scripts/decodetree.py

   1 #!/usr/bin/env python
   2 # Copyright (c) 2018 Linaro Limited
   3 #
   4 # This library is free software; you can redistribute it and/or
   5 # modify it under the terms of the GNU Lesser General Public
   6 # License as published by the Free Software Foundation; either
   7 # version 2 of the License, or (at your option) any later version.
   8 #
   9 # This library is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 # Lesser General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU Lesser General Public
  15 # License along with this library; if not, see <http://www.gnu.org/licenses/>.
  16 #
  17
  18 #
  19 # Generate a decoding tree from a specification file.
  20 #
  21 # The tree is built from instruction "patterns".  A pattern may represent
  22 # a single architectural instruction or a group of same, depending on what
  23 # is convenient for further processing.
  24 #
  25 # Each pattern has "fixedbits" & "fixedmask", the combination of which
  26 # describes the condition under which the pattern is matched:
  27 #
  28 #   (insn & fixedmask) == fixedbits
  29 #
  30 # Each pattern may have "fields", which are extracted from the insn and
  31 # passed along to the translator.  Examples of such are registers,
  32 # immediates, and sub-opcodes.
  33 #
  34 # In support of patterns, one may declare fields, argument sets, and
  35 # formats, each of which may be re-used to simplify further definitions.
  36 #
  37 # *** Field syntax:
  38 #
  39 # field_def     := '%' identifier ( unnamed_field )+ ( !function=identifier )?
  40 # unnamed_field := number ':' ( 's' ) number
  41 #
  42 # For unnamed_field, the first number is the least-significant bit position of
  43 # the field and the second number is the length of the field.  If the 's' is
  44 # present, the field is considered signed.  If multiple unnamed_fields are
  45 # present, they are concatenated.  In this way one can define disjoint fields.
  46 #
  47 # If !function is specified, the concatenated result is passed through the
  48 # named function, taking and returning an integral value.
  49 #
  50 # FIXME: the fields of the structure into which this result will be stored
  51 # is restricted to "int".  Which means that we cannot expand 64-bit items.
  52 #
  53 # Field examples:
  54 #
  55 #   %disp   0:s16          -- sextract(i, 0, 16)
  56 #   %imm9   16:6 10:3      -- extract(i, 16, 6) << 3 | extract(i, 10, 3)
  57 #   %disp12 0:s1 1:1 2:10  -- sextract(i, 0, 1) << 11
  58 #                             | extract(i, 1, 1) << 10
  59 #                             | extract(i, 2, 10)
  60 #   %shimm8 5:s8 13:1 !function=expand_shimm8
  61 #                          -- expand_shimm8(sextract(i, 5, 8) << 1
  62 #                                           | extract(i, 13, 1))
  63 #
  64 # *** Argument set syntax:
  65 #
  66 # args_def    := '&' identifier ( args_elt )+
  67 # args_elt    := identifier
  68 #
  69 # Each args_elt defines an argument within the argument set.
  70 # Each argument set will be rendered as a C structure "arg_$name"
  71 # with each of the fields being one of the member arguments.
  72 #
  73 # Argument set examples:
  74 #
  75 #   &reg3       ra rb rc
  76 #   &loadstore  reg base offset
  77 #
  78 # *** Format syntax:
  79 #
  80 # fmt_def      := '@' identifier ( fmt_elt )+
  81 # fmt_elt      := fixedbit_elt | field_elt | field_ref | args_ref
  82 # fixedbit_elt := [01.-]+
  83 # field_elt    := identifier ':' 's'? number
  84 # field_ref    := '%' identifier | identifier '=' '%' identifier
  85 # args_ref     := '&' identifier
  86 #
  87 # Defining a format is a handy way to avoid replicating groups of fields
  88 # across many instruction patterns.
  89 #
  90 # A fixedbit_elt describes a contiguous sequence of bits that must
  91 # be 1, 0, [.-] for don't care.  The difference between '.' and '-'
  92 # is that '.' means that the bit will be covered with a field or a
  93 # final [01] from the pattern, and '-' means that the bit is really
  94 # ignored by the cpu and will not be specified.
  95 #
  96 # A field_elt describes a simple field only given a width; the position of
  97 # the field is implied by its position with respect to other fixedbit_elt
  98 # and field_elt.
  99 #
 100 # If any fixedbit_elt or field_elt appear then all bits must be defined.
 101 # Padding with a fixedbit_elt of all '.' is an easy way to accomplish that.
