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] == '.' && name[2] != '@') {
 165         error (ERR_NONFATAL, "unrecognised special symbol `%s'", name);
 166         return;
 167     }
 168
 169     sym = saa_wstruct (syms);
 170
 171     sym->strpos = as86_add_string (name);
 172     sym->flags = 0;
 173     if (segment == NO_SEG)
 174         sym->flags |= SYM_ABSOLUTE, sym->segment = 0;
 175     else if (segment == stext.index)
 176         sym->segment = SECT_TEXT;
 177     else if (segment == sdata.index)
 178         sym->segment = SECT_DATA;
 179     else if (segment == bssindex)
 180         sym->segment = SECT_BSS;
 181     else {
 182         sym->flags |= SYM_IMPORT;
 183         sym->segment = 15;
 184     }
 185
 186     if (is_global == 2)
 187         sym->segment = 3;       /* already have IMPORT */
 188
 189     if (is_global && !(sym->flags & SYM_IMPORT))
 190         sym->flags |= SYM_EXPORT;
 191
 192     sym->value = offset;
 193
 194     /*
 195      * define the references from external-symbol segment numbers
 196      * to these symbol records.
 197      */
 198     if (segment != NO_SEG && segment != stext.index &&
 199         segment != sdata.index && segment != bssindex)
 200         bsym = raa_write (bsym, segment, nsyms);
 201
 202     nsyms++;
 203 }
 204
 205 static void as86_add_piece (struct Section *sect, int type, long offset,
 206                             long segment, long bytes, int relative) {
 207     struct Piece *p;
 208
 209     sect->len += bytes;
 210
 211     if (type == 0 && sect->last && sect->last->type == 0) {
 212         sect->last->bytes += bytes;
 213         return;
 214     }
 215
 216     p = sect->last = *sect->tail = nasm_malloc(sizeof(struct Piece));
 217     sect->tail = &p->next;
 218     p->next = NULL;
 219
 220     p->type = type;
 221     p->offset = offset;
 222     p->bytes = bytes;
 223     p->relative = relative;
 224
 225     if (type == 1 && segment == stext.index)
 226         p->number = SECT_TEXT;
 227     else if (type == 1 && segment == sdata.index)
 228         p->number = SECT_DATA;
 229     else if (type == 1 && segment == bssindex)
 230         p->number = SECT_BSS;
 231     else if (type == 1)
 232         p->number = raa_read (bsym, segment), p->type = 2;
 233 }
 234
 235 static void as86_out (long segto, void *data, unsigned long type,
 236                       long segment, long wrt) {
 237     struct Section *s;
 238     long realbytes = type & OUT_SIZMASK;
 239     long offset;
 240     unsigned char mydata[4], *p;
 241
 242     if (wrt != NO_SEG) {
 243         wrt = NO_SEG;                  /* continue to do _something_ */
 244         error (ERR_NONFATAL, "WRT not supported by as86 output format");
 245     }
 246
 247     type &= OUT_TYPMASK;
 248
 249     /*
 250      * handle absolute-assembly (structure definitions)
 251      */
 252     if (segto == NO_SEG) {
 253         if (type != OUT_RESERVE)
 254             error (ERR_NONFATAL, "attempt to assemble code in [ABSOLUTE]"
 255                    " space");
 256         return;
 257     }
 258
 259     if (segto == stext.index)
 260         s = &stext;
 261     else if (segto == sdata.index)
 262         s = &sdata;
 263     else if (segto == bssindex)
 264         s = NULL;
 265     else {
 266         error(ERR_WARNING, "attempt to assemble code in"
 267               " segment %d: defaulting to `.text'", segto);
 268         s = &stext;
 269     }
 270
 271     if (!s && type != OUT_RESERVE) {
 272         error(ERR_WARNING, "attempt to initialise memory in the"
 273               " BSS section: ignored");
 274         if (type == OUT_REL2ADR)
 275             realbytes = 2;
 276         else if (type == OUT_REL4ADR)
 277             realbytes = 4;
 278         bsslen += realbytes;
 279         return;
 280     }
 281
 282     if (type == OUT_RESERVE) {
 283         if (s) {
 284             error(ERR_WARNING, "uninitialised space declared in"
 285                   " %s section: zeroing",
 286                   (segto == stext.index ? "code" : "data"));
 287             as86_sect_write (s, NULL, realbytes);
 288             as86_add_piece (s, 0, 0L, 0L, realbytes, 0);
 289         } else
 290             bsslen += realbytes;
 291     } else if (type == OUT_RAWDATA) {
 292         if (segment != NO_SEG)
 293             error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
 294         as86_sect_write (s, data, realbytes);
 295         as86_add_piece (s, 0, 0L, 0L, realbytes, 0);
 296     } else if (type == OUT_ADDRESS) {
 297         if (segment != NO_SEG) {
 298             if (segment % 2) {
