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

   1 //
   2 // RMAC - Reboot's Macro Assembler for the Atari Jaguar Console System
   3 // EXPR.C - Expression Analyzer
   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 "expr.h"
  10 #include "direct.h"
  11 #include "error.h"
  12 #include "listing.h"
  13 #include "mach.h"
  14 #include "procln.h"
  15 #include "riscasm.h"
  16 #include "sect.h"
  17 #include "symbol.h"
  18 #include "token.h"
  19
  20 #define DEF_KW                                          // Declare keyword values
  21 #include "kwtab.h"                                      // Incl generated keyword tables & defs
  22
  23 // N.B.: The size of tokenClass should be identical to the largest value of
  24 //       a token; we're assuming 256 but not 100% sure!
  25 static char tokenClass[256];            // Generated table of token classes
  26 static VALUE evstk[EVSTACKSIZE];        // Evaluator value stack
  27 static WORD evattr[EVSTACKSIZE];        // Evaluator attribute stack
  28
  29 // Token-class initialization list
  30 char itokcl[] = {
  31         0,                                                              // END
  32         CONST, SYMBOL, 0,                               // ID
  33         '(', '[', '{', 0,                               // OPAR
  34         ')', ']', '}', 0,                               // CPAR
  35         CR_DEFINED, CR_REFERENCED,              // SUNARY (special unary)
  36         CR_STREQ, CR_MACDEF,
  37         CR_DATE, CR_TIME, 0,
  38         '!', '~', UNMINUS, 0,                   // UNARY
  39         '*', '/', '%', 0,                               // MULT
  40         '+', '-', 0,                                    // ADD
  41         SHL, SHR, 0,                                    // SHIFT
  42         LE, GE, '<', '>', NE, '=', 0,   // REL
  43         '&', 0,                                                 // AND
  44         '^', 0,                                                 // XOR
  45         '|', 0,                                                 // OR
  46         1                                                               // (the end)
  47 };
  48
  49 const char missym_error[] = "missing symbol";
  50 const char str_error[] = "missing symbol or string";
  51
  52 // Convert expression to postfix
  53 static TOKEN * evalTokenBuffer;         // Deposit tokens here (this is really a
  54                                                                         // pointer to exprbuf from direct.c)
  55                                                                         // (Can also be from others, like
  56                                                                         // riscasm.c)
  57 static symbolNum;                                       // Pointer to the entry in symbolPtr[]
  58
  59
  60 //
  61 // Obtain a string value
  62 //
  63 static VALUE str_value(char * p)
  64 {
  65         VALUE v;
  66
  67         for(v=0; *p; p++)
  68                 v = (v << 8) | (*p & 0xFF);
  69
  70         return v;
  71 }
  72
  73
  74 //
  75 // Initialize expression analyzer
  76 //
  77 void InitExpression(void)
  78 {
  79         int i;
  80         char * p;
  81
  82         // Initialize token-class table (all set to END)
  83         for(i=0; i<256; i++)
  84                 tokenClass[i] = END;
  85
  86         for(i=0, p=itokcl; *p!=1; p++)
  87         {
  88                 if (*p == 0)
  89                         i++;
  90                 else
  91                         tokenClass[(int)(*p)] = (char)i;
  92         }
  93
  94         symbolNum = 0;
  95 }
  96
  97
  98 //
  99 // Binary operators (all the same precedence)
 100 //
 101 int expr0(void)
 102 {
 103         TOKEN t;
 104
 105         if (expr1() != OK)
 106                 return ERROR;
 107
 108         while (tokenClass[*tok] >= MULT)
 109         {
 110                 t = *tok++;
 111
 112                 if (expr1() != OK)
 113                         return ERROR;
 114
 115                 *evalTokenBuffer++ = t;
 116         }
 117
 118         return OK;
 119 }
 120
 121
 122 //
 123 // Unary operators (detect unary '-')
 124 //
 125 int expr1(void)
 126 {
 127         int class;
 128         TOKEN t;
 129         SYM * sy;
 130         char * p, * p2;
 131         WORD w;
 132         int j;
 133
 134         class = tokenClass[*tok];
 135
 136         if (*tok == '-' || class == UNARY)
 137         {
 138                 t = *tok++;
 139
 140                 if (expr2() != OK)
 141                         return ERROR;
 142
 143                 if (t == '-')
 144                         t = UNMINUS;
 145
 146                 *evalTokenBuffer++ = t;
 147         }
 148         else if (class == SUNARY)
 149         {
 150                 switch ((int)*tok++)
 151                 {
 152                 case CR_TIME:
 153                         *evalTokenBuffer++ = CONST;
 154                         *evalTokenBuffer++ = dos_time();
 155                         break;
 156                 case CR_DATE:
 157                         *evalTokenBuffer++ = CONST;
 158                         *evalTokenBuffer++ = dos_date();
 159                         break;
 160                 case CR_MACDEF:                                    // ^^macdef <macro-name>
 161                         if (*tok++ != SYMBOL)
 162                                 return error(missym_error);
