trunk/src/main.c

/*
 *  Copyright (C) 2003-2005  Anders Gavare.  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright  
 *     notice, this list of conditions and the following disclaimer in the 
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 *  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *  ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE   
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 *  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 *  OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 *  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 *  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *
 *
 *  $Id: main.c,v 1.244 2005/09/07 07:41:29 debug Exp $
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "console.h"
#include "cpu.h"
#include "device.h"
#include "diskimage.h"
#include "emul.h"
#include "machine.h"
#include "misc.h"


extern volatile int single_step;
extern int force_debugger_at_exit;
extern int show_opcode_statistics;

extern int optind;
extern char *optarg;

int extra_argc;
char **extra_argv;
char *progname;

int fully_deterministic = 0;


/*****************************************************************************
 *
 *  NOTE:  debug(), fatal(), and debug_indentation() are not re-entrant.
 *         The global variable quiet_mode can be used to suppress the output
 *         of debug(), but not the output of fatal().
 *
 *****************************************************************************/

int verbose = 0;
int quiet_mode = 0;

static int debug_indent = 0;
static int debug_currently_at_start_of_line = 1;


/*
 *  va_debug():
 *
 *  Used internally by debug() and fatal().
 */
static void va_debug(va_list argp, char *fmt)
{
        char buf[DEBUG_BUFSIZE + 1];
        char *s;
        int i;

        buf[0] = buf[DEBUG_BUFSIZE] = 0;
        vsnprintf(buf, DEBUG_BUFSIZE, fmt, argp);

        s = buf;
        while (*s) {
                if (debug_currently_at_start_of_line) {
                        for (i=0; i<debug_indent; i++)
                                printf(" ");
                }

                printf("%c", *s);

                debug_currently_at_start_of_line = 0;
                if (*s == '\n' || *s == '\r')
                        debug_currently_at_start_of_line = 1;
                s++;
        }
}


/*
 *  debug_indentation():
 *
 *  Modify the debug indentation.
 */
void debug_indentation(int diff)
{
        debug_indent += diff;
        if (debug_indent < 0)
                fprintf(stderr, "WARNING: debug_indent less than 0!\n");
}


/*
 *  debug():
 *
 *  Debug output (ignored if quiet_mode is set).
 */
void debug(char *fmt, ...)
{
        va_list argp;

        if (quiet_mode)
                return;

        va_start(argp, fmt);
        va_debug(argp, fmt);
        va_end(argp);
}


/*
 *  fatal():
 *
 *  Fatal works like debug(), but doesn't care about the quiet_mode
 *  setting.
 */
void fatal(char *fmt, ...)
{
        va_list argp;

        va_start(argp, fmt);
        va_debug(argp, fmt);
        va_end(argp);
}


/*****************************************************************************/


/*
 *  internal_w():
 *
 *  For internal use by gxemul itself.
 */
void internal_w(char *arg)
{
        if (arg == NULL || strncmp(arg, "W@", 2) != 0) {
                fprintf(stderr, "-W is for internal use by gxemul,"
                    " not for manual use.\n");
                exit(1);
        }

        arg += 2;

        switch (arg[0]) {
        case 'S':
                console_slave(arg + 1);
                break;
        default:
                fprintf(stderr, "internal_w(): UNIMPLEMENTED arg = '%s'\n",
                    arg);
        }
}


/*****************************************************************************/


/*
 *  usage():
 *
 *  Prints program usage to stdout.
 */
static void usage(int longusage)
{
        printf("GXemul");
#ifdef VERSION
        printf("-" VERSION);
#endif
        printf("   Copyright (C) 2003-2005  Anders Gavare\n");
        printf("Read the source code and/or documentation for "
            "other Copyright messages.\n");

        printf("\nusage: %s [machine, other, and general options] [file "
            "[...]]\n", progname);
        printf("   or  %s [general options] @configfile\n", progname);
        printf("   or  %s [userland, other, and general options] file "
            "[args ...]\n", progname);

