parser.c

   1 /* parser.c   source line parser for the Netwide Assembler
   2  *
   3  * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
   4  * Julian Hall. All rights reserved. The software is
   5  * redistributable under the licence given in the file "Licence"
   6  * distributed in the NASM archive.
   7  *
   8  * initial version 27/iii/95 by Simon Tatham
   9  */
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <stddef.h>
  14 #include <string.h>
  15 #include <ctype.h>
  16
  17 #include "nasm.h"
  18 #include "nasmlib.h"
  19 #include "parser.h"
  20 #include "float.h"
  21
  22 static long reg_flags[] = {            /* sizes and special flags */
  23     0, REG8, REG_AL, REG_AX, REG8, REG8, REG16, REG16, REG8, REG_CL,
  24     REG_CREG, REG_CREG, REG_CREG, REG_CR4, REG_CS, REG_CX, REG8,
  25     REG16, REG8, REG_DREG, REG_DREG, REG_DREG, REG_DREG, REG_DREG,
  26     REG_DREG, REG_DESS, REG_DX, REG_EAX, REG32, REG32, REG_ECX,
  27     REG32, REG32, REG_DESS, REG32, REG32, REG_FSGS, REG_FSGS,
  28     MMXREG, MMXREG, MMXREG, MMXREG, MMXREG, MMXREG, MMXREG, MMXREG,
  29     REG16, REG16, REG_DESS, FPU0, FPUREG, FPUREG, FPUREG, FPUREG,
  30     FPUREG, FPUREG, FPUREG, REG_TREG, REG_TREG, REG_TREG, REG_TREG,
  31     REG_TREG,
  32     XMMREG, XMMREG, XMMREG, XMMREG, XMMREG, XMMREG, XMMREG, XMMREG
  33 };
  34
  35 enum {                                 /* special tokens */
  36     S_BYTE, S_DWORD, S_FAR, S_LONG, S_NEAR, S_NOSPLIT, S_QWORD,
  37     S_SHORT, S_TO, S_TWORD, S_WORD
  38 };
  39
  40 static int is_comma_next (void);
  41
  42 static int i;
  43 static struct tokenval tokval;
  44 static efunc error;
  45 static struct ofmt *outfmt;  /* Structure of addresses of output routines */
  46 static loc_t *location;      /* Pointer to current line's segment,offset */
  47
  48 void parser_global_info (struct ofmt *output, loc_t *locp)
  49 {
  50     outfmt = output;
  51     location = locp;
  52 }
  53
  54 insn *parse_line (int pass, char *buffer, insn *result,
  55                   efunc errfunc, evalfunc evaluate, ldfunc ldef)
  56 {
  57     int operand;
  58     int critical;
  59     struct eval_hints hints;
  60
  61     result->forw_ref = FALSE;
  62     error = errfunc;
  63
  64     stdscan_reset();
  65     stdscan_bufptr = buffer;
  66     i = stdscan(NULL, &tokval);
  67
  68     result->label = NULL;              /* Assume no label */
  69     result->eops = NULL;               /* must do this, whatever happens */
  70     result->operands = 0;              /* must initialise this */
  71
  72     if (i==0) {                        /* blank line - ignore */
  73         result->opcode = -1;           /* and no instruction either */
  74         return result;
  75     }
  76     if (i != TOKEN_ID && i != TOKEN_INSN && i != TOKEN_PREFIX &&
  77         (i!=TOKEN_REG || (REG_SREG & ~reg_flags[tokval.t_integer]))) {
  78         error (ERR_NONFATAL, "label or instruction expected"
  79                " at start of line");
  80         result->opcode = -1;
  81         return result;
  82     }
  83
  84     if (i == TOKEN_ID) {               /* there's a label here */
  85         result->label = tokval.t_charptr;
  86         i = stdscan(NULL, &tokval);
  87         if (i == ':') {                /* skip over the optional colon */
  88             i = stdscan(NULL, &tokval);
  89         } else if (i == 0) {
  90             error (ERR_WARNING|ERR_WARN_OL|ERR_PASS1,
  91                    "label alone on a line without a colon might be in error");
  92         }
  93         if (i != TOKEN_INSN || tokval.t_integer != I_EQU)
  94         {
  95             /*
  96              * FIXME: location->segment could be NO_SEG, in which case
  97              * it is possible we should be passing 'abs_seg'. Look into this.