 163
 164                         p = string[*tok++];
 165                         w = (lookup(p, MACRO, 0) == NULL ? 0 : 1);
 166                         *evalTokenBuffer++ = CONST;
 167                         *evalTokenBuffer++ = (TOKEN)w;
 168                         break;
 169                 case CR_DEFINED:
 170                         w = DEFINED;
 171                         goto getsym;
 172                 case CR_REFERENCED:
 173                         w = REFERENCED;
 174 getsym:
 175                         if (*tok++ != SYMBOL)
 176                                 return error(missym_error);
 177
 178                         p = string[*tok++];
 179                         j = (*p == '.' ? curenv : 0);
 180                         w = ((sy = lookup(p, LABEL, j)) != NULL && (sy->sattr & w) ? 1 : 0);
 181                         *evalTokenBuffer++ = CONST;
 182                         *evalTokenBuffer++ = (TOKEN)w;
 183                         break;
 184                 case CR_STREQ:
 185                         if (*tok != SYMBOL && *tok != STRING)
 186                                 return error(str_error);
 187
 188                         p = string[tok[1]];
 189                         tok +=2;
 190
 191                         if (*tok++ != ',')
 192                                 return error(comma_error);
 193
 194                         if (*tok != SYMBOL && *tok != STRING)
 195                                 return error(str_error);
 196
 197                         p = string[tok[1]];
 198                         tok += 2;
 199
 200                         w = (WORD)(!strcmp(p, p2));
 201                         *evalTokenBuffer++ = CONST;
 202                         *evalTokenBuffer++ = (TOKEN)w;
 203                         break;
 204                 }
 205         }
 206         else
 207                 return expr2();
 208
 209         return OK;
 210 }
 211
 212
 213 //
 214 // Terminals (CONSTs) and parenthesis grouping
 215 //
 216 int expr2(void)
 217 {
 218         char * p;
 219         SYM * sy;
 220         int j;
 221
 222         switch ((int)*tok++)
 223         {
 224         case CONST:
 225                 *evalTokenBuffer++ = CONST;
 226                 *evalTokenBuffer++ = *tok++;
 227                 break;
 228         case SYMBOL:
 229                 p = string[*tok++];
 230                 j = (*p == '.' ? curenv : 0);
 231                 sy = lookup(p, LABEL, j);
 232
 233                 if (sy == NULL)
 234                         sy = NewSymbol(p, LABEL, j);
 235
 236                 // Check register bank usage
 237                 if (sy->sattre & EQUATEDREG)
 238                 {
 239                         if ((regbank == BANK_0) && (sy->sattre & BANK_1) && !altbankok)
 240                                 warns("equated symbol \'%s\' cannot be used in register bank 0", sy->sname);
 241
 242                         if ((regbank == BANK_1) && (sy->sattre & BANK_0) && !altbankok)
 243                                 warns("equated symbol \'%s\' cannot be used in register bank 1", sy->sname);
 244                 }
 245
 246                 *evalTokenBuffer++ = SYMBOL;
 247                 *evalTokenBuffer++ = symbolNum;
 248                 symbolPtr[symbolNum] = sy;
 249                 symbolNum++;
 250                 break;
 251         case STRING:
 252                 *evalTokenBuffer++ = CONST;
 253                 *evalTokenBuffer++ = str_value(string[*tok++]);
 254                 break;
 255         case '(':
 256                 if (expr0() != OK)
 257                         return ERROR;
 258
 259                 if (*tok++ != ')')
 260                         return error("missing close parenthesis ')'");
 261
 262                 break;
 263         case '[':
 264                 if (expr0() != OK)
 265                         return ERROR;
 266
 267                 if (*tok++ != ']')
 268                         return error("missing close parenthesis ']'");
 269
 270                 break;
 271         case '$':
 272                 *evalTokenBuffer++ = ACONST;                            // Attributed const
 273                 *evalTokenBuffer++ = sloc;                                      // Current location
 274                 *evalTokenBuffer++ = cursect | DEFINED;         // Store attribs
 275                 break;
 276         case '*':
 277                 *evalTokenBuffer++ = ACONST;                            // Attributed const
 278
 279                 // pcloc == location at start of line
 280                 *evalTokenBuffer++ = (orgactive ? orgaddr : pcloc);
 281                 *evalTokenBuffer++ = ABS | DEFINED;                     // Store attribs
 282                 break;
 283         default:
 284                 return error("bad expression");
 285         }
 286
 287         return OK;
 288 }
 289
 290
 291 //
 292 // Recursive-descent expression analyzer (with some simple speed hacks)
 293 //
 294 int expr(TOKEN * otk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
 295 {
 296         // Passed in values (once derefenced, that is) can all be zero. They are
 297         // there so that the expression analyzer can fill them in as needed. The
 298         // expression analyzer gets its input from the global token pointer "tok",
 299         // and not from anything passed in by the user.
