output/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 #include <inttypes.h>
  15
  16 #include "nasm.h"
  17 #include "nasmlib.h"
  18 #include "outform.h"
  19
  20 #ifdef OF_AS86
  21
  22 struct Piece {
  23     struct Piece *next;
  24     int type;                   /* 0 = absolute, 1 = seg, 2 = sym */
  25     int32_t offset;                /* relative offset */
  26     int number;                 /* symbol/segment number (4=bss) */
  27     int32_t bytes;                 /* size of reloc or of absolute data */
  28     int relative;               /* TRUE or FALSE */
  29 };
  30
  31 struct Symbol {
  32     int32_t strpos;                /* string table position of name */
  33     int flags;                  /* symbol flags */
  34     int segment;                /* 4=bss at this point */
  35     int32_t value;                 /* address, or COMMON variable size */
  36 };
  37
  38 /*
  39  * Section IDs - used in Piece.number and Symbol.segment.
  40  */
  41 #define SECT_TEXT 0             /* text section */
  42 #define SECT_DATA 3             /* data section */
  43 #define SECT_BSS 4              /* bss section */
  44
  45 /*
  46  * Flags used in Symbol.flags.
  47  */
  48 #define SYM_ENTRY (1<<8)
  49 #define SYM_EXPORT (1<<7)
  50 #define SYM_IMPORT (1<<6)
  51 #define SYM_ABSOLUTE (1<<4)
  52
  53 struct Section {
  54     struct SAA *data;
  55     uint32_t datalen, size, len;
  56     int32_t index;
  57     struct Piece *head, *last, **tail;
  58 };
  59
  60 static char as86_module[FILENAME_MAX];
  61
  62 static struct Section stext, sdata;
  63 static uint32_t bsslen;
  64 static int32_t bssindex;
  65
  66 static struct SAA *syms;
  67 static uint32_t nsyms;
  68
  69 static struct RAA *bsym;
  70
  71 static struct SAA *strs;
  72 static uint32_t strslen;
  73
  74 static int as86_reloc_size;
  75
  76 static FILE *as86fp;
  77 static efunc error;
  78
  79 static void as86_write(void);
  80 static void as86_write_section(struct Section *, int);
  81 static int as86_add_string(char *name);
  82 static void as86_sect_write(struct Section *, const uint8_t *,
  83                             uint32_t);
  84
  85 static void as86_init(FILE * fp, efunc errfunc, ldfunc ldef, evalfunc eval)
  86 {
  87     as86fp = fp;
  88     error = errfunc;
  89     (void)ldef;                 /* placate optimisers */
  90     (void)eval;
  91     stext.data = saa_init(1L);
  92     stext.datalen = 0L;
  93     stext.head = stext.last = NULL;
  94     stext.tail = &stext.head;
  95     sdata.data = saa_init(1L);
  96     sdata.datalen = 0L;
  97     sdata.head = sdata.last = NULL;
  98     sdata.tail = &sdata.head;
  99     bsslen =
 100         stext.len = stext.datalen = stext.size =
 101         sdata.len = sdata.datalen = sdata.size = 0;
 102     stext.index = seg_alloc();
 103     sdata.index = seg_alloc();
 104     bssindex = seg_alloc();
 105     syms = saa_init((int32_t)sizeof(struct Symbol));
 106     nsyms = 0;
 107     bsym = raa_init();
 108     strs = saa_init(1L);
 109     strslen = 0;
 110
 111     as86_add_string(as86_module);
 112 }
 113
 114 static void as86_cleanup(int debuginfo)
 115 {
 116     struct Piece *p;
 117
 118     (void)debuginfo;
 119
 120     as86_write();
 121     fclose(as86fp);
 122     saa_free(stext.data);
 123     while (stext.head) {
 124         p = stext.head;
 125         stext.head = stext.head->next;
 126         nasm_free(p);
 127     }
 128     saa_free(sdata.data);
 129     while (sdata.head) {
 130         p = sdata.head;
 131         sdata.head = sdata.head->next;
 132         nasm_free(p);
 133     }
 134     saa_free(syms);
 135     raa_free(bsym);
 136     saa_free(strs);
 137 }
 138
 139 static int32_t as86_section_names(char *name, int pass, int *bits)
 140 {
 141
 142     (void)pass;
 143
 144     /*
 145      * Default is 16 bits.
