parser.py revision 6863
1# Copyright (c) 2009 The Hewlett-Packard Development Company 2# All rights reserved. 3# 4# Redistribution and use in source and binary forms, with or without 5# modification, are permitted provided that the following conditions are 6# met: redistributions of source code must retain the above copyright 7# notice, this list of conditions and the following disclaimer; 8# redistributions in binary form must reproduce the above copyright 9# notice, this list of conditions and the following disclaimer in the 10# documentation and/or other materials provided with the distribution; 11# neither the name of the copyright holders nor the names of its 12# contributors may be used to endorse or promote products derived from 13# this software without specific prior written permission. 14# 15# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 18# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 19# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 20# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 21# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 25# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26# 27# Authors: Nathan Binkert 28 29import os.path 30import re 31import sys 32 33from m5.util.grammar import Grammar, TokenError, ParseError 34 35import slicc.ast as ast 36import slicc.util as util 37from slicc.symbols import SymbolTable 38 39def read_slicc(sources): 40 if not isinstance(sources, (list,tuple)): 41 sources = [ sources ] 42 43 for source in sources: 44 for sm_file in file(source, "r"): 45 sm_file = sm_file.strip() 46 if not sm_file: 47 continue 48 if sm_file.startswith("#"): 49 continue 50 yield sm_file 51 52class SLICC(Grammar): 53 def __init__(self, **kwargs): 54 super(SLICC, self).__init__(**kwargs) 55 self.decl_list_vec = [] 56 self.current_file = None 57 self.symtab = SymbolTable() 58 59 def parse(self, filename): 60 self.current_file = filename 61 f = file(filename, 'r') 62 text = f.read() 63 try: 64 decl_list = super(SLICC, self).parse(text) 65 except (TokenError, ParseError), e: 66 sys.exit("%s: %s:%d" % (e, filename, e.token.lineno)) 67 self.decl_list_vec.append(decl_list) 68 self.current_file = None 69 70 def _load(self, *filenames): 71 filenames = list(filenames) 72 while filenames: 73 f = filenames.pop(0) 74 if isinstance(f, (list, tuple)): 75 filenames[0:0] = list(f) 76 continue 77 78 yield f 79 if f.endswith(".slicc"): 80 dirname,basename = os.path.split(f) 81 filenames[0:0] = [ os.path.join(dirname, x) \ 82 for x in read_slicc(f)] 83 else: 84 assert f.endswith(".sm") 85 self.parse(f) 86 87 def load(self, *filenames, **kwargs): 88 verbose = kwargs.pop("verbose", False) 89 if kwargs: 90 raise TypeError 91 92 gen = self._load(*filenames) 93 if verbose: 94 return gen 95 else: 96 # Run out the generator if we don't want the verbosity 97 for foo in gen: 98 pass 99 100 def findMachines(self): 101 for decl_list in self.decl_list_vec: 102 decl_list.findMachines() 103 104 def generate(self): 105 for decl_list in self.decl_list_vec: 106 decl_list.generate() 107 108 def