradient); break;
      case XSCH_CRITICAL_PATH: default:
         /* seek if signal is in a long path*/
         for (ptype=long_path; ptype; ptype=ptype->NEXT) {
            if ((char*)ptype->DATA==locon->NAME) break;
         }
   
         if (ptype) color=XSCH_RED_COLOR;
         else color=XSCH_NEUTRAL_COLOR;
      }
      flush_stream_special(xsch_stream, locon->NAME, color, mes);
   }  


   /*critical path*/
   if (loinschain && long_path && color_mode==XSCH_CRITICAL_PATH) {
      source=NULL;
      last_sig=NULL;
      for (ptype=long_path; ptype; ptype=ptype->NEXT) {
         signame=ptype->DATA;
         for (chain=loinschain; chain; chain=chain->NEXT) {
            loins=chain->DATA;
            /*search signal output*/
            for (locon=loins->LOCON; locon; locon=locon->NEXT) {
               if (locon->DIRECTION==OUT || locon->DIRECTION==INOUT 
                || locon->DIRECTION==TRISTATE || locon->DIRECTION==TRANSCV) {
                  losig=locon->SIG;
                  if (losig->NAMECHAIN->DATA==signame) {
                     dest=loins->INSNAME;
                     break;
                  }
               }   
            }
            if (locon) break;
         }  
         /*if no instance found it is external connector. it has the same name than signal*/
         if (!locon) dest=signame;
      
         if (source)
            flush_path(xsch_stream, source, last_sig, dest, XSCH_RED_COLOR, delay, INTERNAL);
      
         source=dest;
         last_sig=signame;
      }
      
      /*for last signal search output*/
      if (losig) {
         ptype=getptype(losig->USER,LOFIGCHAIN);
         for (chain=ptype->DATA; chain; chain=chain->NEXT) {
            locon=chain->DATA;
            /*port of circuit*/
            if (locon->TYPE==EXTERNAL) {dest=locon->NAME; break;}
            loins=locon->ROOT;
            /*register input if no error*/
            if (locon->DIRECTION==IN || locon->DIRECTION==INOUT || locon->DIRECTION==TRANSCV)
            {dest=loins->INSNAME; break;}
         }
         flush_path(xsch_stream, source, signame, dest, XSCH_RED_COLOR, delay, losig->TYPE);
      }
      
   }

   freechain(loinschain);
}
static ptype_list* search_long_path(loins_list* loins, befig_list* befig)
{
   loins_list* loins_aux, *best_loins=NULL;
   locon_list* locon;
   losig_list* losig, *best_losig=NULL;
   char* signame;
   chain_list* loconchain;
   ptype_list* ptype, *ret;
   float max_delay=-1, delay;
   bereg_list* bereg;
   biabl_list* biabl;

   if (!loins) {
      fprintf(stderr,"search_long_path: NULL pointer\n");
      exit(1);
   }
   
   /*seek the latest input in cell*/
   for (locon=loins->LOCON; locon; locon=locon->NEXT) {
      /*only inputs*/
      if (locon->DIRECTION==OUT || locon->DIRECTION==TRISTATE
       || isvss(locon->NAME) || isvdd(locon->NAME)) continue;
      losig=locon->SIG;
      if (!losig->NAMECHAIN) {
         fprintf(stderr,"search_long_path: NULL pointer\n");
         exit(1);
      }
      signame=(char*) losig->NAMECHAIN->DATA;
      delay=getdelay(signame);
      if (delay>max_delay) {
         best_losig=losig;
         max_delay=delay;
      }   
   }
   
   /*no input found  -> constant*/
   if (!best_losig) return NULL;
   
   losig=best_losig;
   ptype=getptype(losig->USER,LOFIGCHAIN);
   if (!ptype || !ptype->DATA) {
      fprintf(stderr,"search_long_path: NULL pointer\n");
      exit(1);
   }
   signame=(char*) losig->NAMECHAIN->DATA;
   
   ret=addptype(NULL, (int) max_delay, signame);