 102 #
 103 # A field_ref incorporates a field by reference.  This is the only way to
 104 # add a complex field to a format.  A field may be renamed in the process
 105 # via assignment to another identifier.  This is intended to allow the
 106 # same argument set be used with disjoint named fields.
 107 #
 108 # A single args_ref may specify an argument set to use for the format.
 109 # The set of fields in the format must be a subset of the arguments in
 110 # the argument set.  If an argument set is not specified, one will be
 111 # inferred from the set of fields.
 112 #
 113 # It is recommended, but not required, that all field_ref and args_ref
 114 # appear at the end of the line, not interleaving with fixedbit_elf or
 115 # field_elt.
 116 #
 117 # Format examples:
 118 #
 119 #   @opr    ...... ra:5 rb:5 ... 0 ....... rc:5
 120 #   @opi    ...... ra:5 lit:8    1 ....... rc:5
 121 #
 122 # *** Pattern syntax:
 123 #
 124 # pat_def      := identifier ( pat_elt )+
 125 # pat_elt      := fixedbit_elt | field_elt | field_ref
 126 #               | args_ref | fmt_ref | const_elt
 127 # fmt_ref      := '@' identifier
 128 # const_elt    := identifier '=' number
 129 #
 130 # The fixedbit_elt and field_elt specifiers are unchanged from formats.
 131 # A pattern that does not specify a named format will have one inferred
 132 # from a referenced argument set (if present) and the set of fields.
 133 #
 134 # A const_elt allows a argument to be set to a constant value.  This may
 135 # come in handy when fields overlap between patterns and one has to
 136 # include the values in the fixedbit_elt instead.
 137 #
 138 # The decoder will call a translator function for each pattern matched.
 139 #
 140 # Pattern examples:
 141 #
 142 #   addl_r   010000 ..... ..... .... 0000000 ..... @opr
 143 #   addl_i   010000 ..... ..... .... 0000000 ..... @opi
 144 #
 145 # which will, in part, invoke
 146 #
 147 #   trans_addl_r(ctx, &arg_opr, insn)
 148 # and
 149 #   trans_addl_i(ctx, &arg_opi, insn)
 150 #
 151
 152 import os
 153 import re
 154 import sys
 155 import getopt
 156
 157 insnwidth = 32
 158 insnmask = 0xffffffff
 159 fields = {}
 160 arguments = {}
 161 formats = {}
 162 patterns = []
 163
 164 translate_prefix = 'trans'
 165 translate_scope = 'static '
 166 input_file = ''
 167 output_file = None
 168 output_fd = None
 169 insntype = 'uint32_t'
 170
 171 re_ident = '[a-zA-Z][a-zA-Z0-9_]*'
 172
 173
 174 def error(lineno, *args):
 175     """Print an error message from file:line and args and exit."""
 176     global output_file
 177     global output_fd
 178
 179     if lineno:
 180         r = '{0}:{1}: error:'.format(input_file, lineno)
 181     elif input_file:
 182         r = '{0}: error:'.format(input_file)
 183     else:
 184         r = 'error:'
 185     for a in args:
 186         r += ' ' + str(a)
 187     r += '\n'
 188     sys.stderr.write(r)
 189     if output_file and output_fd:
 190         output_fd.close()
 191         os.remove(output_file)
 192     exit(1)
 193
 194
 195 def output(*args):
 196     global output_fd
 197     for a in args:
 198         output_fd.write(a)
 199
 200
 201 if sys.version_info >= (3, 0):
 202     re_fullmatch = re.fullmatch
 203 else:
 204     def re_fullmatch(pat, str):
 205         return re.match('^' + pat + '$', str)
 206
 207
 208 def output_autogen():
 209     output('/* This file is autogenerated by scripts/decodetree.py.  */\n\n')
 210
 211
 212 def str_indent(c):
 213     """Return a string with C spaces"""
 214     return ' ' * c
 215
 216
 217 def str_fields(fields):
 218     """Return a string uniquely identifing FIELDS"""
 219     r = ''
 220     for n in sorted(fields.keys()):
 221         r += '_' + n
 222     return r[1:]
 223
 224
 225 def str_match_bits(bits, mask):
 226     """Return a string pretty-printing BITS/MASK"""
 227     global insnwidth
 228
 229     i = 1 << (insnwidth - 1)
 230     space = 0x01010100
 231     r = ''
 232     while i != 0:
 233         if i & mask:
 234             if i & bits:
 235                 r += '1'
 236             else:
 237                 r += '0'
 238         else:
 239             r += '.'