 146      */
 147     if (!name)
 148         *bits = 16;
 149
 150     if (!name)
 151         return stext.index;
 152
 153     if (!strcmp(name, ".text"))
 154         return stext.index;
 155     else if (!strcmp(name, ".data"))
 156         return sdata.index;
 157     else if (!strcmp(name, ".bss"))
 158         return bssindex;
 159     else
 160         return NO_SEG;
 161 }
 162
 163 static int as86_add_string(char *name)
 164 {
 165     int pos = strslen;
 166     int length = strlen(name);
 167
 168     saa_wbytes(strs, name, (int32_t)(length + 1));
 169     strslen += 1 + length;
 170
 171     return pos;
 172 }
 173
 174 static void as86_deflabel(char *name, int32_t segment, int32_t offset,
 175                           int is_global, char *special)
 176 {
 177     struct Symbol *sym;
 178
 179     if (special)
 180         error(ERR_NONFATAL, "as86 format does not support any"
 181               " special symbol types");
 182
 183     if (name[0] == '.' && name[1] == '.' && name[2] != '@') {
 184         error(ERR_NONFATAL, "unrecognised special symbol `%s'", name);
 185         return;
 186     }
 187
 188     sym = saa_wstruct(syms);
 189
 190     sym->strpos = as86_add_string(name);
 191     sym->flags = 0;
 192     if (segment == NO_SEG)
 193         sym->flags |= SYM_ABSOLUTE, sym->segment = 0;
 194     else if (segment == stext.index)
 195         sym->segment = SECT_TEXT;
 196     else if (segment == sdata.index)
 197         sym->segment = SECT_DATA;
 198     else if (segment == bssindex)
 199         sym->segment = SECT_BSS;
 200     else {
 201         sym->flags |= SYM_IMPORT;
 202         sym->segment = 15;
 203     }
 204
 205     if (is_global == 2)
 206         sym->segment = 3;       /* already have IMPORT */
 207
 208     if (is_global && !(sym->flags & SYM_IMPORT))
 209         sym->flags |= SYM_EXPORT;
 210
 211     sym->value = offset;
 212
 213     /*
 214      * define the references from external-symbol segment numbers
 215      * to these symbol records.
 216      */
 217     if (segment != NO_SEG && segment != stext.index &&
 218         segment != sdata.index && segment != bssindex)
 219         bsym = raa_write(bsym, segment, nsyms);
 220
 221     nsyms++;
 222 }
 223
 224 static void as86_add_piece(struct Section *sect, int type, int32_t offset,
 225                            int32_t segment, int32_t bytes, int relative)
 226 {
 227     struct Piece *p;
 228
 229     sect->len += bytes;
 230
 231     if (type == 0 && sect->last && sect->last->type == 0) {
 232         sect->last->bytes += bytes;
 233         return;
 234     }
 235
 236     p = sect->last = *sect->tail = nasm_malloc(sizeof(struct Piece));
 237     sect->tail = &p->next;
 238     p->next = NULL;
 239
 240     p->type = type;
 241     p->offset = offset;
 242     p->bytes = bytes;
 243     p->relative = relative;
 244
 245     if (type == 1 && segment == stext.index)
 246         p->number = SECT_TEXT;
 247     else if (type == 1 && segment == sdata.index)
 248         p->number = SECT_DATA;
 249     else if (type == 1 && segment == bssindex)
 250         p->number = SECT_BSS;
 251     else if (type == 1)
 252         p->number = raa_read(bsym, segment), p->type = 2;
 253 }
 254
 255 static void as86_out(int32_t segto, const void *data, uint32_t type,
 256                      int32_t segment, int32_t wrt)
 257 {
 258     struct Section *s;
 259     int32_t realbytes = type & OUT_SIZMASK;
 260     int32_t offset;
 261     uint8_t mydata[4], *p;
 262
 263     if (wrt != NO_SEG) {
 264         wrt = NO_SEG;           /* continue to do _something_ */
 265         error(ERR_NONFATAL, "WRT not supported by as86 output format");
 266     }
 267
 268     type &= OUT_TYPMASK;
 269
 270     /*
 271      * handle absolute-assembly (structure definitions)
 272      */
 273     if (segto == NO_SEG) {
 274         if (type != OUT_RESERVE)
 275             error(ERR_NONFATAL, "attempt to assemble code in [ABSOLUTE]"
 276                   " space");
 277         return;
 278     }
 279
 280     if (segto == stext.index)
 281         s = &stext;
 282     else if (segto == sdata.index)
 283         s = &sdata;
 284     else if (segto == bssindex)