  98              * Work out whether that is *really* what we should be doing.
  99              * Generally fix things. I think this is right as it is, but
 100              * am still not certain.
 101              */
 102             ldef (result->label, location->segment,
 103                   location->offset, NULL, TRUE, FALSE, outfmt, errfunc);
 104         }
 105     }
 106
 107     if (i==0) {
 108         result->opcode = -1;           /* this line contains just a label */
 109         return result;
 110     }
 111
 112     result->nprefix = 0;
 113     result->times = 1L;
 114
 115     while (i == TOKEN_PREFIX ||
 116            (i==TOKEN_REG && !(REG_SREG & ~reg_flags[tokval.t_integer])))
 117     {
 118         /*
 119          * Handle special case: the TIMES prefix.
 120          */
 121         if (i == TOKEN_PREFIX && tokval.t_integer == P_TIMES) {
 122             expr *value;
 123
 124             i = stdscan(NULL, &tokval);
 125             value = evaluate (stdscan, NULL, &tokval, NULL, pass, error, NULL);
 126             i = tokval.t_type;
 127             if (!value) {              /* but, error in evaluator */
 128                 result->opcode = -1;   /* unrecoverable parse error: */
 129                 return result;         /* ignore this instruction */
 130             }
 131             if (!is_simple (value)) {
 132                 error (ERR_NONFATAL,
 133                        "non-constant argument supplied to TIMES");
 134                 result->times = 1L;
 135             } else {
 136                 result->times = value->value;
 137                 if (value->value < 0) {
 138                     error(ERR_NONFATAL, "TIMES value %d is negative",
 139                           value->value);
 140                     result->times = 0;
 141                 }
 142             }
 143         } else {
 144             if (result->nprefix == MAXPREFIX)
 145                 error (ERR_NONFATAL,
 146                        "instruction has more than %d prefixes", MAXPREFIX);
 147             else
 148                 result->prefixes[result->nprefix++] = tokval.t_integer;
 149             i = stdscan(NULL, &tokval);
 150         }
 151     }
 152
 153     if (i != TOKEN_INSN) {
 154         if (result->nprefix > 0 && i == 0) {
 155             /*
 156              * Instruction prefixes are present, but no actual
 157              * instruction. This is allowed: at this point we
 158              * invent a notional instruction of RESB 0.
 159              */
 160             result->opcode = I_RESB;
 161             result->operands = 1;
 162             result->oprs[0].type = IMMEDIATE;
 163             result->oprs[0].offset = 0L;
 164             result->oprs[0].segment = result->oprs[0].wrt = NO_SEG;
 165             return result;
 166         } else {
 167             error (ERR_NONFATAL, "parser: instruction expected");
 168             result->opcode = -1;
 169             return result;
 170         }
 171     }
 172
 173     result->opcode = tokval.t_integer;
 174     result->condition = tokval.t_inttwo;
 175
 176     /*
 177      * RESB, RESW and RESD cannot be satisfied with incorrectly
 178      * evaluated operands, since the correct values _must_ be known
 179      * on the first pass. Hence, even in pass one, we set the
 180      * `critical' flag on calling evaluate(), so that it will bomb
 181      * out on undefined symbols. Nasty, but there's nothing we can
 182      * do about it.
 183      *
 184      * For the moment, EQU has the same difficulty, so we'll
 185      * include that.
 186      */
 187     if (result->opcode == I_RESB ||
 188         result->opcode == I_RESW ||
 189         result->opcode == I_RESD ||
 190         result->opcode == I_RESQ ||
 191         result->opcode == I_REST ||
 192         result->opcode == I_EQU)
 193     {
 194         critical = pass;
 195     }
 196     else
 197         critical = (pass==2 ? 2 : 0);
 198
 199     if (result->opcode == I_DB ||
 200         result->opcode == I_DW ||
 201         result->opcode == I_DD ||
 202         result->opcode == I_DQ ||
 203         result->opcode == I_DT ||
 204         result->opcode == I_INCBIN)
 205     {
 206         extop *eop, **tail = &result->eops, **fixptr;
 207         int oper_num = 0;
 208
 209         result->eops_float = FALSE;
 210
 211         /*
 212          * Begin to read the DB/DW/DD/DQ/DT/INCBIN operands.
