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 "riscasm.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
  33 IFENT * ifent;                                  // Current ifent
  34 static IFENT ifent0;                    // Root ifent
  35 static IFENT * f_ifent;                 // Freelist of ifents
  36 static int disabled;                    // Assembly conditionally disabled
  37 int just_bss;                                   // 1, ds.b in microprocessor mode
  38 VALUE pcloc;                                    // Value of "PC" at beginning of line
  39 IFENT * ifent;                                  // Current ifent
  40 SYM * lab_sym;                                  // Label on line (or NULL)
  41
  42 const char extra_stuff[] = "extra (unexpected) text found after addressing mode";
  43 const char comma_error[] = "missing comma";
  44 const char syntax_error[] = "syntax error";
  45 const char locgl_error[] = "cannot GLOBL local symbol";
  46 const 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 InitLineProcessor(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         listflag = 0;                           // Initialise listing flag
 131
 132 loop:                                                   // Line processing loop label
 133
 134         // Get another line of tokens
 135         if (TokenizeLine() == 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 = string[tok[1]];
 183                 equtyp = j;
 184                 tok += 3;
 185                 goto normal;
 186         }
 187
 188         // Skip past label (but record it)
 189         if (j == ':' || j == DCOLON)
 190         {
 191 as68label:
 192 //              label = (char *)tok[1];                         // Get label name
 193                 label = string[tok[1]];                         // Get label name
 194                 labtyp = tok[2];                                        // Get label type
 195                 tok += 3;                                                       // Go to next line token
 196
 197                 // Handle multiple labels; if there's another label, go process it,
 198                 // and come back at `as68label' above.
 199                 if (as68_flag)
 200                 {
 201                         as68mode = 0;
 202
 203                         if (*tok == SYMBOL && tok[2] == ':')
 204                         {
 205                                 as68mode = 1;
 206                                 goto do_label;
 207                         }
 208                 }
 209         }
 210
 211         if (*tok == EOL)                                                // EOL is legal here...
 212                 goto normal;
 213
 214         // Next token MUST be a symbol
 215         if (*tok++ != SYMBOL)
 216         {
 217                 error(syntax_error);
 218                 goto loop;
 219         }
 220
 221 // This is the problem here: On 64-bit platforms, this cuts the native pointer
 222 // in half. We need to figure out how to fix this.
 223 //#warning "!!! Bad pointer !!!"
 224 #if 0
 225         opname = p = (char *)*tok++;                    // Store opcode name here
 226 #else
 227         opname = p = string[*tok++];
 228 #endif
 229
 230         // Check to see if the SYMBOL is a keyword (a mnemonic or directive).
 231         // On output, `state' will have one of the values:
 232         //    -3          there was no symbol (EOL)
 233         //    -2..-1      the symbol didn't match any keyword
 234         //    0..499      vanilla directives (dc, ds, etc.)
 235         //    500..999    electric directives (macro, rept, etc.)
 236         //    1000..+     mnemonics (move, lsr, etc.)
 237         for(state=0; state>=0;)
 238         {
 239                 j = mnbase[state] + (int)tolowertab[*p];
 240
 241                 // Reject, character doesn't match
 242                 if (mncheck[j] != state)
 243                 {
 244                         state = -1;                                             // No match
 245                         break;
 246                 }
 247
 248                 // Must accept or reject at EOS
 249                 if (!*++p)
 250                 {
 251                         state = mnaccept[j];                    // (-1 on no terminal match)
 252                         break;
 253                 }
 254
 255                 state = mntab[j];
 256         }
 257
 258         // Check for ".b" ".w" ".l" after directive, macro or mnemonic.