 240         if i & space:
 241             r += ' '
 242         i >>= 1
 243     return r
 244
 245
 246 def is_pow2(x):
 247     """Return true iff X is equal to a power of 2."""
 248     return (x & (x - 1)) == 0
 249
 250
 251 def ctz(x):
 252     """Return the number of times 2 factors into X."""
 253     r = 0
 254     while ((x >> r) & 1) == 0:
 255         r += 1
 256     return r
 257
 258
 259 def is_contiguous(bits):
 260     shift = ctz(bits)
 261     if is_pow2((bits >> shift) + 1):
 262         return shift
 263     else:
 264         return -1
 265
 266
 267 def eq_fields_for_args(flds_a, flds_b):
 268     if len(flds_a) != len(flds_b):
 269         return False
 270     for k, a in flds_a.items():
 271         if k not in flds_b:
 272             return False
 273     return True
 274
 275
 276 def eq_fields_for_fmts(flds_a, flds_b):
 277     if len(flds_a) != len(flds_b):
 278         return False
 279     for k, a in flds_a.items():
 280         if k not in flds_b:
 281             return False
 282         b = flds_b[k]
 283         if a.__class__ != b.__class__ or a != b:
 284             return False
 285     return True
 286
 287
 288 class Field:
 289     """Class representing a simple instruction field"""
 290     def __init__(self, sign, pos, len):
 291         self.sign = sign
 292         self.pos = pos
 293         self.len = len
 294         self.mask = ((1 << len) - 1) << pos
 295
 296     def __str__(self):
 297         if self.sign:
 298             s = 's'
 299         else:
 300             s = ''
 301         return str(self.pos) + ':' + s + str(self.len)
 302
 303     def str_extract(self):
 304         if self.sign:
 305             extr = 'sextract32'
 306         else:
 307             extr = 'extract32'
 308         return '{0}(insn, {1}, {2})'.format(extr, self.pos, self.len)
 309
 310     def __eq__(self, other):
 311         return self.sign == other.sign and self.sign == other.sign
 312
 313     def __ne__(self, other):
 314         return not self.__eq__(other)
 315 # end Field
 316
 317
 318 class MultiField:
 319     """Class representing a compound instruction field"""
 320     def __init__(self, subs, mask):
 321         self.subs = subs
 322         self.sign = subs[0].sign
 323         self.mask = mask
 324
 325     def __str__(self):
 326         return str(self.subs)
 327
 328     def str_extract(self):
 329         ret = '0'
 330         pos = 0
 331         for f in reversed(self.subs):
 332             if pos == 0:
 333                 ret = f.str_extract()
 334             else:
 335                 ret = 'deposit32({0}, {1}, {2}, {3})' \
 336                       .format(ret, pos, 32 - pos, f.str_extract())
 337             pos += f.len
 338         return ret
 339
 340     def __ne__(self, other):
 341         if len(self.subs) != len(other.subs):
 342             return True
 343         for a, b in zip(self.subs, other.subs):
 344             if a.__class__ != b.__class__ or a != b:
 345                 return True
 346         return False
 347
 348     def __eq__(self, other):
 349         return not self.__ne__(other)
 350 # end MultiField
 351
 352
 353 class ConstField:
 354     """Class representing an argument field with constant value"""
 355     def __init__(self, value):
 356         self.value = value
 357         self.mask = 0
 358         self.sign = value < 0
 359
 360     def __str__(self):
 361         return str(self.value)
 362
 363     def str_extract(self):
 364         return str(self.value)
 365
 366     def __cmp__(self, other):
 367         return self.value - other.value
 368 # end ConstField
 369
 370
 371 class FunctionField:
 372     """Class representing a field passed through an expander"""
 373     def __init__(self, func, base):
 374         self.mask = base.mask
 375         self.sign = base.sign
 376         self.base = base
 377         self.func = func
 378
 379     def __str__(self):
 380         return self.func + '(' + str(self.base) + ')'
 381
 382     def str_extract(self):
 383         return self.func + '(' + self.base.str_extract() + ')'
 384
 385     def __eq__(self, other):
 386         return self.func == other.func and self.base == other.base
 387
 388     def __ne__(self, other):
 389         return not self.__eq__(other)
 390 # end FunctionField
 391
 392
 393 class Arguments:
 394     """Class representing the extracted fields of a format"""
 395     def __init__(self, nm, flds):
 396         self.name = nm
 397         self.fields = sorted(flds)
 398
 399     def __str__(self):
 400         return self.name + ' ' + str(self.fields)
 401