 300         SYM * symbol;
 301         char * p;
 302         int j;
 303
 304         evalTokenBuffer = otk;  // Set token pointer to 'exprbuf' (direct.c)
 305                                                         // Also set in various other places too (riscasm.c, e.g.)
 306
 307 //printf("expr(): tokens 0-2: %i %i %i (%c %c %c); tc[2] = %i\n", tok[0], tok[1], tok[2], tok[0], tok[1], tok[2], tokenClass[tok[2]]);
 308         // Optimize for single constant or single symbol.
 309         // Shamus: Subtle bug here. EOL token is 101; if you have a constant token
 310         //         followed by the value 101, it will trigger a bad evaluation here.
 311         //         This is probably a really bad assumption to be making here...!
 312         //         (assuming tok[1] == EOL is a single token that is)
 313 //      if ((tok[1] == EOL)
 314         if ((tok[1] == EOL && tok[0] != CONST)
 315                 || (((*tok == CONST || *tok == SYMBOL) || (*tok >= KW_R0 && *tok <= KW_R31))
 316                 && (tokenClass[tok[2]] < UNARY)))
 317         {
 318                 if (*tok >= KW_R0 && *tok <= KW_R31)
 319                 {
 320                         *evalTokenBuffer++ = CONST;
 321                         *evalTokenBuffer++ = *a_value = (*tok - KW_R0);
 322                         *a_attr = ABS | DEFINED;
 323
 324                         if (a_esym != NULL)
 325                                 *a_esym = NULL;
 326
 327                         tok++;
 328                 }
 329                 else if (*tok == CONST)
 330                 {
 331                         *evalTokenBuffer++ = CONST;
 332                         *evalTokenBuffer++ = *a_value = tok[1];
 333                         *a_attr = ABS | DEFINED;
 334
 335                         if (a_esym != NULL)
 336                                 *a_esym = NULL;
 337
 338                         tok += 2;
 339 //printf("Quick eval in expr(): CONST = %i, tokenClass[tok[2]] = %i\n", *a_value, tokenClass[*tok]);
 340                 }
 341                 else if (*tok == '*')
 342                 {
 343                         *evalTokenBuffer++ = CONST;
 344
 345                         if (orgactive)
 346                                 *evalTokenBuffer++ = *a_value = orgaddr;
 347                         else
 348                                 *evalTokenBuffer++ = *a_value = pcloc;
 349
 350                         *a_attr = ABS | DEFINED;
 351
 352                         if (a_esym != NULL)
 353                                 *a_esym = NULL;
 354
 355                         tok++;
 356                 }
 357                 else if (*tok == STRING || *tok == SYMBOL)
 358                 {
 359                         p = string[tok[1]];
 360                         j = (*p == '.' ? curenv : 0);
 361                         symbol = lookup(p, LABEL, j);
 362 #if 0
 363 printf("eval: Looking up symbol [=%08X]\n", symbol);
 364 if (symbol)
 365         printf("      attr=%04X, attre=%08X, val=%i, name=%s\n", symbol->sattr, symbol->sattre, symbol->svalue, symbol->sname);
 366 #endif
 367
 368                         if (symbol == NULL)
 369                                 symbol = NewSymbol(p, LABEL, j);
 370
 371                         symbol->sattr |= REFERENCED;
 372
 373                         // Check for undefined register equates
 374                         if (symbol->sattre & UNDEF_EQUR)
 375                         {
 376                                 errors("undefined register equate '%s'", symbol->sname);
 377 //if we return right away, it returns some spurious errors...
