outrdf.c

   1 /* outrdf.c     output routines for the Netwide Assembler to produce
   2  *              RDOFF format object files (which are intended mainly
   3  *              for use in proprietary projects, as the code to load and
   4  *              execute them is very simple). They will also be used
   5  *              for device drivers and possibly some executable files
   6  *              in the MOSCOW operating system. See Rdoff.txt for
   7  *              details.
   8  *
   9  * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
  10  * Julian Hall. All rights reserved. The software is
  11  * redistributable under the licence given in the file "Licence"
  12  * distributed in the NASM archive.
  13  */
  14
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <ctype.h>
  19 #include <assert.h>
  20
  21 #include "nasm.h"
  22 #include "nasmlib.h"
  23 #include "outform.h"
  24
  25 /* VERBOSE_WARNINGS: define this to add some extra warnings... */
  26 #define VERBOSE_WARNINGS
  27
  28 #ifdef OF_RDF
  29
  30 typedef short int16;    /* not sure if this will be required to be altered
  31                            at all... best to typedef it just in case */
  32
  33 static const char *RDOFFId = "RDOFF1";  /* written to start of RDOFF files */
  34
  35 /* the records that can be found in the RDOFF header */
  36
  37 /* Note that whenever a segment is referred to in the RDOFF file, its number
  38  * is always half of the segment number that NASM uses to refer to it; this
  39  * is because NASM only allocates even numbered segments, so as to not
  40  * waste any of the 16 bits of segment number written to the file - this
  41  * allows up to 65533 external labels to be defined; otherwise it would be
  42  * 32764. */
  43
  44 struct RelocRec {
  45   char  type;           /* must be 1 */
  46   char  segment;        /* only 0 for code, or 1 for data supported,
  47                          * but add 64 for relative refs (ie do not require
  48                          * reloc @ loadtime, only linkage) */
  49   long  offset;         /* from start of segment in which reference is loc'd */
  50   char  length;         /* 1 2 or 4 bytes */
  51   int16 refseg;         /* segment to which reference refers to */
  52 };
  53
  54 struct ImportRec {
  55   char  type;           /* must be 2 */
  56   int16 segment;        /* segment number allocated to the label for reloc
  57                          * records - label is assumed to be at offset zero
  58                          * in this segment, so linker must fix up with offset
  59                          * of segment and of offset within segment */
  60   char  label[33];      /* zero terminated... should be written to file until
  61                          * the zero, but not after it - max len = 32 chars */
  62 };
  63
  64 struct ExportRec {
  65   char  type;           /* must be 3 */
  66   char  segment;        /* segment referred to (0/1) */
  67   long  offset;         /* offset within segment */
  68   char  label[33];      /* zero terminated as above. max len = 32 chars */
  69 };
  70
  71 struct DLLRec {
  72   char  type;           /* must be 4 */
  73   char  libname[128];   /* name of library to link with at load time */
  74 };
  75
  76 struct BSSRec {
  77   char  type;           /* must be 5 */
  78   long  amount;         /* number of bytes BSS to reserve */
  79 };
  80
  81 /* code for managing buffers needed to seperate code and data into individual
  82  * sections until they are ready to be written to the file.