   /*stop at leaves or flip-flop */
   if (losig->TYPE==EXTERNAL) return ret;
   for (bereg=befig->BEREG; bereg; bereg=bereg->NEXT) {
      if (bereg->NAME!=signame) continue;
      /*is it a flip-flop?*/
      for (biabl=bereg->BIABL; biabl; biabl=biabl->NEXT) {
         if (getptype(biabl->USER,ABL_STABLE)) return ret; 
      }
   }

   /*search driver of signal (latest if bus)*/
   max_delay=-1;   
   
   for (loconchain=(chain_list*) ptype->DATA; loconchain; loconchain=loconchain->NEXT) {
      locon=(locon_list*) loconchain->DATA;
      /*only outputs*/
      if (locon->DIRECTION==IN || isvss(locon->NAME) || isvdd(locon->NAME) 
       || locon->TYPE==EXTERNAL) continue;
      loins_aux=locon->ROOT;
      if (loins_aux==loins) continue;
      delay=getdelay(loins_aux->INSNAME);
      if (delay>max_delay) {
         best_loins=loins_aux;
         max_delay=delay;
      }   
   }   

   if (!best_loins) {
      fprintf(stderr,"search_long_path: no loins found for driving losig '%s'\n",signame);
      exit(1);
   }
   
   ret->NEXT=search_long_path(best_loins, befig);
   return ret;
}
示例#7
0
static ptype_list* search_long_path(losig_list* losig, int ck_include)
{
    loins_list* best_loins=NULL;
    locon_list* locon;
    losig_list *best_losig=NULL;
    loins_list* loins;
    befig_list* befig;
    char* signame, *ck=NULL;
    int reg=0;  /*flag for flip-flop*/
    chain_list* lofigchain;
    ptype_list* ptype, *ret;
    double max_delay=-1, delay;
    cell_list* cell;
    biabl_list* biabl;

    if (!losig) {
        fprintf(stderr,"search_long_path: NULL pointer\n");
        autexit(1);
    }

    if (!losig->NAMECHAIN) {
        fprintf(stderr,"search_long_path: no losig name\n");
        autexit(1);
    }

    signame=(char*) losig->NAMECHAIN->DATA;


    /*control combinational loop, not to recurse infinitively*/
    if ( searchauthelem( ControlLoop, (char*) losig ) )
    {
        fprintf(stderr,"Warning: combinational loop on signal %s\n", signame );
        return ret;
    }

    addauthelem( ControlLoop, (char*) losig, 1 );


    /*search drivers*/
    ptype=getptype(losig->USER,LOFIGCHAIN);
    if (!ptype || !ptype->DATA) {
        fprintf(stderr,"search_long_path: no lofigchain found\n");
        autexit(1);
    }

    for (lofigchain=(chain_list*) ptype->DATA; lofigchain; lofigchain=lofigchain->NEXT) {
        locon=(locon_list*) lofigchain->DATA;
        if (locon->DIRECTION==UNKNOWN) {
            fprintf(stderr,"BEH: 'linkage %s' isn't accepted\n",
                    locon->NAME);
            autexit(1);
        }
        /*only outputs*/
        if (isvss(locon->NAME) || isvdd(locon->NAME)
                || locon->DIRECTION==IN || locon->TYPE==EXTERNAL) continue;
        loins=locon->ROOT;
        delay=loins_delay(loins,signame);
        if (delay>max_delay) {
            best_loins=loins;
            max_delay=delay;
        }
    }


    loins=best_loins;
    ret=addptype(NULL, (long) max_delay>=0?max_delay:getdelay(signame), losig);
    if (!loins) return ret;

