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(void){
  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, evalfunc eval)
 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,
 265                          int is_global, char *special)
 266 {
 267   struct ExportRec r;
 268   struct ImportRec ri;
 269 #ifdef VERBOSE_WARNINGS
 270   static int warned_common = 0;
 271 #endif
 272
 273   if (special)
 274     error (ERR_NONFATAL, "RDOFF format does not support any"
 275            " special symbol types");
 276
 277   if (name[0] == '.' && name[1] == '.' && name[2] != '@') {
 278     error (ERR_NONFATAL, "unrecognised special symbol `%s'", name);
 279     return;
 280   }
 281
 282   if (is_global == 2) {
 283 #ifdef VERBOSE_WARNINGS
 284     if (!warned_common) {
 285       error(ERR_WARNING,"common declarations not supported: using extern");
 286       warned_common = 1;
 287     }
 288 #endif
 289     is_global = 1;
 290   }
 291
 292   if (segment > 4) {   /* EXTERN declaration */
 293     ri.type = 2;
 294     ri.segment = segment;
 295     strncpy(ri.label,name,32);
 296     ri.label[32] = 0;
 297     write_import_rec(&ri);
 298   } else if (is_global) {
 299     r.type = 3;
 300     r.segment = segment;
 301     r.offset = offset;
 302     strncpy(r.label,name,32);
 303     r.label[32] = 0;
 304     write_export_rec(&r);
 305   }
 306 }
 307
 308 static void rdf_out (long segto, void *data, unsigned long type,
 309                      long segment, long wrt)
 310 {
 311   long bytes = type & OUT_SIZMASK;
 312   struct RelocRec rr;
 313   unsigned char databuf[4],*pd;
 314
 315   segto >>= 1;    /* convert NASM segment no to RDF number */
 316
 317   if (segto != 0 && segto != 1 && segto != 2) {
 318     error(ERR_NONFATAL,"specified segment not supported by rdf output format");
 319     return;
 320   }
 321
 322   if (wrt != NO_SEG) {
 323     wrt = NO_SEG;                      /* continue to do _something_ */
 324     error (ERR_NONFATAL, "WRT not supported by rdf output format");
 325   }
 326
 327   type &= OUT_TYPMASK;
 328
 329   if (segto == 2 && type != OUT_RESERVE)
 330   {
 331       error(ERR_NONFATAL, "BSS segments may not be initialised");
 332
 333       /* just reserve the space for now... */
 334
 335       if (type == OUT_REL2ADR)
 336         bytes = 2;
 337       else
 338         bytes = 4;
 339       type = OUT_RESERVE;
 340   }
 341
 342   if (type == OUT_RESERVE) {
 343       if (segto == 2)           /* BSS segment space reserverd */
 344           bsslength += bytes;
 345       else
 346         while (bytes --)
 347             membufwrite(seg[segto],databuf,1);
 348   }
 349   else if (type == OUT_RAWDATA) {
 350       if (segment != NO_SEG)
 351           error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
 352       membufwrite(seg[segto],data,bytes);
 353   }
 354   else if (type == OUT_ADDRESS) {
 355
 356     /* if segment == NO_SEG then we are writing an address of an
 357        object within the same segment - do not produce reloc rec. */
 358
 359     if (segment != NO_SEG)
 360     {
 361
 362         /* it's an address, so we must write a relocation record */
 363
 364         rr.type = 1;            /* type signature */
 365         rr.segment = segto;             /* segment we're currently in */
 366         rr.offset = membuflength(seg[segto]);   /* current offset */
 367         rr.length = bytes;              /* length of reference */
 368         rr.refseg = segment;    /* segment referred to */
 369         write_reloc_rec(&rr);
 370     }
 371
 372     pd = databuf;       /* convert address to little-endian */
 373     if (bytes == 2)
 374       WRITESHORT (pd, *(long *)data);
 375     else
 376       WRITELONG (pd, *(long *)data);
 377
 378     membufwrite(seg[segto],databuf,bytes);
 379
 380   }
 381   else if (type == OUT_REL2ADR)
 382   {
 383     if (segment == segto)
 384       error(ERR_PANIC, "intra-segment OUT_REL2ADR");