  83  * We'd better hope that it all fits in memory else we're buggered... */
  84
  85 #define BUF_BLOCK_LEN 4088              /* selected to match page size (4096)
  86                                          * on 80x86 machines for efficiency */
  87
  88 typedef struct memorybuffer {
  89   int length;
  90   char buffer[BUF_BLOCK_LEN];
  91   struct memorybuffer *next;
  92 } memorybuffer;
  93
  94 static memorybuffer * newmembuf(){
  95   memorybuffer * t;
  96
  97   t = nasm_malloc(sizeof(memorybuffer));
  98
  99   t->length = 0;
 100   t->next = NULL;
 101   return t;
 102 }
 103
 104 static void membufwrite(memorybuffer *b, void *data, int bytes) {
 105   int16 w;
 106   long l;
 107
 108   if (b->next) {        /* memory buffer full - use next buffer */
 109     membufwrite(b->next,data,bytes);
 110     return;
 111   }
 112   if ((bytes < 0 && b->length - bytes > BUF_BLOCK_LEN)
 113       || (bytes > 0 && b->length + bytes > BUF_BLOCK_LEN)) {
 114
 115     /* buffer full and no next allocated... allocate and initialise next
 116      * buffer */
 117
 118     b->next = newmembuf();
 119     membufwrite(b->next,data,bytes);
 120     return;
 121   }
 122
 123   switch(bytes) {
 124   case -4:              /* convert to little-endian */
 125     l = * (long *) data ;
 126     b->buffer[b->length++] = l & 0xFF;
 127     l >>= 8 ;
 128     b->buffer[b->length++] = l & 0xFF;
 129     l >>= 8 ;
 130     b->buffer[b->length++] = l & 0xFF;
 131     l >>= 8 ;
 132     b->buffer[b->length++] = l & 0xFF;
 133     break;
 134
 135   case -2:
 136     w = * (int16 *) data ;
 137     b->buffer[b->length++] = w & 0xFF;
 138     w >>= 8 ;
 139     b->buffer[b->length++] = w & 0xFF;
 140     break;
 141
 142   default:
 143     while(bytes--) {
 144       b->buffer[b->length++] = *(* (unsigned char **) &data);
 145
 146       (* (unsigned char **) &data)++ ;
 147     }
 148     break;
 149   }
 150 }
 151
 152 static void membufdump(memorybuffer *b,FILE *fp)
 153 {
 154   if (!b) return;
 155
 156   fwrite (b->buffer, 1, b->length, fp);
 157
 158   membufdump(b->next,fp);
 159 }
 160
 161 static int membuflength(memorybuffer *b)
 162 {
 163   if (!b) return 0;
 164   return b->length + membuflength(b->next);
 165 }
 166
 167 static void freemembuf(memorybuffer *b)
 168 {
 169   if (!b) return;
 170   freemembuf(b->next);
 171   nasm_free(b);
 172 }
 173
 174 /***********************************************************************
 175  * Actual code to deal with RDOFF ouput format begins here...
 176  */
 177
 178 /* global variables set during the initialisation phase */
 179
 180 static memorybuffer *seg[2];    /* seg 0 = code, seg 1 = data */
 181 static memorybuffer *header;    /* relocation/import/export records */
 182
 183 static FILE *ofile;
 184
 185 static efunc error;
 186
 187 static int segtext,segdata,segbss;
 188 static long bsslength;
 189
 190 static void rdf_init(FILE *fp, efunc errfunc, ldfunc ldef)
 191 {
 192   ofile = fp;
 193   error = errfunc;
 194   seg[0] = newmembuf();
 195   seg[1] = newmembuf();
 196   header = newmembuf();
 197   segtext = seg_alloc();
 198   segdata = seg_alloc();
 199   segbss = seg_alloc();
 200   if (segtext != 0 || segdata != 2 || segbss != 4)
 201     error(ERR_PANIC,"rdf segment numbers not allocated as expected (%d,%d,%d)",
 202           segtext,segdata,segbss);
 203   bsslength=0;
 204 }
 205
 206 static long rdf_section_names(char *name, int pass, int *bits)
 207 {
 208   /*
 209    * Default is 32 bits.
 210    */
 211   if (!name)
 212     *bits = 32;
 213
 214   if (!name) return 0;
 215   if (!strcmp(name, ".text"))           return 0;
 216   else if (!strcmp(name, ".data"))      return 2;
 217   else if (!strcmp(name, ".bss"))       return 4;
 218   else
 219     return NO_SEG;
 220 }
 221
 222 static void write_reloc_rec(struct RelocRec *r)
 223 {
 224   r->refseg >>= 1;    /* adjust segment nos to RDF rather than NASM */
 225
 226   membufwrite(header,&r->type,1);
 227   membufwrite(header,&r->segment,1);
 228   membufwrite(header,&r->offset,-4);