    /*stop at flip-flop*/
    cell=getCell(loins->FIGNAME);
    if (!cell) {
        fprintf(stderr,"library error: no cell '%s.vbe' found\n",
                loins->FIGNAME);
        autexit(1);
    }
    befig=cell->BEFIG;
    if (befig->BEREG) {
        for ( biabl = cell->BEFIG->BEREG->BIABL; biabl; biabl = biabl->NEXT )
        {
            ptype=getptype(biabl->USER,ABL_STABLE);
            if (ptype) {
                /*do not include clock in path*/
                if (!ck_include) return ret;
                reg=1;
                ck=ptype->DATA;
                break;
            }
        }
    }

    max_delay=-1;
    /*seek the latest input in cell*/
    for (locon=loins->LOCON; locon; locon=locon->NEXT) {
        if (locon->DIRECTION==UNKNOWN) {
            fprintf(stderr,"BEH: 'linkage %s' in figure '%s' isn't accepted\n",
                    locon->NAME,loins->FIGNAME);
            autexit(1);
        }
        /*only inputs*/
        if (locon->DIRECTION==OUT || locon->DIRECTION==TRISTATE
                || isvss(locon->NAME) || isvdd(locon->NAME)) continue;
        /* if flip-flop, accept only clock */
        if (reg && ck!=locon->NAME) continue;
        losig=locon->SIG;
        if (!losig->NAMECHAIN) {
            fprintf(stderr,"search_long_path: no name on signal\n");
            autexit(1);
        }
        signame=(char*) losig->NAMECHAIN->DATA;
        delay=getdelay(signame);
        if (delay>max_delay) {
            best_losig=losig;
            max_delay=delay;
        }
    }

    losig=best_losig;


    /*no input found  -> constant*/
    if (!losig) return ret;

    ret->NEXT=search_long_path(losig,ck_include);
    return ret;
}
示例#8
0
static int insert_buffer(losig_list* losig, lofig_list* lofig, int optim_level, long index)
{
   double capa, init_capa;
   cell_list* buffer;
   chain_list* namechain, *sigchain=NULL;
   char* signame;
   lofig_list* model;
   losig_list* losig_buf;
   loins_list* loins_buf;
   locon_list* locon;
   losig_list* losig_vdd=NULL, *losig_vss=NULL, *losig_aux;
   ptype_list* ptype, *buffer_ptype;
   double delay, best_delay, init_delay;
   loins_list* loins;
   chain_list* lofigchain,*newlofigchain=NULL;
   int buffer_is_better=0, change=1;    /*flags*/
   chain_list* pred;
   chain_list* temp;


   buffer=getCellbuffer();
   /*no buffer in library*/
   if (!buffer) return 0;
   
   if (!losig->NAMECHAIN) {
      fprintf(stderr,"insert_buffer: no name on signal\n");
      autexit(1);
   }

   best_delay=critical_delay(lofig);
   init_capa=getcapacitance(losig->NAMECHAIN->DATA);

   /*add buffer to netlist*/
   signame=getautoname(losig->NAMECHAIN->DATA);
   namechain=addchain(NULL,signame);
   losig_buf=addlosig(lofig,index,namechain,INTERNAL);
   putcapacitance(signame,0);
   putdelay(signame,0);
   model=getlofig(buffer->BEFIG->NAME,'A');
   
   /*search vdd and vss*/
   for (locon=lofig->LOCON; locon; locon=locon->NEXT) {
      if (isvdd(locon->NAME)) losig_vdd=locon->SIG;
      if (isvss(locon->NAME)) losig_vss=locon->SIG;
   }
   
   /*build list of signal*/
   for (locon=model->LOCON;locon; locon=locon->NEXT) {
      if (locon->DIRECTION==UNKNOWN) {
         fprintf(stderr,"BEH: 'linkage %s' in figure '%s' isn't accepted\n",
         locon->NAME,model->NAME);
         autexit(1);
      }
      if (isvdd(locon->NAME)) losig_aux=losig_vdd;
      else if (isvss(locon->NAME)) losig_aux=losig_vss;
      else if (locon->DIRECTION==OUT) losig_aux=losig_buf;
      else if (locon->DIRECTION==IN) losig_aux=losig;
      else {
         fprintf(stderr,"insert_buffer: buffer port '%s' unknown\n",locon->NAME);
         autexit(1);
      }
      sigchain=addchain(sigchain,losig_aux);
   }

   
   sigchain=reverse(sigchain);
   loins_buf=addloins(lofig,signame,model,sigchain);
   freechain(sigchain);
   /*to check changes*/
   init_delay=getdelay(losig->NAMECHAIN->DATA);
   init_capa=getcapacitance(losig->NAMECHAIN->DATA);
   loins_capacitance(loins_buf,1/*add capa*/);
  
