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