#!/usr/bin/env python # Copyright (c) 2018 Linaro Limited # # This library is free software; you can redistribute it and/or # modify it under the terms of the GNU Lesser General Public # License as published by the Free Software Foundation; either # version 2 of the License, or (at your option) any later version. # # This library is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public # License along with this library; if not, see <http://www.gnu.org/licenses/>. # # # Generate a decoding tree from a specification file. # # The tree is built from instruction "patterns". A pattern may represent # a single architectural instruction or a group of same, depending on what # is convenient for further processing. # # Each pattern has "fixedbits" & "fixedmask", the combination of which # describes the condition under which the pattern is matched: # # (insn & fixedmask) == fixedbits # # Each pattern may have "fields", which are extracted from the insn and # passed along to the translator. Examples of such are registers, # immediates, and sub-opcodes. # # In support of patterns, one may declare fields, argument sets, and # formats, each of which may be re-used to simplify further definitions. # # *** Field syntax: # # field_def := '%' identifier ( unnamed_field )+ ( !function=identifier )? # unnamed_field := number ':' ( 's' ) number # # For unnamed_field, the first number is the least-significant bit position of # the field and the second number is the length of the field. If the 's' is # present, the field is considered signed. If multiple unnamed_fields are # present, they are concatenated. In this way one can define disjoint fields. # # If !function is specified, the concatenated result is passed through the # named function, taking and returning an integral value. # # FIXME: the fields of the structure into which this result will be stored # is restricted to "int". Which means that we cannot expand 64-bit items. # # Field examples: # # %disp 0:s16 -- sextract(i, 0, 16) # %imm9 16:6 10:3 -- extract(i, 16, 6) << 3 | extract(i, 10, 3) # %disp12 0:s1 1:1 2:10 -- sextract(i, 0, 1) << 11 # | extract(i, 1, 1) << 10 # | extract(i, 2, 10) # %shimm8 5:s8 13:1 !function=expand_shimm8 # -- expand_shimm8(sextract(i, 5, 8) << 1 # | extract(i, 13, 1)) # # *** Argument set syntax: # # args_def := '&' identifier ( args_elt )+ # args_elt := identifier # # Each args_elt defines an argument within the argument set. # Each argument set will be rendered as a C structure "arg_$name" # with each of the fields being one of the member arguments. # # Argument set examples: # # ®3 ra rb rc # &loadstore reg base offset # # *** Format syntax: # # fmt_def := '@' identifier ( fmt_elt )+ # fmt_elt := fixedbit_elt | field_elt | field_ref | args_ref # fixedbit_elt := [01.-]+ # field_elt := identifier ':' 's'? number # field_ref := '%' identifier | identifier '=' '%' identifier # args_ref := '&' identifier # # Defining a format is a handy way to avoid replicating groups of fields # across many instruction patterns. # # A fixedbit_elt describes a contiguous sequence of bits that must # be 1, 0, [.-] for don't care. The difference between '.' and '-' # is that '.' means that the bit will be covered with a field or a # final [01] from the pattern, and '-' means that the bit is really # ignored by the cpu and will not be specified. # # A field_elt describes a simple field only given a width; the position of # the field is implied by its position with respect to other fixedbit_elt # and field_elt. # # If any fixedbit_elt or field_elt appear then all bits must be defined. # Padding with a fixedbit_elt of all '.' is an easy way to accomplish that. # # A field_ref incorporates a field by reference. This is the only way to # add a complex field to a format. A field may be renamed in the process # via assignment to another identifier. This is intended to allow the # same argument set be used with disjoint named fields. # # A single args_ref may specify an argument set to use for the format. # The set of fields in the format must be a subset of the arguments in # the argument set. If an argument set is not specified, one will be # inferred from the set of fields. # # It is recommended, but not required, that all field_ref and args_ref # appear at the end of the line, not interleaving with fixedbit_elf or # field_elt. # # Format examples: # # @opr ...... ra:5 rb:5 ... 