 402     def struct_name(self):
 403         return 'arg_' + self.name
 404
 405     def output_def(self):
 406         output('typedef struct {\n')
 407         for n in self.fields:
 408             output('    int ', n, ';\n')
 409         output('} ', self.struct_name(), ';\n\n')
 410 # end Arguments
 411
 412
 413 class General:
 414     """Common code between instruction formats and instruction patterns"""
 415     def __init__(self, name, lineno, base, fixb, fixm, udfm, fldm, flds):
 416         self.name = name
 417         self.lineno = lineno
 418         self.base = base
 419         self.fixedbits = fixb
 420         self.fixedmask = fixm
 421         self.undefmask = udfm
 422         self.fieldmask = fldm
 423         self.fields = flds
 424
 425     def __str__(self):
 426         r = self.name
 427         if self.base:
 428             r = r + ' ' + self.base.name
 429         else:
 430             r = r + ' ' + str(self.fields)
 431         r = r + ' ' + str_match_bits(self.fixedbits, self.fixedmask)
 432         return r
 433
 434     def str1(self, i):
 435         return str_indent(i) + self.__str__()
 436 # end General
 437
 438
 439 class Format(General):
 440     """Class representing an instruction format"""
 441
 442     def extract_name(self):
 443         return 'extract_' + self.name
 444
 445     def output_extract(self):
 446         output('static void ', self.extract_name(), '(',
 447                self.base.struct_name(), ' *a, ', insntype, ' insn)\n{\n')
 448         for n, f in self.fields.items():
 449             output('    a->', n, ' = ', f.str_extract(), ';\n')
 450         output('}\n\n')
 451 # end Format
 452
 453
 454 class Pattern(General):
 455     """Class representing an instruction pattern"""
 456
 457     def output_decl(self):
 458         global translate_scope
 459         global translate_prefix
 460         output('typedef ', self.base.base.struct_name(),
 461                ' arg_', self.name, ';\n')
 462         output(translate_scope, 'bool ', translate_prefix, '_', self.name,
 463                '(DisasContext *ctx, arg_', self.name,
 464                ' *a, ', insntype, ' insn);\n')
 465
 466     def output_code(self, i, extracted, outerbits, outermask):
 467         global translate_prefix
 468         ind = str_indent(i)
 469         arg = self.base.base.name
 470         output(ind, '/* line ', str(self.lineno), ' */\n')
 471         if not extracted:
 472             output(ind, self.base.extract_name(), '(&u.f_', arg, ', insn);\n')
 473         for n, f in self.fields.items():
 474             output(ind, 'u.f_', arg, '.', n, ' = ', f.str_extract(), ';\n')
 475         output(ind, 'return ', translate_prefix, '_', self.name,
 476                '(ctx, &u.f_', arg, ', insn);\n')
 477 # end Pattern
 478
 479
 480 def parse_field(lineno, name, toks):
 481     """Parse one instruction field from TOKS at LINENO"""
 482     global fields
 483     global re_ident
 484     global insnwidth
 485
 486     # A "simple" field will have only one entry;
 487     # a "multifield" will have several.
 488     subs = []
 489     width = 0
 490     func = None
 491     for t in toks:
 492         if re_fullmatch('!function=' + re_ident, t):
 493             if func:
 494                 error(lineno, 'duplicate function')
 495             func = t.split('=')
 496             func = func[1]
 497             continue
 498
 499         if re_fullmatch('[0-9]+:s[0-9]+', t):
 500             # Signed field extract
 501             subtoks = t.split(':s')
 502             sign = True
 503         elif re_fullmatch('[0-9]+:[0-9]+', t):
 504             # Unsigned field extract
 505             subtoks = t.split(':')
 506             sign = False
 507         else:
 508             error(lineno, 'invalid field token "{0}"'.format(t))
 509         po = int(subtoks[0])
 510         le = int(subtoks[1])
 511         if po + le > insnwidth:
 512             error(lineno, 'field {0} too large'.format(t))
 513         f = Field(sign, po, le)
 514         subs.append(f)
 515         width += le
 516
 517     if width > insnwidth:
 518         error(lineno, 'field too large')
 519     if len(subs) == 1:
 520         f = subs[0]
 521     else:
 522         mask = 0
 523         for s in subs:
 524             if mask & s.mask:
 525                 error(lineno, 'field components overlap')
 526             mask |= s.mask
 527         f = MultiField(subs, mask)
 528     if func:
 529         f = FunctionField(func, f)
 530
 531     if name in fields:
 532         error(lineno, 'duplicate field', name)
 533     fields[name] = f