 299                 error(ERR_NONFATAL, "as86 format does not support"
 300                       " segment base references");
 301             } else{
 302                 offset = * (long *) data;
 303                 as86_add_piece (s, 1, offset, segment, realbytes, 0);
 304             }
 305         } else {
 306             p = mydata;
 307             WRITELONG (p, * (long *) data);
 308             as86_sect_write (s, data, realbytes);
 309             as86_add_piece (s, 0, 0L, 0L, realbytes, 0);
 310         }
 311     } else if (type == OUT_REL2ADR) {
 312         if (segment == segto)
 313             error(ERR_PANIC, "intra-segment OUT_REL2ADR");
 314         if (segment != NO_SEG) {
 315             if (segment % 2) {
 316                 error(ERR_NONFATAL, "as86 format does not support"
 317                       " segment base references");
 318             } else {
 319                 offset = * (long *) data;
 320                 as86_add_piece (s, 1, offset-realbytes+2, segment, 2L, 1);
 321             }
 322         }
 323     } else if (type == OUT_REL4ADR) {
 324         if (segment == segto)
 325             error(ERR_PANIC, "intra-segment OUT_REL4ADR");
 326         if (segment != NO_SEG) {
 327             if (segment % 2) {
 328                 error(ERR_NONFATAL, "as86 format does not support"
 329                       " segment base references");
 330             } else {
 331                 offset = * (long *) data;
 332                 as86_add_piece (s, 1, offset-realbytes+4, segment, 4L, 1);
 333             }
 334         }
 335     }
 336 }
 337
 338 static void as86_write(void) {
 339     int i;
 340     long symlen, seglen, segsize;
 341
 342     /*
 343      * First, go through the symbol records working out how big
 344      * each will be. Also fix up BSS references at this time, and
 345      * set the flags words up completely.
 346      */
 347     symlen = 0;
 348     saa_rewind (syms);
 349     for (i = 0; i < nsyms; i++) {
 350         struct Symbol *sym = saa_rstruct (syms);
 351         if (sym->segment == SECT_BSS)
 352             sym->segment = SECT_DATA, sym->value += sdata.len;
 353         sym->flags |= sym->segment;
 354         if (sym->value == 0)
 355             sym->flags |= 0 << 14, symlen += 4;
 356         else if (sym->value >= 0 && sym->value <= 255)
 357             sym->flags |= 1 << 14, symlen += 5;
 358         else if (sym->value >= 0 && sym->value <= 65535L)
 359             sym->flags |= 2 << 14, symlen += 6;
 360         else
 361             sym->flags |= 3 << 14, symlen += 8;
 362     }
 363
 364     /*
 365      * Now do the same for the segments, and get the segment size
 366      * descriptor word at the same time.
 367      */
 368     seglen = segsize = 0;
 369     if ((unsigned long) stext.len > 65535L)
 370         segsize |= 0x03000000L, seglen += 4;
 371     else
 372         segsize |= 0x02000000L, seglen += 2;
 373     if ((unsigned long) sdata.len > 65535L)
 374         segsize |= 0xC0000000L, seglen += 4;
 375     else
 376         segsize |= 0x80000000L, seglen += 2;
 377
 378     /*
 379      * Emit the as86 header.
 380      */
 381     fwritelong (0x000186A3L, as86fp);
 382     fputc (0x2A, as86fp);
 383     fwritelong (27+symlen+seglen+strslen, as86fp);   /* header length */
 384     fwritelong (stext.len+sdata.len, as86fp);
 385     fwriteshort (strslen, as86fp);
 386     fwriteshort (0, as86fp);           /* class = revision = 0 */
 387     fwritelong (0x55555555L, as86fp);   /* segment max sizes: always this */
 388     fwritelong (segsize, as86fp);      /* segment size descriptors */
 389     if (segsize & 0x01000000L)
 390         fwritelong (stext.len, as86fp);
 391     else
 392         fwriteshort (stext.len, as86fp);
 393     if (segsize & 0x40000000L)
 394         fwritelong (sdata.len, as86fp);
 395     else
 396         fwriteshort (sdata.len, as86fp);
 397     fwriteshort (nsyms, as86fp);
 398
 399     /*
 400      * Write the symbol table.
 401      */
 402     saa_rewind (syms);
 403     for (i = 0; i < nsyms; i++) {
 404         struct Symbol *sym = saa_rstruct (syms);
 405         fwriteshort (sym->strpos, as86fp);
 406         fwriteshort (sym->flags, as86fp);
 407         switch (sym->flags & (3<<14)) {
 408           case 0<<14: break;
 409           case 1<<14: fputc (sym->value, as86fp); break;
 410           case 2<<14: fwriteshort (sym->value, as86fp); break;
 411           case 3<<14: fwritelong (sym->value, as86fp); break;
 412         }
 413     }
 414
 415     /*
 416      * Write out the string table.
