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 char extra_stuff[] = "extra (unexpected) text found after addressing mode";
  42 char * comma_error = "missing comma";
  43 char * syntax_error = "syntax error";
  44 char * locgl_error = "cannot GLOBL local symbol";
  45 char * lab_ignored = "label ignored";
  46
  47 // Table to convert an addressing-mode number to a bitmask.
  48 LONG amsktab[0112] = {
  49         M_DREG, M_DREG, M_DREG, M_DREG,
  50         M_DREG, M_DREG, M_DREG, M_DREG,
  51
  52         M_AREG, M_AREG, M_AREG, M_AREG,
  53         M_AREG, M_AREG, M_AREG, M_AREG,
  54
  55         M_AIND, M_AIND, M_AIND, M_AIND,
  56         M_AIND, M_AIND, M_AIND, M_AIND,
  57
  58         M_APOSTINC, M_APOSTINC, M_APOSTINC, M_APOSTINC,
  59         M_APOSTINC, M_APOSTINC, M_APOSTINC, M_APOSTINC,
  60
  61         M_APREDEC, M_APREDEC, M_APREDEC, M_APREDEC,
  62         M_APREDEC, M_APREDEC, M_APREDEC, M_APREDEC,
  63
  64         M_ADISP, M_ADISP, M_ADISP, M_ADISP,
  65         M_ADISP, M_ADISP, M_ADISP, M_ADISP,
  66
  67         M_AINDEXED, M_AINDEXED, M_AINDEXED, M_AINDEXED,
  68         M_AINDEXED, M_AINDEXED, M_AINDEXED, M_AINDEXED,
  69
  70         M_ABSW,                                                                                 // 070
  71         M_ABSL,                                                                                 // 071
  72         M_PCDISP,                                                                               // 072
  73         M_PCINDEXED,                                                                    // 073
  74         M_IMMED,                                                                                // 074
  75         0L,                                                                                             // 075
  76         0L,                                                                                             // 076
  77         0L,                                                                                             // 077
  78         M_ABASE,                                                                                // 0100
  79         M_MEMPOST,                                                                              // 0101
  80         M_MEMPRE,                                                                               // 0102
  81         M_PCBASE,                                                                               // 0103
  82         M_PCMPOST,                                                                              // 0104
  83         M_PCMPRE,                                                                               // 0105
  84         M_AM_USP,                                                                               // 0106
  85         M_AM_SR,                                                                                // 0107
  86         M_AM_CCR,                                                                               // 0110
  87         M_AM_NONE                                                                               // 0111
  88 };                                                                                                      // 0112 length
  89
  90
  91 //
  92 // Initialize Line Processor
  93 //
  94 void init_procln(void)
  95 {
  96         disabled = 0;
  97         ifent = &ifent0;
  98         f_ifent = ifent0.if_prev = NULL;
  99         ifent0.if_state = 0;
 100 }
 101
 102
 103 //
 104 // Line Processor
 105 //
 106 void Assemble(void)
 107 {
 108         int state;                                      // Keyword machine state (output)
 109         int j;                                          // Random int, must be fast
 110         char * p;                                       // Random char ptr, must be fast
 111         TOKEN * tk;                                     // First token in line
 112         char * label;                           // Symbol (or NULL)
 113         char * equate;                          // Symbol (or NULL)
 114         int labtyp = 0;                         // Label type (':', DCOLON)
 115         int equtyp = 0;                         // Equ type ('=', DEQUALS)