writeCodeFiles(self, code_path): 109 util.makeDir(code_path) 110 self.symtab.writeCodeFiles(code_path) 111 112 def writeHTMLFiles(self, code_path): 113 util.makeDir(code_path) 114 self.symtab.writeHTMLFiles(code_path) 115 116 def files(self): 117 f = set([ 118 'ControllerFactory.cc', 119 'ControllerFactory.hh', 120 'MachineType.cc', 121 'MachineType.hh', 122 'Types.hh' ]) 123 124 for decl_list in self.decl_list_vec: 125 f |= decl_list.files() 126 127 return f 128 129 t_ignore = '\t ' 130 131 # C or C++ comment (ignore) 132 def t_c_comment(self, t): 133 r'/\*(.|\n)*?\*/' 134 t.lexer.lineno += t.value.count('\n') 135 136 def t_cpp_comment(self, t): 137 r'//.*' 138 139 # Define a rule so we can track line numbers 140 def t_newline(self, t): 141 r'\n+' 142 t.lexer.lineno += len(t.value) 143 144 reserved = { 145 'global' : 'GLOBAL', 146 'machine' : 'MACHINE', 147 'in_port' : 'IN_PORT', 148 'out_port' : 'OUT_PORT', 149 'action' : 'ACTION', 150 'transition' : 'TRANS', 151 'structure' : 'STRUCT', 152 'external_type' : 'EXTERN_TYPE', 153 'enumeration' : 'ENUM', 154 'peek' : 'PEEK', 155 'enqueue' : 'ENQUEUE', 156 'copy_head' : 'COPY_HEAD', 157 'check_allocate' : 'CHECK_ALLOCATE', 158 'check_stop_slots' : 'CHECK_STOP_SLOTS', 159 'if' : 'IF', 160 'else' : 'ELSE', 161 'return' : 'RETURN', 162 'THIS' : 'THIS', 163 'CHIP' : 'CHIP', 164 'void' : 'VOID', 165 'new' : 'NEW', 166 } 167 168 literals = ':[]{}(),=' 169 170 tokens = [ 'EQ', 'NE', 'LT', 'GT', 'LE', 'GE', 171 'LEFTSHIFT', 'RIGHTSHIFT', 172 'NOT', 'AND', 'OR', 173 'PLUS', 'DASH', 'STAR', 'SLASH', 174 'DOUBLE_COLON', 'SEMI', 175 'ASSIGN', 'DOT', 176 'IDENT', 'LIT_BOOL', 'FLOATNUMBER', 'NUMBER', 'STRING' ] 177 tokens += reserved.values() 178 179 t_EQ = r'==' 180 t_NE = r'!=' 181 t_LT = r'<' 182 t_GT = r'>' 183 t_LE = r'<=' 184 t_GE = r'>=' 185 t_LEFTSHIFT = r'<<' 186 t_RIGHTSHIFT = r'>>' 187 t_NOT = r'!' 188 t_AND = r'&&' 189 t_OR = r'\|\|' 190 t_PLUS = r'\+' 191 t_DASH = r'-' 192 t_STAR = r'\*' 193 t_SLASH = r'/' 194 t_DOUBLE_COLON = r'::' 195 t_SEMI = r';' 196 t_ASSIGN = r':=' 197 t_DOT = r'\.' 198 199 precedence = ( 200 ('left', 'AND', 'OR'), 201 ('left', 'EQ', 'NE'), 202 ('left', 'LT', 'GT', 'LE', 'GE'), 203 ('left', 'RIGHTSHIFT', 'LEFTSHIFT'), 204 ('left', 'PLUS', 'DASH'), 205 ('left', 'STAR', 'SLASH'), 206 ('right', 'NOT', 'UMINUS'), 207 ) 208 209 def t_IDENT(self, t): 210 r'[a-zA-Z_][a-zA-Z_0-9]*' 211 if t.value == 'true': 212 t.type = 'LIT_BOOL' 213 t.value = True 214 return t 215 216 if t.value == 'false': 217 t.type = 'LIT_BOOL' 218 t.value = False 219 return t 220 221 # Check for reserved words 222 t.type = self.reserved.get(t.value, 'IDENT') 223 return t 224 225 def t_FLOATNUMBER(self, t): 226 '[0-9]+[.][0-9]+' 227 try: 228 t.value = float(t.value) 229 except ValueError: 230 raise TokenError("Illegal float", t) 231 return t 232 233 def t_NUMBER(self, t): 234 r'[0-9]+' 235 try: 236 t.value = int(t.value) 237 except ValueError: 238 raise TokenError("Illegal number", t) 239 return t 240 241 def t_STRING1(self, t): 242 r'\"[^"\n]*\"' 243 t.type = 'STRING' 244 t.value = t.value[1:-1] 245 return t 246 247 def t_STRING2(self, t): 248 r"\'[^'\n]*\'" 249 t.type = 'STRING' 250 t.value = t.value[1:-1] 251 return t 252 253 def p_file(self, p): 254 "file : decls" 255 p[0] = p[1] 256 257 def p_empty(self, p): 258 "empty :" 259 260 def p_decls(self, p): 261 "decls : declsx" 262 p[0] = ast.DeclListAST(self, p[1]) 263 264 def p_declsx__list(self, p): 265 "declsx : decl declsx" 266 p[0] = [ p[1] ] + p[2] 267 268 def p_declsx__none(self, p): 269 "declsx : empty" 270 p[0] = [] 271 272 def p_decl__machine(self, p): 273 "decl : MACHINE '(' ident pairs ')' ':' params '{' decls '}'" 274 p[0] = ast.MachineAST(self, p[3], p[4], p[7], p[9]) 275 276 def p_decl__action(self, p): 277 "decl : ACTION '(' ident pairs ')' statements" 278 p[0] = ast.ActionDeclAST(self, p[3], p[4], p[6]) 279 280 def p_decl__in_port(self, p): 281 "decl : IN_PORT '(' ident ',' type ',' var pairs ')' statements" 282 p[0] = ast.InPortDeclAST(self, p[3], p[5], p[7], p[8], p[10]) 283 284 def p_decl__out_port(self, p): 285 "decl : OUT_PORT '(' ident ',' type ',' var pairs ')' SEMI" 286 p[0] = ast.OutPortDeclAST(self, p[3], p[5], p[7], p[8]) 287 288 def p_decl__trans0(self, p): 289 "decl : TRANS '(' idents ',' idents ',' ident pairs ')' idents" 290 p[0] = ast.TransitionDeclAST(self, p[3], p[5], p[7], p[8], p[10]) 291 292 def p_decl__trans1(self, p): 293 "decl : TRANS '(' idents ',' idents pairs ')' idents" 294 p[0] = ast.TransitionDeclAST(self, p[3], p[5], None, p[6], p[8]) 295 296 def p_decl__extern0(self, p): 297 "decl : EXTERN_TYPE '(' type pairs ')' SEMI" 298 p[4]["external"] = "yes" 299 p[0] = ast.TypeDeclAST(self, p[3], p[4], []) 300 301 def p_decl__extern1(self, p): 302 "decl : EXTERN_TYPE '(' type pairs ')' '{' type_methods '}'" 303 p[4]["external"] = "yes" 304 p[0] = ast.TypeDeclAST(self, p[3], p[4], p[7]) 305 306 def p_decl__global(self, p): 307 "decl : GLOBAL '(' type pairs ')' '{' type_members '}'" 308 p[4]["global"] = "yes" 309 p[0] = ast.TypeDeclAST(self, p[3], p[4], p[7]) 310 311 def p_decl__struct(self, p): 312 "decl : STRUCT '(' type pairs ')' '{' type_members '}'" 313 p[0] = ast.TypeDeclAST(self, p[3], p[4], p[7]) 314 315 def p_decl__enum(self, p): 316 "decl : ENUM '(' type pairs ')' '{' type_enums '}'" 317 p[4]["enumeration"] = "yes" 318 p[0] = ast.EnumDeclAST(self, p[3], p[4], p[7]) 319 320 def p_decl__object(self, p): 321 "decl : type ident pairs SEMI" 322 p[0] = ast.ObjDeclAST(self, p[1], p[2], p[3]) 323 324 def p_decl__func_decl(self, p): 325 """decl : void ident '(' params ')' pairs SEMI 326 | type ident '(' params ')' pairs SEMI""" 327 p[0] = ast.FuncDeclAST(self, p[1], p[2], p[4], p[6], None) 328 329 def p_decl__func_def(self, p): 330 """decl : void ident '(' params ')' pairs statements 331 | type ident '(' params ')' pairs statements""" 332 p[0] = ast.FuncDeclAST(self, p[1], p[2], p[4], p[6], p[7]) 333 334 # Type fields 335 def p_type_members__list(self, p): 336 "type_members : type_member type_members" 337 p[0] = [ p[1] ] + p[2] 338 339 def p_type_members__empty(self, p): 340 "type_members : empty" 341 p[0] = [] 