        if (!longusage) {
                printf("\nRun  %s -h  for help on command line options.\n",
                    progname);
                return;
        }

        printf("\nMachine selection options:\n");
        printf("  -E t      try to emulate machine type t. (Use -H to get "
            "a list of types.)\n");
        printf("  -e st     try to emulate machine subtype st. (Use this "
            "with -E.)\n");

        printf("\nOther options:\n");
        printf("  -A        disable alignment checks in some cases (for higher"
            " speed)\n");
#ifdef BINTRANS
        printf("  -B        disable dynamic binary translation. (translation"
            " is turned on\n            by default, if the host "
            "supports it)\n");
#endif
        printf("  -C x      try to emulate a specific CPU. (Use -H to get a "
            "list of types.)\n");
        printf("  -d fname  add fname as a disk image. You can add \"xxx:\""
            " as a prefix\n");
        printf("            where xxx is one or more of the following:\n");
        printf("                b      specifies that this is the boot"
            " device\n");
        printf("                c      CD-ROM\n");
        printf("                d      DISK\n");
        printf("                f      FLOPPY\n");
        printf("                gH;S;  set geometry to H heads and S"
            " sectors-per-track\n");
        printf("                i      IDE\n");
        printf("                r      read-only (don't allow changes to the"
            " file)\n");
        printf("                s      SCSI\n");
        printf("                t      tape\n");
        printf("                0-7    force a specific ID\n");
        printf("  -I x      emulate clock interrupts at x Hz (affects"
            " rtc devices only, not\n");
        printf("            actual runtime speed) (this disables automatic"
            " clock adjustments)\n");
        printf("  -i        display each instruction as it is executed\n");
        printf("  -J        disable some speed tricks\n");
        printf("  -j name   set the name of the kernel, for example:\n");
        printf("                -j netbsd          for NetBSD/pmax\n");
        printf("                -j bsd             for OpenBSD/pmax\n");
        printf("                -j vmunix          for Ultrix/RISC\n");
        printf("  -M m      emulate m MBs of physical RAM\n");
        printf("  -m nr     run at most nr instructions (on any cpu)\n");
        printf("  -N        display nr of instructions/second average, at"
            " regular intervals\n");
        printf("  -n nr     set nr of CPUs (for SMP experiments)\n");
        printf("  -O        force netboot (tftp instead of disk), even when"
            " a disk image is\n"
            "            present (for DECstation, SGI, and ARC emulation)\n");
        printf("  -o arg    set the boot argument (for DEC, ARC, or SGI"
            " emulation).\n");
        printf("            Default arg for DEC is '-a', for ARC '-aN'.\n");
        printf("  -p pc     add a breakpoint (remember to use the '0x' "
            "prefix for hex!)\n");
        printf("  -Q        no built-in PROM emulation  (use this for "
            "running ROM images)\n");
        printf("  -R        use random bootstrap cpu, instead of nr 0\n");
        printf("  -r        register dumps before every instruction\n");
        printf("  -S        initialize emulated RAM to random bytes, "
            "instead of zeroes\n");
        printf("  -T        enter the single-step debugger on "
            "unimplemented memory accesses\n");
        printf("  -t        show function trace tree\n");
        printf("  -U        enable slow_serial_interrupts_hack_for_linux\n");
#ifdef WITH_X11
        printf("  -X        use X11\n");
#endif /*  WITH_X11  */
        printf("  -x        open up new xterms for emulated serial ports "
            "(default is on when\n            using configuration files, off"
            " otherwise)\n");
#ifdef WITH_X11
        printf("  -Y n      scale down framebuffer windows by n x n times\n");
#endif /*  WITH_X11  */
        printf("  -y x      set max_random_cycles_per_chunk to x"
            " (experimental)\n");
        printf("  -Z n      set nr of graphics cards, for emulating a "
            "dual-head or tripple-head\n"
            "            environment (only for DECstation emulation)\n");
        printf("  -z disp   add disp as an X11 display to use for "
            "framebuffers\n");

