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) {
  84     as86fp = fp;
  85     error = errfunc;
  86     (void) ldef;                       /* placate optimisers */
  87     stext.data = saa_init(1L); stext.datalen = 0L;
  88     stext.head = stext.last = NULL;
  89     stext.tail = &stext.head;
  90     sdata.data = saa_init(1L); sdata.datalen = 0L;
  91     sdata.head = sdata.last = NULL;
  92     sdata.tail = &sdata.head;
  93     bsslen =
  94         stext.len = stext.datalen = stext.size =
  95         sdata.len = sdata.datalen = sdata.size = 0;
  96     stext.index = seg_alloc();
  97     sdata.index = seg_alloc();
  98     bssindex = seg_alloc();
  99     syms = saa_init((long)sizeof(struct Symbol));
 100     nsyms = 0;
 101     bsym = raa_init();
 102     strs = saa_init(1L);
 103     strslen = 0;
 104
 105     as86_add_string (as86_module);
 106 }
 107
 108 static void as86_cleanup(void) {
 109     struct Piece *p;
 110
 111     as86_write();
 112     fclose (as86fp);
 113     saa_free (stext.data);
 114     while (stext.head) {
 115         p = stext.head;
 116         stext.head = stext.head->next;
 117         nasm_free (p);
 118     }
 119     saa_free (sdata.data);
 120     while (sdata.head) {
 121         p = sdata.head;
 122         sdata.head = sdata.head->next;
 123         nasm_free (p);
 124     }
 125     saa_free (syms);
 126     raa_free (bsym);
 127     saa_free (strs);
 128 }
 129
 130 static long as86_section_names (char *name, int pass, int *bits) {
 131     /*
 132      * Default is 16 bits.
 133      */
 134     if (!name)
 135         *bits = 16;
 136
 137     if (!name)
 138         return stext.index;
 139
 140     if (!strcmp(name, ".text"))
 141         return stext.index;
 142     else if (!strcmp(name, ".data"))
 143         return sdata.index;
 144     else if (!strcmp(name, ".bss"))
 145         return bssindex;
 146     else
 147         return NO_SEG;
 148 }
 149
 150 static int as86_add_string (char *name) {
 151     int pos = strslen;
 152     int length = strlen(name);
 153
 154     saa_wbytes (strs, name, (long)(length+1));
 155     strslen += 1+length;
 156
 157     return pos;
 158 }
 159
 160 static void as86_deflabel (char *name, long segment, long offset,
 161                            int is_global) {
 162     struct Symbol *sym;
 163
 164     if (name[0] == '.' && name[1] == '.') {
 165         return;
 166     }
 167
 168     sym = saa_wstruct (syms);
 169
 170     sym->strpos = as86_add_string (name);
 171     sym->flags = 0;
 172     if (segment == NO_SEG)
 173         sym->flags |= SYM_ABSOLUTE, sym->segment = 0;
 174     else if (segment == stext.index)
 175         sym->segment = SECT_TEXT;
 176     else if (segment == sdata.index)
 177         sym->segment = SECT_DATA;
 178     else if (segment == bssindex)
 179         sym->segment = SECT_BSS;
 180     else {
 181         sym->flags |= SYM_IMPORT;
 182         sym->segment = 15;
 183     }
 184
 185     if (is_global == 2)
 186         sym->segment = 3;       /* already have IMPORT */
 187
 188     if (is_global && !(sym->flags & SYM_IMPORT))
 189         sym->flags |= SYM_EXPORT;
 190
 191     sym->value = offset;
 192
 193     /*
 194      * define the references from external-symbol segment numbers
 195      * to these symbol records.