   /*lofigchain*/
   for (locon=loins_buf->LOCON;locon; locon=locon->NEXT) {
      if (locon->DIRECTION==UNKNOWN) {
         fprintf(stderr,"BEH: 'linkage %s' in figure '%s' isn't accepted\n",
         locon->NAME,loins_buf->INSNAME);
         autexit(1);
      }
      if (isvdd(locon->NAME)) losig_aux=losig_vdd;
      else if (isvss(locon->NAME)) losig_aux=losig_vss;
      else if (locon->DIRECTION==OUT) losig_aux=losig_buf;
      else if (locon->DIRECTION==IN) losig_aux=losig;
      else {
         fprintf(stderr,"insert_buffer: buffer port '%s' unknown\n",locon->NAME);
         autexit(1);
      }
      ptype=getptype(losig_aux->USER,LOFIGCHAIN);
      if (!ptype) losig_aux->USER=addptype(losig_aux->USER,LOFIGCHAIN,addchain(NULL,locon));
      else ptype->DATA=addchain(ptype->DATA,locon);
   }
   
   /*move all instance after buffer*/
   ptype=getptype(losig->USER,LOFIGCHAIN);
   buffer_ptype=getptype(losig_buf->USER,LOFIGCHAIN);
   if (!ptype || !buffer_ptype) {
      fprintf(stderr,"insert_buffer: LOFIGCHAIN not found\n");
      autexit(1);
   }
   
   for (lofigchain=((chain_list*)ptype->DATA)->NEXT/*first is entry of buffer*/;
        lofigchain; lofigchain=lofigchain->NEXT) {
      locon=(locon_list*) lofigchain->DATA;
      if (locon->DIRECTION==UNKNOWN) {
         fprintf(stderr,"BEH: 'linkage %s' isn't accepted\n",
         locon->NAME);
         autexit(1);
      }
      /*do not move drivers and port of circuit*/
      if (locon->TYPE==EXTERNAL || locon->DIRECTION!=IN) {
         newlofigchain=addchain(newlofigchain,locon);
         continue;
      }
      
      loins=locon->ROOT;
      /*change capacitance*/
      loins_capacitance(loins,0/*remove  capa*/);
      /*change netlist*/
      locon->SIG=losig_buf;
      buffer_ptype->DATA=addchain(buffer_ptype->DATA,locon);
      loins_capacitance(loins,1/*add capa*/);
   }
   
   /*put back drivers*/
   freechain(((chain_list*)ptype->DATA)->NEXT/*first is entry of buffer*/);
   ((chain_list*)ptype->DATA)->NEXT=newlofigchain;
   
   /*eval all changes*/
   propagate_loins_delay(loins_buf);

   /*relaxation algorithm*/
   while (change) {
      change=0;
      pred=NULL;
      buffer_ptype=getptype(losig_buf->USER,LOFIGCHAIN);
      ptype=getptype(losig->USER,LOFIGCHAIN);
      if (!buffer_ptype || !buffer_ptype->DATA) {
         fprintf(stderr,"insert_buffer: LOFIGCHAIN is empty\n");
         autexit(1);
      }
      
      /*put critical path before buffer*/
      for (lofigchain=buffer_ptype->DATA; lofigchain->NEXT/*last is buffer output*/;
           lofigchain=lofigchain->NEXT) {
         locon=lofigchain->DATA;
         loins=locon->ROOT;
      
         /*change capacitance*/
         loins_capacitance(loins,0/*remove capa*/);
         /*change netlist*/
         locon->SIG=losig;
         ptype->DATA=addchain(ptype->DATA,locon);
         loins_capacitance(loins,1/*add capa*/);