 229   membufwrite(header,&r->length,1);
 230   membufwrite(header,&r->refseg,-2);    /* 9 bytes written */
 231 }
 232
 233 static void write_export_rec(struct ExportRec *r)
 234 {
 235   r->segment >>= 1;
 236
 237   membufwrite(header,&r->type,1);
 238   membufwrite(header,&r->segment,1);
 239   membufwrite(header,&r->offset,-4);
 240   membufwrite(header,r->label,strlen(r->label) + 1);
 241 }
 242
 243 static void write_import_rec(struct ImportRec *r)
 244 {
 245   r->segment >>= 1;
 246
 247   membufwrite(header,&r->type,1);
 248   membufwrite(header,&r->segment,-2);
 249   membufwrite(header,r->label,strlen(r->label) + 1);
 250 }
 251
 252 static void write_bss_rec(struct BSSRec *r)
 253 {
 254     membufwrite(header,&r->type,1);
 255     membufwrite(header,&r->amount,-4);
 256 }
 257
 258 static void write_dll_rec(struct DLLRec *r)
 259 {
 260     membufwrite(header,&r->type,1);
 261     membufwrite(header,r->libname,strlen(r->libname) + 1);
 262 }
 263
 264 static void rdf_deflabel(char *name, long segment, long offset, int is_global)
 265 {
 266   struct ExportRec r;
 267   struct ImportRec ri;
 268 #ifdef VERBOSE_WARNINGS
 269   static int warned_common = 0;
 270 #endif
 271
 272   if (is_global && segment > 4) {
 273 #ifdef VERBOSE_WARNINGS
 274     if (! warned_common) {
 275       error(ERR_WARNING,"common declarations not supported... using extern");
 276       warned_common = 1;
 277     }
 278 #endif
 279     is_global = 0;
 280   }
 281
 282   if (is_global) {
 283     r.type = 3;
 284     r.segment = segment;
 285     r.offset = offset;
 286     strncpy(r.label,name,32);
 287     r.label[32] = 0;
 288     write_export_rec(&r);
 289   }
 290
 291   if (segment > 4) {   /* EXTERN declaration */
 292     ri.type = 2;
 293     ri.segment = segment;
 294     strncpy(ri.label,name,32);
 295     ri.label[32] = 0;
 296     write_import_rec(&ri);
 297   }
 298 }
 299
 300 static void rdf_out (long segto, void *data, unsigned long type,
 301                      long segment, long wrt)
 302 {
 303   long bytes = type & OUT_SIZMASK;
 304   struct RelocRec rr;
 305   unsigned char databuf[4],*pd;
 306
 307   segto >>= 1;    /* convert NASM segment no to RDF number */
 308
 309   if (segto != 0 && segto != 1 && segto != 2) {
 310     error(ERR_NONFATAL,"specified segment not supported by rdf output format");
 311     return;
 312   }
 313
 314   if (wrt != NO_SEG) {
 315     wrt = NO_SEG;                      /* continue to do _something_ */
 316     error (ERR_NONFATAL, "WRT not supported by rdf output format");
 317   }
 318
 319   type &= OUT_TYPMASK;
 320
 321   if (segto == 2 && type != OUT_RESERVE)
 322   {
 323       error(ERR_NONFATAL, "BSS segments may not be initialised");
 324
 325       /* just reserve the space for now... */
 326
 327       if (type == OUT_REL2ADR)
 328         bytes = 2;
 329       else
 330         bytes = 4;
 331       type = OUT_RESERVE;
 332   }
 333
 334   if (type == OUT_RESERVE) {
 335       if (segto == 2)           /* BSS segment space reserverd */
 336           bsslength += bytes;
 337       else
 338         while (bytes --)
 339             membufwrite(seg[segto],databuf,1);
 340   }
 341   else if (type == OUT_RAWDATA) {
 342       if (segment != NO_SEG)
 343           error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
 344       membufwrite(seg[segto],data,bytes);
 345   }
 346   else if (type == OUT_ADDRESS) {
 347
 348     /* if segment == NO_SEG then we are writing an address of an
 349        object within the same segment - do not produce reloc rec. */
 350
 351     if (segment != NO_SEG)
 352     {
 353
 354         /* it's an address, so we must write a relocation record */
 355
 356         rr.type = 1;            /* type signature */
 357         rr.segment = segto;             /* segment we're currently in */
 358         rr.offset = membuflength(seg[segto]);   /* current offset */
 359         rr.length = bytes;              /* length of reference */
 360         rr.refseg = segment;    /* segment referred to */
 361         write_reloc_rec(&rr);
 362     }
 363
