Shamusworld >> Repos - rmac/blob - procln.c

   1 //
   2 // RMAC - Reboot's Macro Assembler for the Atari Jaguar Console System
   3 // PROCLN.C - Line Processing
   4 // Copyright (C) 199x Landon Dyer, 2011 Reboot and Friends
   5 // RMAC derived from MADMAC v1.07 Written by Landon Dyer, 1986
   6 // Source Utilised with the Kind Permission of Landon Dyer
   7 //
   8
   9 #include "procln.h"
  10 #include "listing.h"
  11 #include "amode.h"
  12 #include "error.h"
  13 #include "sect.h"
  14 #include "expr.h"
  15 #include "mach.h"
  16 #include "direct.h"
  17 #include "macro.h"
  18 #include "symbol.h"
  19 #include "risca.h"
  20
  21 #define DEF_KW                                              // Declare keyword values
  22 #include "kwtab.h"                                          // Incl generated keyword tables & defs
  23
  24 #define DEF_MN                                              // Incl 68k keyword definitions
  25 #define DECL_MN                                             // Incl 68k keyword state machine tables
  26 #include "mntab.h"
  27
  28 #define DEF_MR
  29 #define DECL_MR
  30 #include "risckw.h"
  31
  32 IFENT * ifent;                                               // Current ifent
  33 static IFENT ifent0;                                        // Root ifent
  34 static IFENT * f_ifent;                                      // Freelist of ifents
  35 static int disabled;                                        // Assembly conditionally disabled
  36 int just_bss;                                               // 1, ds.b in microprocessor mode
  37 VALUE pcloc;                                                // Value of "PC" at beginning of line
  38 IFENT * ifent;                                               // Current ifent
  39 SYM * lab_sym;                                               // Label on line (or NULL)
  40
  41
  42 char extra_stuff[] = "extra (unexpected) text found after addressing mode";
  43 char * comma_error = "missing comma";
  44 char * syntax_error = "syntax error";
  45 char * locgl_error = "cannot GLOBL local symbol";
  46 char * lab_ignored = "label ignored";
  47
  48 // Table to convert an addressing-mode number to a bitmask.
  49 LONG amsktab[0112] = {
  50         M_DREG, M_DREG, M_DREG, M_DREG,
  51         M_DREG, M_DREG, M_DREG, M_DREG,
  52
  53         M_AREG, M_AREG, M_AREG, M_AREG,
  54         M_AREG, M_AREG, M_AREG, M_AREG,
  55
  56         M_AIND, M_AIND, M_AIND, M_AIND,
  57         M_AIND, M_AIND, M_AIND, M_AIND,
  58
  59         M_APOSTINC, M_APOSTINC, M_APOSTINC, M_APOSTINC,
  60         M_APOSTINC, M_APOSTINC, M_APOSTINC, M_APOSTINC,
  61
  62         M_APREDEC, M_APREDEC, M_APREDEC, M_APREDEC,
  63         M_APREDEC, M_APREDEC, M_APREDEC, M_APREDEC,
  64
  65         M_ADISP, M_ADISP, M_ADISP, M_ADISP,
  66         M_ADISP, M_ADISP, M_ADISP, M_ADISP,
  67
  68         M_AINDEXED, M_AINDEXED, M_AINDEXED, M_AINDEXED,
  69         M_AINDEXED, M_AINDEXED, M_AINDEXED, M_AINDEXED,
  70
  71         M_ABSW,                                                  // 070
  72         M_ABSL,                                                  // 071
  73         M_PCDISP,                                                // 072
  74         M_PCINDEXED,                                             // 073
  75         M_IMMED,                                                 // 074
  76         0L,                                                      // 075
  77         0L,                                                      // 076
  78         0L,                                                      // 077
  79         M_ABASE,                                                 // 0100
  80         M_MEMPOST,                                               // 0101
  81         M_MEMPRE,                                                // 0102
  82         M_PCBASE,                                                // 0103
  83         M_PCMPOST,                                               // 0104
  84         M_PCMPRE,                                                // 0105
  85         M_AM_USP,                                                // 0106
  86         M_AM_SR,                                                 // 0107
  87         M_AM_CCR,                                                // 0110
  88         M_AM_NONE                                                // 0111
  89 };                                                          // 0112 length
  90
  91
  92 //
  93 // Initialize Line Processor
  94 //
  95 void init_procln(void)
  96 {
  97         disabled = 0;
  98         ifent = &ifent0;
  99         f_ifent = ifent0.if_prev = NULL;
 100         ifent0.if_state = 0;
 101 }
 102
 103
 104 //
 105 // Line Processor
 106 //
 107 void assemble(void)
 108 {
 109         int state;                                               // Keyword machine state (output)
 110         int j;                                                   // Random int, must be fast
 111         char * p;                                                // Random char ptr, must be fast
 112         TOKEN * tk;                                              // First token in line
 113         char * label;                                            // Symbol (or NULL)
 114         char * equate;                                           // Symbol (or NULL)
 115         int labtyp = 0;                                          // Label type (':', DCOLON)
 116         int equtyp = 0;                                          // Equ type ('=', DEQUALS)