 385     if (segment != NO_SEG && segment % 2) {
 386       error(ERR_NONFATAL, "rdf format does not support segment base refs");
 387     }
 388
 389     rr.type = 1;                /* type signature */
 390     rr.segment = segto+64;      /* segment we're currently in + rel flag */
 391     rr.offset = membuflength(seg[segto]);       /* current offset */
 392     rr.length = 2;              /* length of reference */
 393     rr.refseg = segment;        /* segment referred to */
 394     write_reloc_rec(&rr);
 395
 396     /* work out what to put in the code: offset of the end of this operand,
 397      * subtracted from any data specified, so that loader can just add
 398      * address of imported symbol onto it to get address relative to end of
 399      * instruction: import_address + data(offset) - end_of_instrn */
 400
 401     rr.offset = *(long *)data -(rr.offset + bytes);
 402
 403     membufwrite(seg[segto],&rr.offset,-2);
 404   }
 405   else if (type == OUT_REL4ADR)
 406   {
 407     if (segment == segto)
 408       error(ERR_PANIC, "intra-segment OUT_REL4ADR");
 409     if (segment != NO_SEG && segment % 2) {
 410       error(ERR_NONFATAL, "rdf format does not support segment base refs");
 411     }
 412
 413     rr.type = 1;                /* type signature */
 414     rr.segment = segto+64;      /* segment we're currently in + rel tag */
 415     rr.offset = membuflength(seg[segto]);       /* current offset */
 416     rr.length = 4;              /* length of reference */
 417     rr.refseg = segment;        /* segment referred to */
 418     write_reloc_rec(&rr);
 419
 420     rr.offset = *(long *)data -(rr.offset + bytes);
 421     membufwrite(seg[segto],&rr.offset,-4);
 422   }
 423 }
 424
 425 static void rdf_cleanup (void) {
 426   long          l;
 427   unsigned char b[4],*d;
 428   struct BSSRec bs;
 429
 430
 431   /* should write imported & exported symbol declarations to header here */
 432
 433   /* generate the output file... */
 434   fwrite(RDOFFId,6,1,ofile);    /* file type magic number */
 435
 436   if (bsslength != 0)           /* reserve BSS */
 437   {
 438       bs.type = 5;
 439       bs.amount = bsslength;
 440       write_bss_rec(&bs);
 441   }
 442
 443   l = membuflength(header);d=b;
 444   WRITELONG(d,l);
 445
 446   fwrite(b,4,1,ofile);          /* write length of header */
 447   membufdump(header,ofile);     /* dump header */
 448
 449   l = membuflength(seg[0]);d=b; /* code segment */
 450   WRITELONG(d,l);
 451
 452   fwrite(b,4,1,ofile);
 453   membufdump(seg[0],ofile);
 454
 455   l = membuflength(seg[1]);d=b; /* data segment */
 456   WRITELONG(d,l);
 457
 458   fwrite(b,4,1,ofile);
 459   membufdump(seg[1],ofile);
 460
 461   freemembuf(header);
 462   freemembuf(seg[0]);
 463   freemembuf(seg[1]);
 464   fclose(ofile);
 465 }
 466
 467 static long rdf_segbase (long segment) {
 468     return 0;
 469 }
 470
 471 static int rdf_directive (char *directive, char *value, int pass) {
 472     struct DLLRec r;
 473
 474     if (! strcmp(directive, "library")) {
 475         if (pass == 1) {
 476             r.type = 4;
 477             strcpy(r.libname, value);
 478             write_dll_rec(&r);
 479         }
 480         return 1;
 481     }
 482
 483     return 0;
 484 }
 485
 486 static void rdf_filename (char *inname, char *outname, efunc error) {
 487   standard_extension(inname,outname,".rdf",error);
 488 }
 489
 490 static char *rdf_stdmac[] = {
 491     "%define __SECT__ [section .text]",
 492     "%imacro library 1+.nolist",
 493     "[library %1]",
 494     "%endmacro",
 495     NULL
 496 };
 497
 498 struct ofmt of_rdf = {
 499   "Relocatable Dynamic Object File Format v1.1",
 500   "rdf",
 501   rdf_stdmac,
 502   rdf_init,
 503   rdf_out,
 504   rdf_deflabel,
 505   rdf_section_names,
 506   rdf_segbase,
 507   rdf_directive,
 508   rdf_filename,
 509   rdf_cleanup
 510 };
 511
 512 #endif /* OF_RDF */