 285         s = NULL;
 286     else {
 287         error(ERR_WARNING, "attempt to assemble code in"
 288               " segment %d: defaulting to `.text'", segto);
 289         s = &stext;
 290     }
 291
 292     if (!s && type != OUT_RESERVE) {
 293         error(ERR_WARNING, "attempt to initialize memory in the"
 294               " BSS section: ignored");
 295         if (type == OUT_REL2ADR)
 296             realbytes = 2;
 297         else if (type == OUT_REL4ADR)
 298             realbytes = 4;
 299         bsslen += realbytes;
 300         return;
 301     }
 302
 303     if (type == OUT_RESERVE) {
 304         if (s) {
 305             error(ERR_WARNING, "uninitialized space declared in"
 306                   " %s section: zeroing",
 307                   (segto == stext.index ? "code" : "data"));
 308             as86_sect_write(s, NULL, realbytes);
 309             as86_add_piece(s, 0, 0L, 0L, realbytes, 0);
 310         } else
 311             bsslen += realbytes;
 312     } else if (type == OUT_RAWDATA) {
 313         if (segment != NO_SEG)
 314             error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
 315         as86_sect_write(s, data, realbytes);
 316         as86_add_piece(s, 0, 0L, 0L, realbytes, 0);
 317     } else if (type == OUT_ADDRESS) {
 318         if (segment != NO_SEG) {
 319             if (segment % 2) {
 320                 error(ERR_NONFATAL, "as86 format does not support"
 321                       " segment base references");
 322             } else {
 323                 offset = *(int32_t *)data;
 324                 as86_add_piece(s, 1, offset, segment, realbytes, 0);
 325             }
 326         } else {
 327             p = mydata;
 328             WRITELONG(p, *(int32_t *)data);
 329             as86_sect_write(s, data, realbytes);
 330             as86_add_piece(s, 0, 0L, 0L, realbytes, 0);
 331         }
 332     } else if (type == OUT_REL2ADR) {
 333         if (segment == segto)
 334             error(ERR_PANIC, "intra-segment OUT_REL2ADR");
 335         if (segment != NO_SEG) {
 336             if (segment % 2) {
 337                 error(ERR_NONFATAL, "as86 format does not support"
 338                       " segment base references");
 339             } else {
 340                 offset = *(int32_t *)data;
 341                 as86_add_piece(s, 1, offset - realbytes + 2, segment, 2L,
 342                                1);
 343             }
 344         }
 345     } else if (type == OUT_REL4ADR) {
 346         if (segment == segto)
 347             error(ERR_PANIC, "intra-segment OUT_REL4ADR");
 348         if (segment != NO_SEG) {
 349             if (segment % 2) {
 350                 error(ERR_NONFATAL, "as86 format does not support"
 351                       " segment base references");
 352             } else {
 353                 offset = *(int32_t *)data;
 354                 as86_add_piece(s, 1, offset - realbytes + 4, segment, 4L,
 355                                1);
 356             }
 357         }
 358     }
 359 }
 360
 361 static void as86_write(void)
 362 {
 363     uint32_t i;
 364     int32_t symlen, seglen, segsize;
 365
 366     /*
 367      * First, go through the symbol records working out how big
 368      * each will be. Also fix up BSS references at this time, and
 369      * set the flags words up completely.
 370      */
 371     symlen = 0;
 372     saa_rewind(syms);
 373     for (i = 0; i < nsyms; i++) {
 374         struct Symbol *sym = saa_rstruct(syms);
 375         if (sym->segment == SECT_BSS)
 376             sym->segment = SECT_DATA, sym->value += sdata.len;
 377         sym->flags |= sym->segment;
 378         if (sym->value == 0)
 379             sym->flags |= 0 << 14, symlen += 4;
 380         else if (sym->value >= 0 && sym->value <= 255)
 381             sym->flags |= 1 << 14, symlen += 5;
 382         else if (sym->value >= 0 && sym->value <= 65535L)
 383             sym->flags |= 2 << 14, symlen += 6;
 384         else
 385             sym->flags |= 3 << 14, symlen += 8;
 386     }
 387
 388     /*
 389      * Now do the same for the segments, and get the segment size
 390      * descriptor word at the same time.
