outas86.c

   1 /* outas86.c    output routines for the Netwide Assembler to produce
   2  *              Linux as86 (bin86-0.3) object files
   3  *
   4  * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
   5  * Julian Hall. All rights reserved. The software is
   6  * redistributable under the licence given in the file "Licence"
   7  * distributed in the NASM archive.
   8  */
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <ctype.h>
  14
  15 #include "nasm.h"
  16 #include "nasmlib.h"
  17 #include "outform.h"
  18
  19 #ifdef OF_AS86
  20
  21 struct Piece {
  22     struct Piece *next;
  23     int type;                          /* 0 = absolute, 1 = seg, 2 = sym */
  24     long offset;                       /* relative offset */
  25     int number;                        /* symbol/segment number (4=bss) */
  26     long bytes;                        /* size of reloc or of absolute data */
  27     int relative;                      /* TRUE or FALSE */
  28 };
  29
  30 struct Symbol {
  31     long strpos;                       /* string table position of name */
  32     int flags;                         /* symbol flags */
  33     int segment;                       /* 4=bss at this point */
  34     long value;                        /* address, or COMMON variable size */
  35 };
  36
  37 /*
  38  * Section IDs - used in Piece.number and Symbol.segment.
  39  */
  40 #define SECT_TEXT 0                    /* text section */
  41 #define SECT_DATA 3                    /* data section */
  42 #define SECT_BSS 4                     /* bss section */
  43
  44 /*
  45  * Flags used in Symbol.flags.
  46  */
  47 #define SYM_ENTRY (1<<8)
  48 #define SYM_EXPORT (1<<7)
  49 #define SYM_IMPORT (1<<6)
  50 #define SYM_ABSOLUTE (1<<4)
  51
  52 struct Section {
  53     struct SAA *data;
  54     unsigned long datalen, size, len;
  55     long index;
  56     struct Piece *head, *last, **tail;
  57 };
  58
  59 static char as86_module[FILENAME_MAX];
  60
  61 static struct Section stext, sdata;
  62 static unsigned long bsslen;
  63 static long bssindex;
  64
  65 static struct SAA *syms;
  66 static unsigned long nsyms;
  67
  68 static struct RAA *bsym;
  69
  70 static struct SAA *strs;
  71 static unsigned long strslen;
  72
  73 static int as86_reloc_size;
  74
  75 static FILE *as86fp;
  76 static efunc error;
  77
  78 static void as86_write(void);
  79 static void as86_write_section (struct Section *, int);
  80 static int as86_add_string (char *name);
  81 static void as86_sect_write(struct Section *, unsigned char *, unsigned long);
  82
  83 static void as86_init(FILE *fp, efunc errfunc, ldfunc ldef, evalfunc eval)
  84 {
  85     as86fp = fp;
  86     error = errfunc;
  87     (void) ldef;                       /* placate optimisers */
  88     stext.data = saa_init(1L); stext.datalen = 0L;
  89     stext.head = stext.last = NULL;
  90     stext.tail = &stext.head;
  91     sdata.data = saa_init(1L); sdata.datalen = 0L;
  92     sdata.head = sdata.last = NULL;
  93     sdata.tail = &sdata.head;
  94     bsslen =
  95         stext.len = stext.datalen = stext.size =
  96         sdata.len = sdata.datalen = sdata.size = 0;
  97     stext.index = seg_alloc();
  98     sdata.index = seg_alloc();
  99     bssindex = seg_alloc();
 100     syms = saa_init((long)sizeof(struct Symbol));
 101     nsyms = 0;
 102     bsym = raa_init();
 103     strs = saa_init(1L);
 104     strslen = 0;
 105
 106     as86_add_string (as86_module);
 107 }
 108
 109 static void as86_cleanup(int debuginfo)
 110 {
 111     struct Piece *p;
 112
 113     (void) debuginfo;
 114
 115     as86_write();
 116     fclose (as86fp);
 117     saa_free (stext.data);
 118     while (stext.head) {
 119         p = stext.head;
 120         stext.head = stext.head->next;
 121         nasm_free (p);
 122     }
 123     saa_free (sdata.data);
 124     while (sdata.head) {
 125         p = sdata.head;
 126         sdata.head = sdata.head->next;
 127         nasm_free (p);
 128     }
 129     saa_free (syms);
 130     raa_free (bsym);
 131     saa_free (strs);
 132 }
 133
 134 static long as86_section_names (char *name, int pass, int *bits)
 135 {
 136     /*
 137      * Default is 16 bits.
