machine.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

private int printdisp(addr, nbytes, reg, mode)
Address addr;
int nbytes;
char *reg;
int mode;
{
    char byte;
    short hword;
    int argval;
    Symbol f;

    switch (nbytes) {
	case 1:
	    iread(&byte, addr, sizeof(byte));
	    argval = byte;
	    break;

	case 2:
	    iread(&hword, addr, sizeof(hword));
	    argval = hword;
	    break;

	case 4:
	    iread(&argval, addr, sizeof(argval));
	    break;
    }
    if (reg == regname[PROGCTR] && mode >= BYTEDISP) {
	argval += addr + nbytes;
    }
    if (reg == regname[PROGCTR]) {
	f = whatblock((Address) argval + 2);
	if (codeloc(f) == argval + 2) {
	    printf("%s", symname(f));
	} else {
	    printf("%x", argval);
	}
    } else {
	if (varIsSet("$hexoffsets")) {
	    if (argval < 0) {
		printf("-%x(%s)", -(argval), reg);
	    } else {
		printf("%x(%s)", argval, reg);
	    }
	} else {
	    printf("%d(%s)", argval, reg);
	}
    }
    return argval;
}

/*
 * Print the contents of the addresses within the given range
 * according to the given format.
 */

typedef struct {
    String name;
    String printfstring;
    int length;
} Format;

private Format fmt[] = {
    { "d", " %d", sizeof(short) },
    { "D", " %ld", sizeof(long) },
    { "o", " %o", sizeof(short) },
    { "O", " %lo", sizeof(long) },
    { "x", " %04x", sizeof(short) },
    { "X", " %08x", sizeof(long) },
    { "b", " \\%o", sizeof(char) },
    { "c", " '%c'", sizeof(char) },
    { "s", "%c", sizeof(char) },
    { "f", " %f", sizeof(float) },
    { "g", " %g", sizeof(double) },
    { "v", " (%ld,%ld)", 2 * sizeof(long) },
    { "vx", " (0x%X,0x%X)", 2 * sizeof(long) },
    { "vf", " (%f,%f)", sizeof(Vquad) },
    { nil, nil, 0 }
};

private Format *findformat(s)
String s;
{
    register Format *f;

    f = &fmt[0];
    while (f->name != nil and not streq(f->name, s)) {
	++f;
    }
    if (f->name == nil) {
	error("bad print format \"%s\"", s);
    }
    return f;
}

public Address printdata(lowaddr, highaddr, format)
Address lowaddr;
Address highaddr;
String format;
{
    register int n;
    register Address addr;
    register Format *f;
    int value;

    if (lowaddr > highaddr) {
	error("first address larger than second");
    }
    f = findformat(format);
    n = 0;
    value = 0;
    for (addr = lowaddr; addr <= highaddr; addr += f->length) {
	if (n == 0) {
	    printf("%08x: ", addr);
	}
	if(streq(format, "vf")) {
		Vquad value;
		
		dread(&value, addr, f->length);
		printf("(");
	    prtreal(value.val[0]);
		printf(",");
	    prtreal(value.val[1]);
		printf(")");
	}
	else {
		dread(&value, addr, f->length);
		if(streq(format, "g") || streq(format, "f")) {
	    	prtreal(value);
		} else {
			printf(f->printfstring, value);
		}
	}
	++n;
	if (n >= (16 div f->length)) {
	    putchar('\n');
	    n = 0;
	}
    }
    if (n != 0) {
	putchar('\n');
    }
    prtaddr = addr;
    return addr;
}

/*
 * The other approach is to print n items starting with a given address.
 */

public printndata(count, startaddr, format)
int count;
Address startaddr;
String format;
{
    register int i, n;
    register Address addr;
    register Format *f;
    register Boolean isstring;
    char c;
    union {
	char charv;
	short shortv;
	int intv;
	float floatv;
	double doublev;
    } value;

    if (count <= 0) {
	error("non-positive repetition count");
    }
    f = findformat(format);
    isstring = (Boolean) streq(f->name, "s");
    n = 0;
    addr = startaddr;
    value.intv = 0;
    for (i = 0; i < count; i++) {
	if (n == 0) {
	    printf("%08x: ", addr);
	}
	if (isstring) {
	    putchar('"');
	    dread(&c, addr, sizeof(char));
	    while (c != '\0') {
		printchar(c);
		++addr;
		dread(&c, addr, sizeof(char));
	    }
	    putchar('"');
	    putchar('\n');
	    n = 0;
	    addr += sizeof(String);
	} else {
		if(streq(format, "vf")) {
			Vquad value;
		
			dread(&value, addr, f->length);
			printf(" (");
	    	prtreal(value.val[0]);
			printf(",");
	    	prtreal(value.val[1]);
			printf(")");
		}
		else {
			value.doublev = 0.0;
			dread(&value, addr, f->length);
			if(streq(format, "g") || streq(format, "f")) {
				printf(" ");
	    		prtreal(value);
			}else {
				printf(f->printfstring, value);
			}
		}
	    ++n;
	    if (n >= (16 div f->length)) {
		putchar('\n');
		n = 0;
	    }
	    addr += f->length;
	}
    }
    if (n != 0) {
	putchar('\n');
    }
    prtaddr = addr;
}

/*
 * Print out a value according to the given format.
 */

public printvalue(v, format)
long v;
String format;
{
    Format *f;
    char *p, *q;

    f = findformat(format);
    if (streq(f->name, "s")) {
	putchar('"');
	p = (char *) &v;
	q = p + sizeof(v);
	while (p < q) {
	    printchar(*p);
	    ++p;
	}
	putchar('"');
    } else {
	printf(f->printfstring, v);
    }
    putchar('\n');
}