 116         VALUE eval;                                     // Expression value
 117         WORD eattr;                                     // Expression attributes
 118         SYM * esym;                                     // External symbol involved in expr.
 119         WORD siz = 0;                           // Size suffix to mnem/diretve/macro
 120         LONG amsk0, amsk1;                      // Address-type masks for ea0, ea1
 121         MNTAB * m;                                      // Code generation table pointer
 122         SYM * sy, * sy2;                        // Symbol (temp usage)
 123         char * opname = NULL;           // Name of dirctve/mnemonic/macro
 124         int listflag;                           // 0: Don't call listeol()
 125         int as68mode = 0;                       // 1: Handle multiple labels
 126         WORD rmask;                                     // Register list, for REG
 127         int registerbank;                       // RISC register bank
 128         int riscreg;                            // RISC register
 129
 130         listflag = 0;                           // Initialise listing flag
 131
 132 loop:                                                   // Line processing loop label
 133
 134         // Get another line of tokens
 135         if (tokln() == TKEOF)
 136         {
 137 if (verb_flag) printf("Assemble: Found TKEOF flag...\n");
 138                 if (list_flag && listflag)                      // Flush last line of source
 139                         listeol();
 140
 141                 if (ifent->if_prev != NULL)                     // Check conditional token
 142                         error("hit EOF without finding matching .endif");
 143
 144                 return;
 145         }
 146
 147         DEBUG DumpTokenBuffer();
 148
 149         if (list_flag)
 150         {
 151                 if (listflag && listing > 0)
 152                         listeol();                                              // Tell listing generator about EOL
 153
 154                 lstout((char)(disabled ? '-' : lntag)); // Prepare new line for listing
 155                 listflag = 1;                                           // OK to call `listeol' now
 156                 just_bss = 0;                                           // Reset just_bss mode
 157         }
 158
 159         state = -3;                                                             // No keyword (just EOL)
 160         label = NULL;                                                   // No label
 161         lab_sym = NULL;                                                 // No (exported) label
 162         equate = NULL;                                                  // No equate
 163         tk = tok;                                                               // Save first token in line
 164         pcloc = (VALUE)sloc;                                    // Set beginning-of-line PC
 165
 166 loop1:                                                                          // Internal line processing loop
 167
 168         if (*tok == EOL)                                                // Restart loop if end-of-line
 169                 goto loop;
 170
 171         // First token MUST be a symbol
 172         if (*tok != SYMBOL)
 173         {
 174                 error(syntax_error);
 175                 goto loop;
 176         }
 177
 178         j = (int)tok[2];                                                // Skip equates (normal statements)
 179
 180         if (j == '=' || j == DEQUALS || j == SET || j == REG || j == EQUREG || j == CCDEF)
 181         {
 182 //              equate = (char *)tok[1];
 183                 equate = string[tok[1]];
 184                 equtyp = j;
 185                 tok += 3;
 186                 goto normal;
 187         }
 188
 189         // Skip past label (but record it)
 190         if (j == ':' || j == DCOLON)
 191         {
 192 as68label:
 193 //              label = (char *)tok[1];                         // Get label name
 194                 label = string[tok[1]];                         // Get label name
 195                 labtyp = tok[2];                                        // Get label type
 196                 tok += 3;                                                       // Go to next line token
 197
 198                 // Handle multiple labels; if there's another label, go process it,
 199                 // and come back at `as68label' above.
 200                 if (as68_flag)
 201                 {
 202                         as68mode = 0;
 203
 204                         if (*tok == SYMBOL && tok[2] == ':')
 205                         {
 206                                 as68mode = 1;
 207                                 goto do_label;
 208                         }
 209                 }
 210         }
 211
 212         if (*tok == EOL)                                                // EOL is legal here...
 213                 goto normal;
 214
 215         // Next token MUST be a symbol
 216         if (*tok++ != SYMBOL)
 217         {
 218                 error(syntax_error);
 219                 goto loop;
 220         }
 221
 222 // This is the problem here: On 64-bit platforms, this cuts the native pointer
 223 // in half. We need to figure out how to fix this.
 224 //#warning "!!! Bad pointer !!!"
 225 #if 0
 226         opname = p = (char *)*tok++;                    // Store opcode name here
 227 #else
 228         opname = p = string[*tok++];
 229 #endif
 230
 231         // Check to see if the SYMBOL is a keyword (a mnemonic or directive).
 232         // On output, `state' will have one of the values:
 233         //    -3          there was no symbol (EOL)
 234         //    -2..-1      the symbol didn't match any keyword
 235         //    0..499      vanilla directives (dc, ds, etc.)
 236         //    500..999    electric directives (macro, rept, etc.)
 237         //    1000..+     mnemonics (move, lsr, etc.)