0 ....... rc:5 # @opi ...... ra:5 lit:8 1 ....... rc:5 # # *** Pattern syntax: # # pat_def := identifier ( pat_elt )+ # pat_elt := fixedbit_elt | field_elt | field_ref # | args_ref | fmt_ref | const_elt # fmt_ref := '@' identifier # const_elt := identifier '=' number # # The fixedbit_elt and field_elt specifiers are unchanged from formats. # A pattern that does not specify a named format will have one inferred # from a referenced argument set (if present) and the set of fields. # # A const_elt allows a argument to be set to a constant value. This may # come in handy when fields overlap between patterns and one has to # include the values in the fixedbit_elt instead. # # The decoder will call a translator function for each pattern matched. # # Pattern examples: # # addl_r 010000 ..... ..... .... 0000000 ..... @opr # addl_i 010000 ..... ..... .... 0000000 ..... @opi # # which will, in part, invoke # # trans_addl_r(ctx, &arg_opr, insn) # and # trans_addl_i(ctx, &arg_opi, insn) # import io import os import re import sys import getopt import pdb insnwidth = 32 insnmask = 0xffffffff fields = {} arguments = {} formats = {} patterns = [] translate_prefix = 'trans' translate_scope = 'static ' input_file = '' output_file = None output_fd = None insntype = 'uint32_t' re_ident = '[a-zA-Z][a-zA-Z0-9_]*' def error(lineno, *args): """Print an error message from file:line and args and exit.""" global output_file global output_fd if lineno: r = '{0}:{1}: error:'.format(input_file, lineno) elif input_file: r = '{0}: error:'.format(input_file) else: r = 'error:' for a in args: r += ' ' + str(a) r += '\n' sys.stderr.write(r) if output_file and output_fd: output_fd.close() os.remove(output_file) exit(1) def output(*args): global output_fd for a in args: output_fd.write(a) if sys.version_info >= (3, 0): re_fullmatch = re.fullmatch else: def re_fullmatch(pat, str): return re.match('^' + pat + '$', str) def output_autogen(): output('/* This file is autogenerated by scripts/decodetree.py. */\n\n') def str_indent(c): """Return a string with C spaces""" return ' ' * c def str_fields(fields): """Return a string uniquely identifing FIELDS""" r = '' for n in sorted(fields.keys()): r += '_' + n return r[1:] def str_match_bits(bits, mask): """Return a string pretty-printing BITS/MASK""" global insnwidth i = 1 << (insnwidth - 1) space = 0x01010100 r = '' while i != 0: if i & mask: if i & bits: r += '1' else: r += '0' else: r += '.' if i & space: r += ' ' i >>= 1 return r def is_pow2(x): """Return true iff X is equal to a power of 2.""" return (x & (x - 1)) == 0 def ctz(x): """Return the number of times 2 factors into X.""" r = 0 while ((x >> r) & 1) == 0: r += 1 return r def is_contiguous(bits): shift = ctz(bits) if is_pow2((bits >> shift) + 1): return shift else: return -1 def eq_fields_for_args(flds_a, flds_b): if len(flds_a) != len(flds_b): return False for k, a in flds_a.items(): if k not in flds_b: return False return True def eq_fields_for_fmts(flds_a, flds_b): if len(flds_a) != len(flds_b): return False for k, a in flds_a.items(): if k not in flds_b: return False b = flds_b[k] if a.__class__ != b.__class__ or a != b: return False return True class Field: """Class representing a simple instruction field""" def __init__(self, sign, pos, len): self.sign = sign self.pos = pos self.len = len self.mask = ((1 << len) - 1) << pos def __str__(self): if self.sign: s = 's' else: s = '' return str(pos) + ':' + s + str(len) def str_extract(self): if self.sign: extr = 'sextract32' else: extr = 'extract32' return '{0}(insn, {1}, {2})'.format(extr, self.pos, self.len) def __eq__(self, other): return self.sign == other.sign and self.sign == other.sign def __ne__(self, other): return not self.