 213          */
 214         while (1) {
 215             i = stdscan(NULL, &tokval);
 216             if (i == 0)
 217                 break;
 218             fixptr = tail;
 219             eop = *tail = nasm_malloc(sizeof(extop));
 220             tail = &eop->next;
 221             eop->next = NULL;
 222             eop->type = EOT_NOTHING;
 223             oper_num++;
 224
 225             if (i == TOKEN_NUM && tokval.t_charptr && is_comma_next()) {
 226                 eop->type = EOT_DB_STRING;
 227                 eop->stringval = tokval.t_charptr;
 228                 eop->stringlen = tokval.t_inttwo;
 229                 i = stdscan(NULL, &tokval);       /* eat the comma */
 230                 continue;
 231             }
 232
 233             if ((i == TOKEN_FLOAT && is_comma_next()) || i == '-') {
 234                 long sign = +1L;
 235
 236                 if (i == '-') {
 237                     char *save = stdscan_bufptr;
 238                     i = stdscan(NULL, &tokval);
 239                     sign = -1L;
 240                     if (i != TOKEN_FLOAT || !is_comma_next()) {
 241                         stdscan_bufptr = save;
 242                         i = tokval.t_type = '-';
 243                     }
 244                 }
 245
 246                 if (i == TOKEN_FLOAT) {
 247                     eop->type = EOT_DB_STRING;
 248                     result->eops_float = TRUE;
 249                     if (result->opcode == I_DD)
 250                         eop->stringlen = 4;
 251                     else if (result->opcode == I_DQ)
 252                         eop->stringlen = 8;
 253                     else if (result->opcode == I_DT)
 254                         eop->stringlen = 10;
 255                     else {
 256                         error(ERR_NONFATAL, "floating-point constant"
 257                               " encountered in `D%c' instruction",
 258                               result->opcode == I_DW ? 'W' : 'B');
 259                         /*
 260                          * fix suggested by Pedro Gimeno... original line
 261                          * was:
 262                          * eop->type = EOT_NOTHING;
 263                          */
 264                         eop->stringlen = 0;
 265                     }
 266                     eop = nasm_realloc(eop, sizeof(extop)+eop->stringlen);
 267                     tail = &eop->next;
 268                     *fixptr = eop;
 269                     eop->stringval = (char *)eop + sizeof(extop);
 270                     if (eop->stringlen < 4 ||
 271                         !float_const (tokval.t_charptr, sign,
 272                                       (unsigned char *)eop->stringval,
 273                                       eop->stringlen, error))
 274                         eop->type = EOT_NOTHING;
 275                     i = stdscan(NULL, &tokval);       /* eat the comma */
 276                     continue;
 277                 }
 278             }
 279
 280             /* anything else */
 281             {
 282                 expr *value;
 283                 value = evaluate (stdscan, NULL, &tokval, NULL,
 284                                   critical, error, NULL);
 285                 i = tokval.t_type;
 286                 if (!value) {          /* error in evaluator */
 287                     result->opcode = -1;/* unrecoverable parse error: */
 288                     return result;     /* ignore this instruction */
 289                 }
 290                 if (is_unknown(value)) {
 291                     eop->type = EOT_DB_NUMBER;
 292                     eop->offset = 0;   /* doesn't matter what we put */
 293                     eop->segment = eop->wrt = NO_SEG;   /* likewise */
 294                 } else if (is_reloc(value)) {
 295                     eop->type = EOT_DB_NUMBER;
 296                     eop->offset = reloc_value(value);
 297                     eop->segment = reloc_seg(value);
 298                     eop->wrt = reloc_wrt(value);
 299                 } else {
 300                     error (ERR_NONFATAL,
 301                            "operand %d: expression is not simple"
 302                            " or relocatable", oper_num);
 303                 }
 304             }
 305
 306             /*
 307              * We're about to call stdscan(), which will eat the
 308              * comma that we're currently sitting on between
 309              * arguments. However, we'd better check first that it
 310              * _is_ a comma.
