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 // Function prototypes
  93 int HandleLabel(char *, int);
  94
  95
  96 //
  97 // Initialize Line Processor
  98 //
  99 void InitLineProcessor(void)
 100 {
 101         disabled = 0;
 102         ifent = &ifent0;
 103         f_ifent = ifent0.if_prev = NULL;
 104         ifent0.if_state = 0;
 105 }
 106
 107
 108 //
 109 // Line Processor
 110 //
 111 void Assemble(void)
 112 {
 113         int state;                                      // Keyword machine state (output)
 114         int j;                                          // Random int, must be fast
 115         char * p;                                       // Random char ptr, must be fast
 116         TOKEN * tk;                                     // First token in line
 117         char * label;                           // Symbol (or NULL)
 118         char * equate;                          // Symbol (or NULL)
 119         int labtyp = 0;                         // Label type (':', DCOLON)
 120         int equtyp = 0;                         // Equ type ('=', DEQUALS)
 121         VALUE eval;                                     // Expression value
 122         WORD eattr;                                     // Expression attributes
 123         SYM * esym;                                     // External symbol involved in expr.
 124         WORD siz = 0;                           // Size suffix to mnem/diretve/macro
 125         LONG amsk0, amsk1;                      // Address-type masks for ea0, ea1
 126         MNTAB * m;                                      // Code generation table pointer
 127         SYM * sy, * sy2;                        // Symbol (temp usage)
 128         char * opname = NULL;           // Name of dirctve/mnemonic/macro
 129         int listflag;                           // 0: Don't call listeol()
 130 //      int as68mode = 0;                       // 1: Handle multiple labels
 131         WORD rmask;                                     // Register list, for REG
 132         int registerbank;                       // RISC register bank
 133         int riscreg;                            // RISC register
 134         listflag = 0;                           // Initialise listing flag
 135
 136 loop:                                                   // Line processing loop label
 137
 138         // Get another line of tokens
 139         if (TokenizeLine() == TKEOF)
 140         {
 141 if (verb_flag) printf("Assemble: Found TKEOF flag...\n");
 142                 if (list_flag && listflag)                      // Flush last line of source
 143                         listeol();
 144
 145                 if (ifent->if_prev != NULL)                     // Check conditional token
 146                         error("hit EOF without finding matching .endif");
 147
 148                 return;
 149         }
 150
 151         DEBUG DumpTokenBuffer();
 152
 153         if (list_flag)
 154         {
 155                 if (listflag && listing > 0)
 156                         listeol();                                              // Tell listing generator about EOL
 157
 158                 lstout((char)(disabled ? '-' : lntag)); // Prepare new line for listing
 159                 listflag = 1;                                           // OK to call `listeol' now
 160                 just_bss = 0;                                           // Reset just_bss mode
 161         }
 162
 163         state = -3;                                                             // No keyword (just EOL)
 164         label = NULL;                                                   // No label
 165         lab_sym = NULL;                                                 // No (exported) label
 166         equate = NULL;                                                  // No equate
 167         tk = tok;                                                               // Save first token in line
 168         pcloc = (VALUE)sloc;                                    // Set beginning-of-line PC
 169
 170 loop1:                                                                          // Internal line processing loop
 171
 172         if (*tok == EOL)                                                // Restart loop if end-of-line
 173                 goto loop;
 174
 175         // First token MUST be a symbol
 176         if (*tok != SYMBOL)
 177         {
 178 //              error(syntax_error);
 179                 error("syntax error; expected symbol");
 180                 goto loop;
 181         }
 182
 183         j = (int)tok[2];                                                // Skip equates (normal statements)
 184
 185         if (j == '=' || j == DEQUALS || j == SET || j == REG || j == EQUREG || j == CCDEF)
 186         {
 187                 equate = string[tok[1]];
 188                 equtyp = j;
 189                 tok += 3;
 190                 goto normal;
 191         }
 192
 193         // Skip past label (but record it)
 194         if (j == ':' || j == DCOLON)
 195         {
 196 as68label:
 197 //              label = (char *)tok[1];                         // Get label name
 198                 label = string[tok[1]];                         // Get label name
 199                 labtyp = tok[2];                                        // Get label type
 200                 tok += 3;                                                       // Go to next line token
 201
 202                 // Handle multiple labels; if there's another label, go process it,
 203                 // and come back at `as68label' above.