 417      */
 418     saa_fpwrite (strs, as86fp);
 419
 420     /*
 421      * Write the program text.
 422      */
 423     as86_reloc_size = -1;
 424     as86_write_section (&stext, SECT_TEXT);
 425     as86_write_section (&sdata, SECT_DATA);
 426     fputc (0, as86fp);                 /* termination */
 427 }
 428
 429 static void as86_set_rsize (int size) {
 430     if (as86_reloc_size != size) {
 431         switch (as86_reloc_size = size) {
 432           case 1: fputc (0x01, as86fp); break;   /* shouldn't happen */
 433           case 2: fputc (0x02, as86fp); break;
 434           case 4: fputc (0x03, as86fp); break;
 435           default: error (ERR_PANIC, "bizarre relocation size %d", size);
 436         }
 437     }
 438 }
 439
 440 static void as86_write_section (struct Section *sect, int index) {
 441     struct Piece *p;
 442     unsigned long s;
 443     long length;
 444
 445     fputc (0x20+index, as86fp);        /* select the right section */
 446
 447     saa_rewind (sect->data);
 448
 449     for (p = sect->head; p; p = p->next)
 450         switch (p->type) {
 451           case 0:
 452             /*
 453              * Absolute data. Emit it in chunks of at most 64
 454              * bytes.
 455              */
 456             length = p->bytes;
 457             do {
 458                 char buf[64];
 459                 long tmplen = (length > 64 ? 64 : length);
 460                 fputc (0x40 | (tmplen & 0x3F), as86fp);
 461                 saa_rnbytes (sect->data, buf, tmplen);
 462                 fwrite (buf, 1, tmplen, as86fp);
 463                 length -= tmplen;
 464             } while (length > 0);
 465             break;
 466           case 1:
 467             /*
 468              * A segment-type relocation. First fix up the BSS.
 469              */
 470             if (p->number == SECT_BSS)
 471                 p->number = SECT_DATA, p->offset += sdata.len;
 472             as86_set_rsize (p->bytes);
 473             fputc (0x80 | (p->relative ? 0x20 : 0) | p->number, as86fp);
 474             if (as86_reloc_size == 2)
 475                 fwriteshort (p->offset, as86fp);
 476             else
 477                 fwritelong (p->offset, as86fp);
 478             break;
 479           case 2:
 480             /*
 481              * A symbol-type relocation.
 482              */
 483             as86_set_rsize (p->bytes);
 484             s = p->offset;
 485             if (s > 65535L)
 486                 s = 3;
 487             else if (s > 255)
 488                 s = 2;
 489             else if (s > 0)
 490                 s = 1;
 491             else
 492                 s = 0;
 493             fputc (0xC0 |
 494                    (p->relative ? 0x20 : 0) |
 495                    (p->number > 255 ? 0x04 : 0) | s, as86fp);
 496             if (p->number > 255)
 497                 fwriteshort (p->number, as86fp);
 498             else
 499                 fputc (p->number, as86fp);
 500             switch ((int)s) {
 501               case 0: break;
 502               case 1: fputc (p->offset, as86fp); break;
 503               case 2: fwriteshort (p->offset, as86fp); break;
 504               case 3: fwritelong (p->offset, as86fp); break;
 505             }
 506             break;
 507         }
 508 }
 509
 510 static void as86_sect_write (struct Section *sect,
 511                              unsigned char *data, unsigned long len) {
 512     saa_wbytes (sect->data, data, len);
 513     sect->datalen += len;
 514 }
 515
 516 static long as86_segbase (long segment) {
 517     return segment;
 518 }
 519
 520 static int as86_directive (char *directive, char *value, int pass) {
 521     return 0;
 522 }
 523
 524 static void as86_filename (char *inname, char *outname, efunc error) {
 525     char *p;
 526
 527     if ( (p = strrchr (inname, '.')) != NULL) {
 528         strncpy (as86_module, inname, p-inname);
 529         as86_module[p-inname] = '\0';
 530     } else
 531         strcpy (as86_module, inname);
 532
 533     standard_extension (inname, outname, ".o", error);
 534 }
 535
 536 struct ofmt of_as86 = {
 537     "Linux as86 (bin86 version 0.3) object files",
 538     "as86",
 539     as86_init,
 540     as86_out,
 541     as86_deflabel,
 542     as86_section_names,
 543     as86_segbase,
 544     as86_directive,
 545     as86_filename,
 546     as86_cleanup
 547 };
 548
 549 #endif /* OF_AS86 */