 138      */
 139     if (!name)
 140         *bits = 16;
 141
 142     if (!name)
 143         return stext.index;
 144
 145     if (!strcmp(name, ".text"))
 146         return stext.index;
 147     else if (!strcmp(name, ".data"))
 148         return sdata.index;
 149     else if (!strcmp(name, ".bss"))
 150         return bssindex;
 151     else
 152         return NO_SEG;
 153 }
 154
 155 static int as86_add_string (char *name)
 156 {
 157     int pos = strslen;
 158     int length = strlen(name);
 159
 160     saa_wbytes (strs, name, (long)(length+1));
 161     strslen += 1+length;
 162
 163     return pos;
 164 }
 165
 166 static void as86_deflabel (char *name, long segment, long offset,
 167                            int is_global, char *special)
 168 {
 169     struct Symbol *sym;
 170
 171     if (special)
 172         error (ERR_NONFATAL, "as86 format does not support any"
 173                " special symbol types");
 174
 175     if (name[0] == '.' && name[1] == '.' && name[2] != '@') {
 176         error (ERR_NONFATAL, "unrecognised special symbol `%s'", name);
 177         return;
 178     }
 179
 180     sym = saa_wstruct (syms);
 181
 182     sym->strpos = as86_add_string (name);
 183     sym->flags = 0;
 184     if (segment == NO_SEG)
 185         sym->flags |= SYM_ABSOLUTE, sym->segment = 0;
 186     else if (segment == stext.index)
 187         sym->segment = SECT_TEXT;
 188     else if (segment == sdata.index)
 189         sym->segment = SECT_DATA;
 190     else if (segment == bssindex)
 191         sym->segment = SECT_BSS;
 192     else {
 193         sym->flags |= SYM_IMPORT;
 194         sym->segment = 15;
 195     }
 196
 197     if (is_global == 2)
 198         sym->segment = 3;       /* already have IMPORT */
 199
 200     if (is_global && !(sym->flags & SYM_IMPORT))
 201         sym->flags |= SYM_EXPORT;
 202
 203     sym->value = offset;
 204
 205     /*
 206      * define the references from external-symbol segment numbers
 207      * to these symbol records.
 208      */
 209     if (segment != NO_SEG && segment != stext.index &&
 210         segment != sdata.index && segment != bssindex)
 211         bsym = raa_write (bsym, segment, nsyms);
 212
 213     nsyms++;
 214 }
 215
 216 static void as86_add_piece (struct Section *sect, int type, long offset,
 217                             long segment, long bytes, int relative)
 218 {
 219     struct Piece *p;
 220
 221     sect->len += bytes;
 222
 223     if (type == 0 && sect->last && sect->last->type == 0) {
 224         sect->last->bytes += bytes;
 225         return;
 226     }
 227
 228     p = sect->last = *sect->tail = nasm_malloc(sizeof(struct Piece));
 229     sect->tail = &p->next;
 230     p->next = NULL;
 231
 232     p->type = type;
 233     p->offset = offset;
 234     p->bytes = bytes;
 235     p->relative = relative;
 236
 237     if (type == 1 && segment == stext.index)
 238         p->number = SECT_TEXT;
 239     else if (type == 1 && segment == sdata.index)
 240         p->number = SECT_DATA;
 241     else if (type == 1 && segment == bssindex)
 242         p->number = SECT_BSS;
 243     else if (type == 1)
 244         p->number = raa_read (bsym, segment), p->type = 2;
 245 }
 246
 247 static void as86_out (long segto, void *data, unsigned long type,
 248                       long segment, long wrt)
 249 {
 250     struct Section *s;
 251     long realbytes = type & OUT_SIZMASK;
 252     long offset;
 253     unsigned char mydata[4], *p;
 254
 255     if (wrt != NO_SEG) {
 256         wrt = NO_SEG;                  /* continue to do _something_ */
 257         error (ERR_NONFATAL, "WRT not supported by as86 output format");
 258     }
 259
 260     type &= OUT_TYPMASK;
 261
 262     /*