 204                 if (as68_flag)
 205                 {
 206 //                      as68mode = 0;
 207
 208                         // Looks like another label follows the previous one, so handle
 209                         // the previous one
 210                         if (*tok == SYMBOL && tok[2] == ':')
 211                         {
 212 //                              as68mode = 1;
 213 //                              goto do_label;
 214                                 if (HandleLabel(label, labtyp) != 0)
 215                                         goto loop;
 216
 217                                 goto as68label;
 218                         }
 219                 }
 220         }
 221
 222         // EOL is legal here...
 223         if (*tok == EOL)
 224                 goto normal;
 225
 226         // Next token MUST be a symbol
 227         if (*tok++ != SYMBOL)
 228         {
 229 //              error(syntax_error);
 230                 error("syntax error; expected symbol");
 231                 goto loop;
 232         }
 233
 234 // This is the problem here: On 64-bit platforms, this cuts the native pointer
 235 // in half. We need to figure out how to fix this.
 236 //#warning "!!! Bad pointer !!!"
 237 #if 0
 238         opname = p = (char *)*tok++;                    // Store opcode name here
 239 #else
 240         opname = p = string[*tok++];
 241 #endif
 242
 243         // Check to see if the SYMBOL is a keyword (a mnemonic or directive).
 244         // On output, `state' will have one of the values:
 245         //    -3          there was no symbol (EOL)
 246         //    -2..-1      the symbol didn't match any keyword
 247         //    0..499      vanilla directives (dc, ds, etc.)
 248         //    500..999    electric directives (macro, rept, etc.)
 249         //    1000..+     mnemonics (move, lsr, etc.)
 250         for(state=0; state>=0;)
 251         {
 252                 j = mnbase[state] + (int)tolowertab[*p];
 253
 254                 // Reject, character doesn't match
 255                 if (mncheck[j] != state)
 256                 {
 257                         state = -1;                                             // No match
 258                         break;
 259                 }
 260
 261                 // Must accept or reject at EOS
 262                 if (!*++p)
 263                 {
 264                         state = mnaccept[j];                    // (-1 on no terminal match)
 265                         break;
 266                 }
 267
 268                 state = mntab[j];
 269         }
 270
 271         // Check for ".b" ".w" ".l" after directive, macro or mnemonic.
 272         siz = SIZN;
 273
 274         if (*tok == DOTW)
 275                 siz = SIZW, tok++;
 276         else if (*tok == DOTL)
 277                 siz = SIZL, tok++;
 278         else if (*tok == DOTB)
 279                 siz = SIZB, tok++;
 280
 281         // Do special directives (500..999) (These must be handled in "real time")
 282         if (state >= 500 && state < 1000)
 283         {
 284                 switch (state)
 285                 {
 286                 case MN_IF:
 287                         d_if ();
 288                 goto loop;
 289                 case MN_ELSE:
 290                         d_else();
 291                         goto loop;
 292                 case MN_ENDIF:
 293                         d_endif ();
 294                         goto loop;
 295                 case MN_IIF:                                            // .iif --- immediate if
 296                         if (disabled || expr(exprbuf, &eval, &eattr, &esym) != OK)
 297                                 goto loop;
 298
 299                         if (!(eattr & DEFINED))
 300                         {
 301                                 error(undef_error);
 302                                 goto loop;
 303                         }
 304
 305                         if (*tok++ != ',')
 306                         {
 307                                 error(comma_error);
 308                                 goto loop;
 309                         }
 310
 311                         if (eval == 0)
 312                                 goto loop;
 313
 314                         goto loop1;
 315                 case MN_MACRO:                                          // .macro --- macro definition
 316                         if (!disabled)
 317                         {
 318                                 if (label != NULL)
 319                                         warn(lab_ignored);
 320
 321                                 DefineMacro();
 322                         }
 323
 324                         goto loop;
 325                 case MN_EXITM:                                          // .exitm --- exit macro
 326                 case MN_ENDM:                                           // .endm --- same as .exitm
 327                         if (!disabled)
 328                         {
 329                                 // Label on a macro definition is bad mojo... Warn the user
 330                                 if (label != NULL)
 331                                         warn(lab_ignored);
 332
 333                                 ExitMacro();
 334                         }
 335
 336                         goto loop;
 337                 case MN_REPT:
 338                         if (!disabled)
 339                         {
 340 #if 0
 341                                 if (label != NULL)
 342                                         warn(lab_ignored);
 343 #else
 344                                 // Handle labels on REPT directive lines...