        printf("\nUserland options:\n");
        printf("  -u emul   userland-only (syscall) emulation (use -H to"
            " get a list of\n            available emulation modes)\n");

        printf("\nGeneral options:\n");
        printf("  -D        guarantee fully deterministic behaviour\n");
        printf("  -H        display a list of possible CPU and "
            "machine types\n");
        printf("  -h        display this help message\n");
        printf("  -K        force the debugger to be entered at the end "
            "of a simulation\n");
        printf("  -q        quiet mode (don't print startup messages)\n");
        printf("  -s        show opcode usage statistics after simulation\n");
        printf("  -V        start up in the single-step debugger, paused\n");
        printf("  -v        verbose debug messages\n");
        printf("\n");
        printf("If you are selecting a machine type to emulate directly "
            "on the command line,\nthen you must specify one or more names"
            " of files that you wish to load into\n"
            "memory. Supported formats are:   ELF a.out ecoff srec syms raw\n"
            "where syms is the text produced by running 'nm' (or 'nm -S') "
            "on a binary.\n"
            "To load a raw binary into memory, add \"address:\" in front "
            "of the filename,\n"
            "or \"address:skiplen:\" or \"address:skiplen:initialpc:\".\n"
            "Examples:\n"
            "    0xbfc00000:rom.bin                    for a raw ROM image\n"
            "    0xbfc00000:0x100:rom.bin              for an image with "
            "0x100 bytes header\n"
            "    0xbfc00000:0x100:0xbfc00884:rom.bin   "
            "start with pc=0xbfc00884\n");
}


/*
 *  get_cmd_args():
 *
 *  Reads command line arguments.
 */
int get_cmd_args(int argc, char *argv[], struct emul *emul,
        char ***diskimagesp, int *n_diskimagesp)
{
        int ch, res, using_switch_d = 0, using_switch_Z = 0;
        char *type = NULL, *subtype = NULL;
        int n_cpus_set = 0;
        int msopts = 0;         /*  Machine-specific options used  */
        struct machine *m = emul_add_machine(emul, "default");

