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

/*
 * outrdf2.c	output routines for the Netwide Assembler to produce
 *		RDOFF version 2 format object files, which is used as a
 *		main binary format in the RadiOS (http://radios.sf.net).
 *		Originally Julian planned to use it in his MOSCOW
 *		operating system.
 *
 * The Netwide Assembler is copyright (C) 1996-1998 Simon Tatham and
 * Julian Hall. All rights reserved. The software is
 * redistributable under the licence given in the file "Licence"
 * distributed in the NASM archive.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>

#include "nasm.h"
#include "nasmlib.h"
#include "outform.h"

/* VERBOSE_WARNINGS: define this to add some extra warnings... */
#define VERBOSE_WARNINGS

#ifdef OF_RDF2

#include "rdoff/rdoff.h"

/* This signature is written to start of RDOFF files */
static const char *RDOFF2Id = RDOFF2_SIGNATURE;

/* Note that whenever a segment is referred to in the RDOFF file, its number
 * is always half of the segment number that NASM uses to refer to it; this
 * is because NASM only allocates even numbered segments, so as to not
 * waste any of the 16 bits of segment number written to the file - this
 * allows up to 65533 external labels to be defined; otherwise it would be
 * 32764. */

#define COUNT_SEGTYPES 9

static char *segmenttypes[COUNT_SEGTYPES] = {
    "null", "text", "code", "data",
    "comment", "lcomment", "pcomment",
    "symdebug", "linedebug"
};

static int segmenttypenumbers[COUNT_SEGTYPES] = {
    0, 1, 1, 2, 3, 4, 5, 6, 7
};

/* code for managing buffers needed to separate code and data into individual
 * sections until they are ready to be written to the file.
 * We'd better hope that it all fits in memory else we're buggered... */

#define BUF_BLOCK_LEN 4088      /* selected to match page size (4096)
                                 * on 80x86 machines for efficiency */

/***********************************************************************
 * Actual code to deal with RDOFF2 ouput format begins here...
 */

/* global variables set during the initialisation phase */

static struct SAA *seg[RDF_MAXSEGS];    /* seg 0 = code, seg 1 = data */
static struct SAA *header;      /* relocation/import/export records */

static FILE *ofile;

static efunc error;

static struct seginfo {
    char *segname;
    int segnumber;
    uint16 segtype;
    uint16 segreserved;
    long seglength;
} segments[RDF_MAXSEGS];

static int nsegments;

static long bsslength;
static long headerlength;

static void rdf2_init(FILE * fp, efunc errfunc, ldfunc ldef, evalfunc eval)
{
    int segtext, segdata, segbss;

    /* set up the initial segments */
    segments[0].segname = ".text";
    segments[0].segnumber = 0;
    segments[0].segtype = 1;
    segments[0].segreserved = 0;
    segments[0].seglength = 0;

    segments[1].segname = ".data";
    segments[1].segnumber = 1;
    segments[1].segtype = 2;
    segments[1].segreserved = 0;
    segments[1].seglength = 0;

    segments[2].segname = ".bss";
    segments[2].segnumber = 2;
    segments[2].segtype = 0xFFFF;       /* reserved - should never be produced */
    segments[2].segreserved = 0;
    segments[2].seglength = 0;

    nsegments = 3;

    ofile = fp;
    error = errfunc;

    seg[0] = saa_init(1L);
    seg[1] = saa_init(1L);
    seg[2] = NULL;              /* special case! */

    header = saa_init(1L);

    segtext = seg_alloc();
    segdata = seg_alloc();
    segbss = seg_alloc();
    if (segtext != 0 || segdata != 2 || segbss != 4)
        error(ERR_PANIC,
              "rdf segment numbers not allocated as expected (%d,%d,%d)",
              segtext, segdata, segbss);
    bsslength = 0;
    headerlength = 0;
}

static long rdf2_section_names(char *name, int pass, int *bits)
{
    int i;
    char *p, *q;
    int code = -1;
    int reserved = 0;

    /*
     * Default is 32 bits, in the text segment.
     */
    if (!name) {
        *bits = 32;
        return 0;
    }

    /* look for segment type code following segment name */
    p = name;
    while (*p && !isspace(*p))
        p++;
    if (*p) {                   /* we're now in whitespace */
        *p++ = '\0';
        while (*p && isspace(80))
            *p++ = '\0';
    }
    if (*p) {                   /* we're now in an attribute value */
        /*
         * see if we have an optional ',number' following the type code
         */
        if ((q = strchr(p, ','))) {
            *q++ = '\0';

            reserved = readnum(q, &i);
            if (i) {
                error(ERR_NONFATAL,
                      "value following comma must be numeric");
                reserved = 0;
            }
        }
        /*
         * check it against the text strings in segmenttypes 
         */

        for (i = 0; i < COUNT_SEGTYPES; i++)
            if (!nasm_stricmp(p, segmenttypes[i])) {
                code = segmenttypenumbers[i];
                break;
            }
        if (code == -1) {       /* didn't find anything */
            code = readnum(p, &i);
            if (i) {
                error(ERR_NONFATAL, "unrecognised RDF segment type (%s)",
                      p);
                code = 3;
            }
        }
    }
    for (i = 0; i < nsegments; i++) {
        if (!strcmp(name, segments[i].segname)) {
            if (code != -1 || reserved != 0)
                error(ERR_NONFATAL, "segment attributes specified on"
                      " redeclaration of segment");
            return segments[i].segnumber * 2;
        }
    }