 378 //                              return ERROR;
 379                         }
 380
 381                         // Check register bank usage
 382                         if (symbol->sattre & EQUATEDREG)
 383                         {
 384                                 if ((regbank == BANK_0) && (symbol->sattre & BANK_1) && !altbankok)
 385                                         warns("equated symbol '%s' cannot be used in register bank 0", symbol->sname);
 386
 387                                 if ((regbank == BANK_1) && (symbol->sattre & BANK_0) && !altbankok)
 388                                         warns("equated symbol '%s' cannot be used in register bank 1", symbol->sname);
 389                         }
 390
 391                         *evalTokenBuffer++ = SYMBOL;
 392 #if 0
 393                         *evalTokenBuffer++ = (TOKEN)symbol;
 394 #else
 395 /*
 396 While this approach works, it's wasteful. It would be better to use something
 397 that's already available, like the symbol "order defined" table (which needs to
 398 be converted from a linked list into an array).
 399 */
 400                         *evalTokenBuffer++ = symbolNum;
 401                         symbolPtr[symbolNum] = symbol;
 402                         symbolNum++;
 403 #endif
 404
 405                         if (symbol->sattr & DEFINED)
 406                                 *a_value = symbol->svalue;
 407                         else
 408                                 *a_value = 0;
 409
 410 /*
 411 All that extra crap that was put into the svalue when doing the equr stuff is
 412 thrown away right here. What the hell is it for?
 413 */
 414                         if (symbol->sattre & EQUATEDREG)
 415                                 *a_value &= 0x1F;
 416
 417                         *a_attr = (WORD)(symbol->sattr & ~GLOBAL);
 418
 419                         if ((symbol->sattr & (GLOBAL | DEFINED)) == GLOBAL && a_esym != NULL)
 420                                 *a_esym = symbol;
 421
 422                         tok += 2;
 423                 }
 424                 else
 425                 {
 426                         // Unknown type here... Alert the user!
 427                         error("undefined RISC register in expression");
 428                         // Prevent spurious error reporting...
 429                         tok++;
 430                         return ERROR;
 431                 }
 432
 433                 *evalTokenBuffer++ = ENDEXPR;
 434                 return OK;
 435         }
 436
 437         if (expr0() != OK)
 438                 return ERROR;
 439
 440         *evalTokenBuffer++ = ENDEXPR;
 441         return evexpr(otk, a_value, a_attr, a_esym);
 442 }
 443
 444
 445 //
 446 // Evaluate expression.
 447 // If the expression involves only ONE external symbol, the expression is
 448 // UNDEFINED, but it's value includes everything but the symbol value, and
 449 // `a_esym' is set to the external symbol.