 345                                 if (label)
 346                                 {
 347                                         if (HandleLabel(label, labtyp) != 0)
 348                                                 goto loop;
 349                                 }
 350 #endif
 351
 352                                 defrept();
 353                         }
 354
 355                         goto loop;
 356                 case MN_ENDR:
 357                         if (!disabled)
 358                                 error("mis-nested .endr");
 359
 360                         goto loop;
 361                 }
 362         }
 363
 364 normal:
 365         if (disabled)                                                   // Conditionally disabled code
 366                 goto loop;
 367
 368         // Do equates
 369         if (equate != NULL)
 370         {
 371                 // Pick global or local symbol enviroment
 372 #if 0
 373                 j = 0;
 374
 375                 if (*equate == '.')
 376                         j = curenv;
 377 #else
 378                 j = (*equate == '.' ? curenv : 0);
 379 #endif
 380                 sy = lookup(equate, LABEL, j);
 381
 382                 if (sy == NULL)
 383                 {
 384                         sy = NewSymbol(equate, LABEL, j);
 385                         sy->sattr = 0;
 386
 387                         if (equtyp == DEQUALS)
 388                         {
 389                                 // Can't GLOBAL a local symbol
 390                                 if (j)
 391                                 {
 392                                         error(locgl_error);
 393                                         goto loop;
 394                                 }
 395
 396                                 sy->sattr = GLOBAL;
 397                         }
 398                 }
 399                 else if ((sy->sattr & DEFINED) && equtyp != SET)
 400                 {
 401                         if ((equtyp == EQUREG) && (sy->sattre & UNDEF_EQUR))
 402                         {
 403 //REALLY?                               sy->sattre |= ~UNDEF_EQUR;
 404                                 sy->sattre &= ~UNDEF_EQUR;
 405                                 sy->svalue  = 0;
 406                         }
 407                         else if ((equtyp == CCDEF) && (sy->sattre & UNDEF_CC))
 408                         {
 409 //REALLY?                               sy->sattre |= ~UNDEF_CC;
 410                                 sy->sattre &= ~UNDEF_CC;
 411                                 sy->svalue = 0;
 412                         }
 413                         else
 414                         {
 415                                 errors("multiple equate to '%s'", sy->sname);
 416                                 goto loop;
 417                         }
 418                 }
 419
 420                 // Put symbol in "order of definition" list
 421                 if (!(sy->sattr & SDECLLIST))
 422                         sym_decl(sy);
 423
 424                 // Parse value to equate symbol to;
 425                 // o  .equr
 426                 // o  .reg
 427                 // o  everything else
 428                 if (equtyp == EQUREG)
 429                 {
 430 //Linko's request to issue a warning on labels that equated to the same register
 431 //would go here. Not sure how to implement it though. :-/
 432 /*
 433 Maybe like this way:
 434 have an array of bools with 64 entries. Whenever a register is equated, set the
 435 corresponding register bool to true. Whenever it's undef'ed, set it to false. When
 436 checking to see if it's already been equated, issue a warning.
 437 */
 438                         // Check that we are in a RISC section
 439                         if (!rgpu && !rdsp)
 440                         {
 441                                 error(".equr/.regequ must be defined in .gpu/.dsp section");
 442                                 goto loop;
 443                         }
 444
 445                         // Check for register to equate to
 446                         if ((*tok >= KW_R0) && (*tok <= KW_R31))
 447                         {
 448                                 sy->sattre  = EQUATEDREG | RISCSYM;     // Mark as equated register
 449                                 riscreg = (*tok - KW_R0);
 450 //is there any reason to do this, since we're putting this in svalue?
 451 //i'm thinking, no. Let's test that out! :-D
 452 //                              sy->sattre |= (riscreg << 8);           // Store register number
 453 //everything seems to build fine without it... We'll leave it here Just In Case(tm)
 454
 455 #define DEBODGE_REGBANK
 456 #ifdef DEBODGE_REGBANK
 457                                 // Default is current state of "regbank"
 458                                 registerbank = regbank;
 459 #else
 460                                 // Default is no register bank specified
 461                                 registerbank = BANK_N;
 462 #endif
 463
 464                                 // Check for ",<bank #>" override notation
 465                                 if ((tok[1] == ',') && (tok[2] == CONST))
 466                                 {
 467                                         // Advance token pointer to the constant
 468                                         tok += 3;
 469
 470                                         // Anything other than a 0 or a 1 will result in "No Bank"
 471                                         if (*tok == 0)
 472                                                 registerbank = BANK_0;
 473                                         else if (*tok == 1)
 474                                                 registerbank = BANK_1;
 475                                 }
 476
 477 #ifdef DEBODGE_REGBANK
 478                                 sy->sattre |= registerbank;     // Store register bank
 479 #else
 480 // What needs to happen here is to prime registerbank with regbank, then use
 481 // registerbank down below for the bank marking.