342 343 def p_type_member__1(self, p): 344 "type_member : type ident pairs SEMI" 345 p[0] = ast.TypeFieldMemberAST(self, p[1], p[2], p[3], None) 346 347 def p_type_member__2(self, p): 348 "type_member : type ident ASSIGN expr SEMI" 349 p[0] = ast.TypeFieldMemberAST(self, p[1], p[2], 350 ast.PairListAST(self), p[4]) 351 352 # Methods 353 def p_type_methods__list(self, p): 354 "type_methods : type_method type_methods" 355 p[0] = [ p[1] ] + p[2] 356 357 def p_type_methods(self, p): 358 "type_methods : empty" 359 p[0] = [] 360 361 def p_type_method(self, p): 362 "type_method : type_or_void ident '(' types ')' pairs SEMI" 363 p[0] = ast.TypeFieldMethodAST(self, p[1], p[2], p[4], p[6]) 364 365 # Enum fields 366 def p_type_enums__list(self, p): 367 "type_enums : type_enum type_enums" 368 p[0] = [ p[1] ] + p[2] 369 370 def p_type_enums__empty(self, p): 371 "type_enums : empty" 372 p[0] = [] 373 374 def p_type_enum(self, p): 375 "type_enum : ident pairs SEMI" 376 p[0] = ast.TypeFieldEnumAST(self, p[1], p[2]) 377 378 # Type 379 def p_types__multiple(self, p): 380 "types : type ',' types" 381 p[0] = [ p[1] ] + p[3] 382 383 def p_types__one(self, p): 384 "types : type" 385 p[0] = [ p[1] ] 386 387 def p_types__empty(self, p): 388 "types : empty" 389 p[0] = [] 390 391 def p_type(self, p): 392 "type : ident" 393 p[0] = ast.TypeAST(self, p[1]) 394 395 def p_void(self, p): 396 "void : VOID" 397 p[0] = ast.TypeAST(self, p[1]) 398 399 def p_type_or_void(self, p): 400 """type_or_void : type 401 | void""" 402 p[0] = p[1] 403 404 # Formal Param 405 def p_params__many(self, p): 406 "params : param ',' params" 407 p[0] = [ p[1] ] + p[3] 408 409 def p_params__one(self, p): 410 "params : param" 411 p[0] = [ p[1] ] 412 413 def p_params__none(self, p): 414 "params : empty" 415 p[0] = [] 416 417 def p_param(self, p): 418 "param : type ident" 419 p[0] = ast.FormalParamAST(self, p[1], p[2]) 420 421 # Idents and lists 422 def p_idents__braced(self, p): 423 "idents : '{' identx '}'" 424 p[0] = p[2] 425 426 def p_idents__bare(self, p): 427 "idents : ident" 428 p[0] = [ p[1] ] 429 430 def p_identx__multiple_1(self, p): 431 """identx : ident SEMI identx 432 | ident ',' identx""" 433 p[0] = [ p[1] ] + p[3] 434 435 def p_identx__multiple_2(self, p): 436 "identx : ident identx" 437 p[0] = [ p[1] ] + p[2] 438 439 def p_identx__single(self, p): 440 "identx : empty" 441 p[0] = [ ] 442 443 def p_ident(self, p): 444 "ident : IDENT" 445 p[0] = p[1] 446 447 # Pair and pair lists 448 def p_pairs__list(self, p): 449 "pairs : ',' pairsx" 450 p[0] = p[2] 451 452 def p_pairs__empty(self, p): 453 "pairs : empty" 454 p[0] = ast.PairListAST(self) 455 456 def p_pairsx__many(self, p): 457 "pairsx : pair ',' pairsx" 458 p[0] = p[3] 459 p[0].addPair(p[1]) 460 461 def p_pairsx__one(self, p): 462 "pairsx : pair" 463 p[0] = ast.PairListAST(self) 464 p[0].addPair(p[1]) 465 466 def p_pair__assign(self, p): 467 """pair : ident '=' STRING 468 | ident '=' ident""" 469 p[0] = ast.PairAST(self, p[1], p[3]) 470 471 def p_pair__literal(self, p): 472 "pair : STRING" 473 