outrdf2.c

开源的nasm编译器源码,研究编译器原理很有帮且

    ci.size = offset;
    ci.segment = segment;
    strncpy(ci.label, name, 32);
    ci.label[32] = 0;
    ci.reclen = 9 + strlen(ci.label);
    ci.align = 0;
    
    /*
     * Check the special text to see if it's a valid number and power
     * of two; if so, store it as the alignment for the common variable.
     */
    if (special) {
	int err;
        ci.align = readnum(special, &err);
        if (err) error(ERR_NONFATAL, "alignment constraint `%s' is not a"
                    	             " valid number", special);
	else if ( (ci.align | (ci.align-1)) != 2*ci.align - 1)
	    error(ERR_NONFATAL, "alignment constraint `%s' is not a"
	                        " power of two", special);
    }    
    write_common_rec(&ci);
  }

  /* We don't care about local labels or fix-up hints */
  if (is_global != 1) return;

  if (special) {
    while(*special == ' ' || *special == '\t') special++;
    
    if (!nasm_strnicmp(special, "export", 6)) {
      special += 6;
      export_flags |= SYM_GLOBAL;  
    }

    if (*special) {
      while(isspace(*special)) special++;
      if (!nasm_stricmp(special, "far")) {
        farsym = 1;
      }
      else if (!nasm_stricmp(special, "near")) {
        farsym = 0;
      }
      else if (!nasm_stricmp(special, "proc") || 
               !nasm_stricmp(special, "function")) {
        export_flags |= SYM_FUNCTION;  
      }
      else if (!nasm_stricmp(special, "data") ||
               !nasm_stricmp(special, "object")) {
        export_flags |= SYM_DATA;
      }
      else
        error(ERR_NONFATAL, "unrecognised symbol type `%s'", special);
    }	
  }

  if (name[0] == '.' && name[1] == '.' && name[2] != '@') {
    error (ERR_NONFATAL, "unrecognised special symbol `%s'", name);
    return;
  }

  for (i = 0; i < nsegments; i++) {
    if (segments[i].segnumber == segment>>1) break;
  }
  if (i >= nsegments) {   /* EXTERN declaration */
    if (farsym)
      ri.type = RDFREC_FARIMPORT;
    else
      ri.type = RDFREC_IMPORT;
    ri.segment = segment;
    strncpy(ri.label,name,32);
    ri.label[32] = 0;
    ri.reclen = 3 + strlen(ri.label);
    write_import_rec(&ri);
  } else if (is_global) {
    r.type = RDFREC_GLOBAL;
    r.flags = export_flags;
    r.segment = segment;
    r.offset = offset;
    strncpy(r.label,name,32);
    r.label[32] = 0;
    r.reclen = 7 + strlen(r.label);
    write_export_rec(&r);
  }
}

static void membufwrite(int segment, const void * data, int bytes)
{
  int i;
  char buf[4], * b;

  for (i = 0; i < nsegments; i++) {
    if (segments[i].segnumber == segment) break;
  }
  if (i == nsegments)
    error(ERR_PANIC, "can't find segment %d", segment);
  
  if (bytes < 0) {
    b = buf;
    if (bytes == -2)
      WRITESHORT(b,*(short *)data);
    else
      WRITELONG(b,*(long *)data);
    data = buf;
    bytes = -bytes;
  }
  segments[i].seglength += bytes;
  saa_wbytes(seg[i],data,bytes);
}

static int getsegmentlength(int segment)
{
  int i;
  for (i = 0; i < nsegments; i++) {
    if (segments[i].segnumber == segment) break;
  }
  if (i == nsegments)
    error(ERR_PANIC, "can't find segment %d", segment);

  return segments[i].seglength;
}
    
static void rdf2_out (long segto, const void *data, unsigned long type,
		     long segment, long wrt)
{
  long bytes = type & OUT_SIZMASK;
  struct RelocRec rr;
  unsigned char databuf[4],*pd;
  int seg;

