git.rot13.org Git - goodfet/blob - client/GoodFET.py

   1 #!/usr/bin/env python
   2 # GoodFET Client Library
   3 #
   4 # (C) 2009 Travis Goodspeed <travis at radiantmachines.com>
   5 #
   6 # This code is being rewritten and refactored.  You've been warned!
   7
   8 import sys, time, string, cStringIO, struct, glob, os;
   9 import sqlite3;
  10
  11 fmt = ("B", "<H", None, "<L")
  12
  13 def getClient(name="GoodFET"):
  14     import GoodFET, GoodFETCC, GoodFETAVR, GoodFETSPI, GoodFETMSP430, GoodFETNRF, GoodFETCCSPI;
  15     if(name=="GoodFET" or name=="monitor"): return GoodFET.GoodFET();
  16     elif name=="cc" or name=="cc51": return GoodFETCC.GoodFETCC();
  17     elif name=="cc2420" or name=="ccspi": return GoodFETCCSPI.GoodFETCCSPI();
  18     elif name=="avr": return GoodFETAVR.GoodFETAVR();
  19     elif name=="spi": return GoodFETSPI.GoodFETSPI();
  20     elif name=="msp430": return GoodFETMSP430.GoodFETMSP430();
  21     elif name=="nrf": return GoodFETNRF.GoodFETNRF();
  22
  23     print "Unsupported target: %s" % name;
  24     sys.exit(0);
  25
  26 class SymbolTable:
  27     """GoodFET Symbol Table"""
  28     db=sqlite3.connect(":memory:");
  29
  30     def __init__(self, *args, **kargs):
  31         self.db.execute("create table if not exists symbols(adr,name,memory,size,comment);");
  32     def get(self,name):
  33         self.db.commit();
  34         c=self.db.cursor();
  35         try:
  36             c.execute("select adr,memory from symbols where name=?",(name,));
  37             for row in c:
  38                 #print "Found it.";
  39                 sys.stdout.flush();
  40                 return row[0];
  41             #print "No dice.";
  42         except:# sqlite3.OperationalError:
  43             #print "SQL error.";
  44             return eval(name);
  45         return eval(name);
  46     def define(self,adr,name,comment="",memory="vn",size=16):
  47         self.db.execute("insert into symbols(adr,name,memory,size,comment)"
  48                         "values(?,?,?,?,?);", (
  49                 adr,name,memory,size,comment));
  50         #print "Set %s=%s." % (name,adr);
  51
  52 class GoodFET:
  53     """GoodFET Client Library"""
  54
  55     besilent=0;
  56     app=0;
  57     verb=0;
  58     count=0;
  59     data="";
  60     verbose=False
  61
  62     GLITCHAPP=0x71;
  63     MONITORAPP=0x00;
  64     symbols=SymbolTable();
  65
  66     def __init__(self, *args, **kargs):
  67         self.data=[0];
  68     def getConsole(self):
  69         from GoodFETConsole import GoodFETConsole;
  70         return GoodFETConsole(self);
  71     def name2adr(self,name):
  72         return self.symbols.get(name);
  73     def timeout(self):
  74         print "timeout\n";
  75     def serInit(self, port=None, timeout=2, attemptlimit=None):
  76         """Open the serial port"""
  77         # Make timeout None to wait forever, 0 for non-blocking mode.
  78         import serial;
  79
  80         if os.name=='nt' and sys.version.find('64 bit')!=-1:
  81             print "WARNING: PySerial requires a 32-bit Python build in Windows.";
  82
  83         if port is None and os.environ.get("GOODFET")!=None:
  84             glob_list = glob.glob(os.environ.get("GOODFET"));
  85             if len(glob_list) > 0:
  86                 port = glob_list[0];
  87             else:
  88                 port = os.environ.get("GOODFET");
  89         if port is None:
  90             glob_list = glob.glob("/dev/tty.usbserial*");
  91             if len(glob_list) > 0:
  92                 port = glob_list[0];
  93         if port is None:
  94             glob_list = glob.glob("/dev/ttyUSB*");
  95             if len(glob_list) > 0:
  96                 port = glob_list[0];
  97         if port is None:
  98             glob_list = glob.glob("/dev/ttyU0");
  99             if len(glob_list) > 0:
 100                 port = glob_list[0];
 101         if port is None and os.name=='nt':
 102             from scanwin32 import winScan;
 103             scan=winScan();
 104             for order,comport,desc,hwid in sorted(scan.comports()):
 105                 try:
 106                     if hwid.index('FTDI')==0:
 107                         port=comport;
 108                         #print "Using FTDI port %s" % port
 109                 except:
 110                     #Do nothing.