 117         VALUE eval;                                              // Expression value
 118         WORD eattr;                                              // Expression attributes
 119         SYM * esym;                                              // External symbol involved in expr.
 120         WORD siz = 0;                                            // Size suffix to mnem/diretve/macro
 121         LONG amsk0, amsk1;                                       // Address-type masks for ea0, ea1
 122         MNTAB * m;                                               // Code generation table pointer
 123         SYM * sy, * sy2;                                         // Symbol (temp usage)
 124         char * opname = NULL;                                    // Name of dirctve/mnemonic/macro
 125         int listflag;                                            // 0: Don't call listeol()
 126         int as68mode = 0;                                        // 1: Handle multiple labels
 127         WORD rmask;                                              // Register list, for REG
 128         int registerbank;                                        // RISC register bank
 129         int riscreg;                                             // RISC register
 130
 131         listflag = 0;                                            // Initialise listing flag
 132
 133 loop:                                                        // Line processing loop label
 134
 135         if (tokln() == TKEOF)
 136         {                                   // Get another line of tokens
 137                 if (list_flag && listflag)                             // Flush last line of source
 138                         listeol();
 139
 140                 if (ifent->if_prev != NULL)                            // Check conditional token
 141                         error("hit EOF without finding matching .endif");
 142
 143                 return;
 144         }
 145
 146         if (list_flag)
 147         {
 148                 if (listflag && listing > 0)
 149                         listeol();                // Tell listing generator about EOL
 150
 151                 lstout((char)(disabled ? '-' : lntag));             // Prepare new line for listing
 152                 listflag = 1;                                         // OK to call `listeol' now
 153                 just_bss = 0;                                         // Reset just_bss mode
 154         }
 155
 156         state = -3;                                              // No keyword (just EOL)
 157         label = NULL;                                            // No label
 158         lab_sym = NULL;                                          // No (exported) label
 159         equate = NULL;                                           // No equate
 160         tk = tok;                                                // Save first token in line
 161         pcloc = (VALUE)sloc;                                     // Set beginning-of-line PC
 162
 163         loop1:                                                   // Internal line processing loop
 164
 165         if (*tok == EOL)                                          // Restart loop if end-of-line
 166                 goto loop;
 167
 168         if (*tok != SYMBOL)
 169         {                                     // First token MUST be a symbol
 170                 error(syntax_error);
 171                 goto loop;
 172         }
 173
 174         j = (int)tok[2];                                         // Skip equates (normal statements)
 175
 176         if (j == '=' || j == DEQUALS || j == SET || j == REG || j == EQUREG || j == CCDEF)
 177         {
 178                 equate = (char *)tok[1];
 179                 equtyp = j;
 180                 tok += 3;
 181                 goto normal;
 182         }
 183
 184         if (j == ':' || j == DCOLON)
 185         {                            // Skip past label (but record it)
 186 as68label:
 187                 label = (char *)tok[1];                               // Get label name
 188                 labtyp = tok[2];                                      // Get label type
 189                 tok += 3;                                             // Go to next line token
 190
 191                 // Handle multiple labels; if there's another label, go process it,
 192                 // and come back at `as68label' above.
 193                 if (as68_flag)
 194                 {
 195                         as68mode = 0;
 196
 197                         if (*tok == SYMBOL && tok[2] == ':')
 198                         {
 199                                 as68mode = 1;
 200                                 goto do_label;
 201                         }
 202                 }
 203         }
 204
 205         if (*tok == EOL)                                          // EOL is legal here...