        while ((ch = getopt(argc, argv, "ABC:Dd:E:e:HhI:iJj:KM:m:"
            "Nn:Oo:p:QqRrSsTtUu:VvW:XxY:y:Z:z:")) != -1) {
                switch (ch) {
                case 'A':
                        m->dyntrans_alignment_check = 0;
                        msopts = 1;
                        break;
                case 'B':
                        m->bintrans_enable = 0;
                        msopts = 1;
                        break;
                case 'C':
                        m->cpu_name = strdup(optarg);
                        msopts = 1;
                        break;
                case 'D':
                        fully_deterministic = 1;
                        break;
                case 'd':
                        /*  diskimage_add() is called further down  */
                        (*n_diskimagesp) ++;
                        (*diskimagesp) = realloc(*diskimagesp,
                            sizeof(char *) * (*n_diskimagesp));
                        if (*diskimagesp == NULL) {
                                fprintf(stderr, "out of memory\n");
                                exit(1);
                        }
                        (*diskimagesp)[(*n_diskimagesp) - 1] = strdup(optarg);
                        using_switch_d = 1;
                        msopts = 1;
                        break;
                case 'E':
                        type = optarg;
                        msopts = 1;
                        break;
                case 'e':
                        subtype = optarg;
                        msopts = 1;
                        break;
                case 'H':
                        machine_list_available_types_and_cpus();
                        exit(1);
                case 'h':
                        usage(1);
                        exit(1);
                case 'I':
                        m->emulated_hz = atoi(optarg);
                        m->automatic_clock_adjustment = 0;
                        msopts = 1;
                        break;
                case 'i':
                        m->instruction_trace = 1;
                        msopts = 1;
                        break;
                case 'J':
                        m->speed_tricks = 0;
                        msopts = 1;
                        break;
                case 'j':
                        m->boot_kernel_filename = strdup(optarg);
                        if (m->boot_kernel_filename == NULL) {
                                fprintf(stderr, "out of memory\n");
                                exit(1);
                        }
                        msopts = 1;
                        break;
                case 'K':
                        force_debugger_at_exit = 1;
                        break;
                case 'M':
                        m->physical_ram_in_mb = atoi(optarg);
                        msopts = 1;
                        break;
                case 'm':
                        m->max_instructions = atoi(optarg);
                        msopts = 1;
                        break;
                case 'N':
                        m->show_nr_of_instructions = 1;
                        msopts = 1;
                        break;
                case 'n':
                        m->ncpus = atoi(optarg);
                        n_cpus_set = 1;
                        msopts = 1;
                        break;
                case 'O':
                        m->force_netboot = 1;
                        msopts = 1;
                        break;
                case 'o':
                        m->boot_string_argument = strdup(optarg);
                        if (m->boot_string_argument == NULL) {
                                fprintf(stderr, "out of memory\n");
                                exit(1);
                        }
                        msopts = 1;
                        break;
                case 'p':
                        if (m->n_breakpoints >= MAX_BREAKPOINTS) {
                                fprintf(stderr, "too many breakpoints\n");
                                exit(1);
                        }
                        m->breakpoint_string[m->n_breakpoints] = strdup(optarg);
                        if (m->breakpoint_string[m->n_breakpoints] == NULL) {
                                fprintf(stderr, "out of memory\n");
                                exit(1);
                        }
                        m->breakpoint_flags[m->n_breakpoints] = 0;
                        m->n_breakpoints ++;
                        msopts = 1;
                        break;
                case 'Q':
                        m->prom_emulation = 0;
                        msopts = 1;
                        break;
                case 'q':
                        quiet_mode = 1;
                        break;
                case 'R':
                        m->use_random_bootstrap_cpu = 1;
                        msopts = 1;
                        break;
                case 'r':
                        m->register_dump = 1;
                        msopts = 1;
                        break;
                case 'S':
                        m->random_mem_contents = 1;
                        msopts = 1;
                        break;
                case 's':
                        show_opcode_statistics = 1;
                        break;
                case 'T':
                        m->single_step_on_bad_addr = 1;
                        msopts = 1;
                        break;
                case 't':
                        m->show_trace_tree = 1;
                        msopts = 1;
                        break;
                case 'U':
                        m->slow_serial_interrupts_hack_for_linux = 1;
                        msopts = 1;
                        break;
                case 'u':
                        m->userland_emul = strdup(optarg);
                        if (m->userland_emul == NULL) {
                                fprintf(stderr, "out of memory\n");
                                exit(1);
                        }
                        m->machine_type = MACHINE_USERLAND;
                        msopts = 1;
                        break;
                case 'V':
                        single_step = 1;
                        break;
                case 'v':
                        verbose ++;
                        break;
                case 'W':
                        internal_w(optarg);
                        exit(0);
                case 'X':
                        m->use_x11 = 1;
                        msopts = 1;
                        break;
                case 'x':
                        console_allow_slaves(1);
                        break;
                case 'Y':
                        m->x11_scaledown = atoi(optarg);
                        if (m->x11_scaledown < 1) {
                                fprintf(stderr, "Invalid scaledown value.\n");
                                exit(1);
                        }
                        msopts = 1;
                        break;
                case 'y':
                        m->max_random_cycles_per_chunk = atoi(optarg);
                        msopts = 1;
                        break;
                case 'Z':
                        m->n_gfx_cards = atoi(optarg);
                        using_switch_Z = 1;
                        msopts = 1;
                        break;
                case 'z':
                        m->x11_n_display_names ++;
                        m->x11_display_names = realloc(
                            m->x11_display_names,
                            m->x11_n_display_names * sizeof(char *));
                        if (m->x11_display_names == NULL) {
                                fprintf(stderr, "out of memory\n");
                                exit(1);
                        }
                        m->x11_display_names[m->x11_n_display_names-1] =
                            strdup(optarg);
                        if (m->x11_display_names
                            [m->x11_n_display_names-1] == NULL) {
                                fprintf(stderr, "out of memory\n");
                                exit(1);
                        }
                        msopts = 1;
                        break;
                default:
                        fprintf(stderr, "Run  %s -h  for help on command "
                            "line options.\n", progname);
                        exit(1);
                }
        }