__eq__(other) # end Field class MultiField: """Class representing a compound instruction field""" def __init__(self, subs, mask): self.subs = subs self.sign = subs[0].sign self.mask = mask def __str__(self): return str(self.subs) def str_extract(self): ret = '0' pos = 0 for f in reversed(self.subs): if pos == 0: ret = f.str_extract() else: ret = 'deposit32({0}, {1}, {2}, {3})' \ .format(ret, pos, 32 - pos, f.str_extract()) pos += f.len return ret def __ne__(self, other): if len(self.subs) != len(other.subs): return True for a, b in zip(self.subs, other.subs): if a.__class__ != b.__class__ or a != b: return True return False def __eq__(self, other): return not self.__ne__(other) # end MultiField class ConstField: """Class representing an argument field with constant value""" def __init__(self, value): self.value = value self.mask = 0 self.sign = value < 0 def __str__(self): return str(self.value) def str_extract(self): return str(self.value) def __cmp__(self, other): return self.value - other.value # end ConstField class FunctionField: """Class representing a field passed through an expander""" def __init__(self, func, base): self.mask = base.mask self.sign = base.sign self.base = base self.func = func def __str__(self): return self.func + '(' + str(self.base) + ')' def str_extract(self): return self.func + '(' + self.base.str_extract() + ')' def __eq__(self, other): return self.func == other.func and self.base == other.base def __ne__(self, other): return not self.__eq__(other) # end FunctionField class Arguments: """Class representing the extracted fields of a format""" def __init__(self, nm, flds): self.name = nm self.fields = sorted(flds) def __str__(self): return self.name + ' ' + str(self.fields) def struct_name(self): return 'arg_' + self.name def output_def(self): output('typedef struct {\n') for n in self.fields: output(' int ', n, ';\n') output('} ', self.struct_name(), ';\n\n') # end Arguments class General: """Common code between instruction formats and instruction patterns""" def __init__(self, name, lineno, base, fixb, fixm, udfm, fldm, flds): self.name = name self.lineno = lineno self.base = base self.fixedbits = fixb self.fixedmask = fixm self.undefmask = udfm self.fieldmask = fldm self.fields = flds def __str__(self): r = self.name if self.base: r = r + ' ' + self.base.name else: r = r + ' ' + str(self.fields) r = r + ' ' + str_match_bits(self.fixedbits, self.fixedmask) return r def str1(self, i): return str_indent(i) + self.__str__() # end General class Format(General): """Class representing an instruction format""" def extract_name(self): return 'extract_' + self.name def output_extract(self): output('static void ', self.extract_name(), '(', self.base.struct_name(), ' *a, ', insntype, ' insn)\n{\n') for n, f in self.fields.items(): output(' a->', n, ' = ', f.str_extract(), ';\n') output('}\n\n') # end Format class Pattern(General): """Class representing an instruction pattern""" def output_decl(self): global translate_scope global translate_prefix output('typedef ', self.base.base.struct_name(), ' arg_', self.name, ';\n') output(translate_scope, 'void ', translate_prefix, '_', self.name, '(DisasContext *ctx, arg_', self.name, ' *a, ', insntype, ' insn);\n') def output_code(self, i, extracted, outerbits, outermask): global translate_prefix ind = str_indent(i) arg = self.base.base.name output(ind, '/* line ', str(self.lineno), ' */\n') if not extracted: output(ind, self.base.extract_name(), '(&u.f_', arg, ', insn);\n') for n, f in self.fields.items(): output(ind, 'u.f_', arg, '.', n, ' = ', f.str_extract(), ';\n') output(ind, translate_prefix, '_', self.name, '(ctx, &u.f_', arg, ', insn);\n') output(ind, 'return true;\n') # end Pattern def parse_field(lineno, name, toks): """Parse one instruction field from TOKS at LINENO""" global fields global re_ident global insnwidth # A "simple" field will have only one entry; # a "multifield" will have several. subs = [] width = 0 func = None for t in toks: if re_fullmatch('!function=' + re_ident, t): if func: error(lineno, 'duplicate function') func = t.split('=') func = func[1] continue if