 311              */
 312             if (i == 0)                /* also could be EOL */
 313                 break;
 314             if (i != ',') {
 315                 error (ERR_NONFATAL, "comma expected after operand %d",
 316                        oper_num);
 317                 result->opcode = -1;/* unrecoverable parse error: */
 318                 return result;     /* ignore this instruction */
 319             }
 320         }
 321
 322         if (result->opcode == I_INCBIN) {
 323             /*
 324              * Correct syntax for INCBIN is that there should be
 325              * one string operand, followed by one or two numeric
 326              * operands.
 327              */
 328             if (!result->eops || result->eops->type != EOT_DB_STRING)
 329                 error (ERR_NONFATAL, "`incbin' expects a file name");
 330             else if (result->eops->next &&
 331                      result->eops->next->type != EOT_DB_NUMBER)
 332                 error (ERR_NONFATAL, "`incbin': second parameter is",
 333                        " non-numeric");
 334             else if (result->eops->next && result->eops->next->next &&
 335                      result->eops->next->next->type != EOT_DB_NUMBER)
 336                 error (ERR_NONFATAL, "`incbin': third parameter is",
 337                        " non-numeric");
 338             else if (result->eops->next && result->eops->next->next &&
 339                      result->eops->next->next->next)
 340                 error (ERR_NONFATAL, "`incbin': more than three parameters");
 341             else
 342                 return result;
 343             /*
 344              * If we reach here, one of the above errors happened.
 345              * Throw the instruction away.
 346              */
 347             result->opcode = -1;
 348             return result;
 349         } else /* DB ... */
 350             if (oper_num == 0)
 351                 error (ERR_WARNING|ERR_PASS1,
 352                        "no operand for data declaration");
 353             else
 354                 result->operands = oper_num;
 355
 356         return result;
 357     }
 358
 359     /* right. Now we begin to parse the operands. There may be up to three
 360      * of these, separated by commas, and terminated by a zero token. */
 361
 362     for (operand = 0; operand < 3; operand++) {
 363         expr *value;                   /* used most of the time */
 364         int mref;                      /* is this going to be a memory ref? */
 365         int bracket;                   /* is it a [] mref, or a & mref? */
 366         int setsize = 0;
 367
 368         result->oprs[operand].addr_size = 0;/* have to zero this whatever */
 369         result->oprs[operand].eaflags = 0;   /* and this */
 370         result->oprs[operand].opflags = 0;
 371
 372         i = stdscan(NULL, &tokval);
 373         if (i == 0) break;             /* end of operands: get out of here */
 374         result->oprs[operand].type = 0;   /* so far, no override */
 375         while (i == TOKEN_SPECIAL)      {/* size specifiers */
 376             switch ((int)tokval.t_integer) {
 377               case S_BYTE:
 378                 if (!setsize)            /* we want to use only the first */
 379                     result->oprs[operand].type |= BITS8;
 380                 setsize = 1;
 381                 break;
 382               case S_WORD:
 383                 if (!setsize)
 384                     result->oprs[operand].type |= BITS16;
 385                 setsize = 1;
 386                 break;
 387               case S_DWORD:
 388               case S_LONG:
 389                 if (!setsize)
 390                     result->oprs[operand].type |= BITS32;
 391                 setsize = 1;
 392                 break;
 393               case S_QWORD:
 394                 if (!setsize)
 395                     result->oprs[operand].type |= BITS64;
 396                 setsize = 1;
 397                 break;
 398               case S_TWORD:
 399                 if (!setsize)
 400                     result->oprs[operand].type |= BITS80;
 401                 setsize = 1;
 402                 break;
 403               case S_TO:
 404                 result->oprs[operand].type |= TO;
 405                 break;
 406               case S_FAR:
 407                 result->oprs[operand].type |= FAR;
 408                 break;
 409               case S_NEAR:
 410                 result->oprs[operand].type |= NEAR;
 411                 break;
 412               case S_SHORT:
 413                 result->oprs[operand].type |= SHORT;
 414                 break;
 415               default:
 416                 error (ERR_NONFATAL, "invalid operand size specification");
 417             }