 259         siz = SIZN;
 260
 261         if (*tok == DOTW)
 262                 siz = SIZW, ++tok;
 263         else if (*tok == DOTL)
 264                 siz = SIZL, ++tok;
 265         else if (*tok == DOTB)
 266                 siz = SIZB, ++tok;
 267
 268         // Do special directives (500..999) (These must be handled in "real time")
 269         if (state >= 500 && state < 1000)
 270         {
 271                 switch (state)
 272                 {
 273                 case MN_IF:
 274                         d_if ();
 275                 goto loop;
 276                 case MN_ELSE:
 277                         d_else();
 278                         goto loop;
 279                 case MN_ENDIF:
 280                         d_endif ();
 281                         goto loop;
 282                 case MN_IIF:                                            // .iif --- immediate if
 283                         if (disabled || expr(exprbuf, &eval, &eattr, &esym) != OK)
 284                                 goto loop;
 285
 286                         if (!(eattr & DEFINED))
 287                         {
 288                                 error(undef_error);
 289                                 goto loop;
 290                         }
 291
 292                         if (*tok++ != ',')
 293                         {
 294                                 error(comma_error);
 295                                 goto loop;
 296                         }
 297
 298                         if (eval == 0)
 299                                 goto loop;
 300
 301                         goto loop1;
 302                 case MN_MACRO:                                          // .macro --- macro definition
 303                         if (!disabled)
 304                         {
 305                                 if (label != NULL)
 306                                         warn(lab_ignored);
 307
 308                                 DefineMacro();
 309                         }
 310
 311                         goto loop;
 312                 case MN_EXITM:                                          // .exitm --- exit macro
 313                 case MN_ENDM:                                           // .endm --- same as .exitm
 314                         if (!disabled)
 315                         {
 316                                 if (label != NULL)
 317                                         warn(lab_ignored);
 318
 319                                 ExitMacro();
 320                         }
 321
 322                         goto loop;
 323                 case MN_REPT:
 324                         if (!disabled)
 325                         {
 326                                 if (label != NULL)
 327                                         warn(lab_ignored);
 328
 329                                 defrept();
 330                         }
 331
 332                         goto loop;
 333                 case MN_ENDR:
 334                         if (!disabled)
 335                                 error("mis-nested .endr");
 336
 337                         goto loop;
 338                 }
 339         }
 340
 341 normal:
 342         if (disabled)                                                   // Conditionally disabled code
 343                 goto loop;
 344
 345         // Do equates
 346         if (equate != NULL)
 347         {
 348                 // Pick global or local symbol enviroment
 349 #if 0
 350                 j = 0;
 351
 352                 if (*equate == '.')
 353                         j = curenv;
 354 #else
 355                 j = (*equate == '.' ? curenv : 0);
 356 #endif
 357                 sy = lookup(equate, LABEL, j);
 358
 359                 if (sy == NULL)
 360                 {
 361                         sy = NewSymbol(equate, LABEL, j);
 362                         sy->sattr = 0;
 363
 364                         if (equtyp == DEQUALS)
 365                         {
 366                                 // Can't GLOBAL a local symbol
 367                                 if (j)
 368                                 {
 369                                         error(locgl_error);
 370                                         goto loop;
 371                                 }
 372
 373                                 sy->sattr = GLOBAL;
 374                         }
 375                 }
 376                 else if ((sy->sattr & DEFINED) && equtyp != SET)
 377                 {
 378                         if ((equtyp == EQUREG) && (sy->sattre & UNDEF_EQUR))
 379                         {
 380 //REALLY?                               sy->sattre |= ~UNDEF_EQUR;
 381                                 sy->sattre &= ~UNDEF_EQUR;
 382                                 sy->svalue  = 0;
 383                         }
 384                         else if ((equtyp == CCDEF) && (sy->sattre & UNDEF_CC))
 385                         {
 386 //REALLY?                               sy->sattre |= ~UNDEF_CC;
 387                                 sy->sattre &= ~UNDEF_CC;
 388                                 sy->svalue = 0;
 389                         }
 390                         else
 391                         {
 392                                 errors("multiple equate to '%s'", sy->sname);
 393                                 goto loop;
 394                         }
 395                 }
 396
 397                 // Put symbol in "order of definition" list
 398                 if (!(sy->sattr & SDECLLIST))
 399                         sym_decl(sy);
 400
 401                 // Parse value to equate symbol to;
 402                 // o  .equr
 403                 // o  .reg
 404                 // o  everything else
 405                 if (equtyp == EQUREG)
 406                 {
 407 //Linko's request to issue a warning on labels that equated to the same register
 408 //would go here. Not sure how to implement it though. :-/
 409 /*
 410 Maybe like this way:
 411 have an array of bools with 64 entries. Whenever a register is equated, set the
 412 corresponding register bool to true. Whenever it's undef'ed, set it to false. When
 413 checking to see if it's already been equated, issue a warning.