 534 # end parse_field
 535
 536
 537 def parse_arguments(lineno, name, toks):
 538     """Parse one argument set from TOKS at LINENO"""
 539     global arguments
 540     global re_ident
 541
 542     flds = []
 543     for t in toks:
 544         if not re_fullmatch(re_ident, t):
 545             error(lineno, 'invalid argument set token "{0}"'.format(t))
 546         if t in flds:
 547             error(lineno, 'duplicate argument "{0}"'.format(t))
 548         flds.append(t)
 549
 550     if name in arguments:
 551         error(lineno, 'duplicate argument set', name)
 552     arguments[name] = Arguments(name, flds)
 553 # end parse_arguments
 554
 555
 556 def lookup_field(lineno, name):
 557     global fields
 558     if name in fields:
 559         return fields[name]
 560     error(lineno, 'undefined field', name)
 561
 562
 563 def add_field(lineno, flds, new_name, f):
 564     if new_name in flds:
 565         error(lineno, 'duplicate field', new_name)
 566     flds[new_name] = f
 567     return flds
 568
 569
 570 def add_field_byname(lineno, flds, new_name, old_name):
 571     return add_field(lineno, flds, new_name, lookup_field(lineno, old_name))
 572
 573
 574 def infer_argument_set(flds):
 575     global arguments
 576
 577     for arg in arguments.values():
 578         if eq_fields_for_args(flds, arg.fields):
 579             return arg
 580
 581     name = str(len(arguments))
 582     arg = Arguments(name, flds.keys())
 583     arguments[name] = arg
 584     return arg
 585
 586
 587 def infer_format(arg, fieldmask, flds):
 588     global arguments
 589     global formats
 590
 591     const_flds = {}
 592     var_flds = {}
 593     for n, c in flds.items():
 594         if c is ConstField:
 595             const_flds[n] = c
 596         else:
 597             var_flds[n] = c
 598
 599     # Look for an existing format with the same argument set and fields
 600     for fmt in formats.values():
 601         if arg and fmt.base != arg:
 602             continue
 603         if fieldmask != fmt.fieldmask:
 604             continue
 605         if not eq_fields_for_fmts(flds, fmt.fields):
 606             continue
 607         return (fmt, const_flds)
 608
 609     name = 'Fmt_' + str(len(formats))
 610     if not arg:
 611         arg = infer_argument_set(flds)
 612
 613     fmt = Format(name, 0, arg, 0, 0, 0, fieldmask, var_flds)
 614     formats[name] = fmt
 615
 616     return (fmt, const_flds)
 617 # end infer_format
 618
 619
 620 def parse_generic(lineno, is_format, name, toks):
 621     """Parse one instruction format from TOKS at LINENO"""
 622     global fields
 623     global arguments
 624     global formats
 625     global patterns
 626     global re_ident
 627     global insnwidth
 628     global insnmask
 629
 630     fixedmask = 0
 631     fixedbits = 0
 632     undefmask = 0
 633     width = 0
 634     flds = {}
 635     arg = None
 636     fmt = None
 637     for t in toks:
 638         # '&Foo' gives a format an explcit argument set.
 639         if t[0] == '&':
 640             tt = t[1:]
 641             if arg:
 642                 error(lineno, 'multiple argument sets')
 643             if tt in arguments:
 644                 arg = arguments[tt]
 645             else:
 646                 error(lineno, 'undefined argument set', t)
 647             continue
 648
 649         # '@Foo' gives a pattern an explicit format.
 650         if t[0] == '@':
 651             tt = t[1:]
 652             if fmt:
 653                 error(lineno, 'multiple formats')
 654             if tt in formats:
 655                 fmt = formats[tt]
 656             else:
 657                 error(lineno, 'undefined format', t)
 658             continue
 659
 660         # '%Foo' imports a field.
 661         if t[0] == '%':
 662             tt = t[1:]
 663             flds = add_field_byname(lineno, flds, tt, tt)
 664             continue
 665
 666         # 'Foo=%Bar' imports a field with a different name.
 667         if re_fullmatch(re_ident + '=%' + re_ident, t):
 668             (fname, iname) = t.split('=%')
 669             flds = add_field_byname(lineno, flds, fname, iname)
 670             continue
 671
 672         # 'Foo=number' sets an argument field to a constant value
 673         if re_fullmatch(re_ident + '=[0-9]+', t):
 674             (fname, value) = t.split('=')
 675             value = int(value)
 676             flds = add_field(lineno, flds, fname, ConstField(value))
 677             continue
 678
 679         # Pattern of 0s, 1s, dots and dashes indicate required zeros,
 680         # required ones, or dont-cares.