 238         for(state=0; state>=0;)
 239         {
 240                 j = mnbase[state] + (int)tolowertab[*p];
 241
 242                 // Reject, character doesn't match
 243                 if (mncheck[j] != state)
 244                 {
 245                         state = -1;                                             // No match
 246                         break;
 247                 }
 248
 249                 // Must accept or reject at EOS
 250                 if (!*++p)
 251                 {
 252                         state = mnaccept[j];                    // (-1 on no terminal match)
 253                         break;
 254                 }
 255
 256                 state = mntab[j];
 257         }
 258
 259         // Check for ".b" ".w" ".l" after directive, macro or mnemonic.
 260         siz = SIZN;
 261
 262         if (*tok == DOTW)
 263                 siz = SIZW, ++tok;
 264         else if (*tok == DOTL)
 265                 siz = SIZL, ++tok;
 266         else if (*tok == DOTB)
 267                 siz = SIZB, ++tok;
 268
 269         // Do special directives (500..999) (These must be handled in "real time")
 270         if (state >= 500 && state < 1000)
 271         {
 272                 switch (state)
 273                 {
 274                 case MN_IF:
 275                         d_if ();
 276                 goto loop;
 277                 case MN_ELSE:
 278                         d_else();
 279                         goto loop;
 280                 case MN_ENDIF:
 281                         d_endif ();
 282                         goto loop;
 283                 case MN_IIF:                                            // .iif --- immediate if
 284                         if (disabled || expr(exprbuf, &eval, &eattr, &esym) != OK)
 285                                 goto loop;
 286
 287                         if (!(eattr & DEFINED))
 288                         {
 289                                 error(undef_error);
 290                                 goto loop;
 291                         }
 292
 293                         if (*tok++ != ',')
 294                         {
 295                                 error(comma_error);
 296                                 goto loop;
 297                         }
 298
 299                         if (eval == 0)
 300                                 goto loop;
 301
 302                         goto loop1;
 303                 case MN_MACRO:                                          // .macro --- macro definition
 304                         if (!disabled)
 305                         {
 306                                 if (label != NULL)
 307                                         warn(lab_ignored);
 308
 309                                 DefineMacro();
 310                         }
 311
 312                         goto loop;
 313                 case MN_EXITM:                                          // .exitm --- exit macro
 314                 case MN_ENDM:                                           // .endm --- same as .exitm
 315                         if (!disabled)
 316                         {
 317                                 if (label != NULL)
 318                                         warn(lab_ignored);
 319
 320                                 ExitMacro();
 321                         }
 322
 323                         goto loop;
 324                 case MN_REPT:
 325                         if (!disabled)
 326                         {
 327                                 if (label != NULL)
 328                                         warn(lab_ignored);
 329
 330                                 defrept();
 331                         }
 332
 333                         goto loop;
 334                 case MN_ENDR:
 335                         if (!disabled)
 336                                 error("mis-nested .endr");
 337
 338                         goto loop;
 339                 }
 340         }
 341
 342 normal:
 343         if (disabled)                                                   // Conditionally disabled code
 344                 goto loop;
 345
 346         // Do equates
 347         if (equate != NULL)
 348         {
 349                 j = 0;                                                          // Pick global or local sym enviroment
 350
 351                 if (*equate == '.')