  if (segto == NO_SEG) {
      if ((type & OUT_TYPMASK) != OUT_RESERVE)
	  error (ERR_NONFATAL, "attempt to assemble code in ABSOLUTE space");
      return;
  }

  segto >>= 1;    /* convert NASM segment no to RDF number */

  for (seg = 0; seg < nsegments; seg++) {
    if (segments[seg].segnumber == segto) break;
  }
  if (seg >= nsegments) {
    error(ERR_NONFATAL,"specified segment not supported by rdf output format");
    return;
  }

  if (wrt != NO_SEG) {
    wrt = NO_SEG;		       /* continue to do _something_ */
    error (ERR_NONFATAL, "WRT not supported by rdf output format");
  }

  type &= OUT_TYPMASK;

  if (segto == 2 && type != OUT_RESERVE)
  {
      error(ERR_NONFATAL, "BSS segments may not be initialised");

      /* just reserve the space for now... */

      if (type == OUT_REL2ADR)
	bytes = 2;
      else
	bytes = 4;
      type = OUT_RESERVE;
  }

  if (type == OUT_RESERVE) {
      if (segto == 2)		/* BSS segment space reserverd */
	  bsslength += bytes;
      else
	while (bytes --)
	    membufwrite(segto,databuf,1);
  }
  else if (type == OUT_RAWDATA) {
      if (segment != NO_SEG)
	  error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");

      membufwrite(segto,data,bytes);
  }
  else if (type == OUT_ADDRESS) {

    /* if segment == NO_SEG then we are writing an address of an
       object within the same segment - do not produce reloc rec. */

    /* FIXME - is this behaviour sane? at first glance it doesn't
       appear to be. Must test this thoroughly...! */

    if (segment != NO_SEG)
    {
	/* it's an address, so we must write a relocation record */

	rr.type = RDFREC_RELOC;			/* type signature */
	rr.reclen = 8;
	rr.segment = segto;			/* segment we're currently in */
	rr.offset = getsegmentlength(segto);	/* current offset */
	rr.length = bytes;			/* length of reference */
	rr.refseg = segment;			/* segment referred to */
	write_reloc_rec(&rr);
    }

    pd = databuf;	/* convert address to little-endian */
    if (bytes == 2)
      WRITESHORT (pd, *(long *)data);
    else
      WRITELONG (pd, *(long *)data);

    membufwrite(segto,databuf,bytes);

  }
  else if (type == OUT_REL2ADR)
  {
    if (segment == segto)
      error(ERR_PANIC, "intra-segment OUT_REL2ADR");

    rr.reclen = 8;
    rr.offset = getsegmentlength(segto);	/* current offset */
    rr.length = 2;		/* length of reference */
    rr.refseg = segment;	/* segment referred to (will be >>1'd)*/

    if (segment != NO_SEG && segment % 2) {
      rr.type = RDFREC_SEGRELOC;
      rr.segment = segto;	/* memory base refs *aren't ever* relative! */
      write_reloc_rec(&rr);

      /* what do we put in the code? Simply the data. This should almost
       * always be zero, unless someone's doing segment arithmetic...
       */
      rr.offset = *(long *) data;
    }
    else
    {
      rr.type = RDFREC_RELOC;	/* type signature */
      rr.segment = segto+64;	/* segment we're currently in + rel flag */
      write_reloc_rec(&rr);