 391      */
 392     seglen = segsize = 0;
 393     if ((uint32_t)stext.len > 65535L)
 394         segsize |= 0x03000000L, seglen += 4;
 395     else
 396         segsize |= 0x02000000L, seglen += 2;
 397     if ((uint32_t)sdata.len > 65535L)
 398         segsize |= 0xC0000000L, seglen += 4;
 399     else
 400         segsize |= 0x80000000L, seglen += 2;
 401
 402     /*
 403      * Emit the as86 header.
 404      */
 405     fwriteint32_t(0x000186A3L, as86fp);
 406     fputc(0x2A, as86fp);
 407     fwriteint32_t(27 + symlen + seglen + strslen, as86fp); /* header length */
 408     fwriteint32_t(stext.len + sdata.len + bsslen, as86fp);
 409     fwriteint16_t(strslen, as86fp);
 410     fwriteint16_t(0, as86fp);     /* class = revision = 0 */
 411     fwriteint32_t(0x55555555L, as86fp);    /* segment max sizes: always this */
 412     fwriteint32_t(segsize, as86fp);        /* segment size descriptors */
 413     if (segsize & 0x01000000L)
 414         fwriteint32_t(stext.len, as86fp);
 415     else
 416         fwriteint16_t(stext.len, as86fp);
 417     if (segsize & 0x40000000L)
 418         fwriteint32_t(sdata.len + bsslen, as86fp);
 419     else
 420         fwriteint16_t(sdata.len + bsslen, as86fp);
 421     fwriteint16_t(nsyms, as86fp);
 422
 423     /*
 424      * Write the symbol table.
 425      */
 426     saa_rewind(syms);
 427     for (i = 0; i < nsyms; i++) {
 428         struct Symbol *sym = saa_rstruct(syms);
 429         fwriteint16_t(sym->strpos, as86fp);
 430         fwriteint16_t(sym->flags, as86fp);
 431         switch (sym->flags & (3 << 14)) {
 432         case 0 << 14:
 433             break;
 434         case 1 << 14:
 435             fputc(sym->value, as86fp);
 436             break;
 437         case 2 << 14:
 438             fwriteint16_t(sym->value, as86fp);
 439             break;
 440         case 3 << 14:
 441             fwriteint32_t(sym->value, as86fp);
 442             break;
 443         }
 444     }
 445
 446     /*
 447      * Write out the string table.
 448      */
 449     saa_fpwrite(strs, as86fp);
 450
 451     /*
 452      * Write the program text.
 453      */
 454     as86_reloc_size = -1;
 455     as86_write_section(&stext, SECT_TEXT);
 456     as86_write_section(&sdata, SECT_DATA);
 457     /*
 458      * Append the BSS section to the .data section
 459      */
 460     if (bsslen > 65535L) {
 461         fputc(0x13, as86fp);
 462         fwriteint32_t(bsslen, as86fp);
 463     } else if (bsslen > 255) {
 464         fputc(0x12, as86fp);
 465         fwriteint16_t(bsslen, as86fp);
 466     } else if (bsslen) {
 467         fputc(0x11, as86fp);
 468         fputc(bsslen, as86fp);
 469     }
 470
 471     fputc(0, as86fp);           /* termination */
 472 }
 473
 474 static void as86_set_rsize(int size)
 475 {
 476     if (as86_reloc_size != size) {
 477         switch (as86_reloc_size = size) {
 478         case 1:
 479             fputc(0x01, as86fp);
 480             break;
 481         case 2:
 482             fputc(0x02, as86fp);
 483             break;
 484         case 4:
 485             fputc(0x03, as86fp);
 486             break;
 487         default:
 488             error(ERR_PANIC, "bizarre relocation size %d", size);
 489         }
 490     }
 491 }
 492
 493 static void as86_write_section(struct Section *sect, int index)
 494 {
 495     struct Piece *p;
 496     uint32_t s;
 497     int32_t length;
 498
 499     fputc(0x20 + index, as86fp);        /* select the right section */
 500
 501     saa_rewind(sect->data);
 502
 503     for (p = sect->head; p; p = p->next)
 504         switch (p->type) {
 505         case 0:
 506             /*
 507              * Absolute data. Emit it in chunks of at most 64
 508              * bytes.
