outcoff.c

开源的nasm编译器源码,研究编译器原理很有帮且

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

    s = NULL;
    for (i=0; i<nsects; i++)
	if (segto == sects[i]->index) {
	    s = sects[i];
	    break;
	}
    if (!s) {
	int tempint;		       /* ignored */
	if (segto != coff_section_names (".text", 2, &tempint))
	    error (ERR_PANIC, "strange segment conditions in COFF driver");
	else
	    s = sects[nsects-1];
    }

    if (!s->data && type != OUT_RESERVE) {
	error(ERR_WARNING, "attempt to initialise memory in"
	      " BSS section `%s': ignored", s->name);
	if (type == OUT_REL2ADR)
	    realbytes = 2;
	else if (type == OUT_REL4ADR)
	    realbytes = 4;
	s->len += realbytes;
	return;
    }

    if (type == OUT_RESERVE) {
	if (s->data) {
	    error(ERR_WARNING, "uninitialised space declared in"
		  " non-BSS section `%s': zeroing", s->name);
	    coff_sect_write (s, NULL, realbytes);
	} else
	    s->len += realbytes;
    } else if (type == OUT_RAWDATA) {
	if (segment != NO_SEG)
	    error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
	coff_sect_write (s, data, realbytes);
    } else if (type == OUT_ADDRESS) {
	if (realbytes != 4 && (segment != NO_SEG || wrt != NO_SEG))
	    error(ERR_NONFATAL, "COFF format does not support non-32-bit"
		  " relocations");
	else {
	    long fix = 0;
	    if (segment != NO_SEG || wrt != NO_SEG) {
		if (wrt != NO_SEG) {
		    error(ERR_NONFATAL, "COFF format does not support"
			  " WRT types");
		} else if (segment % 2) {
		    error(ERR_NONFATAL, "COFF format does not support"
			  " segment base references");
		} else
		    fix = coff_add_reloc (s, segment, FALSE);
	    }
	    p = mydata;
	    WRITELONG (p, *(long *)data + fix);
	    coff_sect_write (s, mydata, realbytes);
	}
    } else if (type == OUT_REL2ADR) {
	error(ERR_NONFATAL, "COFF format does not support 16-bit"
	      " relocations");
    } else if (type == OUT_REL4ADR) {
	if (segment == segto)
	    error(ERR_PANIC, "intra-segment OUT_REL4ADR");
	else if (segment == NO_SEG && win32)
	    error(ERR_NONFATAL, "Win32 COFF does not correctly support"
		  " relative references to absolute addresses");
	else {
	    long fix = 0;
	    if (segment != NO_SEG && segment % 2) {
		error(ERR_NONFATAL, "COFF format does not support"
		      " segment base references");
	    } else
		fix = coff_add_reloc (s, segment, TRUE);
	    p = mydata;
	    if (win32) {
		WRITELONG (p, *(long*)data + 4 - realbytes + fix);
	    } else {
		WRITELONG (p, *(long*)data-(realbytes + s->len) + fix);
	    }
	    coff_sect_write (s, mydata, 4L);
	}
    }
}

static void coff_sect_write (struct Section *sect,
			     const unsigned char *data, unsigned long len) 
{
    saa_wbytes (sect->data, data, len);
    sect->len += len;
}

typedef struct tagString {
	struct tagString *Next;
	int len;
	char *String;
} STRING;

#define EXPORT_SECTION_NAME ".drectve"
#define EXPORT_SECTION_FLAGS INFO_FLAGS 
/* 
#define EXPORT_SECTION_NAME ".text"
#define EXPORT_SECTION_FLAGS TEXT_FLAGS
*/

static STRING *Exports = NULL;
static struct Section *directive_sec;
void AddExport(char *name)
{
	STRING *rvp = Exports,*newS;

	newS = (STRING *)nasm_malloc(sizeof(STRING));
	newS->len = strlen(name);
	newS->Next = NULL;
	newS->String = (char*)nasm_malloc( newS->len + 1 );
	strcpy( newS->String, name );
	if (rvp == NULL)
	{
		int i;
	   for (i=0; i<nsects; i++)


