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, 2017 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 #define DEF_MP                  /* include 6502 keyword definitions */
  33 #define DECL_MP                 /* include 6502 keyword state machine tables */
  34 #include "6502.h"
  35 extern int m6502;               /* 1, assembler in .6502 mode */
  36 extern VOID m6502cg();          /* 6502 code generator */
  37 extern VOID m6502obj(int ofd);
  38
  39 IFENT * ifent;                                  // Current ifent
  40 static IFENT ifent0;                    // Root ifent
  41 static IFENT * f_ifent;                 // Freelist of ifents
  42 static int disabled;                    // Assembly conditionally disabled
  43 int just_bss;                                   // 1, ds.b in microprocessor mode
  44 VALUE pcloc;                                    // Value of "PC" at beginning of line
  45 SYM * lab_sym;                                  // Label on line (or NULL)
  46
  47 const char extra_stuff[] = "extra (unexpected) text found after addressing mode";
  48 const char comma_error[] = "missing comma";
  49 const char syntax_error[] = "syntax error";
  50 const char locgl_error[] = "cannot GLOBL local symbol";
  51 const char lab_ignored[] = "label ignored";
  52
  53 // Table to convert an addressing-mode number to a bitmask.
  54 LONG amsktab[0112] = {
  55         M_DREG, M_DREG, M_DREG, M_DREG,
  56         M_DREG, M_DREG, M_DREG, M_DREG,
  57
  58         M_AREG, M_AREG, M_AREG, M_AREG,
  59         M_AREG, M_AREG, M_AREG, M_AREG,
  60
  61         M_AIND, M_AIND, M_AIND, M_AIND,
  62         M_AIND, M_AIND, M_AIND, M_AIND,
  63
  64         M_APOSTINC, M_APOSTINC, M_APOSTINC, M_APOSTINC,
  65         M_APOSTINC, M_APOSTINC, M_APOSTINC, M_APOSTINC,
  66
  67         M_APREDEC, M_APREDEC, M_APREDEC, M_APREDEC,
  68         M_APREDEC, M_APREDEC, M_APREDEC, M_APREDEC,
  69
  70         M_ADISP, M_ADISP, M_ADISP, M_ADISP,
  71         M_ADISP, M_ADISP, M_ADISP, M_ADISP,
  72
  73         M_AINDEXED, M_AINDEXED, M_AINDEXED, M_AINDEXED,
  74         M_AINDEXED, M_AINDEXED, M_AINDEXED, M_AINDEXED,
  75
  76         M_ABSW,                                                                                 // 070
  77         M_ABSL,                                                                                 // 071
  78         M_PCDISP,                                                                               // 072
  79         M_PCINDEXED,                                                                    // 073
  80         M_IMMED,                                                                                // 074
  81         0L,                                                                                             // 075
  82         0L,                                                                                             // 076
  83         0L,                                                                                             // 077
  84         M_ABASE,                                                                                // 0100
  85         M_MEMPOST,                                                                              // 0101
  86         M_MEMPRE,                                                                               // 0102
  87         M_PCBASE,                                                                               // 0103
  88         M_PCMPOST,                                                                              // 0104
  89         M_PCMPRE,                                                                               // 0105
  90         M_AM_USP,                                                                               // 0106
  91         M_AM_SR,                                                                                // 0107
  92         M_AM_CCR,                                                                               // 0110
  93         M_AM_NONE                                                                               // 0111
  94 };                                                                                                      // 0112 length
  95
  96
  97 // Function prototypes
  98 int HandleLabel(char *, int);
  99
 100
 101 //
 102 // Initialize line processor
 103 //
 104 void InitLineProcessor(void)
 105 {
 106         disabled = 0;
 107         ifent = &ifent0;
 108         f_ifent = ifent0.if_prev = NULL;
 109         ifent0.if_state = 0;
 110 }
 111
 112
 113 //
 114 // Line processor
 115 //
 116 void Assemble(void)
 117 {
 118         int state;                                      // Keyword machine state (output)
 119         int j;                                          // Random int, must be fast
 120         char * p;                                       // Random char ptr, must be fast
 121         TOKEN * tk;                                     // First token in line
 122         char * label;                           // Symbol (or NULL)
 123         char * equate;                          // Symbol (or NULL)
 124         int labtyp = 0;                         // Label type (':', DCOLON)
 125         int equtyp = 0;                         // Equ type ('=', DEQUALS)