 352                         j = curenv;
 353
 354                 sy = lookup(equate, LABEL, j);
 355
 356                 if (sy == NULL)
 357                 {
 358                         sy = NewSymbol(equate, LABEL, j);
 359                         sy->sattr = 0;
 360
 361                         if (equtyp == DEQUALS)
 362                         {
 363                                 // Can't GLOBAL a local symbol
 364                                 if (j)
 365                                 {
 366                                         error(locgl_error);
 367                                         goto loop;
 368                                 }
 369
 370                                 sy->sattr = GLOBAL;
 371                         }
 372                 }
 373                 else if ((sy->sattr & DEFINED) && equtyp != SET)
 374                 {
 375                         if ((equtyp == EQUREG) && (sy->sattre & UNDEF_EQUR))
 376                         {
 377                                 sy->sattre |= ~UNDEF_EQUR;
 378                                 sy->svalue  = 0;
 379                         }
 380                         else if ((equtyp == CCDEF) && (sy->sattre & UNDEF_CC))
 381                         {
 382                                 sy->sattre |= ~UNDEF_CC;
 383                                 sy->svalue = 0;
 384                         }
 385                         else
 386                         {
 387                                 errors("multiple equate to '%s'", sy->sname);
 388                                 goto loop;
 389                         }
 390                 }
 391
 392                 // Put symbol in "order of definition" list
 393                 if (!(sy->sattr & SDECLLIST))
 394                         sym_decl(sy);
 395
 396                 // Parse value to equate symbol to;
 397                 // o  .equr
 398                 // o  .reg
 399                 // o  everything else
 400                 if (equtyp == EQUREG)
 401                 {
 402                         // Check that we are in a RISC section
 403                         if (!rgpu && !rdsp)
 404                         {
 405                                 error(".equr/.regequ must be defined in .gpu/.dsp section");
 406                                 goto loop;
 407                         }
 408
 409                         // Check for register to equate to
 410                         if ((*tok >= KW_R0) && (*tok <= KW_R31))
 411                         {
 412                                 sy->sattre  = EQUATEDREG | RISCSYM;     // Mark as equated register
 413                                 riscreg = (*tok - KW_R0);
 414                                 sy->sattre |= (riscreg << 8);           // Store register number
 415
 416                                 if ((tok[1] == ',') && (tok[2] == CONST))
 417                                 {
 418                                         tok += 3;
 419
 420                                         if (*tok == 0)
 421                                                 registerbank = BANK_0;
 422                                         else if (*tok == 1)
 423                                                 registerbank = BANK_1;
 424                                         else
 425                                                 registerbank = BANK_N;
 426                                 }
 427                                 else
 428                                 {
 429                                         registerbank = BANK_N;
 430                                 }
 431
 432                                 sy->sattre |= regbank;          // Store register bank
 433                                 eattr = ABS | DEFINED | GLOBAL;
 434                                 eval = 0x80000080 + (riscreg) + (registerbank << 8);
 435                                 tok++;
 436                         }
 437                         // Checking for a register symbol
 438                         else if (tok[0] == SYMBOL)
 439                         {
 440 //                              sy2 = lookup((char *)tok[1], LABEL, j);
 441                                 sy2 = lookup(string[tok[1]], LABEL, j);
 442
 443                                 // Make sure symbol is a valid equreg
 444                                 if (!sy2 || !(sy2->sattre & EQUATEDREG))
 445                                 {
 446                                         error("invalid GPU/DSP .equr/.regequ definition");
 447                                         goto loop;
 448                                 }
 449                                 else
 450                                 {
 451                                         eattr = ABS | DEFINED | GLOBAL; // Copy symbols attributes
 452                                         sy->sattre = sy2->sattre;
 453                                         eval = (sy2->svalue & 0xFFFFF0FF);
 454                                         tok += 2;
 455                                 }
 456                         }
 457                         else
 458                         {
 459                                 error("invalid GPU/DSP .equr/.regequ definition");
 460                                 goto loop;
 461                         }
 462                 }
 463                 else if (equtyp == REG)
 464                 {
 465                         if (reglist(&rmask) < 0)