 263      * handle absolute-assembly (structure definitions)
 264      */
 265     if (segto == NO_SEG) {
 266         if (type != OUT_RESERVE)
 267             error (ERR_NONFATAL, "attempt to assemble code in [ABSOLUTE]"
 268                    " space");
 269         return;
 270     }
 271
 272     if (segto == stext.index)
 273         s = &stext;
 274     else if (segto == sdata.index)
 275         s = &sdata;
 276     else if (segto == bssindex)
 277         s = NULL;
 278     else {
 279         error(ERR_WARNING, "attempt to assemble code in"
 280               " segment %d: defaulting to `.text'", segto);
 281         s = &stext;
 282     }
 283
 284     if (!s && type != OUT_RESERVE) {
 285         error(ERR_WARNING, "attempt to initialise memory in the"
 286               " BSS section: ignored");
 287         if (type == OUT_REL2ADR)
 288             realbytes = 2;
 289         else if (type == OUT_REL4ADR)
 290             realbytes = 4;
 291         bsslen += realbytes;
 292         return;
 293     }
 294
 295     if (type == OUT_RESERVE) {
 296         if (s) {
 297             error(ERR_WARNING, "uninitialised space declared in"
 298                   " %s section: zeroing",
 299                   (segto == stext.index ? "code" : "data"));
 300             as86_sect_write (s, NULL, realbytes);
 301             as86_add_piece (s, 0, 0L, 0L, realbytes, 0);
 302         } else
 303             bsslen += realbytes;
 304     } else if (type == OUT_RAWDATA) {
 305         if (segment != NO_SEG)
 306             error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
 307         as86_sect_write (s, data, realbytes);
 308         as86_add_piece (s, 0, 0L, 0L, realbytes, 0);
 309     } else if (type == OUT_ADDRESS) {
 310         if (segment != NO_SEG) {
 311             if (segment % 2) {
 312                 error(ERR_NONFATAL, "as86 format does not support"
 313                       " segment base references");
 314             } else{
 315                 offset = * (long *) data;
 316                 as86_add_piece (s, 1, offset, segment, realbytes, 0);
 317             }
 318         } else {
 319             p = mydata;
 320             WRITELONG (p, * (long *) data);
 321             as86_sect_write (s, data, realbytes);
 322             as86_add_piece (s, 0, 0L, 0L, realbytes, 0);
 323         }
 324     } else if (type == OUT_REL2ADR) {
 325         if (segment == segto)
 326             error(ERR_PANIC, "intra-segment OUT_REL2ADR");
 327         if (segment != NO_SEG) {
 328             if (segment % 2) {
 329                 error(ERR_NONFATAL, "as86 format does not support"
 330                       " segment base references");
 331             } else {
 332                 offset = * (long *) data;
 333                 as86_add_piece (s, 1, offset-realbytes+2, segment, 2L, 1);
 334             }
 335         }
 336     } else if (type == OUT_REL4ADR) {
 337         if (segment == segto)
 338             error(ERR_PANIC, "intra-segment OUT_REL4ADR");
 339         if (segment != NO_SEG) {
 340             if (segment % 2) {
 341                 error(ERR_NONFATAL, "as86 format does not support"
 342                       " segment base references");
 343             } else {
 344                 offset = * (long *) data;
 345                 as86_add_piece (s, 1, offset-realbytes+4, segment, 4L, 1);
 346             }
 347         }
 348     }
 349 }
 350
 351 static void as86_write(void)
 352 {
 353     unsigned long i;
 354     long symlen, seglen, segsize;
 355
 356     /*
 357      * First, go through the symbol records working out how big
 358      * each will be. Also fix up BSS references at this time, and
 359      * set the flags words up completely.