        if (type != NULL || subtype != NULL) {
                if (type == NULL)
                        type = "";
                if (subtype == NULL)
                        subtype = "";
                res = machine_name_to_type(type, subtype,
                    &m->machine_type, &m->machine_subtype, &m->arch);
                if (!res)
                        exit(1);
        }

        argc -= optind;
        argv += optind;

        extra_argc = argc;
        extra_argv = argv;


        if (m->machine_type == MACHINE_NONE && msopts) {
                fprintf(stderr, "Machine specific options used directly on "
                    "the command line, but no machine\nemulation specified?\n");
                exit(1);
        }


        /*  -i and -r are pretty verbose:  */

        if (m->instruction_trace && !verbose) {
                fprintf(stderr, "Implicitly %sturning on -v, because"
                    " of -i\n", quiet_mode? "turning off -q and " : "");
                verbose = 1;
                quiet_mode = 0;
        }

        if (m->register_dump && !verbose) {
                fprintf(stderr, "Implicitly %sturning on -v, because"
                    " of -r\n", quiet_mode? "turning off -q and " : "");
                verbose = 1;
                quiet_mode = 0;
        }

        if ((m->instruction_trace || m->register_dump || m->show_trace_tree)
            && m->bintrans_enable) {
                fprintf(stderr, "Implicitly turning off bintrans.\n");
                m->bintrans_enable = 0;
        }


        /*
         *  Usually, an executable filename must be supplied.
         *
         *  However, it is possible to boot directly from a harddisk image
         *  file. If no kernel is supplied, but a diskimage is being used,
         *  then try to boot from disk.
         */
        if (extra_argc == 0) {
                if (using_switch_d) {
                        /*  Booting directly from a disk image...  */
                } else {
                        usage(0);
                        fprintf(stderr, "\nNo filename given. Aborting.\n");
                        exit(1);
                }
        } else if (m->boot_kernel_filename[0] == '\0') {
                /*
                 *  Default boot_kernel_filename is "", which can be overriden
                 *  by the -j command line option.  If it is still "" here,
                 *  and we're not booting directly from a disk image, then
                 *  try to set it to the last part of the last file name
                 *  given on the command line. (Last part = the stuff after
                 *  the last slash.)
                 */
                char *s = extra_argv[extra_argc - 1];
                char *s2;

                s2 = strrchr(s, '/');
                if (s2 == NULL)
                        s2 = s;
                else
                        s2 ++;

                m->boot_kernel_filename = strdup(s2);
                if (m->boot_kernel_filename == NULL) {
                        fprintf(stderr, "out of memory\n");
                        exit(1);
                }
        }

        if (m->n_gfx_cards < 0 || m->n_gfx_cards > 3) {
                fprintf(stderr, "Bad number of gfx cards (-Z).\n");
                exit(1);
        }

        if (m->bintrans_enable) {
                m->speed_tricks = 0;
                /*  TODO: Print a warning about this?  */
        }

        if (m->n_breakpoints > 0 &&
            m->bintrans_enable && m->arch == ARCH_MIPS) {
                fprintf(stderr, "Breakpoints and MIPS binary translation "
                    "don't work too well together right now.\n");
                exit(1);
        }

#ifndef BINTRANS
        if (m->bintrans_enable) {
                fprintf(stderr, "WARNING: %s was compiled without "
                    "bintrans support. Ignoring -b.\n", progname);
                m->bintrans_enable = 0;
        }
#endif