 418             i = stdscan(NULL, &tokval);
 419         }
 420
 421         if (i == '[' || i == '&') {    /* memory reference */
 422             mref = TRUE;
 423             bracket = (i == '[');
 424             i = stdscan(NULL, &tokval);
 425             if (i == TOKEN_SPECIAL) {  /* check for address size override */
 426                 switch ((int)tokval.t_integer) {
 427                   case S_NOSPLIT:
 428                     result->oprs[operand].eaflags |= EAF_TIMESTWO;
 429                     break;
 430                   case S_BYTE:
 431                     result->oprs[operand].eaflags |= EAF_BYTEOFFS;
 432                     break;
 433                   case S_WORD:
 434                     result->oprs[operand].addr_size = 16;
 435                     result->oprs[operand].eaflags |= EAF_WORDOFFS;
 436                     break;
 437                   case S_DWORD:
 438                   case S_LONG:
 439                     result->oprs[operand].addr_size = 32;
 440                     result->oprs[operand].eaflags |= EAF_WORDOFFS;
 441                     break;
 442                   default:
 443                     error (ERR_NONFATAL, "invalid size specification in"
 444                            " effective address");
 445                 }
 446                 i = stdscan(NULL, &tokval);
 447             }
 448         } else {                       /* immediate operand, or register */
 449             mref = FALSE;
 450             bracket = FALSE;           /* placate optimisers */
 451         }
 452
 453         value = evaluate (stdscan, NULL, &tokval,
 454                           &result->oprs[operand].opflags,
 455                           critical, error, &hints);
 456         i = tokval.t_type;
 457         if (result->oprs[operand].opflags & OPFLAG_FORWARD) {
 458             result->forw_ref = TRUE;
 459         }
 460         if (!value) {                  /* error in evaluator */
 461             result->opcode = -1;       /* unrecoverable parse error: */
 462             return result;             /* ignore this instruction */
 463         }
 464         if (i == ':' && mref) {        /* it was seg:offset */
 465             /*
 466              * Process the segment override.
 467              */
 468             if (value[1].type!=0 || value->value!=1 ||
 469                 REG_SREG & ~reg_flags[value->type])
 470                 error (ERR_NONFATAL, "invalid segment override");
 471             else if (result->nprefix == MAXPREFIX)
 472                 error (ERR_NONFATAL,
 473                        "instruction has more than %d prefixes",
 474                        MAXPREFIX);
 475             else
 476                 result->prefixes[result->nprefix++] = value->type;
 477
 478             i = stdscan(NULL, &tokval);        /* then skip the colon */
 479             if (i == TOKEN_SPECIAL) {  /* another check for size override */
 480                 switch ((int)tokval.t_integer) {
 481                   case S_WORD:
 482                     result->oprs[operand].addr_size = 16;
 483                     break;
 484                   case S_DWORD:
 485                   case S_LONG:
 486                     result->oprs[operand].addr_size = 32;
 487                     break;
 488                   default:
 489                     error (ERR_NONFATAL, "invalid size specification in"
 490                            " effective address");
 491                 }
 492                 i = stdscan(NULL, &tokval);
 493             }
 494             value = evaluate (stdscan, NULL, &tokval,
 495                               &result->oprs[operand].opflags,
 496                               critical, error, &hints);
 497             i = tokval.t_type;
 498             if (result->oprs[operand].opflags & OPFLAG_FORWARD) {
 499                 result->forw_ref = TRUE;
 500             }
 501             /* and get the offset */
 502             if (!value) {              /* but, error in evaluator */
 503                 result->opcode = -1;   /* unrecoverable parse error: */
 504                 return result;         /* ignore this instruction */
 505             }
 506         }
 507         if (mref && bracket) {         /* find ] at the end */
 508             if (i != ']') {
 509                 error (ERR_NONFATAL, "parser: expecting ]");
 510                 do {                   /* error recovery again */
 511                     i = stdscan(NULL, &tokval);
 512                 } while (i != 0 && i != ',');
 513             } else                     /* we got the required ] */
 514                 i = stdscan(NULL, &tokval);
 515         } else {                       /* immediate operand */
 516             if (i != 0 && i != ',' && i != ':') {