 360      */
 361     symlen = 0;
 362     saa_rewind (syms);
 363     for (i = 0; i < nsyms; i++) {
 364         struct Symbol *sym = saa_rstruct (syms);
 365         if (sym->segment == SECT_BSS)
 366             sym->segment = SECT_DATA, sym->value += sdata.len;
 367         sym->flags |= sym->segment;
 368         if (sym->value == 0)
 369             sym->flags |= 0 << 14, symlen += 4;
 370         else if (sym->value >= 0 && sym->value <= 255)
 371             sym->flags |= 1 << 14, symlen += 5;
 372         else if (sym->value >= 0 && sym->value <= 65535L)
 373             sym->flags |= 2 << 14, symlen += 6;
 374         else
 375             sym->flags |= 3 << 14, symlen += 8;
 376     }
 377
 378     /*
 379      * Now do the same for the segments, and get the segment size
 380      * descriptor word at the same time.
 381      */
 382     seglen = segsize = 0;
 383     if ((unsigned long) stext.len > 65535L)
 384         segsize |= 0x03000000L, seglen += 4;
 385     else
 386         segsize |= 0x02000000L, seglen += 2;
 387     if ((unsigned long) sdata.len > 65535L)
 388         segsize |= 0xC0000000L, seglen += 4;
 389     else
 390         segsize |= 0x80000000L, seglen += 2;
 391
 392     /*
 393      * Emit the as86 header.
 394      */
 395     fwritelong (0x000186A3L, as86fp);
 396     fputc (0x2A, as86fp);
 397     fwritelong (27+symlen+seglen+strslen, as86fp);   /* header length */
 398     fwritelong (stext.len+sdata.len, as86fp);
 399     fwriteshort (strslen, as86fp);
 400     fwriteshort (0, as86fp);           /* class = revision = 0 */
 401     fwritelong (0x55555555L, as86fp);   /* segment max sizes: always this */
 402     fwritelong (segsize, as86fp);      /* segment size descriptors */
 403     if (segsize & 0x01000000L)
 404         fwritelong (stext.len, as86fp);
 405     else
 406         fwriteshort (stext.len, as86fp);
 407     if (segsize & 0x40000000L)
 408         fwritelong (sdata.len, as86fp);
 409     else
 410         fwriteshort (sdata.len, as86fp);
 411     fwriteshort (nsyms, as86fp);
 412
 413     /*
 414      * Write the symbol table.
 415      */
 416     saa_rewind (syms);
 417     for (i = 0; i < nsyms; i++) {
 418         struct Symbol *sym = saa_rstruct (syms);
 419         fwriteshort (sym->strpos, as86fp);
 420         fwriteshort (sym->flags, as86fp);
 421         switch (sym->flags & (3<<14)) {
 422           case 0<<14: break;
 423           case 1<<14: fputc (sym->value, as86fp); break;
 424           case 2<<14: fwriteshort (sym->value, as86fp); break;
 425           case 3<<14: fwritelong (sym->value, as86fp); break;
 426         }
 427     }
 428
 429     /*
 430      * Write out the string table.
 431      */
 432     saa_fpwrite (strs, as86fp);
 433
 434     /*
 435      * Write the program text.
 436      */
 437     as86_reloc_size = -1;
 438     as86_write_section (&stext, SECT_TEXT);
 439     as86_write_section (&sdata, SECT_DATA);
 440     fputc (0, as86fp);                 /* termination */
 441 }
 442
 443 static void as86_set_rsize (int size)
 444 {
 445     if (as86_reloc_size != size) {
 446         switch (as86_reloc_size = size) {
 447           case 1: fputc (0x01, as86fp); break;
 448           case 2: fputc (0x02, as86fp); break;
 449           case 4: fputc (0x03, as86fp); break;
 450           default: error (ERR_PANIC, "bizarre relocation size %d", size);
 451         }
 452     }
 453 }
 454
 455 static void as86_write_section (struct Section *sect, int index)
 456 {
 457     struct Piece *p;
 458     unsigned long s;
 459     long length;
 460
 461     fputc (0x20+index, as86fp);        /* select the right section */
 462
 463     saa_rewind (sect->data);
 464
 465     for (p = sect->head; p; p = p->next)
 466         switch (p->type) {
 467           case 0:
 468             /*
 469              * Absolute data. Emit it in chunks of at most 64
 470              * bytes.