 196      */
 197     if (segment != NO_SEG && segment != stext.index &&
 198         segment != sdata.index && segment != bssindex)
 199         bsym = raa_write (bsym, segment, nsyms);
 200
 201     nsyms++;
 202 }
 203
 204 static void as86_add_piece (struct Section *sect, int type, long offset,
 205                             long segment, long bytes, int relative) {
 206     struct Piece *p;
 207
 208     sect->len += bytes;
 209
 210     if (type == 0 && sect->last && sect->last->type == 0) {
 211         sect->last->bytes += bytes;
 212         return;
 213     }
 214
 215     p = sect->last = *sect->tail = nasm_malloc(sizeof(struct Piece));
 216     sect->tail = &p->next;
 217     p->next = NULL;
 218
 219     p->type = type;
 220     p->offset = offset;
 221     p->bytes = bytes;
 222     p->relative = relative;
 223
 224     if (type == 1 && segment == stext.index)
 225         p->number = SECT_TEXT;
 226     else if (type == 1 && segment == sdata.index)
 227         p->number = SECT_DATA;
 228     else if (type == 1 && segment == bssindex)
 229         p->number = SECT_BSS;
 230     else if (type == 1)
 231         p->number = raa_read (bsym, segment), p->type = 2;
 232 }
 233
 234 static void as86_out (long segto, void *data, unsigned long type,
 235                       long segment, long wrt) {
 236     struct Section *s;
 237     long realbytes = type & OUT_SIZMASK;
 238     long offset;
 239     unsigned char mydata[4], *p;
 240
 241     if (wrt != NO_SEG) {
 242         wrt = NO_SEG;                  /* continue to do _something_ */
 243         error (ERR_NONFATAL, "WRT not supported by as86 output format");
 244     }
 245
 246     type &= OUT_TYPMASK;
 247
 248     /*
 249      * handle absolute-assembly (structure definitions)
 250      */
 251     if (segto == NO_SEG) {
 252         if (type != OUT_RESERVE)
 253             error (ERR_NONFATAL, "attempt to assemble code in [ABSOLUTE]"
 254                    " space");
 255         return;
 256     }
 257
 258     if (segto == stext.index)
 259         s = &stext;
 260     else if (segto == sdata.index)
 261         s = &sdata;
 262     else if (segto == bssindex)
 263         s = NULL;
 264     else {
 265         error(ERR_WARNING, "attempt to assemble code in"
 266               " segment %d: defaulting to `.text'", segto);
 267         s = &stext;
 268     }
 269
 270     if (!s && type != OUT_RESERVE) {
 271         error(ERR_WARNING, "attempt to initialise memory in the"
 272               " BSS section: ignored");
 273         if (type == OUT_REL2ADR)
 274             realbytes = 2;
 275         else if (type == OUT_REL4ADR)
 276             realbytes = 4;
 277         bsslen += realbytes;
 278         return;
 279     }
 280
 281     if (type == OUT_RESERVE) {
 282         if (s) {
 283             error(ERR_WARNING, "uninitialised space declared in"
 284                   " %s section: zeroing",
 285                   (segto == stext.index ? "code" : "data"));
 286             as86_sect_write (s, NULL, realbytes);
 287             as86_add_piece (s, 0, 0L, 0L, realbytes, 0);
 288         } else
 289             bsslen += realbytes;
 290     } else if (type == OUT_RAWDATA) {
 291         if (segment != NO_SEG)
 292             error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
 293         as86_sect_write (s, data, realbytes);
 294         as86_add_piece (s, 0, 0L, 0L, realbytes, 0);
 295     } else if (type == OUT_ADDRESS) {
 296         if (segment != NO_SEG) {
 297             if (segment % 2) {
 298                 error(ERR_NONFATAL, "as86 format does not support"
 299                       " segment base references");
 300             } else{
 301                 offset = * (long *) data;
 302                 as86_add_piece (s, 1, offset, segment, realbytes, 0);
 303             }
 304         } else {
 305             p = mydata;
 306             WRITELONG (p, * (long *) data);
 307             as86_sect_write (s, data, realbytes);
 308             as86_add_piece (s, 0, 0L, 0L, realbytes, 0);
 309         }
 310     } else if (type == OUT_REL2ADR) {
 311         if (segment == segto)
 312             error(ERR_PANIC, "intra-segment OUT_REL2ADR");
 313         if (segment != NO_SEG) {
 314             if (segment % 2) {
 315                 error(ERR_NONFATAL, "as86 format does not support"
 316                       " segment base references");
 317             } else {
 318                 offset = * (long *) data;
 319                 as86_add_piece (s, 1, offset-realbytes+2, segment, 2L, 1);
 320             }
 321         }
 322     } else if (type == OUT_REL4ADR) {
 323         if (segment == segto)
 324             error(ERR_PANIC, "intra-segment OUT_REL4ADR");
 325         if (segment != NO_SEG) {
 326             if (segment % 2) {
 327                 error(ERR_NONFATAL, "as86 format does not support"
 328                       " segment base references");
 329             } else {
 330                 offset = * (long *) data;
 331                 as86_add_piece (s, 1, offset-realbytes+4, segment, 4L, 1);
 332             }
 333         }
 334     }
 335 }
 336
 337 static void as86_write(void) {
 338     int i;
 339     long symlen, seglen, segsize;
 340
 341     /*
 342      * First, go through the symbol records working out how big
 343      * each will be. Also fix up BSS references at this time, and
 344      * set the flags words up completely.