re_fullmatch('[0-9]+:s[0-9]+', t): # Signed field extract subtoks = t.split(':s') sign = True elif re_fullmatch('[0-9]+:[0-9]+', t): # Unsigned field extract subtoks = t.split(':') sign = False else: error(lineno, 'invalid field token "{0}"'.format(t)) po = int(subtoks[0]) le = int(subtoks[1]) if po + le > insnwidth: error(lineno, 'field {0} too large'.format(t)) f = Field(sign, po, le) subs.append(f) width += le if width > insnwidth: error(lineno, 'field too large') if len(subs) == 1: f = subs[0] else: mask = 0 for s in subs: if mask & s.mask: error(lineno, 'field components overlap') mask |= s.mask f = MultiField(subs, mask) if func: f = FunctionField(func, f) if name in fields: error(lineno, 'duplicate field', name) fields[name] = f # end parse_field def parse_arguments(lineno, name, toks): """Parse one argument set from TOKS at LINENO""" global arguments global re_ident flds = [] for t in toks: if not re_fullmatch(re_ident, t): error(lineno, 'invalid argument set token "{0}"'.format(t)) if t in flds: error(lineno, 'duplicate argument "{0}"'.format(t)) flds.append(t) if name in arguments: error(lineno, 'duplicate argument set', name) arguments[name] = Arguments(name, flds) # end parse_arguments def lookup_field(lineno, name): global fields if name in fields: return fields[name] error(lineno, 'undefined field', name) def add_field(lineno, flds, new_name, f): if new_name in flds: error(lineno, 'duplicate field', new_name) flds[new_name] = f return flds def add_field_byname(lineno, flds, new_name, old_name): return add_field(lineno, flds, new_name, lookup_field(lineno, old_name)) def infer_argument_set(flds): global arguments for arg in arguments.values(): if eq_fields_for_args(flds, arg.fields): return arg name = str(len(arguments)) arg = Arguments(name, flds.keys()) arguments[name] = arg return arg def infer_format(arg, fieldmask, flds): global arguments global formats const_flds = {} var_flds = {} for n, c in flds.items(): if c is ConstField: const_flds[n] = c else: var_flds[n] = c # Look for an existing format with the same argument set and fields for fmt in formats.values(): if arg and fmt.base != arg: continue if fieldmask != fmt.fieldmask: continue if not eq_fields_for_fmts(flds, fmt.fields): continue return (fmt, const_flds) name = 'Fmt_' + str(len(formats)) if not arg: arg = infer_argument_set(flds) fmt = Format(name, 0, arg, 0, 0, 0, fieldmask, var_flds) formats[name] = fmt return (fmt, const_flds) # end infer_format def parse_generic(lineno, is_format, name, toks): """Parse one instruction format from TOKS at LINENO""" global fields global arguments global formats global patterns global re_ident global insnwidth global insnmask fixedmask = 0 fixedbits = 0 undefmask = 0 width = 0 flds = {} arg = None fmt = None for t in toks: # '&Foo' gives a format an explcit argument set. if t[0] == '&': tt = t[1:] if arg: error(lineno, 'multiple argument sets') if tt in arguments: arg = arguments[tt] else: error(lineno, 'undefined argument set', t) continue # '@Foo' gives a pattern an explicit format. if t[0] == '@': tt = t[1:] if fmt: error(lineno, 'multiple formats') if tt in formats: fmt = formats[tt] else: error(lineno, 'undefined format', t) continue # '%Foo' imports a field. if t[0] == '%': tt = t[1:] flds = add_field_byname(lineno, flds, tt, tt) continue # 'Foo=%Bar' imports a field with a different name. if re_fullmatch(re_ident + '=%' + re_ident, t): (fname, iname) = t.split('=%') flds = add_field_byname(lineno, flds, fname, iname) continue # 'Foo=number' sets an argument field to a constant value if re_fullmatch(re_ident + '=[0-9]+', t): (fname, value) = t.split('=') value = int(value) flds = add_field(lineno, flds, fname, ConstField(value)) continue # Pattern of 0s, 1s, dots and dashes indicate required zeros, # required ones, or dont-cares. if re_fullmatch('[01.-]+', t): shift = len(t) fms = t.replace('0', '1') fms = fms.replace('.', '0') fms = fms.replace('-', '0') fbs = t.replace('.', '0') fbs = fbs.replace('-', '0') ubm = t.replace('1', '0') ubm = ubm.replace('.', '0') ubm = ubm.replace('-', '1') fms = int(fms, 2) fbs = int(fbs, 2) ubm = int(ubm, 2) fixedbits = (fixedbits << shift) | fbs fixedmask = (fixedmask << shift) | fms undefmask = (undefmask << shift) | ubm # Otherwise, fieldname:fieldwidth elif re_fullmatch(re_ident + ':s?