 206                 goto normal;
 207
 208         if (*tok++ != SYMBOL)
 209         {                                   // Next token MUST be a symbol
 210                 error(syntax_error);
 211                 goto loop;
 212         }
 213
 214         opname = p = (char *)*tok++;                             // Store opcode name here
 215
 216         // Check to see if the SYMBOL is a keyword (a mnemonic or directive).
 217         // On output, `state' will have one of the values:
 218         //    -3          there was no symbol (EOL)
 219         //    -2..-1      the symbol didn't match any keyword
 220         //    0..499      vanilla directives (dc, ds, etc.)
 221         //    500..999    electric directives (macro, rept, etc.)
 222         //    1000..+     mnemonics (move, lsr, etc.)
 223         for(state=0; state>=0;)
 224         {
 225                 j = mnbase[state] + (int)tolowertab[*p];
 226
 227                 if (mncheck[j] != state)
 228                 {                             // Reject, character doesn't match
 229                         state = -1;                                        // No match
 230                         break;
 231                 }
 232
 233                 if (!*++p)
 234                 {                                           // Must accept or reject at EOS
 235                         state = mnaccept[j];                               // (-1 on no terminal match)
 236                         break;
 237                 }
 238
 239                 state = mntab[j];
 240         }
 241
 242         // Check for ".b" ".w" ".l" after directive, macro or mnemonic.
 243         siz = SIZN;
 244
 245         if (*tok == DOTW)
 246                 siz = SIZW, ++tok;
 247         else if (*tok == DOTL)
 248                 siz = SIZL, ++tok;
 249         else if (*tok == DOTB)
 250                 siz = SIZB, ++tok;
 251
 252         // Do special directives (500..999) (These must be handled in "real time")
 253         if (state >= 500 && state < 1000)
 254         {
 255                 switch (state)
 256                 {
 257                 case MN_IF:
 258                         d_if ();
 259                 goto loop;
 260                 case MN_ELSE:
 261                         d_else();
 262                         goto loop;
 263                 case MN_ENDIF:
 264                         d_endif ();
 265                         goto loop;
 266                 case MN_IIF:                                       // .iif --- immediate if
 267                         if (disabled || expr(exprbuf, &eval, &eattr, &esym) != OK)
 268                                 goto loop;
 269
 270                         if (!(eattr & DEFINED))
 271                         {
 272                                 error(undef_error);
 273                                 goto loop;
 274                         }
 275
 276                         if (*tok++ != ',')
 277                         {
 278                                 error(comma_error);
 279                                 goto loop;
 280                         }
 281
 282                         if (eval == 0)
 283                                 goto loop;
 284
 285                         goto loop1;
 286                 case MN_MACRO:                                     // .macro --- macro definition
 287                         if (!disabled)
 288                         {
 289                                 if (label != NULL)
 290                                         warn(lab_ignored);
 291
 292                                 defmac();
 293                         }
 294
 295                         goto loop;
 296                 case MN_EXITM:                                     // .exitm --- exit macro
 297                 case MN_ENDM:                                      // .endm --- same as .exitm
 298                         if (!disabled)
 299                         {
 300                                 if (label != NULL)
 301                                         warn(lab_ignored);
 302
 303                                 exitmac();
 304                         }
 305
 306                         goto loop;
 307                 case MN_REPT:
 308                         if (!disabled)
 309                         {
 310                                 if (label != NULL)
 311                                         warn(lab_ignored);
 312
 313                                 defrept();
 314                         }
 315
 316                         goto loop;
 317                 case MN_ENDR:
 318                         if (!disabled)
 319                                 error("mis-nested .endr");
 320
 321                         goto loop;
 322                 }
 323         }
 324
 325 normal:
 326         if (disabled)                                             // Conditionally disabled code
 327                 goto loop;
 328
 329         // Do equates
 330         if (equate != NULL)
 331         {
 332                 j = 0;                                                // Pick global or local sym enviroment
 333
 334                 if (*equate == '.')