 345      */
 346     symlen = 0;
 347     saa_rewind (syms);
 348     for (i = 0; i < nsyms; i++) {
 349         struct Symbol *sym = saa_rstruct (syms);
 350         if (sym->segment == SECT_BSS)
 351             sym->segment = SECT_DATA, sym->value += sdata.len;
 352         sym->flags |= sym->segment;
 353         if (sym->value == 0)
 354             sym->flags |= 0 << 14, symlen += 4;
 355         else if (sym->value >= 0 && sym->value <= 255)
 356             sym->flags |= 1 << 14, symlen += 5;
 357         else if (sym->value >= 0 && sym->value <= 65535)
 358             sym->flags |= 2 << 14, symlen += 6;
 359         else
 360             sym->flags |= 3 << 14, symlen += 8;
 361     }
 362
 363     /*
 364      * Now do the same for the segments, and get the segment size
 365      * descriptor word at the same time.
 366      */
 367     seglen = segsize = 0;
 368     if ((unsigned long) stext.len > 65535)
 369         segsize |= 0x03000000, seglen += 4;
 370     else
 371         segsize |= 0x02000000, seglen += 2;
 372     if ((unsigned long) sdata.len > 65535)
 373         segsize |= 0xC0000000, seglen += 4;
 374     else
 375         segsize |= 0x80000000, seglen += 2;
 376
 377     /*
 378      * Emit the as86 header.
 379      */
 380     fwritelong (0x000186A3, as86fp);
 381     fputc (0x2A, as86fp);
 382     fwritelong (27+symlen+seglen+strslen, as86fp);   /* header length */
 383     fwritelong (stext.len+sdata.len, as86fp);
 384     fwriteshort (strslen, as86fp);
 385     fwriteshort (0, as86fp);           /* class = revision = 0 */
 386     fwritelong (0x55555555, as86fp);   /* segment max sizes: always this */
 387     fwritelong (segsize, as86fp);      /* segment size descriptors */
 388     if (segsize & 0x01000000)
 389         fwritelong (stext.len, as86fp);
 390     else
 391         fwriteshort (stext.len, as86fp);
 392     if (segsize & 0x40000000)
 393         fwritelong (sdata.len, as86fp);
 394     else
 395         fwriteshort (sdata.len, as86fp);
 396     fwriteshort (nsyms, as86fp);
 397
 398     /*
 399      * Write the symbol table.
 400      */
 401     saa_rewind (syms);
 402     for (i = 0; i < nsyms; i++) {
 403         struct Symbol *sym = saa_rstruct (syms);
 404         fwriteshort (sym->strpos, as86fp);
 405         fwriteshort (sym->flags, as86fp);
 406         switch (sym->flags & (3<<14)) {
 407           case 0<<14: break;
 408           case 1<<14: fputc (sym->value, as86fp); break;
 409           case 2<<14: fwriteshort (sym->value, as86fp); break;
 410           case 3<<14: fwritelong (sym->value, as86fp); break;
 411         }
 412     }
 413
 414     /*
 415      * Write out the string table.
 416      */
 417     saa_fpwrite (strs, as86fp);
 418
 419     /*
 420      * Write the program text.