 450 //
 451 int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
 452 {
 453         WORD * sattr;
 454         VALUE * sval;
 455         WORD attr;
 456         SYM * sy;
 457         SYM * esym;
 458         WORD sym_seg;
 459
 460         sval = evstk;                                                   // (Empty) initial stack
 461         sattr = evattr;
 462         esym = NULL;                                                    // No external symbol involved
 463         sym_seg = 0;
 464
 465         while (*tk != ENDEXPR)
 466         {
 467                 switch ((int)*tk++)
 468                 {
 469                 case SYMBOL:
 470 //printf("evexpr(): SYMBOL\n");
 471                         sy = symbolPtr[*tk++];
 472                         sy->sattr |= REFERENCED;                // Set "referenced" bit
 473
 474                         if (!(sy->sattr & DEFINED))
 475                         {
 476                                 // Reference to undefined symbol
 477                                 if (!(sy->sattr & GLOBAL))
 478                                 {
 479                                         *a_attr = 0;
 480                                         *a_value = 0;
 481                                         return OK;
 482                                 }
 483
 484                                 if (esym != NULL)                       // Check for multiple externals
 485                                         return error(seg_error);
 486
 487                                 esym = sy;
 488                         }
 489
 490                         if (sy->sattr & DEFINED)
 491                         {
 492                                 *++sval = sy->svalue;           // Push symbol's value
 493                         }
 494                         else
 495                         {
 496                                 *++sval = 0;                            // 0 for undefined symbols
 497                         }
 498
 499                         *++sattr = (WORD)(sy->sattr & ~GLOBAL); // Push attribs
 500                         sym_seg = (WORD)(sy->sattr & (TEXT | DATA | BSS));
 501                         break;
 502                 case CONST:
 503 //printf("evexpr(): CONST = %i\n", *tk);
 504                         *++sval = *tk++;                                // Push value
 505                         *++sattr = ABS | DEFINED;               // Push simple attribs
 506                         break;
 507                 case ACONST:
 508 //printf("evexpr(): ACONST = %i\n", *tk);
 509                         *++sval = *tk++;                                // Push value
 510                         *++sattr = (WORD)*tk++;                 // Push attribs
 511                         break;
 512
 513                         // Binary "+" and "-" matrix:
 514                         //
 515                         //                ABS    Sect     Other
 516                         //     ----------------------------
 517                         //   ABS     |  ABS   |  Sect  |  Other |
 518                         //   Sect    |  Sect  |  [1]   |  Error |
 519                         //   Other   |  Other |  Error |  [1]   |
 520                         //      ----------------------------
 521                         //
 522                         //   [1] + : Error
 523                         //       - : ABS
 524                 case '+':
 525 //printf("evexpr(): +\n");
 526                         --sval;                                                 // Pop value
 527                         --sattr;                                                // Pop attrib
 528                         *sval += sval[1];                               // Compute value
 529
 530                         if (!(*sattr & (TEXT | DATA | BSS)))
 531                                 *sattr = sattr[1];
 532                         else if (sattr[1] & (TEXT | DATA | BSS))
 533                                 return error(seg_error);
 534
 535                         break;
 536                 case '-':
 537 //printf("evexpr(): -\n");
 538                         --sval;                                                 // Pop value
 539                         --sattr;                                                // Pop attrib
 540                         *sval -= sval[1];                               // Compute value
 541
 542                         attr = (WORD)(*sattr & (TEXT | DATA | BSS));
 543
 544                         if (!attr)
 545                                 *sattr = sattr[1];
 546                         else if (sattr[1] & (TEXT | DATA | BSS))
 547                         {
 548                                 if (!(attr & sattr[1]))
 549                                         return error(seg_error);
 550                                 else
 551                                         *sattr &= ~(TEXT | DATA | BSS);
 552                         }
 553
 554                         break;
 555                 // Unary operators only work on ABS items
 556                 case UNMINUS:
 557 //printf("evexpr(): UNMINUS\n");
 558                         if (*sattr & (TEXT | DATA | BSS))
 559                                 error(seg_error);
 560
 561                         *sval = -(int)*sval;
 562                         *sattr = ABS | DEFINED;                 // Expr becomes absolute
 563                         break;
 564                 case '!':
 565 //printf("evexpr(): !\n");
 566                         if (*sattr & (TEXT | DATA | BSS))
 567                                 error(seg_error);
 568
 569                         *sval = !*sval;
 570                         *sattr = ABS | DEFINED;                 // Expr becomes absolute
 571                         break;
 572                 case '~':
 573 //printf("evexpr(): ~\n");
 574                         if (*sattr & (TEXT | DATA | BSS))
 575                                 error(seg_error);
 576
 577                         *sval = ~*sval;
 578                         *sattr = ABS | DEFINED;                 // Expr becomes absolute
 579                         break;
 580                 // Comparison operators must have two values that
 581                 // are in the same segment, but that's the only requirement.