#ifndef WITH_X11
        if (m->use_x11) {
                fprintf(stderr, "WARNING: %s was compiled without "
                    "X11 support. Ignoring -X.\n", progname);
                m->use_x11 = 0;
        }
#endif

        if (!using_switch_Z && !m->use_x11)
                m->n_gfx_cards = 0;

        m->bintrans_enabled_from_start = m->bintrans_enable;

        return 0;
}


/*
 *  main():
 *
 *  Two kinds of emulations are started from here:
 *
 *      o)  Simple emulations, using command line arguments, compatible with
 *          earlier version of GXemul/mips64emul.
 *
 *      o)  Emulations set up by parsing special config files. (0 or more.)
 */
int main(int argc, char *argv[])
{
        struct emul **emuls;
        char **diskimages = NULL;
        int n_diskimages = 0;
        int n_emuls;
        int i;

        progname = argv[0];

        console_init();
        cpu_init();
        device_init();
        machine_init();
        useremul_init();

        emuls = malloc(sizeof(struct emul *));
        if (emuls == NULL) {
                fprintf(stderr, "out of memory\n");
                exit(1);
        }

        /*  Allocate space for a simple emul setup:  */
        n_emuls = 1;
        emuls[0] = emul_new(NULL);
        if (emuls[0] == NULL) {
                fprintf(stderr, "out of memory\n");
                exit(1);
        }

        get_cmd_args(argc, argv, emuls[0], &diskimages, &n_diskimages);

        if (!fully_deterministic) {
                /*  TODO: More than just time(). Use gettimeofday().  */
                srandom(time(NULL) ^ (getpid() << 12));
        } else {
                /*  Fully deterministic. -I must have been supplied.  */
                if (emuls[0]->machines[0]->automatic_clock_adjustment) {
                        fatal("Cannot have -D without -I.\n");
                        exit(1);
                }
        }

        /*  Print startup message:  */
        debug("GXemul");
#ifdef VERSION
        debug("-" VERSION);
#endif
        debug("   Copyright (C) 2003-2005  Anders Gavare\n");
        debug("Read the source code and/or documentation for "
            "other Copyright messages.\n\n");

        if (emuls[0]->machines[0]->machine_type == MACHINE_NONE)
                n_emuls --;
        else {
                for (i=0; i<n_diskimages; i++)
                        diskimage_add(emuls[0]->machines[0], diskimages[i]);
        }

        /*  Simple initialization, from command line arguments:  */
        if (n_emuls > 0) {
                /*  Make sure that there are no configuration files as well:  */
                for (i=1; i<argc; i++)
                        if (argv[i][0] == '@') {
                                fprintf(stderr, "You can either start one "
                                    "emulation with one machine directly from "
                                    "the command\nline, or start one or more "
                                    "emulations using configuration files."
                                    " Not both.\n");
                                exit(1);
                        }

                /*  Initialize one emul:  */
                emul_simple_init(emuls[0]);
        }

        /*  Initialize emulations from config files:  */
        for (i=1; i<argc; i++) {
                if (argv[i][0] == '@') {
                        char *s = argv[i] + 1;
                        if (strlen(s) == 0 && i+1 < argc &&
                            argv[i+1][0] != '@') {
                                i++;
                                s = argv[i];
                        }
                        n_emuls ++;
                        emuls = realloc(emuls, sizeof(struct emul *) * n_emuls);
                        if (emuls == NULL) {
                                fprintf(stderr, "out of memory\n");
                                exit(1);
                        }
                        emuls[n_emuls - 1] =
                            emul_create_from_configfile(s);

                        /*  Always allow slave xterms when using multiple
                            emulations:  */
                        console_allow_slaves(1);
                }
        }

        if (n_emuls == 0) {
                fprintf(stderr, "No emulations defined. Maybe you forgot to "
                    "use -E xx and/or -e yy, to specify\nthe machine type."
                    " For example:\n\n    %s -e 3max -d disk.img\n\n"
                    "to boot an emulated DECstation 5000/200 with a disk "
                    "image.\n", progname);
                exit(1);
        }

        device_set_exit_on_error(0);

        /*  Run all emulations:  */
        emul_run(emuls, n_emuls);

        return 0;
}