         /*put over*/
         if (pred) pred->NEXT=lofigchain->NEXT;
         else buffer_ptype->DATA=lofigchain->NEXT;
      
         /*eval all changes*/
         propagate_loins_delay(loins);
         propagate_loins_delay(loins_buf);
         delay=critical_delay(lofig);
      
         if (delay<best_delay) {
            /*finish change*/
            best_delay=delay; 
            change=1;   /*flag of change*/
            buffer_is_better=1;
            lofigchain->NEXT=NULL;
            freechain(lofigchain);
            break;
         }
         else {
            /*remove change*/
            if (pred) pred->NEXT=lofigchain;
            else buffer_ptype->DATA=lofigchain;
            
            /*unchange capacitance*/
            loins_capacitance(loins,0/*remove capa*/);
            /*unchange netlist*/
            locon->SIG=losig_buf;
            temp=ptype->DATA;
            ptype->DATA=temp->NEXT;
            temp->NEXT=NULL;
            freechain(temp);
            loins_capacitance(loins,1/*add capa*/);
            /*avoid change*/
            propagate_loins_delay(loins_buf);
            propagate_loins_delay(loins);
            
            /*for next loop*/
            pred=lofigchain;
         }
      }
      
   }/*end of while*/
   
   if (buffer_is_better) {
      /*chose the best buffer*/
      change_instance(loins_buf, losig_buf, lofig, optim_level);
   }   
   else {  /*if insert buffer is worst than before, remove it*/
      /*remove all references of buffer in lofigchain*/
      for (locon=loins_buf->LOCON; locon; locon=locon->NEXT) {
         losig_aux=locon->SIG;
         ptype=getptype(losig_aux->USER,LOFIGCHAIN);
         if (!ptype) break;
         pred=NULL;
         for (lofigchain=ptype->DATA; lofigchain; lofigchain=lofigchain->NEXT) {
            if (lofigchain->DATA==locon) {
               if (pred) pred->NEXT=lofigchain->NEXT;
               else ptype->DATA=lofigchain->NEXT;
               lofigchain->NEXT=NULL;
               freechain(lofigchain);
               break;
            }
            pred=lofigchain;
         }
      }
      
      buffer_ptype=getptype(losig_buf->USER,LOFIGCHAIN);
      ptype=getptype(losig->USER,LOFIGCHAIN);
      if (buffer_ptype) {
       for (lofigchain=buffer_ptype->DATA; lofigchain; lofigchain=lofigchain->NEXT) {
         locon=lofigchain->DATA;
         loins=locon->ROOT;
         /*change capacitance*/
         loins_capacitance(loins,0/*remove capa*/);
         /*change netlist*/
         locon->SIG=losig;
         ptype->DATA=addchain(ptype->DATA,locon);
         loins_capacitance(loins,1/*add capa*/);
         propagate_loins_delay(loins);
       }
      
       freechain(buffer_ptype->DATA);
       buffer_ptype->DATA=NULL;
      }
      
      loins_capacitance(loins_buf,0/*remove capa*/);
      dellosig(lofig,index);
      delloins(lofig,loins_buf->INSNAME);
      propagate_losig_delay(losig);
   
      /*verify no change on timing*/
      delay=critical_delay(lofig);
      capa=getcapacitance(losig->NAMECHAIN->DATA);
      //01/09/2004 xtof's modification: rounding problem
      if ((int)(capa + 0.5)!=(int)(init_capa + 0.5) || (int)(delay + 0.5)!=(int)(best_delay + 0.5) 
       || (int)(init_delay + 0.5)!=(int)(getdelay(losig->NAMECHAIN->DATA) + 0.5)) {
         fprintf(stderr,
         "insert_buffer: compute error %e!=%e fF   %f!=%f ps    %f!=%f ps\n",
         capa,init_capa,delay,best_delay, init_delay, getdelay(losig->NAMECHAIN->DATA));
         autexit(1);
      }   
   
   }
      
   return buffer_is_better;
}