 509              */
 510             length = p->bytes;
 511             do {
 512                 char buf[64];
 513                 int32_t tmplen = (length > 64 ? 64 : length);
 514                 fputc(0x40 | (tmplen & 0x3F), as86fp);
 515                 saa_rnbytes(sect->data, buf, tmplen);
 516                 fwrite(buf, 1, tmplen, as86fp);
 517                 length -= tmplen;
 518             } while (length > 0);
 519             break;
 520         case 1:
 521             /*
 522              * A segment-type relocation. First fix up the BSS.
 523              */
 524             if (p->number == SECT_BSS)
 525                 p->number = SECT_DATA, p->offset += sdata.len;
 526             as86_set_rsize(p->bytes);
 527             fputc(0x80 | (p->relative ? 0x20 : 0) | p->number, as86fp);
 528             if (as86_reloc_size == 2)
 529                 fwriteint16_t(p->offset, as86fp);
 530             else
 531                 fwriteint32_t(p->offset, as86fp);
 532             break;
 533         case 2:
 534             /*
 535              * A symbol-type relocation.
 536              */
 537             as86_set_rsize(p->bytes);
 538             s = p->offset;
 539             if (s > 65535L)
 540                 s = 3;
 541             else if (s > 255)
 542                 s = 2;
 543             else if (s > 0)
 544                 s = 1;
 545             else
 546                 s = 0;
 547             fputc(0xC0 |
 548                   (p->relative ? 0x20 : 0) |
 549                   (p->number > 255 ? 0x04 : 0) | s, as86fp);
 550             if (p->number > 255)
 551                 fwriteint16_t(p->number, as86fp);
 552             else
 553                 fputc(p->number, as86fp);
 554             switch ((int)s) {
 555             case 0:
 556                 break;
 557             case 1:
 558                 fputc(p->offset, as86fp);
 559                 break;
 560             case 2:
 561                 fwriteint16_t(p->offset, as86fp);
 562                 break;
 563             case 3:
 564                 fwriteint32_t(p->offset, as86fp);
 565                 break;
 566             }
 567             break;
 568         }
 569 }
 570
 571 static void as86_sect_write(struct Section *sect,
 572                             const uint8_t *data, uint32_t len)
 573 {
 574     saa_wbytes(sect->data, data, len);
 575     sect->datalen += len;
 576 }
 577
 578 static int32_t as86_segbase(int32_t segment)
 579 {
 580     return segment;
 581 }
 582
 583 static int as86_directive(char *directive, char *value, int pass)
 584 {
 585     (void)directive;
 586     (void)value;
 587     (void)pass;
 588     return 0;
 589 }
 590
 591 static void as86_filename(char *inname, char *outname, efunc error)
 592 {
 593     char *p;
 594
 595     if ((p = strrchr(inname, '.')) != NULL) {
 596         strncpy(as86_module, inname, p - inname);
 597         as86_module[p - inname] = '\0';
 598     } else
 599         strcpy(as86_module, inname);
 600
 601     standard_extension(inname, outname, ".o", error);
 602 }
 603
 604 static const char *as86_stdmac[] = {
 605     "%define __SECT__ [section .text]",
 606     "%macro __NASM_CDecl__ 1",
 607     "%endmacro",
 608     NULL
 609 };
 610
 611 static int as86_set_info(enum geninfo type, char **val)
 612 {
 613     (void)type;
 614     (void)val;
 615     return 0;
 616 }
 617 void as86_linenumber(char *name, int32_t segment, int32_t offset, int is_main,
 618                      int lineno)
 619 {
 620     (void)name;
 621     (void)segment;
 622     (void)offset;
 623     (void)is_main;
 624     (void)lineno;
 625 }
 626 struct ofmt of_as86 = {
 627     "Linux as86 (bin86 version 0.3) object files",
 628     "as86",
 629     NULL,
 630     null_debug_arr,
 631     &null_debug_form,
 632     as86_stdmac,
 633     as86_init,
 634     as86_set_info,
 635     as86_out,
 636     as86_deflabel,
 637     as86_section_names,
 638     as86_segbase,
 639     as86_directive,
 640     as86_filename,
 641     as86_cleanup
 642 };
 643
 644 #endif                          /* OF_AS86 */