 471              */
 472             length = p->bytes;
 473             do {
 474                 char buf[64];
 475                 long tmplen = (length > 64 ? 64 : length);
 476                 fputc (0x40 | (tmplen & 0x3F), as86fp);
 477                 saa_rnbytes (sect->data, buf, tmplen);
 478                 fwrite (buf, 1, tmplen, as86fp);
 479                 length -= tmplen;
 480             } while (length > 0);
 481             break;
 482           case 1:
 483             /*
 484              * A segment-type relocation. First fix up the BSS.
 485              */
 486             if (p->number == SECT_BSS)
 487                 p->number = SECT_DATA, p->offset += sdata.len;
 488             as86_set_rsize (p->bytes);
 489             fputc (0x80 | (p->relative ? 0x20 : 0) | p->number, as86fp);
 490             if (as86_reloc_size == 2)
 491                 fwriteshort (p->offset, as86fp);
 492             else
 493                 fwritelong (p->offset, as86fp);
 494             break;
 495           case 2:
 496             /*
 497              * A symbol-type relocation.
 498              */
 499             as86_set_rsize (p->bytes);
 500             s = p->offset;
 501             if (s > 65535L)
 502                 s = 3;
 503             else if (s > 255)
 504                 s = 2;
 505             else if (s > 0)
 506                 s = 1;
 507             else
 508                 s = 0;
 509             fputc (0xC0 |
 510                    (p->relative ? 0x20 : 0) |
 511                    (p->number > 255 ? 0x04 : 0) | s, as86fp);
 512             if (p->number > 255)
 513                 fwriteshort (p->number, as86fp);
 514             else
 515                 fputc (p->number, as86fp);
 516             switch ((int)s) {
 517               case 0: break;
 518               case 1: fputc (p->offset, as86fp); break;
 519               case 2: fwriteshort (p->offset, as86fp); break;
 520               case 3: fwritelong (p->offset, as86fp); break;
 521             }
 522             break;
 523         }
 524 }
 525
 526 static void as86_sect_write (struct Section *sect,
 527                              unsigned char *data, unsigned long len)
 528 {
 529     saa_wbytes (sect->data, data, len);
 530     sect->datalen += len;
 531 }
 532
 533 static long as86_segbase (long segment)
 534 {
 535     return segment;
 536 }
 537
 538 static int as86_directive (char *directive, char *value, int pass)
 539 {
 540     return 0;
 541 }
 542
 543 static void as86_filename (char *inname, char *outname, efunc error)
 544 {
 545     char *p;
 546
 547     if ( (p = strrchr (inname, '.')) != NULL) {
 548         strncpy (as86_module, inname, p-inname);
 549         as86_module[p-inname] = '\0';
 550     } else
 551         strcpy (as86_module, inname);
 552
 553     standard_extension (inname, outname, ".o", error);
 554 }
 555
 556 static char *as86_stdmac[] = {
 557     "%define __SECT__ [section .text]",
 558     "%macro __NASM_CDecl__ 1",
 559     "%endmacro",
 560     NULL
 561 };
 562
 563 static int as86_set_info(enum geninfo type, char **val)
 564 {
 565     return 0;
 566 }
 567 void as86_linenumber (char *name, long segment, long offset, int is_main,
 568                     int lineno)
 569 {
 570 }
 571 struct ofmt of_as86 = {
 572     "Linux as86 (bin86 version 0.3) object files",
 573     "as86",
 574     NULL,
 575     null_debug_arr,
 576     &null_debug_form,
 577     as86_stdmac,
 578     as86_init,
 579     as86_set_info,
 580     as86_out,
 581     as86_deflabel,
 582     as86_section_names,
 583     as86_segbase,
 584     as86_directive,
 585     as86_filename,
 586     as86_cleanup
 587 };
 588
 589 #endif /* OF_AS86 */