 466                                 goto loop;
 467
 468                         eval = (VALUE)rmask;
 469                         eattr = ABS | DEFINED;
 470                 }
 471                 else if (equtyp == CCDEF)
 472                 {
 473                         sy->sattre |= EQUATEDCC;
 474                         eattr = ABS | DEFINED | GLOBAL;
 475
 476                         if (tok[0] == SYMBOL)
 477                         {
 478 //                              sy2 = lookup((char *)tok[1], LABEL, j);
 479                                 sy2 = lookup(string[tok[1]], LABEL, j);
 480
 481                                 if (!sy2 || !(sy2->sattre & EQUATEDCC))
 482                                 {
 483                                         error("invalid gpu/dsp .ccdef definition");
 484                                         goto loop;
 485                                 }
 486                                 else
 487                                 {
 488                                         eattr = ABS | DEFINED | GLOBAL;
 489                                         sy->sattre = sy2->sattre;
 490                                         eval = sy2->svalue;
 491                                         tok += 2;
 492                                 }
 493                         }
 494                         else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 495                                 goto loop;
 496                 }
 497                 //equ a equr
 498                 else if (*tok == SYMBOL)
 499                 {
 500 //                      sy2 = lookup((char *)tok[1], LABEL, j);
 501                         sy2 = lookup(string[tok[1]], LABEL, j);
 502
 503                         if (sy2 && (sy2->sattre & EQUATEDREG))
 504                         {
 505                                 sy->stype = sy2->stype;
 506                                 sy->sattr = sy2->sattr;
 507                                 sy->sattre = sy2->sattre;
 508                                 sy->svalue = (sy2->svalue & 0xFFFFF0FF);
 509                                 goto loop;
 510                         }
 511                         else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 512                                 goto loop;
 513                 }
 514                 else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 515                         goto loop;
 516
 517                 if (!(eattr & DEFINED))
 518                 {
 519                         error(undef_error);
 520                         goto loop;
 521                 }
 522
 523                 sy->sattr |= eattr | EQUATED;           // Symbol inherits value and attributes
 524                 sy->svalue = eval;
 525
 526                 if (list_flag)                                          // Put value in listing
 527                         listvalue(eval);
 528
 529                 at_eol();                                                       // Must be at EOL now
 530                 goto loop;
 531         }
 532
 533         // Do labels
 534         if (label != NULL)
 535         {
 536 do_label:
 537                 // Check for dot in front of label; means this is a local label if present
 538 #if 0
 539                 j = 0;
 540
 541                 if (*label == '.')
 542                         j = curenv;
 543 #else
 544                 j = (*label == '.' ? curenv : 0);
 545 #endif
 546
 547                 sy = lookup(label, LABEL, j);
 548
 549                 if (sy == NULL)
 550                 {
 551                         sy = NewSymbol(label, LABEL, j);
 552                         sy->sattr = 0;
 553                         sy->sattre = RISCSYM;
 554                 }
 555                 else if (sy->sattr & DEFINED)
 556                 {
 557                         errors("multiply-defined label '%s'", label);
 558                         goto loop;
 559                 }
 560
 561                 // Put symbol in "order of definition" list
 562                 if (!(sy->sattr & SDECLLIST))
 563                         sym_decl(sy);
 564
 565                 if (orgactive)
 566                 {
 567                         sy->svalue = orgaddr;
 568                         sy->sattr |= ABS | DEFINED | EQUATED;
 569                 }
 570                 else
 571                 {
 572                         sy->svalue = sloc;
 573                         sy->sattr |= DEFINED | cursect;
 574                 }
 575
 576                 lab_sym = sy;
 577
 578                 if (!j)
 579                         curenv++;
 580
 581                 // Make label global
 582                 if (labtyp == DCOLON)
 583                 {
 584                         if (j)
 585                         {
 586                                 error(locgl_error);
 587                                 goto loop;
 588                         }
 589
 590                         sy->sattr |= GLOBAL;
 591                 }
 592
 593                 // If we're in as68 mode, and there's another label, go back and handle it
 594                 if (as68_flag && as68mode)
 595                         goto as68label;
 596         }
 597
 598         // Punt on EOL
 599         if (state == -3)
 600                 goto loop;
 601
 602         // If we are in GPU or DSP mode and still in need of a mnemonic then search
 603         // for one
 604         if ((rgpu || rdsp) && (state < 0 || state >= 1000))