 681         if re_fullmatch('[01.-]+', t):
 682             shift = len(t)
 683             fms = t.replace('0', '1')
 684             fms = fms.replace('.', '0')
 685             fms = fms.replace('-', '0')
 686             fbs = t.replace('.', '0')
 687             fbs = fbs.replace('-', '0')
 688             ubm = t.replace('1', '0')
 689             ubm = ubm.replace('.', '0')
 690             ubm = ubm.replace('-', '1')
 691             fms = int(fms, 2)
 692             fbs = int(fbs, 2)
 693             ubm = int(ubm, 2)
 694             fixedbits = (fixedbits << shift) | fbs
 695             fixedmask = (fixedmask << shift) | fms
 696             undefmask = (undefmask << shift) | ubm
 697         # Otherwise, fieldname:fieldwidth
 698         elif re_fullmatch(re_ident + ':s?[0-9]+', t):
 699             (fname, flen) = t.split(':')
 700             sign = False
 701             if flen[0] == 's':
 702                 sign = True
 703                 flen = flen[1:]
 704             shift = int(flen, 10)
 705             f = Field(sign, insnwidth - width - shift, shift)
 706             flds = add_field(lineno, flds, fname, f)
 707             fixedbits <<= shift
 708             fixedmask <<= shift
 709             undefmask <<= shift
 710         else:
 711             error(lineno, 'invalid token "{0}"'.format(t))
 712         width += shift
 713
 714     # We should have filled in all of the bits of the instruction.
 715     if not (is_format and width == 0) and width != insnwidth:
 716         error(lineno, 'definition has {0} bits'.format(width))
 717
 718     # Do not check for fields overlaping fields; one valid usage
 719     # is to be able to duplicate fields via import.
 720     fieldmask = 0
 721     for f in flds.values():
 722         fieldmask |= f.mask
 723
 724     # Fix up what we've parsed to match either a format or a pattern.
 725     if is_format:
 726         # Formats cannot reference formats.
 727         if fmt:
 728             error(lineno, 'format referencing format')
 729         # If an argument set is given, then there should be no fields
 730         # without a place to store it.
 731         if arg:
 732             for f in flds.keys():
 733                 if f not in arg.fields:
 734                     error(lineno, 'field {0} not in argument set {1}'
 735                                   .format(f, arg.name))
 736         else:
 737             arg = infer_argument_set(flds)
 738         if name in formats:
 739             error(lineno, 'duplicate format name', name)
 740         fmt = Format(name, lineno, arg, fixedbits, fixedmask,
 741                      undefmask, fieldmask, flds)
 742         formats[name] = fmt
 743     else:
 744         # Patterns can reference a format ...
 745         if fmt:
 746             # ... but not an argument simultaneously
 747             if arg:
 748                 error(lineno, 'pattern specifies both format and argument set')
 749             if fixedmask & fmt.fixedmask:
 750                 error(lineno, 'pattern fixed bits overlap format fixed bits')
 751             fieldmask |= fmt.fieldmask
 752             fixedbits |= fmt.fixedbits
 753             fixedmask |= fmt.fixedmask
 754             undefmask |= fmt.undefmask
 755         else:
 756             (fmt, flds) = infer_format(arg, fieldmask, flds)
 757         arg = fmt.base
 758         for f in flds.keys():
 759             if f not in arg.fields:
 760                 error(lineno, 'field {0} not in argument set {1}'
 761                               .format(f, arg.name))
 762             if f in fmt.fields.keys():
 763                 error(lineno, 'field {0} set by format and pattern'.format(f))
 764         for f in arg.fields:
 765             if f not in flds.keys() and f not in fmt.fields.keys():
 766                 error(lineno, 'field {0} not initialized'.format(f))
 767         pat = Pattern(name, lineno, fmt, fixedbits, fixedmask,
 768                       undefmask, fieldmask, flds)
 769         patterns.append(pat)
 770
 771     # Validate the masks that we have assembled.