 517                 error (ERR_NONFATAL, "comma or end of line expected");
 518                 do {                   /* error recovery */
 519                     i = stdscan(NULL, &tokval);
 520                 } while (i != 0 && i != ',');
 521             } else if (i == ':') {
 522                 result->oprs[operand].type |= COLON;
 523             }
 524         }
 525
 526         /* now convert the exprs returned from evaluate() into operand
 527          * descriptions... */
 528
 529         if (mref) {                    /* it's a memory reference */
 530             expr *e = value;
 531             int b, i, s;               /* basereg, indexreg, scale */
 532             long o;                    /* offset */
 533
 534             b = i = -1, o = s = 0;
 535             result->oprs[operand].hintbase = hints.base;
 536             result->oprs[operand].hinttype = hints.type;
 537
 538             if (e->type <= EXPR_REG_END) {   /* this bit's a register */
 539                 if (e->value == 1) /* in fact it can be basereg */
 540                     b = e->type;
 541                 else           /* no, it has to be indexreg */
 542                     i = e->type, s = e->value;
 543                 e++;
 544             }
 545             if (e->type && e->type <= EXPR_REG_END)   /* it's a 2nd register */
 546             {
 547                 if (b != -1)               /* If the first was the base, ... */
 548                     i = e->type, s = e->value;  /* second has to be indexreg */
 549
 550                 else if (e->value != 1)          /* If both want to be index */
 551                 {
 552                     error(ERR_NONFATAL, "invalid effective address");
 553                     result->opcode = -1;
 554                     return result;
 555                 }
 556                 else
 557                     b = e->type;
 558                 e++;
 559             }
 560             if (e->type != 0) {        /* is there an offset? */
 561                 if (e->type <= EXPR_REG_END)  /* in fact, is there an error? */
 562                 {
 563                     error (ERR_NONFATAL, "invalid effective address");
 564                     result->opcode = -1;
 565                     return result;
 566                 }
 567                 else
 568                 {
 569                     if (e->type == EXPR_UNKNOWN) {
 570                         o = 0;                       /* doesn't matter what */
 571                         result->oprs[operand].wrt = NO_SEG;     /* nor this */
 572                         result->oprs[operand].segment = NO_SEG;  /* or this */
 573                         while (e->type) e++;   /* go to the end of the line */
 574                     }
 575                     else
 576                     {
 577                         if (e->type == EXPR_SIMPLE) {
 578                             o = e->value;
 579                             e++;
 580                         }
 581                         if (e->type == EXPR_WRT) {
 582                             result->oprs[operand].wrt = e->value;
 583                             e++;
 584                         } else
 585                             result->oprs[operand].wrt = NO_SEG;
 586                         /*
 587                          * Look for a segment base type.
 588                          */
 589                         if (e->type && e->type < EXPR_SEGBASE) {
 590                             error (ERR_NONFATAL, "invalid effective address");
 591                             result->opcode = -1;
 592                             return result;
 593                         }
 594                         while (e->type && e->value == 0)
 595                             e++;
 596                         if (e->type && e->value != 1) {
 597                             error (ERR_NONFATAL, "invalid effective address");
 598                             result->opcode = -1;
 599                             return result;
 600                         }
 601                         if (e->type) {
 602                             result->oprs[operand].segment =
 603                                 e->type - EXPR_SEGBASE;
 604                             e++;
 605                         } else
 606                             result->oprs[operand].segment = NO_SEG;
 607                         while (e->type && e->value == 0)
 608                             e++;
 609                         if (e->type) {
 610                             error (ERR_NONFATAL, "invalid effective address");
 611                             result->opcode = -1;
 612                             return result;
 613                         }
 614                     }
 615                 }