 335                         j = curenv;
 336
 337                 sy = lookup(equate, LABEL, j);
 338
 339                 if (sy == NULL)
 340                 {
 341                         sy = newsym(equate, LABEL, j);
 342                         sy->sattr = 0;
 343
 344                         if (equtyp == DEQUALS)
 345                         {
 346                                 if (j)
 347                                 {                                         // Can't GLOBAL a local symbol
 348                                         error(locgl_error);
 349                                         goto loop;
 350                                 }
 351
 352                                 sy->sattr = GLOBAL;
 353                         }
 354                 }
 355                 else if ((sy->sattr & DEFINED) && equtyp != SET)
 356                 {
 357                         if ((equtyp == EQUREG) && (sy->sattre & UNDEF_EQUR))
 358                         {
 359                                 sy->sattre |= ~UNDEF_EQUR;
 360                                 sy->svalue  = 0;
 361                         }
 362                         else if ((equtyp == CCDEF) && (sy->sattre & UNDEF_CC))
 363                         {
 364                                 sy->sattre |= ~UNDEF_CC;
 365                                 sy->svalue = 0;
 366                         }
 367                         else
 368                         {
 369                                 errors("multiple equate to '%s'", sy->sname);
 370                                 goto loop;
 371                         }
 372                 }
 373
 374                 // Put symbol in "order of definition" list
 375                 if (!(sy->sattr & SDECLLIST))
 376                         sym_decl(sy);
 377
 378                 // Parse value to equate symbol to;
 379                 // o  .equr
 380                 // o  .reg
 381                 // o  everything else
 382                 if (equtyp == EQUREG)
 383                 {
 384                         if (!rgpu && !rdsp)
 385                         {                               // Check that we are in a RISC section
 386                                 error(".equr/.regequ must be defined in .gpu/.dsp section");
 387                                 goto loop;
 388                         }
 389
 390                         if ((*tok >= KW_R0) && (*tok <= KW_R31))
 391                         {          // Check for register to equate to
 392                                 sy->sattre  = EQUATEDREG | RISCSYM;             // Mark as equated register
 393                                 riscreg = (*tok - KW_R0);
 394                                 sy->sattre |= (riscreg << 8);                   // Store register number
 395
 396                                 if ((tok[1] == ',') && (tok[2] == CONST))
 397                                 {
 398                                         tok += 3;
 399
 400                                         if (*tok == 0)
 401                                                 registerbank = BANK_0;
 402                                         else if (*tok == 1)
 403                                                 registerbank = BANK_1;
 404                                         else
 405                                                 registerbank = BANK_N;
 406                                 }
 407                                 else
 408                                 {
 409                                         registerbank = BANK_N;
 410                                 }
 411
 412                                 sy->sattre |= regbank;                          // Store register bank
 413                                 eattr = ABS | DEFINED | GLOBAL;
 414                                 eval = 0x80000080 + (riscreg) + (registerbank << 8);
 415                                 tok++;
 416                         }
 417                         else if (tok[0] == SYMBOL)
 418                         {                      // Checking for a register symbol
 419                                 sy2 = lookup((char *)tok[1], LABEL, j);
 420
 421                                 if (!sy2 || !(sy2->sattre & EQUATEDREG))
 422                                 {       // Make sure symbol is a valid equreg
 423                                         error("invalid GPU/DSP .equr/.regequ definition");
 424                                         goto loop;
 425                                 }
 426                                 else
 427                                 {
 428                                         eattr = ABS | DEFINED | GLOBAL;              // Copy symbols attributes
 429                                         sy->sattre = sy2->sattre;
 430                                         eval = (sy2->svalue & 0xFFFFF0FF);
 431                                         tok += 2;
 432                                 }
 433                         }
 434                         else
 435                         {
 436                                 error("invalid GPU/DSP .equr/.regequ definition");
 437                                 goto loop;
 438                         }
 439                 }
 440                 else if (equtyp == REG)
 441                 {