 482 #warning "!!! regbank <-> registerbank confusion here !!!"
 483 // The question here is why, if we're allowed to override the ".regbankN" rules above,
 484 // then why is it using the one set by the directive in the extended attributes and
 485 // not in what ends up in symbol->svalue?
 486 // ".regbankN" is not an original Madmac directive, so it's suspect
 487                                 sy->sattre |= regbank;          // Store register bank
 488 #endif
 489                                 eattr = ABS | DEFINED | GLOBAL;
 490 // & what does this $80000080 constant mean???
 491 //                              eval = 0x80000080 + (riscreg) + (registerbank << 8);
 492                                 eval = riscreg;
 493                                 tok++;
 494                         }
 495                         // Checking for a register symbol
 496                         else if (tok[0] == SYMBOL)
 497                         {
 498                                 sy2 = lookup(string[tok[1]], LABEL, j);
 499
 500                                 // Make sure symbol is a valid equreg
 501                                 if (!sy2 || !(sy2->sattre & EQUATEDREG))
 502                                 {
 503                                         error("invalid GPU/DSP .equr/.regequ definition");
 504                                         goto loop;
 505                                 }
 506                                 else
 507                                 {
 508                                         eattr = ABS | DEFINED | GLOBAL; // Copy symbols attributes
 509                                         sy->sattre = sy2->sattre;
 510                                         eval = (sy2->svalue & 0xFFFFF0FF);
 511                                         tok += 2;
 512                                 }
 513                         }
 514                         else
 515                         {
 516                                 error("invalid GPU/DSP .equr/.regequ definition");
 517                                 goto loop;
 518                         }
 519                 }
 520                 else if (equtyp == REG)
 521                 {
 522                         if (reglist(&rmask) < 0)
 523                                 goto loop;
 524
 525                         eval = (VALUE)rmask;
 526                         eattr = ABS | DEFINED;
 527                 }
 528                 else if (equtyp == CCDEF)
 529                 {
 530                         sy->sattre |= EQUATEDCC;
 531                         eattr = ABS | DEFINED | GLOBAL;
 532
 533                         if (tok[0] == SYMBOL)
 534                         {
 535                                 sy2 = lookup(string[tok[1]], LABEL, j);
 536
 537                                 if (!sy2 || !(sy2->sattre & EQUATEDCC))
 538                                 {
 539                                         error("invalid gpu/dsp .ccdef definition");
 540                                         goto loop;
 541                                 }
 542                                 else
 543                                 {
 544                                         eattr = ABS | DEFINED | GLOBAL;
 545                                         sy->sattre = sy2->sattre;
 546                                         eval = sy2->svalue;
 547                                         tok += 2;
 548                                 }
 549                         }
 550                         else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 551                                 goto loop;
 552                 }
 553                 //equ a equr
 554                 else if (*tok == SYMBOL)
 555                 {
 556                         sy2 = lookup(string[tok[1]], LABEL, j);
 557
 558                         if (sy2 && (sy2->sattre & EQUATEDREG))
 559                         {
 560                                 sy->stype = sy2->stype;
 561                                 sy->sattr = sy2->sattr;
 562                                 sy->sattre = sy2->sattre;
 563 //ICK                           sy->svalue = (sy2->svalue & 0xFFFFF0FF);
 564                                 sy->svalue = sy2->svalue;
 565                                 goto loop;
 566                         }
 567                         else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 568                                 goto loop;
 569                 }
 570                 else if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 571                         goto loop;
 572
 573                 if (!(eattr & DEFINED))
 574                 {
 575                         error(undef_error);
 576                         goto loop;
 577                 }
 578
 579                 sy->sattr |= eattr | EQUATED;           // Symbol inherits value and attributes