 111                     a=1;
 112
 113         baud=115200;
 114         if(os.environ.get("platform")=='arduino'):
 115             baud=19200; #Slower, for now.
 116         self.serialport = serial.Serial(
 117             port,
 118             #9600,
 119             baud,
 120             parity = serial.PARITY_NONE,
 121             timeout=timeout
 122             )
 123
 124         self.verb=0;
 125         attempts=0;
 126         connected=0;
 127         while connected==0:
 128             while self.verb!=0x7F or self.data!="http://goodfet.sf.net/":
 129             #while self.data!="http://goodfet.sf.net/":
 130                 #print "'%s'!=\n'%s'" % (self.data,"http://goodfet.sf.net/");
 131                 if attemptlimit is not None and attempts >= attemptlimit:
 132                     return
 133                 elif attempts>2:
 134                     print "Resyncing.";
 135                 self.serialport.flushInput()
 136                 self.serialport.flushOutput()
 137
 138                 #TelosB reset, prefer software to I2C SPST Switch.
 139                 if(os.environ.get("platform")=='telosb'):
 140                     #print "TelosB Reset";
 141                     self.telosBReset();
 142                 else:
 143                     #Explicitly set RTS and DTR to halt board.
 144                     self.serialport.setRTS(1);
 145                     self.serialport.setDTR(1);
 146                     #Drop DTR, which is !RST, low to begin the app.
 147                     self.serialport.setDTR(0);
 148
 149                 #self.serialport.write(chr(0x80));
 150                 #self.serialport.write(chr(0x80));
 151                 #self.serialport.write(chr(0x80));
 152                 #self.serialport.write(chr(0x80));
 153
 154
 155                 #self.serialport.flushInput()
 156                 #self.serialport.flushOutput()
 157                 #time.sleep(60);
 158                 attempts=attempts+1;
 159                 self.readcmd(); #Read the first command.
 160                 #print "Got %02x,%02x:'%s'" % (self.app,self.verb,self.data);
 161             #Here we have a connection, but maybe not a good one.
 162             #print "We have a connection."
 163             connected=1;
 164             olds=self.infostring();
 165             clocking=self.monitorclocking();
 166             #if(os.environ.get("platform")!='arduino'):
 167             for foo in range(1,30):
 168                 if not self.monitorecho():
 169                     if self.verbose:
 170                         print "Comm error on %i try, resyncing out of %s." % (foo,
 171                                                                               clocking);
 172                         connected=0;
 173                         break;
 174         if self.verbose: print "Connected after %02i attempts." % attempts;
 175         self.mon_connected();
 176         self.serialport.setTimeout(12);
 177     def serClose(self):
 178         self.serialport.close();
 179     def telosSetSCL(self, level):
 180         self.serialport.setRTS(not level)
 181     def telosSetSDA(self, level):
 182         self.serialport.setDTR(not level)
 183
 184     def telosI2CStart(self):
 185         self.telosSetSDA(1)
 186         self.telosSetSCL(1)
 187         self.telosSetSDA(0)
 188
 189     def telosI2CStop(self):
 190         self.telosSetSDA(0)
 191         self.telosSetSCL(1)
 192         self.telosSetSDA(1)
 193
 194     def telosI2CWriteBit(self, bit):
 195         self.telosSetSCL(0)
 196         self.telosSetSDA(bit)
 197         time.sleep(2e-6)
 198         self.telosSetSCL(1)
 199         time.sleep(1e-6)
 200         self.telosSetSCL(0)
 201
 202     def telosI2CWriteByte(self, byte):
 203         self.telosI2CWriteBit( byte & 0x80 );
 204         self.telosI2CWriteBit( byte & 0x40 );
 205         self.telosI2CWriteBit( byte & 0x20 );
 206         self.telosI2CWriteBit( byte & 0x10 );