      /* work out what to put in the code: offset of the end of this operand,
       * subtracted from any data specified, so that loader can just add
       * address of imported symbol onto it to get address relative to end of
       * instruction: import_address + data(offset) - end_of_instrn */

      rr.offset = *(long *)data -(rr.offset + bytes);
    }
    
    membufwrite(segto,&rr.offset,-2);
  }
  else if (type == OUT_REL4ADR)
  {
    if (segment == segto)
      error(ERR_PANIC, "intra-segment OUT_REL4ADR");
    if (segment != NO_SEG && segment % 2) {
      error(ERR_PANIC, "erm... 4 byte segment base ref?");
    }

    rr.type = RDFREC_RELOC;	/* type signature */
    rr.segment = segto+64;	/* segment we're currently in + rel tag */
    rr.offset = getsegmentlength(segto);	/* current offset */
    rr.length = 4;		/* length of reference */
    rr.refseg = segment;	/* segment referred to */
    rr.reclen = 8;
    write_reloc_rec(&rr);

    rr.offset = *(long *)data -(rr.offset + bytes);

    membufwrite(segto,&rr.offset,-4);
  }
}

static void rdf2_cleanup (int debuginfo) {
  long		l;
  struct BSSRec	bs;
  int		i;

    (void) debuginfo;

  /* should write imported & exported symbol declarations to header here */

  /* generate the output file... */
  fwrite(RDOFF2Id,6,1,ofile);	/* file type magic number */

  if (bsslength != 0)		/* reserve BSS */
  {
      bs.type = RDFREC_BSS;
      bs.amount = bsslength;
      bs.reclen = 4;
      write_bss_rec(&bs);
  }

  /*
   * calculate overall length of the output object
   */
  l = headerlength + 4;
  
  for (i = 0; i < nsegments; i++) {
    if (i == 2) continue;	/* skip BSS segment */
    l += 10 + segments[i].seglength;
  }
  l += 10;	/* null segment */

  fwritelong(l, ofile);

  fwritelong(headerlength, ofile);
  saa_fpwrite(header,ofile);	/* dump header */
  saa_free(header);

  for (i = 0; i < nsegments; i++) {
    if (i == 2) continue;

    fwriteshort(segments[i].segtype, ofile);
    fwriteshort(segments[i].segnumber, ofile);
    fwriteshort(segments[i].segreserved, ofile);
    fwritelong(segments[i].seglength, ofile);

    saa_fpwrite(seg[i], ofile);
    saa_free(seg[i]);
  }

  /* null segment - write 10 bytes of zero */
  fwritelong(0,ofile);
  fwritelong(0,ofile);
  fwriteshort(0,ofile);

  fclose(ofile);
}

static long rdf2_segbase (long segment) {
    return segment;
}

static int rdf2_directive (char *directive, char *value, int pass) {
    struct DLLModRec r;

    if (! strcmp(directive, "library")) {
	if (pass == 1) {
	    r.type = RDFREC_DLL;
	    r.reclen=strlen(value)+1;
	    strcpy(r.name, value);
	    write_dllmod_rec(&r);
	}
	return 1;
    }

    if (! strcmp(directive, "module")) {
	if (pass == 1) {
	    r.type = RDFREC_MODNAME;
	    r.reclen=strlen(value)+1;
	    strcpy(r.name, value);
	    write_dllmod_rec(&r);
	}
	return 1;
    }
    
    return 0;
}

static void rdf2_filename (char *inname, char *outname, efunc error) {
  standard_extension(inname,outname,".rdf",error);
}

static const char *rdf2_stdmac[] = {
    "%define __SECT__ [section .text]",
    "%imacro library 1+.nolist",
    "[library %1]",
    "%endmacro",
    "%imacro module 1+.nolist",
    "[module %1]",
    "%endmacro",
    "%macro __NASM_CDecl__ 1",
    "%endmacro",
    NULL
};

static int rdf2_set_info(enum geninfo type, char **val)
{
    return 0;
}


struct ofmt of_rdf2 = {
  "Relocatable Dynamic Object File Format v2.0",
  "rdf",
  NULL,
  null_debug_arr,
  &null_debug_form,
  rdf2_stdmac,
  rdf2_init,
  rdf2_set_info,
  rdf2_out,
  rdf2_deflabel,
  rdf2_section_names,
  rdf2_segbase,
  rdf2_directive,
  rdf2_filename,
  rdf2_cleanup
};

#endif /* OF_RDF2 */