 442                         if (reglist(&rmask) < 0)
 443                                 goto loop;
 444
 445                         eval = (VALUE)rmask;
 446                         eattr = ABS | DEFINED;
 447                 }
 448                 else if (equtyp == CCDEF)
 449                 {
 450                         sy->sattre |= EQUATEDCC;
 451                         eattr = ABS | DEFINED | GLOBAL;
 452
 453                         if (tok[0] == SYMBOL)
 454                         {
 455                                 sy2 = lookup((char *)tok[1], LABEL, j);
 456
 457                                 if (!sy2 || !(sy2->sattre & EQUATEDCC))
 458                                 {
 459                                         error("invalid gpu/dsp .ccdef definition");
 460                                         goto loop;
 461                                 }
 462                                 else
 463                                 {
 464                                         eattr = ABS | DEFINED | GLOBAL;
 465                                         sy->sattre = sy2->sattre;
 466                                         eval = sy2->svalue;
 467                                         tok += 2;
 468                                 }
 469                         }
 470                         else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 471                                 goto loop;
 472                 }
 473                 else if (*tok == SYMBOL)
 474                 {  //equ a equr
 475                         sy2 = lookup((char *)tok[1], LABEL, j);
 476
 477                         if (sy2 && (sy2->sattre & EQUATEDREG))
 478                         {
 479                                 sy->stype = sy2->stype;
 480                                 sy->sattr = sy2->sattr;
 481                                 sy->sattre = sy2->sattre;
 482                                 sy->svalue = (sy2->svalue & 0xFFFFF0FF);
 483                                 goto loop;
 484                         }
 485                         else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 486                                 goto loop;
 487                 }
 488                 else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 489                         goto loop;
 490
 491                 if (!(eattr & DEFINED))
 492                 {
 493                         error(undef_error);
 494                         goto loop;
 495                 }
 496
 497
 498                 sy->sattr |= eattr | EQUATED;                         // Symbol inherits value and attributes
 499                 sy->svalue = eval;
 500                 if (list_flag)                                         // Put value in listing
 501                         listvalue(eval);
 502
 503                 at_eol();                                             // Must be at EOL now
 504                 goto loop;
 505         }
 506
 507         // Do labels
 508         if (label != NULL)
 509         {
 510 do_label:
 511                 j = 0;
 512
 513                 if (*label == '.')
 514                         j = curenv;
 515
 516                 sy = lookup(label, LABEL, j);
 517
 518                 if (sy == NULL)
 519                 {
 520                         sy = newsym(label, LABEL, j);
 521                         sy->sattr = 0;
 522                         sy->sattre = RISCSYM;
 523                 }
 524                 else if (sy->sattr & DEFINED)
 525                 {
 526                         errors("multiply-defined label '%s'", label);
 527                         goto loop;
 528                 }
 529
 530                 // Put symbol in "order of definition" list
 531                 if (!(sy->sattr & SDECLLIST))
 532                         sym_decl(sy);
 533
 534                 if (orgactive)
 535                 {
 536                         sy->svalue = orgaddr;
 537                         sy->sattr |= ABS | DEFINED | EQUATED;
 538                 }
 539                 else
 540                 {
 541                         sy->svalue = sloc;
 542                         sy->sattr |= DEFINED | cursect;
 543                 }
 544
 545                 lab_sym = sy;
 546
 547                 if (!j)
 548                         ++curenv;
 549
 550                 if (labtyp == DCOLON)
 551                 {                                // Make label global
 552                         if (j)
 553                         {
 554                                 error(locgl_error);
 555                                 goto loop;
 556                         }
 557
 558                         sy->sattr |= GLOBAL;
 559                 }
 560
 561                 // If we're in as68 mode, and there's another label, go back and handle it
 562                 if (as68_flag && as68mode)
 563                         goto as68label;
 564         }
 565
 566         // Punt on EOL
 567         if (state == -3)
 568                 goto loop;
 569
 570         // If we are in GPU or DSP mode and still in need of a mnemonic then search for one
 571         if ((rgpu || rdsp) && (state < 0 || state >= 1000))
 572         {
 573                 for(state=0, p=opname; state>=0;)
 574                 {
 575                         j = mrbase[state] + (int)tolowertab[*p];