 126         VALUE eval;                                     // Expression value
 127         WORD eattr;                                     // Expression attributes
 128         SYM * esym;                                     // External symbol involved in expr.
 129         WORD siz = 0;                           // Size suffix to mnem/diretve/macro
 130         LONG amsk0, amsk1;                      // Address-type masks for ea0, ea1
 131         MNTAB * m;                                      // Code generation table pointer
 132         SYM * sy, * sy2;                        // Symbol (temp usage)
 133         char * opname = NULL;           // Name of dirctve/mnemonic/macro
 134         int listflag;                           // 0: Don't call listeol()
 135         WORD rmask;                                     // Register list, for REG
 136         int registerbank;                       // RISC register bank
 137         int riscreg;                            // RISC register
 138         listflag = 0;                           // Initialise listing flag
 139
 140 loop:                                                   // Line processing loop label
 141
 142         // Get another line of tokens
 143         if (TokenizeLine() == TKEOF)
 144         {
 145 if (debug) printf("Assemble: Found TKEOF flag...\n");
 146                 if (list_flag && listflag)                      // Flush last line of source
 147                         listeol();
 148
 149                 if (ifent->if_prev != NULL)                     // Check conditional token
 150                         error("hit EOF without finding matching .endif");
 151
 152                 return;
 153         }
 154
 155         DEBUG DumpTokenBuffer();
 156
 157         if (list_flag)
 158         {
 159                 if (listflag && listing > 0)
 160                         listeol();                                              // Tell listing generator about EOL
 161
 162                 lstout((char)(disabled ? '-' : lntag)); // Prepare new line for listing
 163                 listflag = 1;                                           // OK to call `listeol' now
 164                 just_bss = 0;                                           // Reset just_bss mode
 165         }
 166
 167         state = -3;                                                             // No keyword (just EOL)
 168         label = NULL;                                                   // No label
 169         lab_sym = NULL;                                                 // No (exported) label
 170         equate = NULL;                                                  // No equate
 171         tk = tok;                                                               // Save first token in line
 172         pcloc = (VALUE)sloc;                                    // Set beginning-of-line PC
 173
 174 loop1:                                                                          // Internal line processing loop
 175
 176         if (*tok == EOL)                                                // Restart loop if end-of-line
 177                 goto loop;
 178
 179         // First token MUST be a symbol (Shamus: not sure why :-/)
 180         if (*tok != SYMBOL)
 181         {
 182                 error("syntax error; expected symbol");
 183                 goto loop;
 184         }
 185
 186         j = (int)tok[2];                                                // Skip equates (normal statements)
 187
 188         if (j == '=' || j == DEQUALS || j == SET || j == REG || j == EQUREG || j == CCDEF)
 189         {
 190                 equate = string[tok[1]];
 191                 equtyp = j;
 192                 tok += 3;
 193                 goto normal;
 194         }
 195
 196         // Skip past label (but record it)
 197         if (j == ':' || j == DCOLON)
 198         {
 199 as68label:
 200                 label = string[tok[1]];                         // Get label name
 201                 labtyp = tok[2];                                        // Get label type
 202                 tok += 3;                                                       // Go to next line token
 203
 204                 // AS68 MODE:
 205                 // Looks like another label follows the previous one, so handle
 206                 // the previous one until there aren't any more
 207                 if (as68_flag && (*tok == SYMBOL && tok[2] == ':'))
 208                 {
 209                         if (HandleLabel(label, labtyp) != 0)
 210                                 goto loop;
 211
 212                         goto as68label;
 213                 }
 214         }
 215
 216         // EOL is legal here...