 580                 sy->svalue = eval;
 581
 582                 if (list_flag)                                          // Put value in listing
 583                         listvalue(eval);
 584
 585                 at_eol();                                                       // Must be at EOL now
 586                 goto loop;
 587         }
 588
 589         // Do labels
 590         if (label != NULL)
 591         {
 592 do_label:
 593 #if 0
 594                 // Check for dot in front of label; means this is a local label if present
 595                 j = (*label == '.' ? curenv : 0);
 596                 sy = lookup(label, LABEL, j);
 597
 598                 if (sy == NULL)
 599                 {
 600                         sy = NewSymbol(label, LABEL, j);
 601                         sy->sattr = 0;
 602                         sy->sattre = RISCSYM;
 603                 }
 604                 else if (sy->sattr & DEFINED)
 605                 {
 606                         errors("multiply-defined label '%s'", label);
 607                         goto loop;
 608                 }
 609
 610                 // Put symbol in "order of definition" list
 611                 if (!(sy->sattr & SDECLLIST))
 612                         sym_decl(sy);
 613
 614                 if (orgactive)
 615                 {
 616                         sy->svalue = orgaddr;
 617                         sy->sattr |= ABS | DEFINED | EQUATED;
 618                 }
 619                 else
 620                 {
 621                         sy->svalue = sloc;
 622                         sy->sattr |= DEFINED | cursect;
 623                 }
 624
 625                 lab_sym = sy;
 626
 627                 if (!j)
 628                         curenv++;
 629
 630                 // Make label global
 631                 if (labtyp == DCOLON)
 632                 {
 633                         if (j)
 634                         {
 635                                 error(locgl_error);
 636                                 goto loop;
 637                         }
 638
 639                         sy->sattr |= GLOBAL;
 640                 }
 641 #else
 642                 // Non-zero == error occurred
 643                 if (HandleLabel(label, labtyp) != 0)
 644                         goto loop;
 645 #endif
 646                 // If we're in as68 mode, and there's another label, go back and handle it
 647 //              if (as68_flag && as68mode)
 648 //                      goto as68label;
 649         }
 650
 651         // Punt on EOL
 652         if (state == -3)
 653                 goto loop;
 654
 655         // If we are in GPU or DSP mode and still in need of a mnemonic then search
 656         // for one
 657         if ((rgpu || rdsp) && (state < 0 || state >= 1000))
 658         {
 659                 for(state=0, p=opname; state>=0;)
 660                 {
 661                         j = mrbase[state] + (int)tolowertab[*p];
 662
 663                         // Reject, character doesn't match
 664                         if (mrcheck[j] != state)
 665                         {
 666                                 state = -1;                                     // No match
 667                                 break;
 668                         }
 669
 670                         // Must accept or reject at EOS
 671                         if (!*++p)
 672                         {
 673                                 state = mraccept[j];            // (-1 on no terminal match)
 674                                 break;
 675                         }
 676
 677                         state = mrtab[j];
 678                 }
 679
 680                 // Call RISC code generator if we found a mnemonic
 681                 if (state >= 3000)
 682                 {
 683                         GenerateRISCCode(state);
 684                         goto loop;
 685                 }
 686         }
 687
 688         // Invoke macro or complain about bad mnemonic
 689         if (state < 0)
 690         {
 691                 if ((sy = lookup(opname, MACRO, 0)) != NULL)
 692                         InvokeMacro(sy, siz);
 693                 else
 694                         errors("unknown op '%s'", opname);
 695
 696                 goto loop;
 697         }
 698
 699         // Call directive handlers
 700         if (state < 500)
 701         {
 702                 (*dirtab[state])(siz);
 703                 goto loop;
 704         }
 705
 706         // Do mnemonics
 707         // o  can't deposit instrs in BSS or ABS
 708         // o  do automatic .EVEN for instrs
 709         // o  allocate space for largest possible instr
 710         // o  can't do ".b" operations with an address register
 711         if (scattr & SBSS)
 712         {
 713                 error("cannot initialize non-storage (BSS) section");