 414 */
 415                         // Check that we are in a RISC section
 416                         if (!rgpu && !rdsp)
 417                         {
 418                                 error(".equr/.regequ must be defined in .gpu/.dsp section");
 419                                 goto loop;
 420                         }
 421
 422                         // Check for register to equate to
 423                         if ((*tok >= KW_R0) && (*tok <= KW_R31))
 424                         {
 425                                 sy->sattre  = EQUATEDREG | RISCSYM;     // Mark as equated register
 426                                 riscreg = (*tok - KW_R0);
 427 //is there any reason to do this, since we're putting this in svalue?
 428 //i'm thinking, no. Let's test that out! :-D
 429 //                              sy->sattre |= (riscreg << 8);           // Store register number
 430 //everything seems to build fine without it... We'll leave it here Just In Case(tm)
 431
 432 #define DEBODGE_REGBANK
 433 #ifdef DEBODGE_REGBANK
 434                                 // Default is current state of "regbank"
 435                                 registerbank = regbank;
 436 #else
 437                                 // Default is no register bank specified
 438                                 registerbank = BANK_N;
 439 #endif
 440
 441                                 // Check for ",<bank #>" override notation
 442                                 if ((tok[1] == ',') && (tok[2] == CONST))
 443                                 {
 444                                         // Advance token pointer to the constant
 445                                         tok += 3;
 446
 447                                         // Anything other than a 0 or a 1 will result in "No Bank"
 448                                         if (*tok == 0)
 449                                                 registerbank = BANK_0;
 450                                         else if (*tok == 1)
 451                                                 registerbank = BANK_1;
 452                                 }
 453
 454 #ifdef DEBODGE_REGBANK
 455                                 sy->sattre |= registerbank;     // Store register bank
 456 #else
 457 // What needs to happen here is to prime registerbank with regbank, then use
 458 // registerbank down below for the bank marking.
 459 #warning "!!! regbank <-> registerbank confusion here !!!"
 460 // The question here is why, if we're allowed to override the ".regbankN" rules above,
 461 // then why is it using the one set by the directive in the extended attributes and
 462 // not in what ends up in symbol->svalue?
 463 // ".regbankN" is not an original Madmac directive, so it's suspect
 464                                 sy->sattre |= regbank;          // Store register bank
 465 #endif
 466                                 eattr = ABS | DEFINED | GLOBAL;
 467 // & what does this $80000080 constant mean???
 468 //                              eval = 0x80000080 + (riscreg) + (registerbank << 8);
 469                                 eval = riscreg;
 470                                 tok++;
 471                         }
 472                         // Checking for a register symbol
 473                         else if (tok[0] == SYMBOL)
 474                         {
 475                                 sy2 = lookup(string[tok[1]], LABEL, j);
 476
 477                                 // Make sure symbol is a valid equreg
 478                                 if (!sy2 || !(sy2->sattre & EQUATEDREG))
 479                                 {
 480                                         error("invalid GPU/DSP .equr/.regequ definition");
 481                                         goto loop;
 482                                 }
 483                                 else
 484                                 {
 485                                         eattr = ABS | DEFINED | GLOBAL; // Copy symbols attributes
 486                                         sy->sattre = sy2->sattre;
 487                                         eval = (sy2->svalue & 0xFFFFF0FF);
 488                                         tok += 2;
 489                                 }
 490                         }
 491                         else
 492                         {
 493                                 error("invalid GPU/DSP .equr/.regequ definition");
 494                                 goto loop;
 495                         }
 496                 }
 497                 else if (equtyp == REG)
 498                 {
 499                         if (reglist(&rmask) < 0)
 500                                 goto loop;
 501
 502                         eval = (VALUE)rmask;
 503                         eattr = ABS | DEFINED;
 504                 }
 505                 else if (equtyp == CCDEF)
 506                 {
 507                         sy->sattre |= EQUATEDCC;
 508                         eattr = ABS | DEFINED | GLOBAL;
 509
 510                         if (tok[0] == SYMBOL)
 511                         {
 512                                 sy2 = lookup(string[tok[1]], LABEL, j);