 217         if (*tok == EOL)
 218                 goto normal;
 219
 220         // Next token MUST be a symbol
 221         if (*tok++ != SYMBOL)
 222         {
 223                 error("syntax error; expected symbol");
 224                 goto loop;
 225         }
 226
 227         opname = p = string[*tok++];
 228
 229         // Check to see if the SYMBOL is a keyword (a mnemonic or directive).
 230         // On output, `state' will have one of the values:
 231         //    -3          there was no symbol (EOL)
 232         //    -2..-1      the symbol didn't match any keyword
 233         //    0..499      vanilla directives (dc, ds, etc.)
 234         //    500..999    electric directives (macro, rept, etc.)
 235         //    1000..+     mnemonics (move, lsr, etc.)
 236         for(state=0; state>=0;)
 237         {
 238                 j = mnbase[state] + (int)tolowertab[*p];
 239
 240                 // Reject, character doesn't match
 241                 if (mncheck[j] != state)
 242                 {
 243                         state = -1;                                             // No match
 244                         break;
 245                 }
 246
 247                 // Must accept or reject at EOS
 248                 if (!*++p)
 249                 {
 250                         state = mnaccept[j];                    // (-1 on no terminal match)
 251                         break;
 252                 }
 253
 254                 state = mntab[j];
 255         }
 256
 257         // Check for ".b" ".w" ".l" after directive, macro or mnemonic.
 258         siz = SIZN;
 259
 260         if (*tok == DOTW)
 261                 siz = SIZW, tok++;
 262         else if (*tok == DOTL)
 263                 siz = SIZL, tok++;
 264         else if (*tok == DOTB)
 265                 siz = SIZB, tok++;
 266
 267         // Do special directives (500..999) (These must be handled in "real time")
 268         if (state >= 500 && state < 1000)
 269         {
 270                 switch (state)
 271                 {
 272                 case MN_IF:
 273                         d_if();
 274                 goto loop;
 275                 case MN_ELSE:
 276                         d_else();
 277                         goto loop;
 278                 case MN_ENDIF:
 279                         d_endif();
 280                         goto loop;
 281                 case MN_IIF:                                            // .iif --- immediate if
 282                         if (disabled || expr(exprbuf, &eval, &eattr, &esym) != OK)
 283                                 goto loop;
 284
 285                         if (!(eattr & DEFINED))
 286                         {
 287                                 error(undef_error);
 288                                 goto loop;
 289                         }
 290
 291                         if (*tok++ != ',')
 292                         {
 293                                 error(comma_error);
 294                                 goto loop;
 295                         }
 296
 297                         if (eval == 0)
 298                                 goto loop;
 299
 300                         goto loop1;
 301                 case MN_MACRO:                                          // .macro --- macro definition
 302                         if (!disabled)
 303                         {
 304                                 // Label on a macro definition is bad mojo... Warn the user
 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                                 // Handle labels on REPT directive lines...