 605         {
 606                 for(state=0, p=opname; state>=0;)
 607                 {
 608                         j = mrbase[state] + (int)tolowertab[*p];
 609
 610                         // Reject, character doesn't match
 611                         if (mrcheck[j] != state)
 612                         {
 613                                 state = -1;                                     // No match
 614                                 break;
 615                         }
 616
 617                         // Must accept or reject at EOS
 618                         if (!*++p)
 619                         {
 620                                 state = mraccept[j];            // (-1 on no terminal match)
 621                                 break;
 622                         }
 623
 624                         state = mrtab[j];
 625                 }
 626
 627                 // Call RISC code generator if we found a mnemonic
 628                 if (state >= 3000)
 629                 {
 630                         risccg(state);
 631                         goto loop;
 632                 }
 633         }
 634
 635         // Invoke macro or complain about bad mnemonic
 636         if (state < 0)
 637         {
 638                 if ((sy = lookup(opname, MACRO, 0)) != NULL)
 639                         InvokeMacro(sy, siz);
 640                 else
 641                         errors("unknown op '%s'", opname);
 642
 643                 goto loop;
 644         }
 645
 646         // Call directive handlers
 647         if (state < 500)
 648         {
 649                 (*dirtab[state])(siz);
 650                 goto loop;
 651         }
 652
 653         // Do mnemonics
 654         // o  can't deposit instrs in BSS or ABS
 655         // o  do automatic .EVEN for instrs
 656         // o  allocate space for largest possible instr
 657         // o  can't do ".b" operations with an address register
 658         if (scattr & SBSS)
 659         {
 660                 error("cannot initialize non-storage (BSS) section");
 661                 goto loop;
 662         }
 663
 664         if (sloc & 1)                                                   // Automatic .even
 665                 auto_even();
 666
 667         if (challoc - ch_size < 18)                             // Make sure have space in current chunk
 668                 chcheck(0);
 669
 670         m = &machtab[state - 1000];
 671
 672         // Call special-mode handler
 673         if (m->mnattr & CGSPECIAL)
 674         {
 675                 (*m->mnfunc)(m->mninst, siz);
 676                 goto loop;
 677         }
 678
 679         if (amode(1) < 0)                                               // Parse 0, 1 or 2 addr modes
 680                 goto loop;
 681
 682         if (*tok != EOL)
 683                 error(extra_stuff);
 684
 685         amsk0 = amsktab[am0];
 686         amsk1 = amsktab[am1];
 687
 688         // Catch attempts to use ".B" with an address register (yes, this check
 689         // does work at this level)
 690         if (siz == SIZB && (am0 == AREG || am1 == AREG))
 691         {
 692                 error("cannot use '.b' with an address register");
 693                 goto loop;
 694         }
 695
 696         for(;;)
 697         {
 698                 if ((m->mnattr & siz) && (amsk0 & m->mn0) != 0 && (amsk1 & m->mn1) != 0)
 699                 {
 700                         (*m->mnfunc)(m->mninst, siz);
 701                         goto loop;
 702                 }
 703
 704                 m = &machtab[m->mncont];
 705         }
 706 }
 707
 708
 709 //
 710 // .if, Start Conditional Assembly
 711 //
 712 int d_if(void)
 713 {
 714         IFENT * rif;
 715         WORD eattr;
 716         VALUE eval;
 717         SYM * esym;
 718
 719         // Alloc an IFENTRY
 720         if ((rif = f_ifent) == NULL)
 721                 rif = (IFENT *)malloc(sizeof(IFENT));
 722         else
 723                 f_ifent = rif->if_prev;
 724
 725         rif->if_prev = ifent;
 726         ifent = rif;
 727
 728         if (!disabled)
 729         {
 730                 if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 731                         return 0;
 732
 733                 if ((eattr & DEFINED) == 0)
 734                         return error(undef_error);
 735
 736                 disabled = !eval;
 737         }
 738
 739         rif->if_state = (WORD)disabled;
 740         return 0;
 741 }
 742
 743
 744 //
 745 // .else, Do Alternate Case For .if
 746 //
 747 int d_else(void)
 748 {
 749         IFENT * rif = ifent;
 750
 751         if (rif->if_prev == NULL)
 752                 return error("mismatched .else");
 753
 754         if (disabled)
 755                 disabled = rif->if_prev->if_state;
 756         else
 757                 disabled = 1;
 758
 759         rif->if_state = (WORD)disabled;
 760         return 0;
 761 }
 762
 763
 764 //
 765 // .endif, End of conditional assembly block
 766 // This is also called by fpop() to pop levels of IFENTs in case a macro or
 767 // include file exits early with `exitm' or `end'.
 768 //
 769 int d_endif (void)
 770 {
 771         IFENT * rif = ifent;
 772
 773         if (rif->if_prev == NULL)
 774                 return error("mismatched .endif");
 775
 776         ifent = rif->if_prev;
 777         disabled = rif->if_prev->if_state;
 778         rif->if_prev = f_ifent;
 779         f_ifent = rif;
 780         return 0;
 781 }