   	    if (!strcmp( EXPORT_SECTION_NAME, sects[i]->name))
      	      break;
		if( i == nsects )
			directive_sec = sects[coff_make_section( EXPORT_SECTION_NAME, EXPORT_SECTION_FLAGS )];
		else
			directive_sec = sects[i];
		Exports = newS;
	}	
	else {
		while (rvp->Next) {
			if (!strcmp(rvp->String,name))
				return;
			rvp = rvp->Next;
		}
		rvp->Next = newS;
	}
}

void BuildExportTable(void)
{
	STRING *rvp = Exports, *next;
	unsigned char buf[256];
	int len;
	if (rvp == NULL) return;
	while (rvp) {
		len = sprintf( (char*)buf, "-export:%s ", rvp->String );
		coff_sect_write( directive_sec, buf, len );
        	rvp = rvp->Next;
	}

	next = Exports;
	while( ( rvp = next ) )
	{
		next = rvp->Next;
		nasm_free( rvp->String );
		nasm_free( rvp );
	}
	Exports = NULL;
}


static int coff_directives (char *directive, char *value, int pass) 
{
    if (!strcmp(directive, "export")) {
        char *q, *name;

        if (pass == 2)
            return 1;                  /* ignore in pass two */
        name = q = value;
        while (*q && !isspace(*q))
            q++;
        if (isspace(*q)) {
            *q++ = '\0';
            while (*q && isspace(*q))
                q++;
        }

        if (!*name) {
            error(ERR_NONFATAL, "`export' directive requires export name");
            return 1;
        }
        if(*q) {
            error(ERR_NONFATAL, "unrecognised export qualifier `%s'", q);
            return 1;
        }
        AddExport( name );
        return 1;
    }
    return 0;
}

static void coff_write (void) 
{
    long pos, sympos, vsize;
    int i;

    BuildExportTable(); /* fill in the .drectve section with -export's */
    /*
     * Work out how big the file will get. Calculate the start of
     * the `real' symbols at the same time.
     */
    pos = 0x14 + 0x28 * nsects;
    initsym = 3;		       /* two for the file, one absolute */
    for (i=0; i<nsects; i++) {
	if (sects[i]->data) {
	    sects[i]->pos = pos;
	    pos += sects[i]->len;
	    sects[i]->relpos = pos;
	    pos += 10 * sects[i]->nrelocs;
	} else
	    sects[i]->pos = sects[i]->relpos = 0L;
	initsym += 2;		       /* two for each section */
    }
    sympos = pos;

    /*
     * Output the COFF header.
     */
    fwriteshort (0x14C, coffp);	       /* MACHINE_i386 */
    fwriteshort (nsects, coffp);       /* number of sections */
    fwritelong (time(NULL), coffp);    /* time stamp */
    fwritelong (sympos, coffp);
    fwritelong (nsyms + initsym, coffp);
    fwriteshort (0, coffp);	       /* no optional header */
    /* Flags: 32-bit, no line numbers. Win32 doesn't even bother with them. */
    fwriteshort (win32 ? 0 : 0x104, coffp);

    /*
     * Output the section headers.
     */
    vsize = 0L;
    for (i=0; i<nsects; i++) {
	coff_section_header (sects[i]->name, vsize, sects[i]->len,
			     sects[i]->pos, sects[i]->relpos,
			     sects[i]->nrelocs, sects[i]->flags);
	vsize += sects[i]->len;
    }

    /*
     * Output the sections and their relocations.
     */
    for (i=0; i<nsects; i++)
	if (sects[i]->data) {
	    saa_fpwrite (sects[i]->data, coffp);
	    coff_write_relocs (sects[i]);
	}

    /*
     * Output the symbol and string tables.
     */
    coff_write_symbols();
    fwritelong (strslen+4, coffp);     /* length includes length count */
    saa_fpwrite (strs, coffp);
}

static void coff_section_header (char *name, long vsize,
				 long datalen, long datapos,
				 long relpos, int nrelocs, long flags) 
{
    char padname[8];

    memset (padname, 0, 8);
    strncpy (padname, name, 8);
    fwrite (padname, 8, 1, coffp);
    fwritelong (vsize, coffp);
    fwritelong (0L, coffp);	       /* RVA/offset - we ignore */
    fwritelong (datalen, coffp);
    fwritelong (datapos, coffp);
    fwritelong (relpos, coffp);
    fwritelong (0L, coffp);	       /* no line numbers - we don't do 'em */
    fwriteshort (nrelocs, coffp);
    fwriteshort (0, coffp);	       /* again, no line numbers */
    fwritelong (flags, coffp);
}