 327                                 if (label)
 328                                 {
 329                                         if (HandleLabel(label, labtyp) != 0)
 330                                                 goto loop;
 331                                 }
 332
 333                                 defrept();
 334                         }
 335
 336                         goto loop;
 337                 case MN_ENDR:
 338                         if (!disabled)
 339                                 error("mis-nested .endr");
 340
 341                         goto loop;
 342                 }
 343         }
 344
 345 normal:
 346         if (disabled)                                                   // Conditionally disabled code
 347                 goto loop;
 348
 349         // Do equates
 350         if (equate != NULL)
 351         {
 352                 // Pick global or local symbol enviroment
 353                 j = (*equate == '.' ? curenv : 0);
 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 //REALLY?                               sy->sattre |= ~UNDEF_EQUR;
 378                                 sy->sattre &= ~UNDEF_EQUR;
 379                                 sy->svalue = 0;
 380                         }
 381                         else if ((equtyp == CCDEF) && (sy->sattre & UNDEF_CC))
 382                         {
 383 //REALLY?                               sy->sattre |= ~UNDEF_CC;
 384                                 sy->sattre &= ~UNDEF_CC;
 385                                 sy->svalue = 0;
 386                         }
 387                         else
 388                         {
 389                                 errors("multiple equate to '%s'", sy->sname);
 390                                 goto loop;
 391                         }
 392                 }
 393
 394                 // Put symbol in "order of definition" list if it's not already there
 395                 AddToSymbolDeclarationList(sy);
 396
 397                 // Parse value to equate symbol to;
 398                 // o  .equr
 399                 // o  .reg
 400                 // o  everything else
 401                 if (equtyp == EQUREG)
 402                 {
 403 //Linko's request to issue a warning on labels that equated to the same
 404 //register would go here. Not sure how to implement it though. :-/
 405 /*
 406 Maybe like this way:
 407 have an array of bools with 64 entries. Whenever a register is equated, set the
 408 corresponding register bool to true. Whenever it's undef'ed, set it to false.
 409 When checking to see if it's already been equated, issue a warning.
 410 */
 411                         // Check that we are in a RISC section
 412                         if (!rgpu && !rdsp)
 413                         {
 414                                 error(".equr/.regequ must be defined in .gpu/.dsp section");
 415                                 goto loop;
 416                         }
 417
 418                         // Check for register to equate to
 419                         if ((*tok >= KW_R0) && (*tok <= KW_R31))
 420                         {
 421 //                              sy->sattre  = EQUATEDREG | RISCSYM;     // Mark as equated register
 422                                 sy->sattre  = EQUATEDREG;       // Mark as equated register
 423                                 riscreg = (*tok - KW_R0);
 424 //is there any reason to do this, since we're putting this in svalue?
 425 //i'm thinking, no. Let's test that out! :-D
 426 //                              sy->sattre |= (riscreg << 8);           // Store register number
 427 //everything seems to build fine without it... We'll leave it here Just In Case(tm)
 428
 429 #define DEBODGE_REGBANK
 430 #ifdef DEBODGE_REGBANK
 431                                 // Default is current state of "regbank"
 432                                 registerbank = regbank;
 433 #else
 434                                 // Default is no register bank specified
 435                                 registerbank = BANK_N;
 436 #endif
 437
 438                                 // Check for ",<bank #>" override notation
 439                                 if ((tok[1] == ',') && (tok[2] == CONST))
 440                                 {
 441                                         // Advance token pointer to the constant
 442                                         tok += 3;
 443
 444                                         // Anything other than a 0 or a 1 will result in "No Bank"
 445                                         if (*tok == 0)
 446                                                 registerbank = BANK_0;
 447                                         else if (*tok == 1)
 448                                                 registerbank = BANK_1;
 449                                 }
 450
 451 #ifdef DEBODGE_REGBANK
 452                                 sy->sattre |= registerbank;     // Store register bank
 453 #else
 454 // What needs to happen here is to prime registerbank with regbank, then use
 455 // registerbank down below for the bank marking.
 456 #warning "!!! regbank <-> registerbank confusion here !!!"
 457 // The question here is why, if we're allowed to override the ".regbankN" rules
 458 // above, then why is it using the one set by the directive in the extended
 459 // attributes and not in what ends up in symbol->svalue?
 460 // ".regbankN" is not an original Madmac directive, so it's suspect
 461                                 sy->sattre |= regbank;          // Store register bank
 462 #endif
 463                                 eattr = ABS | DEFINED | GLOBAL;
 464 // & what does this $80000080 constant mean???