p[0] = ast.PairAST(self, "short", p[1]) 474 475 # Below are the rules for action descriptions 476 def p_statements__inner(self, p): 477 "statements : '{' statements_inner '}'" 478 p[0] = ast.StatementListAST(self, p[2]) 479 480 def p_statements__none(self, p): 481 "statements : '{' '}'" 482 p[0] = ast.StatementListAST(self, []) 483 484 def p_statements_inner__many(self, p): 485 "statements_inner : statement statements_inner" 486 p[0] = [ p[1] ] + p[2] 487 488 def p_statements_inner__one(self, p): 489 "statements_inner : statement" 490 p[0] = [ p[1] ] 491 492 def p_exprs__multiple(self, p): 493 "exprs : expr ',' exprs" 494 p[0] = [ p[1] ] + p[3] 495 496 def p_exprs__one(self, p): 497 "exprs : expr" 498 p[0] = [ p[1] ] 499 500 def p_exprs__empty(self, p): 501 "exprs : empty""" 502 p[0] = [] 503 504 def p_statement__expression(self, p): 505 "statement : expr SEMI" 506 p[0] = ast.ExprStatementAST(self, p[1]) 507 508 def p_statement__assign(self, p): 509 "statement : expr ASSIGN expr SEMI" 510 p[0] = ast.AssignStatementAST(self, p[1], p[3]) 511 512 def p_statement__enqueue(self, p): 513 "statement : ENQUEUE '(' var ',' type pairs ')' statements" 514 p[0] = ast.EnqueueStatementAST(self, p[3], p[5], p[6], p[8]) 515 516 def p_statement__peek(self, p): 517 "statement : PEEK '(' var ',' type pairs ')' statements" 518 p[0] = ast.PeekStatementAST(self, p[3], p[5], p[6], p[8], "peek") 519 520 def p_statement__copy_head(self, p): 521 "statement : COPY_HEAD '(' var ',' var pairs ')' SEMI" 522 p[0] = ast.CopyHeadStatementAST(self, p[3], p[5], p[6]) 523 524 def p_statement__check_allocate(self, p): 525 "statement : CHECK_ALLOCATE '(' var ')' SEMI" 526 p[0] = ast.CheckAllocateStatementAST(self, p[3]) 527 528 def p_statement__check_stop(self, p): 529 "statement : CHECK_STOP_SLOTS '(' var ',' STRING ',' STRING ')' SEMI" 530 p[0] = ast.CheckStopStatementAST(self, p[3], p[5], p[7]) 531 532 def p_statement__return(self, p): 533 "statement : RETURN expr SEMI" 534 p[0] = ast.ReturnStatementAST(self, p[2]) 535 536 def p_statement__if(self, p): 537 "statement : if_statement" 538 p[0] = p[1] 539 540 def p_if_statement__if(self, p): 541 "if_statement : IF '(' expr ')' statements" 542 p[0] = ast.IfStatementAST(self, p[3], p[5], None) 543 544 def p_if_statement__if_else(self, p): 545 "if_statement : IF '(' expr ')' statements ELSE statements" 546 p[0] = ast.IfStatementAST(self, p[3], p[5], p[7]) 547 548 def p_statement__if_else_if(self, p): 549 "if_statement : IF '(' expr ')' statements ELSE if_statement" 550 p[0] = ast.IfStatementAST(self, p[3], p[5], 551 ast.StatementListAST(self, p[7])) 552 553 def p_expr__var(self, p): 554 "aexpr : var" 555 p[0] = p[1] 556 557 def p_expr__literal(self, p): 558 "aexpr : literal" 559 p[0] = p[1] 560 561 def p_expr__enumeration(self, p): 562 "aexpr : enumeration" 563 p[0] = p[1] 564 565 def p_expr__func_call(self, p): 566 "aexpr : ident '(' exprs ')'" 567 p[0] = ast.FuncCallExprAST(self, p[1], p[3]) 568 569 def p_expr__new(self, p): 570 "aexpr : NEW type" 571 p[0] = ast.NewExprAST(self, p[2]) 572 573 # globally access a local