 576
 577                         if (mrcheck[j] != state)
 578                         {                          // Reject, character doesn't match
 579                                 state = -1;                                     // No match
 580                                 break;
 581                         }
 582
 583                         if (!*++p)
 584                         {                                        // Must accept or reject at EOS
 585                                 state = mraccept[j];                            // (-1 on no terminal match)
 586                                 break;
 587                         }
 588
 589                         state = mrtab[j];
 590                 }
 591
 592                 // Call RISC code generator if we found a mnemonic
 593                 if (state >= 3000)
 594                 {
 595                         risccg(state);
 596                         goto loop;
 597                 }
 598         }
 599
 600         // Invoke macro or complain about bad mnemonic
 601         if (state < 0)
 602         {
 603                 if ((sy = lookup(opname, MACRO, 0)) != NULL)
 604                         invokemac(sy, siz);
 605                 else
 606                         errors("unknown op '%s'", opname);
 607
 608                 goto loop;
 609         }
 610
 611         // Call directive handlers
 612         if (state < 500)
 613         {
 614                 (*dirtab[state])(siz);
 615                 goto loop;
 616         }
 617
 618         // Do mnemonics
 619         // o  can't deposit instrs in BSS or ABS
 620         // o  do automatic .EVEN for instrs
 621         // o  allocate space for largest possible instr
 622         // o  can't do ".b" operations with an address register
 623         if (scattr & SBSS)
 624         {
 625                 error("cannot initialize non-storage (BSS) section");
 626                 goto loop;
 627         }
 628
 629         if (sloc & 1)                                             // Automatic .even
 630                 auto_even();
 631
 632         if (challoc - ch_size < 18)                               // Make sure have space in current chunk
 633                 chcheck(0L);
 634
 635         m = &machtab[state - 1000];
 636
 637         if (m->mnattr & CGSPECIAL)
 638         {                              // Call special-mode handler
 639                 (*m->mnfunc)(m->mninst, siz);
 640                 goto loop;
 641         }
 642
 643         if (amode(1) < 0)                                         // Parse 0, 1 or 2 addr modes
 644                 goto loop;
 645
 646         if (*tok != EOL)
 647                 error(extra_stuff);
 648
 649         amsk0 = amsktab[am0];
 650         amsk1 = amsktab[am1];
 651
 652         // Catch attempts to use ".B" with an address register (yes, this check does work at this level)
 653         if (siz == SIZB && (am0 == AREG || am1 == AREG))
 654         {
 655                 error("cannot use '.b' with an address register");
 656                 goto loop;
 657         }
 658
 659         for(;;)
 660         {
 661                 if ((m->mnattr & siz) && (amsk0 & m->mn0) != 0 && (amsk1 & m->mn1) != 0)
 662                 {
 663                         (*m->mnfunc)(m->mninst, siz);
 664                         goto loop;
 665                 }
 666
 667                 m = &machtab[m->mncont];
 668         }
 669 }
 670
 671
 672 //
 673 // .if, Start Conditional Assembly
 674 //
 675 int d_if (void)
 676 {
 677         IFENT * rif;
 678         WORD eattr;
 679         VALUE eval;
 680         SYM * esym;
 681
 682         // Alloc an IFENTRY
 683         if ((rif = f_ifent) == NULL)
 684                 rif = (IFENT *)amem((LONG)sizeof(IFENT));
 685         else
 686                 f_ifent = rif->if_prev;
 687
 688         rif->if_prev = ifent;
 689         ifent = rif;
 690
 691         if (!disabled)
 692         {
 693                 if (expr(exprbuf, &eval, &eattr, &esym) != OK) return 0;
 694
 695                 if ((eattr & DEFINED) == 0)
 696                         return error(undef_error);
 697
 698                 disabled = !eval;
 699         }
 700
 701         rif->if_state = (WORD)disabled;
 702         return 0;
 703 }
 704
 705
 706 //
 707 // .else, Do Alternate Case For .if
 708 //
 709 int d_else(void)
 710 {
 711         IFENT * rif = ifent;
 712
 713         if (rif->if_prev == NULL)
 714                 return error("mismatched .else");
 715
 716         if (disabled)
 717                 disabled = rif->if_prev->if_state;
 718         else
 719                 disabled = 1;
 720
 721         rif->if_state = (WORD)disabled;
 722         return 0;
 723 }
 724
 725
 726 //
 727 // .endif, End of conditional assembly block
 728 // This is also called by fpop() to pop levels of IFENTs in case a macro or
 729 // include file exits early with `exitm' or `end'.
 730 //
 731 int d_endif (void)
 732 {
 733         IFENT * rif = ifent;
 734
 735         if (rif->if_prev == NULL)
 736                 return error("mismatched .endif");
 737
 738         ifent = rif->if_prev;
 739         disabled = rif->if_prev->if_state;
 740         rif->if_prev = f_ifent;
 741         f_ifent = rif;
 742         return 0;
 743 }