 465 //                              eval = 0x80000080 + (riscreg) + (registerbank << 8);
 466                                 eval = riscreg;
 467                                 tok++;
 468                         }
 469                         // Checking for a register symbol
 470                         else if (tok[0] == SYMBOL)
 471                         {
 472                                 sy2 = lookup(string[tok[1]], LABEL, j);
 473
 474                                 // Make sure symbol is a valid equreg
 475                                 if (!sy2 || !(sy2->sattre & EQUATEDREG))
 476                                 {
 477                                         error("invalid GPU/DSP .equr/.regequ definition");
 478                                         goto loop;
 479                                 }
 480                                 else
 481                                 {
 482                                         eattr = ABS | DEFINED | GLOBAL; // Copy symbols attributes
 483                                         sy->sattre = sy2->sattre;
 484                                         eval = (sy2->svalue & 0xFFFFF0FF);
 485                                         tok += 2;
 486                                 }
 487                         }
 488                         else
 489                         {
 490                                 error("invalid GPU/DSP .equr/.regequ definition");
 491                                 goto loop;
 492                         }
 493                 }
 494                 else if (equtyp == REG)
 495                 {
 496                         if (reglist(&rmask) < 0)
 497                                 goto loop;
 498
 499                         eval = (VALUE)rmask;
 500                         eattr = ABS | DEFINED;
 501                 }
 502                 else if (equtyp == CCDEF)
 503                 {
 504                         sy->sattre |= EQUATEDCC;
 505                         eattr = ABS | DEFINED | GLOBAL;
 506
 507                         if (tok[0] == SYMBOL)
 508                         {
 509                                 sy2 = lookup(string[tok[1]], LABEL, j);
 510
 511                                 if (!sy2 || !(sy2->sattre & EQUATEDCC))
 512                                 {
 513                                         error("invalid gpu/dsp .ccdef definition");
 514                                         goto loop;
 515                                 }
 516                                 else
 517                                 {
 518                                         eattr = ABS | DEFINED | GLOBAL;
 519                                         sy->sattre = sy2->sattre;
 520                                         eval = sy2->svalue;
 521                                         tok += 2;
 522                                 }
 523                         }
 524                         else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 525                                 goto loop;
 526                 }
 527                 //equ a equr
 528                 else if (*tok == SYMBOL)
 529                 {
 530                         sy2 = lookup(string[tok[1]], LABEL, j);
 531
 532                         if (sy2 && (sy2->sattre & EQUATEDREG))
 533                         {
 534                                 sy->stype = sy2->stype;
 535                                 sy->sattr = sy2->sattr;
 536                                 sy->sattre = sy2->sattre;
 537 //ICK                           sy->svalue = (sy2->svalue & 0xFFFFF0FF);
 538                                 sy->svalue = sy2->svalue;
 539                                 goto loop;
 540                         }
 541                         else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 542                                 goto loop;
 543                 }
 544                 else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 545                         goto loop;
 546
 547                 if (!(eattr & DEFINED))
 548                 {
 549                         error(undef_error);
 550                         goto loop;
 551                 }
 552
 553                 sy->sattr |= eattr | EQUATED;   // Symbol inherits value and attributes
 554                 sy->svalue = eval;
 555
 556                 if (list_flag)                                  // Put value in listing
 557                         listvalue(eval);
 558
 559                 at_eol();                                               // Must be at EOL now
 560                 goto loop;
 561         }
 562
 563         // Do labels
 564         if (label != NULL)
 565         {
 566                 // Non-zero == error occurred
 567                 if (HandleLabel(label, labtyp) != 0)
 568                         goto loop;
 569         }
 570
 571         // Punt on EOL
 572         if (state == -3)
 573                 goto loop;
 574
 575         /*
 576          *  If we're in 6502 mode and are still in need
 577          *  of a mnemonic, then search for valid 6502 mnemonic.