 714                 goto loop;
 715         }
 716
 717         if (sloc & 1)                                                   // Automatic .even
 718                 auto_even();
 719
 720         if (challoc - ch_size < 18)                             // Make sure have space in current chunk
 721                 chcheck(0);
 722
 723         m = &machtab[state - 1000];
 724
 725         // Call special-mode handler
 726         if (m->mnattr & CGSPECIAL)
 727         {
 728                 (*m->mnfunc)(m->mninst, siz);
 729                 goto loop;
 730         }
 731
 732         if (amode(1) < 0)                                               // Parse 0, 1 or 2 addr modes
 733                 goto loop;
 734
 735         if (*tok != EOL)
 736                 error(extra_stuff);
 737
 738         amsk0 = amsktab[am0];
 739         amsk1 = amsktab[am1];
 740
 741         // Catch attempts to use ".B" with an address register (yes, this check
 742         // does work at this level)
 743         if (siz == SIZB && (am0 == AREG || am1 == AREG))
 744         {
 745                 error("cannot use '.b' with an address register");
 746                 goto loop;
 747         }
 748
 749         for(;;)
 750         {
 751                 if ((m->mnattr & siz) && (amsk0 & m->mn0) != 0 && (amsk1 & m->mn1) != 0)
 752                 {
 753                         (*m->mnfunc)(m->mninst, siz);
 754                         goto loop;
 755                 }
 756
 757                 m = &machtab[m->mncont];
 758         }
 759 }
 760
 761
 762 //
 763 // Handle the creation of labels
 764 //
 765 int HandleLabel(char * label, int labelType)
 766 {
 767         // Check for dot in front of label; means this is a local label if present
 768         int j = (*label == '.' ? curenv : 0);
 769         SYM * sy = lookup(label, LABEL, j);
 770
 771         if (sy == NULL)
 772         {
 773                 sy = NewSymbol(label, LABEL, j);
 774                 sy->sattr = 0;
 775                 sy->sattre = RISCSYM;
 776         }
 777         else if (sy->sattr & DEFINED)
 778                 return errors("multiply-defined label '%s'", label);
 779
 780         // Put symbol in "order of definition" list
 781         if (!(sy->sattr & SDECLLIST))
 782                 sym_decl(sy);
 783
 784         if (orgactive)
 785         {
 786                 sy->svalue = orgaddr;
 787                 sy->sattr |= ABS | DEFINED | EQUATED;
 788         }
 789         else
 790         {
 791                 sy->svalue = sloc;
 792                 sy->sattr |= DEFINED | cursect;
 793         }
 794
 795         lab_sym = sy;
 796
 797         if (!j)
 798                 curenv++;
 799
 800         // Make label global if it has a double colon
 801         if (labelType == DCOLON)
 802         {
 803                 if (j)
 804                         return error(locgl_error);
 805
 806                 sy->sattr |= GLOBAL;
 807         }
 808
 809         return 0;
 810 }
 811
 812
 813 //
 814 // .if, Start Conditional Assembly
 815 //
 816 int d_if(void)
 817 {
 818         IFENT * rif;
 819         WORD eattr;
 820         VALUE eval;
 821         SYM * esym;
 822
 823         // Alloc an IFENTRY
 824         if ((rif = f_ifent) == NULL)
 825                 rif = (IFENT *)malloc(sizeof(IFENT));
 826         else
 827                 f_ifent = rif->if_prev;
 828
 829         rif->if_prev = ifent;
 830         ifent = rif;
 831
 832         if (!disabled)
 833         {
 834                 if (expr(exprbuf, &eval, &eattr, &esym) != OK)
 835                         return 0;
 836
 837                 if ((eattr & DEFINED) == 0)
 838                         return error(undef_error);
 839
 840                 disabled = !eval;
 841         }
 842
 843         rif->if_state = (WORD)disabled;
 844         return 0;
 845 }
 846
 847
 848 //
 849 // .else, Do Alternate Case For .if
 850 //
 851 int d_else(void)
 852 {
 853         IFENT * rif = ifent;
 854
 855         if (rif->if_prev == NULL)
 856                 return error("mismatched .else");
 857
 858         if (disabled)
 859                 disabled = rif->if_prev->if_state;
 860         else
 861                 disabled = 1;
 862
 863         rif->if_state = (WORD)disabled;
 864         return 0;
 865 }
 866
 867
 868 //
 869 // .endif, End of conditional assembly block
 870 // This is also called by fpop() to pop levels of IFENTs in case a macro or
 871 // include file exits early with `exitm' or `end'.
 872 //
 873 int d_endif (void)
 874 {
 875         IFENT * rif = ifent;
 876
 877         if (rif->if_prev == NULL)
 878                 return error("mismatched .endif");
 879
 880         ifent = rif->if_prev;
 881         disabled = rif->if_prev->if_state;
 882         rif->if_prev = f_ifent;
 883         f_ifent = rif;
 884         return 0;
 885 }