 513
 514                                 if (!sy2 || !(sy2->sattre & EQUATEDCC))
 515                                 {
 516                                         error("invalid gpu/dsp .ccdef definition");
 517                                         goto loop;
 518                                 }
 519                                 else
 520                                 {
 521                                         eattr = ABS | DEFINED | GLOBAL;
 522                                         sy->sattre = sy2->sattre;
 523                                         eval = sy2->svalue;
 524                                         tok += 2;
 525                                 }
 526                         }
 527                         else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 528                                 goto loop;
 529                 }
 530                 //equ a equr
 531                 else if (*tok == SYMBOL)
 532                 {
 533                         sy2 = lookup(string[tok[1]], LABEL, j);
 534
 535                         if (sy2 && (sy2->sattre & EQUATEDREG))
 536                         {
 537                                 sy->stype = sy2->stype;
 538                                 sy->sattr = sy2->sattr;
 539                                 sy->sattre = sy2->sattre;
 540 //ICK                           sy->svalue = (sy2->svalue & 0xFFFFF0FF);
 541                                 sy->svalue = sy2->svalue;
 542                                 goto loop;
 543                         }
 544                         else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 545                                 goto loop;
 546                 }
 547                 else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 548                         goto loop;
 549
 550                 if (!(eattr & DEFINED))
 551                 {
 552                         error(undef_error);
 553                         goto loop;
 554                 }
 555
 556                 sy->sattr |= eattr | EQUATED;           // Symbol inherits value and attributes
 557                 sy->svalue = eval;
 558
 559                 if (list_flag)                                          // Put value in listing
 560                         listvalue(eval);
 561
 562                 at_eol();                                                       // Must be at EOL now
 563                 goto loop;
 564         }
 565
 566         // Do labels
 567         if (label != NULL)
 568         {
 569 do_label:
 570                 // Check for dot in front of label; means this is a local label if present
 571                 j = (*label == '.' ? curenv : 0);
 572                 sy = lookup(label, LABEL, j);
 573
 574                 if (sy == NULL)
 575                 {
 576                         sy = NewSymbol(label, LABEL, j);
 577                         sy->sattr = 0;
 578                         sy->sattre = RISCSYM;
 579                 }
 580                 else if (sy->sattr & DEFINED)
 581                 {
 582                         errors("multiply-defined label '%s'", label);
 583                         goto loop;
 584                 }
 585
 586                 // Put symbol in "order of definition" list
 587                 if (!(sy->sattr & SDECLLIST))
 588                         sym_decl(sy);
 589
 590                 if (orgactive)
 591                 {
 592                         sy->svalue = orgaddr;
 593                         sy->sattr |= ABS | DEFINED | EQUATED;
 594                 }
 595                 else
 596                 {
 597                         sy->svalue = sloc;
 598                         sy->sattr |= DEFINED | cursect;
 599                 }
 600
 601                 lab_sym = sy;
 602
 603                 if (!j)
 604                         curenv++;
 605
 606                 // Make label global
 607                 if (labtyp == DCOLON)
 608                 {
 609                         if (j)
 610                         {
 611                                 error(locgl_error);
 612                                 goto loop;
 613                         }
 614
 615                         sy->sattr |= GLOBAL;
 616                 }
 617
 618                 // If we're in as68 mode, and there's another label, go back and handle it
 619                 if (as68_flag && as68mode)
 620                         goto as68label;
 621         }
 622
 623         // Punt on EOL
 624         if (state == -3)
 625                 goto loop;
 626
 627         // If we are in GPU or DSP mode and still in need of a mnemonic then search
 628         // for one
 629         if ((rgpu || rdsp) && (state < 0 || state >= 1000))
 630         {
 631                 for(state=0, p=opname; state>=0;)
 632                 {
 633                         j = mrbase[state] + (int)tolowertab[*p];
 634
 635                         // Reject, character doesn't match
 636                         if (mrcheck[j] != state)
 637                         {