 207         self.telosI2CWriteBit( byte & 0x08 );
 208         self.telosI2CWriteBit( byte & 0x04 );
 209         self.telosI2CWriteBit( byte & 0x02 );
 210         self.telosI2CWriteBit( byte & 0x01 );
 211         self.telosI2CWriteBit( 0 );  # "acknowledge"
 212
 213     def telosI2CWriteCmd(self, addr, cmdbyte):
 214         self.telosI2CStart()
 215         self.telosI2CWriteByte( 0x90 | (addr << 1) )
 216         self.telosI2CWriteByte( cmdbyte )
 217         self.telosI2CStop()
 218
 219     def telosBReset(self,invokeBSL=0):
 220         # "BSL entry sequence at dedicated JTAG pins"
 221         # rst !s0: 0 0 0 0 1 1
 222         # tck !s1: 1 0 1 0 0 1
 223         #   s0|s1: 1 3 1 3 2 0
 224
 225         # "BSL entry sequence at shared JTAG pins"
 226         # rst !s0: 0 0 0 0 1 1
 227         # tck !s1: 0 1 0 1 1 0
 228         #   s0|s1: 3 1 3 1 0 2
 229
 230         if invokeBSL:
 231             self.telosI2CWriteCmd(0,1)
 232             self.telosI2CWriteCmd(0,3)
 233             self.telosI2CWriteCmd(0,1)
 234             self.telosI2CWriteCmd(0,3)
 235             self.telosI2CWriteCmd(0,2)
 236             self.telosI2CWriteCmd(0,0)
 237         else:
 238             self.telosI2CWriteCmd(0,3)
 239             self.telosI2CWriteCmd(0,2)
 240
 241         # This line was not defined inside the else: block, not sure where it
 242         # should be however
 243         self.telosI2CWriteCmd(0,0)
 244         time.sleep(0.250)       #give MSP430's oscillator time to stabilize
 245         self.serialport.flushInput()  #clear buffers
 246
 247
 248     def getbuffer(self,size=0x1c00):
 249         writecmd(0,0xC2,[size&0xFF,(size>>16)&0xFF]);
 250         print "Got %02x%02x buffer size." % (self.data[1],self.data[0]);
 251     def writecmd(self, app, verb, count=0, data=[]):
 252         """Write a command and some data to the GoodFET."""
 253         self.serialport.write(chr(app));
 254         self.serialport.write(chr(verb));
 255
 256         #if data!=None:
 257         #    count=len(data); #Initial count ignored.
 258
 259         #print "TX %02x %02x %04x" % (app,verb,count);
 260
 261         #little endian 16-bit length
 262         self.serialport.write(chr(count&0xFF));
 263         self.serialport.write(chr(count>>8));
 264
 265         if self.verbose:
 266             print "Tx: ( 0x%02x, 0x%02x, 0x%04x )" % ( app, verb, count )
 267
 268         #print "count=%02x, len(data)=%04x" % (count,len(data));
 269
 270         if count!=0:
 271             if(isinstance(data,list)):
 272                 for i in range(0,count):
 273                 #print "Converting %02x at %i" % (data[i],i)
 274                     data[i]=chr(data[i]);
 275             #print type(data);
 276             outstr=''.join(data);
 277             self.serialport.write(outstr);
 278         if not self.besilent:
 279             return self.readcmd()
 280         else:
 281             return []
 282
 283     def readcmd(self):
 284         """Read a reply from the GoodFET."""
 285         while 1:#self.serialport.inWaiting(): # Loop while input data is available
 286             try:
 287                 #print "Reading...";
 288                 self.app=ord(self.serialport.read(1));
 289                 #print "APP=%02x" % self.app;
 290                 self.verb=ord(self.serialport.read(1));
 291
 292                 #Fixes an obscure bug in the TelosB.
 293                 if self.app==0x00:
 294                     while self.verb==0x00:
 295                         self.verb=ord(self.serialport.read(1));
 296
 297                 #print "VERB=%02x" % self.verb;
 298                 self.count=(
 299                     ord(self.serialport.read(1))
 300                     +(ord(self.serialport.read(1))<<8)
 301                     );
 302
 303                 #if self.verbose:
 304                 #print "Rx: ( 0x%02x, 0x%02x, 0x%04x )" % ( self.app, self.verb, self.count )
 305
 306                 #Debugging string; print, but wait.