 582                 case LE:
 583 //printf("evexpr(): LE\n");
 584                         --sattr;
 585                         --sval;
 586
 587                         if ((*sattr & TDB) != (sattr[1] & TDB))
 588                                 error(seg_error);
 589
 590                         *sattr = ABS | DEFINED;
 591                         *sval = *sval <= sval[1];
 592                         break;
 593                 case GE:
 594 //printf("evexpr(): GE\n");
 595                         --sattr;
 596                         --sval;
 597
 598                         if ((*sattr & TDB) != (sattr[1] & TDB))
 599                                 error(seg_error);
 600
 601                         *sattr = ABS | DEFINED;
 602                         *sval = *sval >= sval[1];
 603                         break;
 604                 case '>':
 605 //printf("evexpr(): >\n");
 606                         --sattr;
 607                         --sval;
 608
 609                         if ((*sattr & TDB) != (sattr[1] & TDB))
 610                                 error(seg_error);
 611
 612                         *sattr = ABS | DEFINED;
 613                         *sval = *sval > sval[1];
 614                         break;
 615                 case '<':
 616 //printf("evexpr(): <\n");
 617                         --sattr;
 618                         --sval;
 619
 620                         if ((*sattr & TDB) != (sattr[1] & TDB))
 621                                 error(seg_error);
 622
 623                         *sattr = ABS | DEFINED;
 624                         *sval = *sval < sval[1];
 625                         break;
 626                 case NE:
 627 //printf("evexpr(): NE\n");
 628                         --sattr;
 629                         --sval;
 630
 631                         if ((*sattr & TDB) != (sattr[1] & TDB))
 632                                 error(seg_error);
 633
 634                         *sattr = ABS | DEFINED;
 635                         *sval = *sval != sval[1];
 636                         break;
 637                 case '=':
 638 //printf("evexpr(): =\n");
 639                         --sattr;
 640                         --sval;
 641
 642                         if ((*sattr & TDB) != (sattr[1] & TDB))
 643                                 error(seg_error);
 644
 645                         *sattr = ABS | DEFINED;
 646                         *sval = *sval == sval[1];
 647                         break;
 648                 // All other binary operators must have two ABS items
 649                 // to work with.  They all produce an ABS value.
 650                 default:
 651 //printf("evexpr(): default\n");
 652                         // GH - Removed for v1.0.15 as part of the fix for indexed loads.
 653                         //if ((*sattr & (TEXT|DATA|BSS)) || (*--sattr & (TEXT|DATA|BSS)))
 654                         //error(seg_error);
 655                         *sattr = ABS | DEFINED;                 // Expr becomes absolute
 656
 657                         switch ((int)tk[-1])
 658                         {
 659                         case '*':
 660                                 --sval;
 661                                 --sattr;                                        // Pop attrib
 662                                 *sval *= sval[1];
 663                                 break;
 664                         case '/':
 665                                 --sval;
 666                                 --sattr;                                        // Pop attrib
 667
 668                                 if (sval[1] == 0)
 669                                         return error("divide by zero");
 670
 671                                 *sval /= sval[1];
 672                                 break;
 673                         case '%':
 674                                 --sval;
 675                                 --sattr;                                        // Pop attrib
 676
 677                                 if (sval[1] == 0)
 678                                         return error("mod (%) by zero");
 679
 680                                 *sval %= sval[1];
 681                                 break;
 682                         case SHL:
 683                                 --sval;
 684                                 --sattr;                                        // Pop attrib
 685                                 *sval <<= sval[1];
 686                                 break;
 687                         case SHR:
 688                                 --sval;
 689                                 --sattr;                                        // Pop attrib
 690                                 *sval >>= sval[1];
 691                                 break;
 692                         case '&':
 693                                 --sval;
 694                                 --sattr;                                        // Pop attrib
 695                                 *sval &= sval[1];
 696                                 break;
 697                         case '^':
 698                                 --sval;
 699                                 --sattr;                                        // Pop attrib
 700                                 *sval ^= sval[1];
 701                                 break;
 702                         case '|':
 703                                 --sval;
 704                                 --sattr;                                        // Pop attrib
 705                                 *sval |= sval[1];
 706                                 break;
 707                         default:
 708                                 interror(5);                            // Bad operator in expression stream
 709                         }
 710                 }
 711         }
 712
 713         if (esym != NULL)
 714                 *sattr &= ~DEFINED;
 715
 716         if (a_esym != NULL)
 717                 *a_esym = esym;
 718
 719         // sym_seg added in 1.0.16 to solve a problem with forward symbols in
 720         // expressions where absolute values also existed. The absolutes were
 721         // overiding the symbol segments and not being included :(
 722         //*a_attr = *sattr | sym_seg;                                        // Copy value + attrib
 723
 724         *a_attr = *sattr;                                               // Copy value + attrib
 725         *a_value = *sval;
 726
 727         return OK;
 728 }
 729