 638                                 state = -1;                                     // No match
 639                                 break;
 640                         }
 641
 642                         // Must accept or reject at EOS
 643                         if (!*++p)
 644                         {
 645                                 state = mraccept[j];            // (-1 on no terminal match)
 646                                 break;
 647                         }
 648
 649                         state = mrtab[j];
 650                 }
 651
 652                 // Call RISC code generator if we found a mnemonic
 653                 if (state >= 3000)
 654                 {
 655                         GenerateRISCCode(state);
 656                         goto loop;
 657                 }
 658         }
 659
 660         // Invoke macro or complain about bad mnemonic
 661         if (state < 0)
 662         {
 663                 if ((sy = lookup(opname, MACRO, 0)) != NULL)
 664                         InvokeMacro(sy, siz);
 665                 else
 666                         errors("unknown op '%s'", opname);
 667
 668                 goto loop;
 669         }
 670
 671         // Call directive handlers
 672         if (state < 500)
 673         {
 674                 (*dirtab[state])(siz);
 675                 goto loop;
 676         }
 677
 678         // Do mnemonics
 679         // o  can't deposit instrs in BSS or ABS
 680         // o  do automatic .EVEN for instrs
 681         // o  allocate space for largest possible instr
 682         // o  can't do ".b" operations with an address register
 683         if (scattr & SBSS)
 684         {
 685                 error("cannot initialize non-storage (BSS) section");
 686                 goto loop;
 687         }
 688
 689         if (sloc & 1)                                                   // Automatic .even
 690                 auto_even();
 691
 692         if (challoc - ch_size < 18)                             // Make sure have space in current chunk
 693                 chcheck(0);
 694
 695         m = &machtab[state - 1000];
 696
 697         // Call special-mode handler
 698         if (m->mnattr & CGSPECIAL)
 699         {
 700                 (*m->mnfunc)(m->mninst, siz);
 701                 goto loop;
 702         }
 703
 704         if (amode(1) < 0)                                               // Parse 0, 1 or 2 addr modes
 705                 goto loop;
 706
 707         if (*tok != EOL)
 708                 error(extra_stuff);
 709
 710         amsk0 = amsktab[am0];
 711         amsk1 = amsktab[am1];
 712
 713         // Catch attempts to use ".B" with an address register (yes, this check
 714         // does work at this level)
 715         if (siz == SIZB && (am0 == AREG || am1 == AREG))
 716         {
 717                 error("cannot use '.b' with an address register");
 718                 goto loop;
 719         }
 720
 721         for(;;)
 722         {
 723                 if ((m->mnattr & siz) && (amsk0 & m->mn0) != 0 && (amsk1 & m->mn1) != 0)
 724                 {
 725                         (*m->mnfunc)(m->mninst, siz);
 726                         goto loop;
 727                 }
 728
 729                 m = &machtab[m->mncont];
 730         }
 731 }
 732
 733
 734 //
 735 // .if, Start Conditional Assembly
 736 //
 737 int d_if(void)
 738 {
 739         IFENT * rif;
 740         WORD eattr;
 741         VALUE eval;
 742         SYM * esym;
 743
 744         // Alloc an IFENTRY
 745         if ((rif = f_ifent) == NULL)
 746                 rif = (IFENT *)malloc(sizeof(IFENT));
 747         else
 748                 f_ifent = rif->if_prev;
 749
 750         rif->if_prev = ifent;
 751         ifent = rif;
 752
 753         if (!disabled)
 754         {
 755                 if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 756                         return 0;
 757
 758                 if ((eattr & DEFINED) == 0)
 759                         return error(undef_error);
 760
 761                 disabled = !eval;
 762         }
 763
 764         rif->if_state = (WORD)disabled;
 765         return 0;
 766 }
 767
 768
 769 //
 770 // .else, Do Alternate Case For .if
 771 //
 772 int d_else(void)
 773 {
 774         IFENT * rif = ifent;
 775
 776         if (rif->if_prev == NULL)
 777                 return error("mismatched .else");
 778
 779         if (disabled)
 780                 disabled = rif->if_prev->if_state;
 781         else
 782                 disabled = 1;
 783
 784         rif->if_state = (WORD)disabled;
 785         return 0;
 786 }
 787
 788
 789 //
 790 // .endif, End of conditional assembly block
 791 // This is also called by fpop() to pop levels of IFENTs in case a macro or
 792 // include file exits early with `exitm' or `end'.
 793 //
 794 int d_endif (void)
 795 {
 796         IFENT * rif = ifent;
 797
 798         if (rif->if_prev == NULL)
 799                 return error("mismatched .endif");
 800
 801         ifent = rif->if_prev;
 802         disabled = rif->if_prev->if_state;
 803         rif->if_prev = f_ifent;
 804         f_ifent = rif;
 805         return 0;
 806 }