 307                 if self.app==0xFF:
 308                     if self.verb==0xFF:
 309                         print "# DEBUG %s" % self.serialport.read(self.count)
 310                     elif self.verb==0xFE:
 311                         print "# DEBUG 0x%x" % struct.unpack(fmt[self.count-1], self.serialport.read(self.count))[0]
 312                     elif self.verb==0xFD:
 313                         #Do nothing, just wait so there's no timeout.
 314                         print "# NOP.";
 315
 316                     sys.stdout.flush();
 317                 else:
 318                     self.data=self.serialport.read(self.count);
 319                     return self.data;
 320             except TypeError:
 321                 if self.connected:
 322                     print "Warning: waiting for serial read timed out (most likely).";
 323                     #print "This shouldn't happen after syncing.  Exiting for safety.";
 324                     #sys.exit(-1)
 325                 return self.data;
 326     #Glitching stuff.
 327     def glitchApp(self,app):
 328         """Glitch into a device by its application."""
 329         self.data=[app&0xff];
 330         self.writecmd(self.GLITCHAPP,0x80,1,self.data);
 331         #return ord(self.data[0]);
 332     def glitchVerb(self,app,verb,data):
 333         """Glitch during a transaction."""
 334         if data==None: data=[];
 335         self.data=[app&0xff, verb&0xFF]+data;
 336         self.writecmd(self.GLITCHAPP,0x81,len(self.data),self.data);
 337         #return ord(self.data[0]);
 338     def glitchstart(self):
 339         """Glitch into the AVR application."""
 340         self.glitchVerb(self.APP,0x20,None);
 341     def glitchstarttime(self):
 342         """Measure the timer of the START verb."""
 343         return self.glitchTime(self.APP,0x20,None);
 344     def glitchTime(self,app,verb,data):
 345         """Time the execution of a verb."""
 346         if data==None: data=[];
 347         self.data=[app&0xff, verb&0xFF]+data;
 348         print "Timing app %02x verb %02x." % (app,verb);
 349         self.writecmd(self.GLITCHAPP,0x82,len(self.data),self.data);
 350         time=ord(self.data[0])+(ord(self.data[1])<<8);
 351         print "Timed to be %i." % time;
 352         return time;
 353     def glitchVoltages(self,low=0x0880, high=0x0fff):
 354         """Set glitching voltages. (0x0fff is max.)"""
 355         self.data=[low&0xff, (low>>8)&0xff,
 356                    high&0xff, (high>>8)&0xff];
 357         self.writecmd(self.GLITCHAPP,0x90,4,self.data);
 358         #return ord(self.data[0]);
 359     def glitchRate(self,count=0x0800):
 360         """Set glitching count period."""
 361         self.data=[count&0xff, (count>>8)&0xff];
 362         self.writecmd(self.GLITCHAPP,0x91,2,
 363                       self.data);
 364         #return ord(self.data[0]);
 365
 366
 367     #Monitor stuff
 368     def silent(self,s=0):
 369         """Transmissions halted when 1."""
 370         self.besilent=s;
 371         print "besilent is %i" % self.besilent;
 372         self.writecmd(0,0xB0,1,[s]);
 373     connected=0;
 374     def mon_connected(self):
 375         """Announce to the monitor that the connection is good."""
 376         self.connected=1;
 377         self.writecmd(0,0xB1,0,[]);
 378     def out(self,byte):
 379         """Write a byte to P5OUT."""
 380         self.writecmd(0,0xA1,1,[byte]);
 381     def dir(self,byte):
 382         """Write a byte to P5DIR."""
 383         self.writecmd(0,0xA0,1,[byte]);
 384     def call(self,adr):
 385         """Call to an address."""
 386         self.writecmd(0,0x30,2,
 387                       [adr&0xFF,(adr>>8)&0xFF]);
 388     def execute(self,code):
 389         """Execute supplied code."""
 390         self.writecmd(0,0x31,2,#len(code),
 391                       code);
 392     def MONpeek8(self,address):
 393         """Read a byte of memory from the monitor."""
 394         self.data=[address&0xff,address>>8];
 395         self.writecmd(0,0x02,2,self.data);
 396         #self.readcmd();
 397         return ord(self.data[0]);
 398     def MONpeek16(self,address):
 399         """Read a word of memory from the monitor."""
 400         return self.MONpeek8(address)+(self.MONpeek8(address+1)<<8);
 401     def peek(self,address):
 402         """Read a word of memory from the monitor."""