 364     pd = databuf;       /* convert address to little-endian */
 365     if (bytes == 2)
 366       WRITESHORT (pd, *(long *)data);
 367     else
 368       WRITELONG (pd, *(long *)data);
 369
 370     membufwrite(seg[segto],databuf,bytes);
 371
 372   }
 373   else if (type == OUT_REL2ADR)
 374   {
 375     if (segment == segto)
 376       error(ERR_PANIC, "intra-segment OUT_REL2ADR");
 377     if (segment != NO_SEG && segment % 2) {
 378       error(ERR_NONFATAL, "rdf format does not support segment base refs");
 379     }
 380
 381     rr.type = 1;                /* type signature */
 382     rr.segment = segto+64;      /* segment we're currently in + rel flag */
 383     rr.offset = membuflength(seg[segto]);       /* current offset */
 384     rr.length = 2;              /* length of reference */
 385     rr.refseg = segment;        /* segment referred to */
 386     write_reloc_rec(&rr);
 387
 388     /* work out what to put in the code: offset of the end of this operand,
 389      * subtracted from any data specified, so that loader can just add
 390      * address of imported symbol onto it to get address relative to end of
 391      * instruction: import_address + data(offset) - end_of_instrn */
 392
 393     rr.offset = *(long *)data -(rr.offset + bytes);
 394
 395     membufwrite(seg[segto],&rr.offset,-2);
 396   }
 397   else if (type == OUT_REL4ADR)
 398   {
 399     if (segment == segto)
 400       error(ERR_PANIC, "intra-segment OUT_REL4ADR");
 401     if (segment != NO_SEG && segment % 2) {
 402       error(ERR_NONFATAL, "rdf format does not support segment base refs");
 403     }
 404
 405     rr.type = 1;                /* type signature */
 406     rr.segment = segto+64;      /* segment we're currently in + rel tag */
 407     rr.offset = membuflength(seg[segto]);       /* current offset */
 408     rr.length = 4;              /* length of reference */
 409     rr.refseg = segment;        /* segment referred to */
 410     write_reloc_rec(&rr);
 411
 412     rr.offset = *(long *)data -(rr.offset + bytes);
 413     membufwrite(seg[segto],&rr.offset,-4);
 414   }
 415 }
 416
 417 static void rdf_cleanup (void) {
 418   long          l;
 419   unsigned char b[4],*d;
 420   struct BSSRec bs;
 421
 422
 423   /* should write imported & exported symbol declarations to header here */
 424
 425   /* generate the output file... */
 426   fwrite(RDOFFId,6,1,ofile);    /* file type magic number */
 427
 428   if (bsslength != 0)           /* reserve BSS */
 429   {
 430       bs.type = 5;
 431       bs.amount = bsslength;
 432       write_bss_rec(&bs);
 433   }
 434
 435   l = membuflength(header);d=b;
 436   WRITELONG(d,l);
 437
 438   fwrite(b,4,1,ofile);          /* write length of header */
 439   membufdump(header,ofile);     /* dump header */
 440
 441   l = membuflength(seg[0]);d=b; /* code segment */
 442   WRITELONG(d,l);
 443
 444   fwrite(b,4,1,ofile);
 445   membufdump(seg[0],ofile);
 446
 447   l = membuflength(seg[1]);d=b; /* data segment */
 448   WRITELONG(d,l);
 449
 450   fwrite(b,4,1,ofile);
 451   membufdump(seg[1],ofile);
 452
 453   freemembuf(header);
 454   freemembuf(seg[0]);
 455   freemembuf(seg[1]);
 456   fclose(ofile);
 457 }
 458
 459 static long rdf_segbase (long segment) {
 460     return 0;
 461 }
 462
 463 static int rdf_directive (char *directive, char *value, int pass) {
 464     struct DLLRec r;
 465
 466     if (! strcmp(directive, "library")) {
 467         if (pass == 1) {
 468             r.type = 4;
 469             strcpy(r.libname, value);
 470             write_dll_rec(&r);
 471         }
 472         return 1;
 473     }
 474
 475     return 0;
 476 }
 477
 478 static void rdf_filename (char *inname, char *outname, efunc error) {
 479   standard_extension(inname,outname,".rdf",error);
 480 }
 481
 482 struct ofmt of_rdf = {
 483   "Relocatable Dynamic Object File Format v1.1",
 484   "rdf",
 485   rdf_init,
 486   rdf_out,
 487   rdf_deflabel,
 488   rdf_section_names,
 489   rdf_segbase,
 490   rdf_directive,
 491   rdf_filename,
 492   rdf_cleanup
 493 };
 494
 495 #endif /* OF_RDF */