 578          */
 579         if (m6502 &&
 580                   (state < 0 || state >= 1000))
 581         {
 582 #ifdef ST
 583                 state = kmatch(opname, mpbase, mpcheck, mptab, mpaccept);
 584 #else
 585                 for (state = 0, p = opname; state >= 0;)
 586                 {
 587                         j = mpbase[state] + tolowertab[*p];
 588                         if (mpcheck[j] != state)        /* reject, character doesn't match */
 589                         {
 590                                 state = -1;             /* no match */
 591                                 break;
 592                         }
 593
 594                         if (!*++p)
 595                         {                       /* must accept or reject at EOS */
 596                                 state = mpaccept[j];    /* (-1 on no terminal match) */
 597                                 break;
 598                         }
 599                         state = mptab[j];
 600                 }
 601 #endif
 602
 603                 /*
 604                  *  Call 6502 code generator if we found a mnemonic
 605                  */
 606                 if (state >= 2000)
 607                 {
 608                         m6502cg(state - 2000);
 609                         goto loop;
 610                 }
 611         }
 612
 613         // If we are in GPU or DSP mode and still in need of a mnemonic then search
 614         // for one
 615         if ((rgpu || rdsp) && (state < 0 || state >= 1000))
 616         {
 617                 for(state=0, p=opname; state>=0;)
 618                 {
 619                         j = mrbase[state] + (int)tolowertab[*p];
 620
 621                         // Reject, character doesn't match
 622                         if (mrcheck[j] != state)
 623                         {
 624                                 state = -1;                                     // No match
 625                                 break;
 626                         }
 627
 628                         // Must accept or reject at EOS
 629                         if (!*++p)
 630                         {
 631                                 state = mraccept[j];            // (-1 on no terminal match)
 632                                 break;
 633                         }
 634
 635                         state = mrtab[j];
 636                 }
 637
 638                 // Call RISC code generator if we found a mnemonic
 639                 if (state >= 3000)
 640                 {
 641                         GenerateRISCCode(state);
 642                         goto loop;
 643                 }
 644         }
 645
 646         // Invoke macro or complain about bad mnemonic
 647         if (state < 0)
 648         {
 649                 if ((sy = lookup(opname, MACRO, 0)) != NULL)
 650                         InvokeMacro(sy, siz);
 651                 else
 652                         errors("unknown op '%s'", opname);
 653
 654                 goto loop;
 655         }
 656
 657         // Call directive handlers
 658         if (state < 500)
 659         {
 660                 (*dirtab[state])(siz);
 661                 goto loop;
 662         }
 663
 664         // Do mnemonics
 665         // o  can't deposit instrs in BSS or ABS
 666         // o  do automatic .EVEN for instrs
 667         // o  allocate space for largest possible instr
 668         // o  can't do ".b" operations with an address register
 669         if (scattr & SBSS)
 670         {
 671                 error("cannot initialize non-storage (BSS) section");
 672                 goto loop;
 673         }
 674
 675         if (sloc & 1)                                   // Automatic .even
 676                 auto_even();
 677
 678         if (challoc - ch_size < 18)             // Make sure have space in current chunk
 679                 chcheck(0);
 680
 681         m = &machtab[state - 1000];
 682
 683         // Call special-mode handler
 684         if (m->mnattr & CGSPECIAL)
 685         {
 686                 (*m->mnfunc)(m->mninst, siz);
 687                 goto loop;
 688         }
 689
 690         if (amode(1) < 0)                               // Parse 0, 1 or 2 addr modes
 691                 goto loop;
 692
 693         if (*tok != EOL)
 694                 error(extra_stuff);
