outrdf2.c

nasm的全套源代码,有些我做了些修改,以方便您更方便更容易调试成功,方便学习做编译器

    /* 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;
            symflags |= SYM_GLOBAL;
        } else if (!nasm_strnicmp(special, "import", 6)) {
            special += 6;
            symflags |= SYM_IMPORT;
        }

        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")) {
                symflags |= SYM_FUNCTION;
            } else if (!nasm_stricmp(special, "data") ||
                       !nasm_stricmp(special, "object")) {
                symflags |= 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 */
        ri.type = farsym ? RDFREC_FARIMPORT : RDFREC_IMPORT;
        if (symflags & SYM_GLOBAL)
            error(ERR_NONFATAL,
                  "symbol type conflict - EXTERN cannot be EXPORT");
        ri.flags = symflags;
        ri.segment = segment;
        strcpy(ri.label, name);
        ri.reclen = 4 + len;
        write_import_rec(&ri);
    } else if (is_global) {
        r.type = RDFREC_GLOBAL; /* GLOBAL declaration */
        if (symflags & SYM_IMPORT)
            error(ERR_NONFATAL,
                  "symbol type conflict - GLOBAL cannot be IMPORT");
        r.flags = symflags;
        r.segment = segment;
        r.offset = offset;
        strcpy(r.label, name);
        r.reclen = 7 + len;
        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;
}

/*
 * Handle RDOFF2 specific directives
 */
static int rdf2_directive(char *directive, char *value, int pass)
{
    int n;

    /* Check if the name length is OK */
    if ((n = strlen(value)) >= MODLIB_NAME_MAX) {
        error(ERR_NONFATAL, "name size exceeds %d bytes", MODLIB_NAME_MAX);
        return 0;
    }

    if (!strcmp(directive, "library")) {
        if (pass == 1) {
            struct DLLRec r;
            r.type = RDFREC_DLL;
            r.reclen = n + 1;
            strcpy(r.libname, value);
            write_dll_rec(&r);
        }
        return 1;
    }

    if (!strcmp(directive, "module")) {
        if (pass == 1) {
            struct ModRec r;
            r.type = RDFREC_MODNAME;
            r.reclen = n + 1;
            strcpy(r.modname, value);
            write_modname_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 */