 772     if fieldmask & fixedmask:
 773         error(lineno, 'fieldmask overlaps fixedmask (0x{0:08x} & 0x{1:08x})'
 774                       .format(fieldmask, fixedmask))
 775     if fieldmask & undefmask:
 776         error(lineno, 'fieldmask overlaps undefmask (0x{0:08x} & 0x{1:08x})'
 777                       .format(fieldmask, undefmask))
 778     if fixedmask & undefmask:
 779         error(lineno, 'fixedmask overlaps undefmask (0x{0:08x} & 0x{1:08x})'
 780                       .format(fixedmask, undefmask))
 781     if not is_format:
 782         allbits = fieldmask | fixedmask | undefmask
 783         if allbits != insnmask:
 784             error(lineno, 'bits left unspecified (0x{0:08x})'
 785                           .format(allbits ^ insnmask))
 786 # end parse_general
 787
 788
 789 def parse_file(f):
 790     """Parse all of the patterns within a file"""
 791
 792     # Read all of the lines of the file.  Concatenate lines
 793     # ending in backslash; discard empty lines and comments.
 794     toks = []
 795     lineno = 0
 796     for line in f:
 797         lineno += 1
 798
 799         # Discard comments
 800         end = line.find('#')
 801         if end >= 0:
 802             line = line[:end]
 803
 804         t = line.split()
 805         if len(toks) != 0:
 806             # Next line after continuation
 807             toks.extend(t)
 808         elif len(t) == 0:
 809             # Empty line
 810             continue
 811         else:
 812             toks = t
 813
 814         # Continuation?
 815         if toks[-1] == '\\':
 816             toks.pop()
 817             continue
 818
 819         if len(toks) < 2:
 820             error(lineno, 'short line')
 821
 822         name = toks[0]
 823         del toks[0]
 824
 825         # Determine the type of object needing to be parsed.
 826         if name[0] == '%':
 827             parse_field(lineno, name[1:], toks)
 828         elif name[0] == '&':
 829             parse_arguments(lineno, name[1:], toks)
 830         elif name[0] == '@':
 831             parse_generic(lineno, True, name[1:], toks)
 832         else:
 833             parse_generic(lineno, False, name, toks)
 834         toks = []
 835 # end parse_file
 836
 837
 838 class Tree:
 839     """Class representing a node in a decode tree"""
 840
 841     def __init__(self, fm, tm):
 842         self.fixedmask = fm
 843         self.thismask = tm
 844         self.subs = []
 845         self.base = None
 846
 847     def str1(self, i):
 848         ind = str_indent(i)
 849         r = '{0}{1:08x}'.format(ind, self.fixedmask)
 850         if self.format:
 851             r += ' ' + self.format.name
 852         r += ' [\n'
 853         for (b, s) in self.subs:
 854             r += '{0}  {1:08x}:\n'.format(ind, b)
 855             r += s.str1(i + 4) + '\n'
 856         r += ind + ']'
 857         return r
 858
 859     def __str__(self):
 860         return self.str1(0)
 861
 862     def output_code(self, i, extracted, outerbits, outermask):
 863         ind = str_indent(i)
 864
 865         # If we identified all nodes below have the same format,
 866         # extract the fields now.
 867         if not extracted and self.base:
 868             output(ind, self.base.extract_name(),
 869                    '(&u.f_', self.base.base.name, ', insn);\n')
 870             extracted = True
 871
 872         # Attempt to aid the compiler in producing compact switch statements.
 873         # If the bits in the mask are contiguous, extract them.
 874         sh = is_contiguous(self.thismask)
 875         if sh > 0:
 876             # Propagate SH down into the local functions.
 877             def str_switch(b, sh=sh):
 878                 return '(insn >> {0}) & 0x{1:x}'.format(sh, b >> sh)
 879
 880             def str_case(b, sh=sh):
 881                 return '0x{0:x}'.format(b >> sh)
 882         else:
 883             def str_switch(b):
 884                 return 'insn & 0x{0:08x}'.format(b)
 885
 886             def str_case(b):
 887                 return '0x{0:08x}'.format(b)
 888
 889         output(ind, 'switch (', str_switch(self.thismask), ') {\n')
 890         for b, s in sorted(self.subs):
 891             assert (self.thismask & ~s.fixedmask) == 0
 892             innermask = outermask | self.thismask
 893             innerbits = outerbits | b
 894             output(ind, 'case ', str_case(b), ':\n')
 895             output(ind, '    /* ',
 896                    str_match_bits(innerbits, innermask), ' */\n')
 897             s.output_code(i + 4, extracted, innerbits, innermask)
 898         output(ind, '}\n')
 899         output(ind, 'return false;\n')
 900 # end Tree
 901
 902
 903 def build_tree(pats, outerbits, outermask):
 904     # Find the intersection of all remaining fixedmask.
 905     innermask = ~outermask
 906     for i in pats:
 907         innermask &= i.fixedmask
 908
 909     if innermask == 0:
 910         pnames = []
 911         for p in pats:
 912             pnames.append(p.name + ':' + str(p.lineno))
 913         error(pats[0].lineno, 'overlapping patterns:', pnames)
 914
 915     fullmask = outermask | innermask
 916
 917     # Sort each element of pats into the bin selected by the mask.
