/*
 *      install --- add a symbol to the table
 */
install(str,val)
char    *str;
int     val;
{
        struct link *lp;
        struct nlist *np,*p,*backp;
        struct nlist *lookup();
        int     i;

        if( !alpha(*str) ){
                error("Illegal Symbol Name");
                return(NO);
                }
        if( (np = lookup(str)) != NULL ){
                if( Pass==2 ){
                        if( np->def == val )
                                return(YES);
                        else{
                                error("Phasing Error");
                                return(NO);
                                }
                        }
                error("Symbol Redefined");
                return(NO);
                }
        /* enter new symbol */
#ifdef DEBUG
        printf("Installing %s as %d\n",str,val);
#endif
        np = (struct nlist *) alloc(sizeof(struct nlist));
        if( np == (struct nlist *)ERR ){
                error("Symbol table full");
                return(NO);
                }
        np->name = alloc(strlen(str)+1);
        if( np->name == (char *)ERR ){
                error("Symbol table full");
                return(NO);
                }
        strcpy(np->name,str);
        np->def = val;
        np->Lnext = NULL;
        np->Rnext = NULL;
           lp = (struct link *) alloc(sizeof(struct link));
           np->L_list = lp;
           lp->L_num = Line_num;
           lp->next = NULL;
        p = root;
          backp = NULL;
           while (p != NULL)
            {
              backp = p;
              i = strcmp (str,p->name);
               if (i<0)
                   p=p->Lnext;
                  else p=p->Rnext;
            }
          if (backp == NULL)
              root = np;
             else if (strcmp(str,backp->name)<0)
                  backp->Lnext = np;
                 else backp->Rnext = np;
          return (YES);
}

/*
 *      lookup --- find string in symbol table
 */
struct nlist *
lookup(name)
char    *name;
{
        struct nlist *np;
        int     i;

        np = root;
         while (np != NULL)
          {
            i = strcmp(name,np->name);
             if (i == 0)
               {
                 Last_sym = np->def;
                 return (np);
               }
             else if (i < 0)
                 np = np->Lnext;
                else np = np->Rnext;
          }
      Last_sym = 0;
      if (Pass == 2)
          errors( "symbol Undefined on pass 2", name );
        return (NULL);
}


#define NMNE (sizeof(table)/ sizeof(struct oper))
#define NPSE (sizeof(pseudo)/ sizeof(struct oper))
/*
 *      mne_look --- mnemonic lookup
 *
 *      Return pointer to an oper structure if found.
 *      Searches both the machine mnemonic table and the pseudo table.
 */
struct oper *
mne_look(str)
char    *str;
{
        struct oper *low,*high,*mid;
        int     cond;

        /* Search machine mnemonics first */
        low =  &table[0];
        high = &table[ NMNE-1 ];
        while (low <= high){
                mid = low + (high-low)/2;
                if( ( cond = strcmp(str,mid->mnemonic)) < 0)
                        high = mid - 1;
                else if (cond > 0)
                        low = mid + 1;
                else
                        return(mid);
        }

        /* Check for pseudo ops */
        low =  &pseudo[0];
        high = &pseudo[ NPSE-1 ];
        while (low <= high){
                mid = low + (high-low)/2;
                if( ( cond = strcmp(str,mid->mnemonic)) < 0)
                        high = mid - 1;
                else if (cond > 0)
                        low = mid + 1;
                else
                        return(mid);
        }

        return(NULL);
}