 421      */
 422     as86_reloc_size = -1;
 423     as86_write_section (&stext, SECT_TEXT);
 424     as86_write_section (&sdata, SECT_DATA);
 425     fputc (0, as86fp);                 /* termination */
 426 }
 427
 428 static void as86_set_rsize (int size) {
 429     if (as86_reloc_size != size) {
 430         switch (as86_reloc_size = size) {
 431           case 1: fputc (0x01, as86fp); break;   /* shouldn't happen */
 432           case 2: fputc (0x02, as86fp); break;
 433           case 4: fputc (0x03, as86fp); break;
 434           default: error (ERR_PANIC, "bizarre relocation size %d", size);
 435         }
 436     }
 437 }
 438
 439 static void as86_write_section (struct Section *sect, int index) {
 440     struct Piece *p;
 441     unsigned long s;
 442     long length;
 443
 444     fputc (0x20+index, as86fp);        /* select the right section */
 445
 446     saa_rewind (sect->data);
 447
 448     for (p = sect->head; p; p = p->next)
 449         switch (p->type) {
 450           case 0:
 451             /*
 452              * Absolute data. Emit it in chunks of at most 64
 453              * bytes.
 454              */
 455             length = p->bytes;
 456             do {
 457                 char buf[64];
 458                 long tmplen = (length > 64 ? 64 : length);
 459                 fputc (0x40 | (tmplen & 0x3F), as86fp);
 460                 saa_rnbytes (sect->data, buf, tmplen);
 461                 fwrite (buf, 1, tmplen, as86fp);
 462                 length -= tmplen;
 463             } while (length > 0);
 464             break;
 465           case 1:
 466             /*
 467              * A segment-type relocation. First fix up the BSS.
 468              */
 469             if (p->number == SECT_BSS)
 470                 p->number = SECT_DATA, p->offset += sdata.len;
 471             as86_set_rsize (p->bytes);
 472             fputc (0x80 | (p->relative ? 0x20 : 0) | p->number, as86fp);
 473             if (as86_reloc_size == 2)
 474                 fwriteshort (p->offset, as86fp);
 475             else
 476                 fwritelong (p->offset, as86fp);
 477             break;
 478           case 2:
 479             /*
 480              * A symbol-type relocation.
 481              */
 482             as86_set_rsize (p->bytes);
 483             s = p->offset;
 484             if (s > 65535)
 485                 s = 3;
 486             else if (s > 255)
 487                 s = 2;
 488             else if (s > 0)
 489                 s = 1;
 490             else
 491                 s = 0;
 492             fputc (0xC0 |
 493                    (p->relative ? 0x20 : 0) |
 494                    (p->number > 255 ? 0x04 : 0) | s, as86fp);
 495             if (p->number > 255)
 496                 fwriteshort (p->number, as86fp);
 497             else
 498                 fputc (p->number, as86fp);
 499             switch ((int)s) {
 500               case 0: break;
 501               case 1: fputc (p->offset, as86fp); break;
 502               case 2: fwriteshort (p->offset, as86fp); break;
 503               case 3: fwritelong (p->offset, as86fp); break;
 504             }
 505             break;
 506         }
 507 }
 508
 509 static void as86_sect_write (struct Section *sect,
 510                              unsigned char *data, unsigned long len) {
 511     saa_wbytes (sect->data, data, len);
 512     sect->datalen += len;
 513 }
 514
 515 static long as86_segbase (long segment) {
 516     return segment;
 517 }
 518
 519 static int as86_directive (char *directive, char *value, int pass) {
 520     return 0;
 521 }
 522
 523 static void as86_filename (char *inname, char *outname, efunc error) {
 524     char *p;
 525
 526     if ( (p = strrchr (inname, '.')) != NULL) {
 527         strncpy (as86_module, inname, p-inname);
 528         as86_module[p-inname] = '\0';
 529     } else
 530         strcpy (as86_module, inname);
 531
 532     standard_extension (inname, outname, ".o", error);
 533 }
 534
 535 struct ofmt of_as86 = {
 536     "Linux as86 (bin86 version 0.3) object files",
 537     "as86",
 538     as86_init,
 539     as86_out,
 540     as86_deflabel,
 541     as86_section_names,
 542     as86_segbase,
 543     as86_directive,
 544     as86_filename,
 545     as86_cleanup
 546 };
 547
 548 #endif /* OF_AS86 */