chip component and call a method 574 def p_expr__local_chip_method(self, p): 575 "aexpr : THIS DOT var '[' expr ']' DOT var DOT ident '(' exprs ')'" 576 p[0] = ast.LocalChipMethodAST(self, p[3], p[5], p[8], p[10], p[12]) 577 578 # globally access a local chip component and access a data member 579 def p_expr__local_chip_member(self, p): 580 "aexpr : THIS DOT var '[' expr ']' DOT var DOT field" 581 p[0] = ast.LocalChipMemberAST(self, p[3], p[5], p[8], p[10]) 582 583 # globally access a specified chip component and call a method 584 def p_expr__specified_chip_method(self, p): 585 "aexpr : CHIP '[' expr ']' DOT var '[' expr ']' DOT var DOT ident '(' exprs ')'" 586 p[0] = ast.SpecifiedChipMethodAST(self, p[3], p[6], p[8], p[11], p[13], 587 p[15]) 588 589 # globally access a specified chip component and access a data member 590 def p_expr__specified_chip_member(self, p): 591 "aexpr : CHIP '[' expr ']' DOT var '[' expr ']' DOT var DOT field" 592 p[0] = ast.SpecifiedChipMemberAST(self, p[3], p[6], p[8], p[11], p[13]) 593 594 def p_expr__member(self, p): 595 "aexpr : aexpr DOT ident" 596 p[0] = ast.MemberExprAST(self, p[1], p[3]) 597 598 def p_expr__member_method_call(self, p): 599 "aexpr : aexpr DOT ident '(' exprs ')'" 600 p[0] = ast.MemberMethodCallExprAST(self, p[1], p[3], p[5]) 601 602 def p_expr__member_method_call_lookup(self, p): 603 "aexpr : aexpr '[' exprs ']'" 604 p[0] = ast.MemberMethodCallExprAST(self, p[1], "lookup", p[3]) 605 606 def p_expr__class_method_call(self, p): 607 "aexpr : type DOUBLE_COLON ident '(' exprs ')'" 608 p[0] = ast.ClassMethodCallExprAST(self, p[1], p[3], p[5]) 609 610 def p_expr__aexpr(self, p): 611 "expr : aexpr" 612 p[0] = p[1] 613 614 def p_expr__binary_op(self, p): 615 """expr : expr STAR expr 616 | expr SLASH expr 617 | expr PLUS expr 618 | expr DASH expr 619 | expr LT expr 620 | expr GT expr 621 | expr LE expr 622 | expr GE expr 623 | expr EQ expr 624 | expr NE expr 625 | expr AND expr 626 | expr OR expr 627 | expr RIGHTSHIFT expr 628 | expr LEFTSHIFT expr""" 629 p[0] = ast.InfixOperatorExprAST(self, p[1], p[2], p[3]) 630 631 # FIXME - unary not 632 def p_expr__unary_op(self, p): 633 """expr : NOT expr 634 | DASH expr %prec UMINUS""" 635 p[0] = PrefixOperatorExpr(p[1], p[2]) 636 637 def p_expr__parens(self, p): 638 "aexpr : '(' expr ')'" 639 p[0] = p[2] 640 641 def p_literal__string(self, p): 642 "literal : STRING" 643 p[0] = ast.LiteralExprAST(self, p[1], "string") 644 645 def p_literal__number(self, p): 646 "literal : NUMBER" 647 p[0] = ast.LiteralExprAST(self, p[1], "int") 648 649 def p_literal__float(self, p): 650 "literal : FLOATNUMBER" 651 p[0] = ast.LiteralExprAST(self, p[1], "int") 652 653 def p_literal__bool(self, p): 654 "literal : LIT_BOOL" 655 p[0] = ast.LiteralExprAST(self, p[1], "bool") 656 657 def p_enumeration(self, p): 658 "enumeration : ident ':' ident" 659 p[0] = ast.EnumExprAST(self, ast.TypeAST(self, p[1]), p[3]) 660 661 def p_var(self, p): 662 "var : ident" 663 p[0] = ast.VarExprAST(self, p[1]) 664 665 def p_field(self, p): 666 "field : ident" 667 p[0] = p[1] 668