 695
 696         amsk0 = amsktab[am0];
 697         amsk1 = amsktab[am1];
 698
 699         // Catch attempts to use ".B" with an address register (yes, this check
 700         // does work at this level)
 701         if (siz == SIZB && (am0 == AREG || am1 == AREG))
 702         {
 703                 error("cannot use '.b' with an address register");
 704                 goto loop;
 705         }
 706
 707         // Keep a backup of chptr (used for optimisations during codegen)
 708         chptr_opcode = chptr;
 709
 710         for(;;)
 711         {
 712                 if ((m->mnattr & siz) && (amsk0 & m->mn0) != 0 && (amsk1 & m->mn1) != 0)
 713                 {
 714                         (*m->mnfunc)(m->mninst, siz);
 715                         goto loop;
 716                 }
 717
 718                 m = &machtab[m->mncont];
 719         }
 720 }
 721
 722
 723 //
 724 // Handle the creation of labels
 725 //
 726 int HandleLabel(char * label, int labelType)
 727 {
 728         // Check for dot in front of label; means this is a local label if present
 729         int environment = (*label == '.' ? curenv : 0);
 730         SYM * symbol = lookup(label, LABEL, environment);
 731
 732         if (symbol == NULL)
 733         {
 734                 symbol = NewSymbol(label, LABEL, environment);
 735                 symbol->sattr = 0;
 736 //              symbol->sattre = RISCSYM;
 737                 symbol->sattre = 0;
 738         }
 739         else if (symbol->sattr & DEFINED)
 740                 return errors("multiply-defined label '%s'", label);
 741
 742         // Put symbol in "order of definition" list if it's not already in it
 743         AddToSymbolDeclarationList(symbol);
 744
 745         if (orgactive)
 746         {
 747                 symbol->svalue = orgaddr;
 748                 symbol->sattr |= ABS | DEFINED | EQUATED;
 749         }
 750         else
 751         {
 752                 symbol->svalue = sloc;
 753                 symbol->sattr |= DEFINED | cursect;
 754         }
 755
 756         lab_sym = symbol;
 757
 758         if (0 == environment)
 759                 curenv++;
 760
 761         // Make label global if it has a double colon
 762         if (labelType == DCOLON)
 763         {
 764                 if (environment != 0)
 765                         return error(locgl_error);
 766
 767                 symbol->sattr |= GLOBAL;
 768         }
 769
 770         return 0;
 771 }
 772
 773
 774 //
 775 // .if, Start conditional assembly
 776 //
 777 int d_if(void)
 778 {
 779         IFENT * rif;
 780         WORD eattr;
 781         VALUE eval;
 782         SYM * esym;
 783
 784         // Alloc an IFENTRY
 785         if ((rif = f_ifent) == NULL)
 786                 rif = (IFENT *)malloc(sizeof(IFENT));
 787         else
 788                 f_ifent = rif->if_prev;
 789
 790         rif->if_prev = ifent;
 791         ifent = rif;
 792
 793         if (!disabled)
 794         {
 795                 if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 796                         return 0;
 797
 798                 if ((eattr & DEFINED) == 0)
 799                         return error(undef_error);
 800
 801                 disabled = !eval;
 802         }
 803
 804         rif->if_state = (WORD)disabled;
 805         return 0;
 806 }
 807
 808
 809 //
 810 // .else, Do alternate case for .if
 811 //
 812 int d_else(void)
 813 {
 814         IFENT * rif = ifent;
 815
 816         if (rif->if_prev == NULL)
 817                 return error("mismatched .else");
 818
 819         if (disabled)
 820                 disabled = rif->if_prev->if_state;
 821         else
 822                 disabled = 1;
 823
 824         rif->if_state = (WORD)disabled;
 825         return 0;
 826 }
 827
 828
 829 //
 830 // .endif, End of conditional assembly block
 831 // This is also called by fpop() to pop levels of IFENTs in case a macro or
 832 // include file exits early with `exitm' or `end'.
 833 //
 834 int d_endif (void)
 835 {
 836         IFENT * rif = ifent;
 837
 838         if (rif->if_prev == NULL)
 839                 return error("mismatched .endif");
 840
 841         ifent = rif->if_prev;
 842         disabled = rif->if_prev->if_state;
 843         rif->if_prev = f_ifent;
 844         f_ifent = rif;
 845         return 0;
 846 }
 847