 403         return self.MONpeek8(address)+(self.MONpeek8(address+1)<<8);
 404     def eeprompeek(self,address):
 405         """Read a word of memory from the monitor."""
 406         print "EEPROM peeking not supported for the monitor.";
 407         #return self.MONpeek8(address)+(self.MONpeek8(address+1)<<8);
 408     def peekbysym(self,name):
 409         """Read a value by its symbol name."""
 410         #TODO include memory in symbol.
 411         reg=self.symbols.get(name);
 412         return self.peek8(reg,"data");
 413     def pokebysym(self,name,val):
 414         """Write a value by its symbol name."""
 415         #TODO include memory in symbol.
 416         reg=self.symbols.get(name);
 417         return self.pokebyte(reg,val);
 418     def pokebyte(self,address,value,memory="vn"):
 419         """Set a byte of memory by the monitor."""
 420         self.data=[address&0xff,address>>8,value];
 421         self.writecmd(0,0x03,3,self.data);
 422         return ord(self.data[0]);
 423     def poke16(self,address,value):
 424         """Set a word of memory by the monitor."""
 425         self.pokebyte(address,value&0xFF);
 426         self.pokebyte(address,(value>>8)&0xFF);
 427         return value;
 428     def setsecret(self,value):
 429         """Set a secret word for later retreival.  Used by glitcher."""
 430         #self.eeprompoke(0,value);
 431         #self.eeprompoke(1,value);
 432         print "Secret setting is not yet suppored for this target.";
 433         print "Aborting.";
 434
 435     def getsecret(self):
 436         """Get a secret word.  Used by glitcher."""
 437         #self.eeprompeek(0);
 438         print "Secret getting is not yet suppored for this target.";
 439         print "Aborting.";
 440         sys.exit();
 441
 442     def dumpmem(self,begin,end):
 443         i=begin;
 444         while i<end:
 445             print "%04x %04x" % (i, self.MONpeek16(i));
 446             i+=2;
 447     def monitor_ram_pattern(self):
 448         """Overwrite all of RAM with 0xBEEF."""
 449         self.writecmd(0,0x90,0,self.data);
 450         return;
 451     def monitor_ram_depth(self):
 452         """Determine how many bytes of RAM are unused by looking for 0xBEEF.."""
 453         self.writecmd(0,0x91,0,self.data);
 454         return ord(self.data[0])+(ord(self.data[1])<<8);
 455
 456     #Baud rates.
 457     baudrates=[115200,
 458                9600,
 459                19200,
 460                38400,
 461                57600,
 462                115200];
 463     def setBaud(self,baud):
 464         """Change the baud rate.  TODO fix this."""
 465         rates=self.baudrates;
 466         self.data=[baud];
 467         print "Changing FET baud."
 468         self.serialport.write(chr(0x00));
 469         self.serialport.write(chr(0x80));
 470         self.serialport.write(chr(1));
 471         self.serialport.write(chr(baud));
 472
 473         print "Changed host baud."
 474         self.serialport.setBaudrate(rates[baud]);
 475         time.sleep(1);
 476         self.serialport.flushInput()
 477         self.serialport.flushOutput()
 478
 479         print "Baud is now %i." % rates[baud];
 480         return;
 481     def readbyte(self):
 482         return ord(self.serialport.read(1));
 483     def findbaud(self):
 484         for r in self.baudrates:
 485             print "\nTrying %i" % r;
 486             self.serialport.setBaudrate(r);
 487             #time.sleep(1);
 488             self.serialport.flushInput()
 489             self.serialport.flushOutput()
 490
 491             for i in range(1,10):
 492                 self.readbyte();
 493
 494             print "Read %02x %02x %02x %02x" % (
 495                 self.readbyte(),self.readbyte(),self.readbyte(),self.readbyte());
 496     def monitortest(self):
 497         """Self-test several functions through the monitor."""