    /* declaring a new segment! */

    if (code == -1) {
        error(ERR_NONFATAL, "new segment declared without type code");
        code = 3;
    }
    if (nsegments == RDF_MAXSEGS) {
        error(ERR_FATAL, "reached compiled-in maximum segment limit (%d)",
              RDF_MAXSEGS);
        return NO_SEG;
    }

    segments[nsegments].segname = nasm_strdup(name);
    i = seg_alloc();
    if (i % 2 != 0)
        error(ERR_PANIC, "seg_alloc() returned odd number");
    segments[nsegments].segnumber = i >> 1;
    segments[nsegments].segtype = code;
    segments[nsegments].segreserved = reserved;
    segments[nsegments].seglength = 0;

    seg[nsegments] = saa_init(1L);

    return i;
}

/*
 * Write relocation record
 */
static void write_reloc_rec(struct RelocRec *r)
{
    char buf[4], *b;

    if (r->refseg != (uint16) NO_SEG && (r->refseg & 1))        /* segment base ref */
        r->type = RDFREC_SEGRELOC;

    r->refseg >>= 1;            /* adjust segment nos to RDF rather than NASM */

    saa_wbytes(header, &r->type, 1);
    saa_wbytes(header, &r->reclen, 1);
    saa_wbytes(header, &r->segment, 1);
    b = buf;
    WRITELONG(b, r->offset);
    saa_wbytes(header, buf, 4);
    saa_wbytes(header, &r->length, 1);
    b = buf;
    WRITESHORT(b, r->refseg);
    saa_wbytes(header, buf, 2);
    headerlength += r->reclen + 2;
}

/*
 * Write export record
 */
static void write_export_rec(struct ExportRec *r)
{
    char buf[4], *b;

    r->segment >>= 1;

    saa_wbytes(header, &r->type, 1);
    saa_wbytes(header, &r->reclen, 1);
    saa_wbytes(header, &r->flags, 1);
    saa_wbytes(header, &r->segment, 1);
    b = buf;
    WRITELONG(b, r->offset);
    saa_wbytes(header, buf, 4);
    saa_wbytes(header, r->label, strlen(r->label) + 1);
    headerlength += r->reclen + 2;
}

static void write_import_rec(struct ImportRec *r)
{
    char buf[4], *b;

    r->segment >>= 1;

    saa_wbytes(header, &r->type, 1);
    saa_wbytes(header, &r->reclen, 1);
    saa_wbytes(header, &r->flags, 1);
    b = buf;
    WRITESHORT(b, r->segment);
    saa_wbytes(header, buf, 2);
    saa_wbytes(header, r->label, strlen(r->label) + 1);
    headerlength += r->reclen + 2;
}

/*
 * Write BSS record
 */
static void write_bss_rec(struct BSSRec *r)
{
    char buf[4], *b;

    saa_wbytes(header, &r->type, 1);
    saa_wbytes(header, &r->reclen, 1);
    b = buf;
    WRITELONG(b, r->amount);
    saa_wbytes(header, buf, 4);
    headerlength += r->reclen + 2;
}

/*
 * Write common variable record
 */
static void write_common_rec(struct CommonRec *r)
{
    char buf[4], *b;

    r->segment >>= 1;

    saa_wbytes(header, &r->type, 1);
    saa_wbytes(header, &r->reclen, 1);
    b = buf;
    WRITESHORT(b, r->segment);
    saa_wbytes(header, buf, 2);
    b = buf;
    WRITELONG(b, r->size);
    saa_wbytes(header, buf, 4);
    b = buf;
    WRITESHORT(b, r->align);
    saa_wbytes(header, buf, 2);
    saa_wbytes(header, r->label, strlen(r->label) + 1);
    headerlength += r->reclen + 2;
}

/*
 * Write library record
 */
static void write_dll_rec(struct DLLRec *r)
{
    saa_wbytes(header, &r->type, 1);
    saa_wbytes(header, &r->reclen, 1);
    saa_wbytes(header, r->libname, strlen(r->libname) + 1);
    headerlength += r->reclen + 2;
}

/*
 * Write module name record
 */
static void write_modname_rec(struct ModRec *r)
{
    saa_wbytes(header, &r->type, 1);
    saa_wbytes(header, &r->reclen, 1);
    saa_wbytes(header, r->modname, strlen(r->modname) + 1);
    headerlength += r->reclen + 2;
}

/*
 * Handle export, import and common records.
 */
static void rdf2_deflabel(char *name, long segment, long offset,
                          int is_global, char *special)
{
    struct ExportRec r;
    struct ImportRec ri;
    struct CommonRec ci;
    static int farsym = 0;
    static int i;
    byte symflags = 0;
    int len;

    /* Check if the label length is OK */
    if ((len = strlen(name)) >= EXIM_LABEL_MAX) {
        error(ERR_NONFATAL, "label size exceeds %d bytes", EXIM_LABEL_MAX);
        return;
    }
    if (!len) {
        error(ERR_NONFATAL, "zero-length label");
        return;
    }

    if (is_global == 2) {
        /* Common variable */
        ci.type = RDFREC_COMMON;
        ci.size = offset;
        ci.segment = segment;
        strcpy(ci.label, name);
        ci.reclen = 9 + len;
        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);
    }