 918     bins = {}
 919     for i in pats:
 920         fb = i.fixedbits & innermask
 921         if fb in bins:
 922             bins[fb].append(i)
 923         else:
 924             bins[fb] = [i]
 925
 926     # We must recurse if any bin has more than one element or if
 927     # the single element in the bin has not been fully matched.
 928     t = Tree(fullmask, innermask)
 929
 930     for b, l in bins.items():
 931         s = l[0]
 932         if len(l) > 1 or s.fixedmask & ~fullmask != 0:
 933             s = build_tree(l, b | outerbits, fullmask)
 934         t.subs.append((b, s))
 935
 936     return t
 937 # end build_tree
 938
 939
 940 def prop_format(tree):
 941     """Propagate Format objects into the decode tree"""
 942
 943     # Depth first search.
 944     for (b, s) in tree.subs:
 945         if isinstance(s, Tree):
 946             prop_format(s)
 947
 948     # If all entries in SUBS have the same format, then
 949     # propagate that into the tree.
 950     f = None
 951     for (b, s) in tree.subs:
 952         if f is None:
 953             f = s.base
 954             if f is None:
 955                 return
 956         if f is not s.base:
 957             return
 958     tree.base = f
 959 # end prop_format
 960
 961
 962 def main():
 963     global arguments
 964     global formats
 965     global patterns
 966     global translate_scope
 967     global translate_prefix
 968     global output_fd
 969     global output_file
 970     global input_file
 971     global insnwidth
 972     global insntype
 973     global insnmask
 974
 975     decode_function = 'decode'
 976     decode_scope = 'static '
 977
 978     long_opts = ['decode=', 'translate=', 'output=', 'insnwidth=']
 979     try:
 980         (opts, args) = getopt.getopt(sys.argv[1:], 'o:w:', long_opts)
 981     except getopt.GetoptError as err:
 982         error(0, err)
 983     for o, a in opts:
 984         if o in ('-o', '--output'):
 985             output_file = a
 986         elif o == '--decode':
 987             decode_function = a
 988             decode_scope = ''
 989         elif o == '--translate':
 990             translate_prefix = a
 991             translate_scope = ''
 992         elif o in ('-w', '--insnwidth'):
 993             insnwidth = int(a)
 994             if insnwidth == 16:
 995                 insntype = 'uint16_t'
 996                 insnmask = 0xffff
 997             elif insnwidth != 32:
 998                 error(0, 'cannot handle insns of width', insnwidth)
 999         else:
1000             assert False, 'unhandled option'
1001
1002     if len(args) < 1:
1003         error(0, 'missing input file')
1004     input_file = args[0]
1005     f = open(input_file, 'r')
1006     parse_file(f)
1007     f.close()
1008
1009     t = build_tree(patterns, 0, 0)
1010     prop_format(t)
1011
1012     if output_file:
1013         output_fd = open(output_file, 'w')
1014     else:
1015         output_fd = sys.stdout
1016
1017     output_autogen()
1018     for n in sorted(arguments.keys()):
1019         f = arguments[n]
1020         f.output_def()
1021
1022     # A single translate function can be invoked for different patterns.
1023     # Make sure that the argument sets are the same, and declare the
1024     # function only once.
1025     out_pats = {}
1026     for i in patterns:
1027         if i.name in out_pats:
1028             p = out_pats[i.name]
1029             if i.base.base != p.base.base:
1030                 error(0, i.name, ' has conflicting argument sets')
1031         else:
1032             i.output_decl()
1033             out_pats[i.name] = i
1034     output('\n')
1035
1036     for n in sorted(formats.keys()):
1037         f = formats[n]
1038         f.output_extract()
1039
1040     output(decode_scope, 'bool ', decode_function,
1041            '(DisasContext *ctx, ', insntype, ' insn)\n{\n')
1042
1043     i4 = str_indent(4)
1044     output(i4, 'union {\n')
1045     for n in sorted(arguments.keys()):
1046         f = arguments[n]
1047         output(i4, i4, f.struct_name(), ' f_', f.name, ';\n')
1048     output(i4, '} u;\n\n')
1049
1050     t.output_code(4, False, 0, 0)
1051
1052     output('}\n')
1053
1054     if output_file:
1055         output_fd.close()
1056 # end main
1057
1058
1059 if __name__ == '__main__':
1060     main()