 498         print "Performing monitor self-test.";
 499         self.monitorclocking();
 500         for f in range(0,3000):
 501             a=self.MONpeek16(0x0c00);
 502             b=self.MONpeek16(0x0c02);
 503             if a!=0x0c04 and a!=0x0c06:
 504                 print "ERROR Fetched %04x, %04x" % (a,b);
 505             self.pokebyte(0x0021,0); #Drop LED
 506             if self.MONpeek8(0x0021)!=0:
 507                 print "ERROR, P1OUT not cleared.";
 508             self.pokebyte(0x0021,1); #Light LED
 509             if not self.monitorecho():
 510                 print "Echo test failed.";
 511         print "Self-test complete.";
 512         self.monitorclocking();
 513     def monitorecho(self):
 514         data="The quick brown fox jumped over the lazy dog.";
 515         self.writecmd(self.MONITORAPP,0x81,len(data),data);
 516         if self.data!=data:
 517             print "Comm error recognized by monitorecho(), got:\n%s" % self.data;
 518             return 0;
 519         return 1;
 520
 521     def monitor_info(self):
 522         print "GoodFET with %s MCU" % self.infostring();
 523         print "Clocked at %s" % self.monitorclocking();
 524         return 1;
 525
 526     def monitor_list_apps(self, full=False):
 527         self.monitor_info()
 528         old_value = self.besilent
 529         self.besilent = True    # turn off automatic call to readcmd
 530         self.writecmd(self.MONITORAPP, 0x82, 1, [int(full)]);
 531         self.besilent = old_value
 532
 533         # read the build date string
 534         self.readcmd()
 535         print "Build Date: %s" % self.data
 536         print "Firmware apps:"
 537         while True:
 538             self.readcmd()
 539             if self.count == 0:
 540                 break
 541             print self.data
 542         return 1;
 543
 544     def monitorclocking(self):
 545         """Return the 16-bit clocking value."""
 546         return "0x%04x" % self.monitorgetclock();
 547
 548     def monitorsetclock(self,clock):
 549         """Set the clocking value."""
 550         self.MONpoke16(0x56, clock);
 551     def monitorgetclock(self):
 552         """Get the clocking value."""
 553         if(os.environ.get("platform")=='arduino'):
 554             return 0xDEAD;
 555         #Check for MSP430 before peeking this.
 556         return self.MONpeek16(0x56);
 557     # The following functions ought to be implemented in
 558     # every client.
 559
 560     def infostring(self):
 561         if(os.environ.get("platform")=='arduino'):
 562             return "Arduino";
 563         else:
 564             a=self.MONpeek8(0xff0);
 565             b=self.MONpeek8(0xff1);
 566             return "%02x%02x" % (a,b);
 567     def lock(self):
 568         print "Locking Unsupported.";
 569     def erase(self):
 570         print "Erasure Unsupported.";
 571     def setup(self):
 572         return;
 573     def start(self):
 574         return;
 575     def test(self):
 576         print "Unimplemented.";
 577         return;
 578     def status(self):
 579         print "Unimplemented.";
 580         return;
 581     def halt(self):
 582         print "Unimplemented.";
 583         return;
 584     def resume(self):
 585         print "Unimplemented.";
 586         return;
 587     def getpc(self):
 588         print "Unimplemented.";
 589         return 0xdead;
 590     def flash(self,file):
 591         """Flash an intel hex file to code memory."""
 592         print "Flash not implemented.";
 593     def dump(self,file,start=0,stop=0xffff):
 594         """Dump an intel hex file from code memory."""
 595         print "Dump not implemented.";
 596     def peek32(self,address, memory="vn"):
 597         """Peek 32 bits."""
 598         return (self.peek16(address,memory)+
 599                 (self.peek16(address+2,memory)<<16));
 600     def peek16(self,address, memory="vn"):
 601         """Peek 16 bits of memory."""
 602         return (self.peek8(address,memory)+
 603                 (self.peek8(address+1,memory)<<8));
 604     def peek8(self,address, memory="vn"):
 605         """Peek a byte of memory."""
 606         return self.MONpeek8(address); #monitor
 607     def peekblock(self,address,length,memory="vn"):
 608         """Return a block of data."""
 609         data=range(0,length);
 610         for foo in range(0,length):
 611             data[foo]=self.peek8(address+foo,memory);
 612         return data;
 613     def pokeblock(self,address,bytes,memory="vn"):
 614         """Poke a block of a data into memory at an address."""
 615         for foo in bytes:
 616             self.pokebyte(address,foo,memory);
 617             address=address+1;
 618         return;
 619     def loadsymbols(self):
 620         """Load symbols from a file."""
 621         return;