/*
 * Print out an execution time error.
 * Assumes the source position of the error has been calculated.
 *
 * Have to check if the -r option was specified; if so then
 * the object file information hasn't been read in yet.
 */

public printerror()
{
    extern Integer sys_nsig;
    extern String sys_siglist[];
    integer err;

    if (isfinished(process)) {
	err = exitcode(process);
	if (err == 0) {
	    printf("\"%s\" terminated normally\n", objname);
	} else {
	    printf("\"%s\" terminated abnormally (exit code %d)\n",
		objname, err
	    );
	}
	erecover();
    }
    if (runfirst) {
	fprintf(stderr, "Entering debugger ...\n");
	init();
    }
    err = errnum(process);
    putchar('\n');
    printsig(err);
    putchar(' ');
    printloc();
    putchar('\n');
    if (curline > 0) {
	printlines(curline, curline);
    } else {
	printinst(pc, pc);
    }
    erecover();
}

/*
 * Print out a signal.
 */

private String illinames[] = {
    "reserved addressing fault",
    "privileged instruction fault",
    "reserved operand fault"
};

private String fpenames[] = {
    nil,
    "integer overflow trap",
    "integer divide by zero trap",
    "floating overflow trap",
    "floating/decimal divide by zero trap",
    "floating underflow trap",
    "decimal overflow trap",
    "subscript out of range trap",
    "floating overflow fault",
    "floating divide by zero fault",
    "floating underflow fault"
};

public printsig (signo)
integer signo;
{
    integer code;

    if (signo < 0 or signo > sys_nsig) {
	printf("[signal %d]", signo);
    } else {
	printf("%s", sys_siglist[signo]);
    }
    code = errcode(process);
    if (signo == SIGILL) {
	if (code >= 0 and code < sizeof(illinames) / sizeof(illinames[0])) {
	    printf(" (%s)", illinames[code]);
	}
    } else if (signo == SIGFPE) {
	if (code > 0 and code < sizeof(fpenames) / sizeof(fpenames[0])) {
	    printf(" (%s)", fpenames[code]);
	}
    }
}

/*
 * Merge bit field into old value (on top of expression stack).
 */

public void depositField(value, s)
long value;
Symbol s;
{
    unsigned n;
    unsigned long offset;
    unsigned long length;

    offset = s->symvalue.field.offset mod 8;
    length = s->symvalue.field.length;
    n = pop(long);

    n = (n & ((1 << length) - 1));
    n = (n << offset) |
	(value & ~( ((1 << length) - 1) << offset ));
    push(long, n);
}

/*
 * Note the termination of the program.  We do this so as to avoid
 * having the process exit, which would make the values of variables
 * inaccessible.  We do want to flush all output buffers here,
 * otherwise it'll never get done.
 */

public endprogram()
{
    Integer exitcode;

    stepto(nextaddr(pc, true));
    printnews();
    exitcode = argn(1, nil);
    if (exitcode != 0) {
	printf("\nexecution completed (exit code %d)\n", exitcode);
    } else {
	printf("\nexecution completed\n");
    }
    getsrcpos();
    erecover();
}

/*
 * Single step the machine a source line (or instruction if "inst_tracing"
 * is true).  If "isnext" is true, skip over procedure calls.
 */

private Address getcall();

public Boolean dostep(isnext, isvector)
Boolean isnext, isvector;
{
    register Address addr;
    register Lineno line;
    String filename;
	Boolean ret = false;

    addr = nextaddr(pc, isnext);
	if(!(isvector && found_a_vec_inst)) {
    	if (not inst_tracing and nlhdr.nlines != 0) {
			line = linelookup(addr);
			while (line == 0) {
	    		addr = nextaddr(addr, isnext);
	    		line = linelookup(addr);
			}
			curline = line;
    	} else {
			curline = 0;
    	}
/* jlr005
 * No need to check for one-line loops: since nextaddr() steps if there's
 * a jump, if addr==starting addr, there must have been a jump, and we're
 * already done.
 */
    	stepto(addr);
	}
	else {
		ret = true;
	}
    filename = srcfilename(addr);
    setsource(filename);
	return(ret);
}

/*
 * Compute the next address that will be executed from the given one.
 * If "isnext" is true then consider a procedure call as straight line code.
 *
 * We must unfortunately do much of the same work that is necessary
 * to print instructions.  In addition we have to deal with branches.
 * Unconditional branches we just follow, for conditional branches
 * we continue execution to the current location and then single step
 * the machine.  We assume that the last argument in an instruction
 * that branches is the branch address (or relative offset).
 */

private Address findnextaddr();

public Address nextaddr(startaddr, isnext)
Address startaddr;
boolean isnext;
{
    Address addr;

    addr = usignal(process);
    if (addr == 0 or addr == 1) {
	addr = findnextaddr(startaddr, isnext);
    }
    return addr;
}

/*
 * Determine if it's ok to skip function f entered by instruction ins.
 * If so, we're going to compute the return address and step to it.
 * Therefore we cannot skip over a function entered by a jsb or bsb,
 * since the return address is not easily computed for them.
 */

private boolean skipfunc (ins, f)
VaxOpcode ins;
Symbol f;
{
    boolean b;

    b = (boolean) (
	ins != O_JSB and ins != O_BSBB and ins != O_BSBW and
	not inst_tracing and nlhdr.nlines != 0 and
	nosource(curfunc) and canskip(curfunc)
    );
    return b;
}

private Address findnextaddr(startaddr, isnext)
Address startaddr;
Boolean isnext;
{
    register Address addr;
    Optab op;
    VaxOpcode ins, ins2;
    unsigned char mode;