static void coff_write_relocs (struct Section *s) 
{
    struct Reloc *r;

    for (r = s->head; r; r = r->next) {
	fwritelong (r->address, coffp);
	fwritelong (r->symbol + (r->symbase == REAL_SYMBOLS ? initsym :
				 r->symbase == ABS_SYMBOL ? initsym-1 :
				 r->symbase == SECT_SYMBOLS ? 2 : 0), coffp);
	/*
	 * Strange: Microsoft's COFF documentation says 0x03 for an
	 * absolute relocation, but both Visual C++ and DJGPP agree
	 * that in fact it's 0x06. I'll use 0x06 until someone
	 * argues.
	 */
	fwriteshort (r->relative ? 0x14 : 0x06, coffp);
    }
}

static void coff_symbol (char *name, long strpos, long value,
			 int section, int type, int aux) 
{
    char padname[8];

    if (name) {
	memset (padname, 0, 8);
	strncpy (padname, name, 8);
	fwrite (padname, 8, 1, coffp);
    } else {
	fwritelong (0L, coffp);
	fwritelong (strpos, coffp);
    }
    fwritelong (value, coffp);
    fwriteshort (section, coffp);
    fwriteshort (0, coffp);
    fputc (type, coffp);
    fputc (aux, coffp);
}

static void coff_write_symbols (void)
{
    char filename[18];
    unsigned long i;

    /*
     * The `.file' record, and the file name auxiliary record.
     */
    coff_symbol (".file", 0L, 0L, -2, 0x67, 1);
    memset (filename, 0, 18);
    strncpy (filename, coff_infile, 18);
    fwrite (filename, 18, 1, coffp);

    /*
     * The section records, with their auxiliaries.
     */
    memset (filename, 0, 18);	       /* useful zeroed buffer */

    for (i = 0; i < nsects; i++) {
	coff_symbol (sects[i]->name, 0L, 0L, i+1, 3, 1);
	fwritelong (sects[i]->len, coffp);
	fwriteshort (sects[i]->nrelocs, coffp);
	fwrite (filename, 12, 1, coffp);
    }

    /*
     * The absolute symbol, for relative-to-absolute relocations.
     */
    coff_symbol (".absolut", 0L, 0L, -1, 3, 0);

    /*
     * The real symbols.
     */
    saa_rewind (syms);
    for (i = 0; i < nsyms; i++) {
	struct Symbol *sym = saa_rstruct (syms);
	coff_symbol (sym->strpos == -1 ? sym->name : NULL,
		     sym->strpos, sym->value, sym->section,
		     sym->is_global ? 2 : 3, 0);
    }
}

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

static void coff_std_filename (char *inname, char *outname, efunc error) 
{
    strcpy(coff_infile, inname);
    standard_extension (inname, outname, ".o", error);
}

static void coff_win32_filename (char *inname, char *outname, efunc error) 
{
    strcpy(coff_infile, inname);
    standard_extension (inname, outname, ".obj", error);
}

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

static int coff_set_info(enum geninfo type, char **val)
{
    return 0;
}
#endif /* defined(OF_COFF) || defined(OF_WIN32) */

#ifdef OF_COFF

struct ofmt of_coff = {
    "COFF (i386) object files (e.g. DJGPP for DOS)",
    "coff",
    NULL,
    null_debug_arr,
    &null_debug_form,
    coff_stdmac,
    coff_std_init,
    coff_set_info,
    coff_out,
    coff_deflabel,
    coff_section_names,
    coff_segbase,
    coff_directives,
    coff_std_filename,
    coff_cleanup
};

#endif

#ifdef OF_WIN32

struct ofmt of_win32 = {
    "Microsoft Win32 (i386) object files",
    "win32",
    NULL,
    null_debug_arr,
    &null_debug_form,
    coff_stdmac,
    coff_win32_init,
    coff_set_info,
    coff_out,
    coff_deflabel,
    coff_section_names,
    coff_segbase,
    coff_directives,
    coff_win32_filename,
    coff_cleanup
};

#endif