 616             } else {
 617                 o = 0;
 618                 result->oprs[operand].wrt = NO_SEG;
 619                 result->oprs[operand].segment = NO_SEG;
 620             }
 621
 622             if (e->type != 0) {    /* there'd better be nothing left! */
 623                 error (ERR_NONFATAL, "invalid effective address");
 624                 result->opcode = -1;
 625                 return result;
 626             }
 627
 628             result->oprs[operand].type |= MEMORY;
 629             if (b==-1 && (i==-1 || s==0))
 630                 result->oprs[operand].type |= MEM_OFFS;
 631             result->oprs[operand].basereg = b;
 632             result->oprs[operand].indexreg = i;
 633             result->oprs[operand].scale = s;
 634             result->oprs[operand].offset = o;
 635         }
 636         else                                  /* it's not a memory reference */
 637         {
 638             if (is_just_unknown(value)) {     /* it's immediate but unknown */
 639                 result->oprs[operand].type |= IMMEDIATE;
 640                 result->oprs[operand].offset = 0;   /* don't care */
 641                 result->oprs[operand].segment = NO_SEG; /* don't care again */
 642                 result->oprs[operand].wrt = NO_SEG;/* still don't care */
 643             }
 644             else if (is_reloc(value))         /* it's immediate */
 645             {
 646                 result->oprs[operand].type |= IMMEDIATE;
 647                 result->oprs[operand].offset = reloc_value(value);
 648                 result->oprs[operand].segment = reloc_seg(value);
 649                 result->oprs[operand].wrt = reloc_wrt(value);
 650                 if (is_simple(value) && reloc_value(value)==1)
 651                     result->oprs[operand].type |= UNITY;
 652             }
 653             else               /* it's a register */
 654             {
 655                 int i;
 656
 657                 if (value->type>=EXPR_SIMPLE || value->value!=1) {
 658                     error (ERR_NONFATAL, "invalid operand type");
 659                     result->opcode = -1;
 660                     return result;
 661                 }
 662
 663                 /*
 664                  * check that its only 1 register, not an expression...
 665                  */
 666                 for (i = 1; value[i].type; i++)
 667                     if (value[i].value) {
 668                         error (ERR_NONFATAL, "invalid operand type");
 669                         result->opcode = -1;
 670                         return result;
 671                     }
 672
 673                 /* clear overrides, except TO which applies to FPU regs */
 674                 if (result->oprs[operand].type & ~TO) {
 675                     /*
 676                      * we want to produce a warning iff the specified size
 677                      * is different from the register size
 678                      */
 679                     i = result->oprs[operand].type & SIZE_MASK;
 680                 }
 681                 else
 682                     i = 0;
 683
 684                 result->oprs[operand].type &= TO;
 685                 result->oprs[operand].type |= REGISTER;
 686                 result->oprs[operand].type |= reg_flags[value->type];
 687                 result->oprs[operand].basereg = value->type;
 688
 689                 if (i && (result->oprs[operand].type & SIZE_MASK) != i)
 690                     error (ERR_WARNING|ERR_PASS1,
 691                            "register size specification ignored");
 692             }
 693         }
 694     }
 695
 696     result->operands = operand;       /* set operand count */
 697
 698     while (operand<3)                  /* clear remaining operands */
 699         result->oprs[operand++].type = 0;
 700
 701     /*
 702      * Transform RESW, RESD, RESQ, REST into RESB.
 703      */
 704     switch (result->opcode) {
 705       case I_RESW: result->opcode=I_RESB; result->oprs[0].offset*=2; break;
 706       case I_RESD: result->opcode=I_RESB; result->oprs[0].offset*=4; break;
 707       case I_RESQ: result->opcode=I_RESB; result->oprs[0].offset*=8; break;
 708       case I_REST: result->opcode=I_RESB; result->oprs[0].offset*=10; break;
 709     }
 710
 711     return result;
 712 }
 713
 714 static int is_comma_next (void)
 715 {
 716     char *p;
 717     int i;
 718     struct tokenval tv;
 719
 720     p = stdscan_bufptr;
 721     i = stdscan (NULL, &tv);
 722     stdscan_bufptr = p;
 723     return (i == ',' || i == ';' || !i);
 724 }
 725
 726 void cleanup_insn (insn *i)
 727 {
 728     extop *e;
 729
 730     while (i->eops) {
 731         e = i->eops;
 732         i->eops = i->eops->next;
 733         nasm_free (e);
 734     }
 735 }