[0-9]+', t): (fname, flen) = t.split(':') sign = False if flen[0] == 's': sign = True flen = flen[1:] shift = int(flen, 10) f = Field(sign, insnwidth - width - shift, shift) flds = add_field(lineno, flds, fname, f) fixedbits <<= shift fixedmask <<= shift undefmask <<= shift else: error(lineno, 'invalid token "{0}"'.format(t)) width += shift # We should have filled in all of the bits of the instruction. if not (is_format and width == 0) and width != insnwidth: error(lineno, 'definition has {0} bits'.format(width)) # Do not check for fields overlaping fields; one valid usage # is to be able to duplicate fields via import. fieldmask = 0 for f in flds.values(): fieldmask |= f.mask # Fix up what we've parsed to match either a format or a pattern. if is_format: # Formats cannot reference formats. if fmt: error(lineno, 'format referencing format') # If an argument set is given, then there should be no fields # without a place to store it. if arg: for f in flds.keys(): if f not in arg.fields: error(lineno, 'field {0} not in argument set {1}' .format(f, arg.name)) else: arg = infer_argument_set(flds) if name in formats: error(lineno, 'duplicate format name', name) fmt = Format(name, lineno, arg, fixedbits, fixedmask, undefmask, fieldmask, flds) formats[name] = fmt else: # Patterns can reference a format ... if fmt: # ... but not an argument simultaneously if arg: error(lineno, 'pattern specifies both format and argument set') if fixedmask & fmt.fixedmask: error(lineno, 'pattern fixed bits overlap format fixed bits') fieldmask |= fmt.fieldmask fixedbits |= fmt.fixedbits fixedmask |= fmt.fixedmask undefmask |= fmt.undefmask else: (fmt, flds) = infer_format(arg, fieldmask, flds) arg = fmt.base for f in flds.keys(): if f not in arg.fields: error(lineno, 'field {0} not in argument set {1}' .format(f, arg.name)) if f in fmt.fields.keys(): error(lineno, 'field {0} set by format and pattern'.format(f)) for f in arg.fields: if f not in flds.keys() and f not in fmt.fields.keys(): error(lineno, 'field {0} not initialized'.format(f)) pat = Pattern(name, lineno, fmt, fixedbits, fixedmask, undefmask, fieldmask, flds) patterns.append(pat) # Validate the masks that we have assembled. if fieldmask & fixedmask: error(lineno, 'fieldmask overlaps fixedmask (0x{0:08x} & 0x{1:08x})' .format(fieldmask, fixedmask)) if fieldmask & undefmask: error(lineno, 'fieldmask overlaps undefmask (0x{0:08x} & 0x{1:08x})' .format(fieldmask, undefmask)) if fixedmask & undefmask: error(lineno, 'fixedmask overlaps undefmask (0x{0:08x} & 0x{1:08x})' .format(fixedmask, undefmask)) if not is_format: allbits = fieldmask | fixedmask | undefmask if allbits != insnmask: error(lineno, 'bits left unspecified (0x{0:08x})' .format(allbits ^ insnmask)) # end parse_general def parse_file(f): """Parse all of the patterns within a file""" # Read all of the lines of the file. Concatenate lines # ending in backslash; discard empty lines and comments. toks = [] lineno = 0 for line in f: lineno += 1 # Discard comments end = line.find('#') if end >= 0: line = line[:end] t = line.split() if len(toks) != 0: # Next line after continuation toks.extend(t) elif len(t) == 0: # Empty line continue else: toks = t # Continuation? if toks[-1] == '\\': toks.pop() continue if len(toks) < 2: error(lineno, 'short line') name = toks[0] del toks[0] # Determine the type of object needing to be parsed. if name[0] == '%': parse_field(lineno, name[1:], toks) elif name[0] == '&': parse_arguments(lineno, name[1:], toks) elif name[0] == '@': parse_generic(lineno, True, name[1:], toks) else: parse_generic(lineno, False, name, toks) toks = [] # end parse_file class Tree: """Class representing a node in a decode tree""" def __init__(self, fm, tm): self.fixedmask = fm self.thismask = tm self.subs = [] self.base = None def str1(self, i): ind = str_indent(i) r = '{0}{1:08x}'.format(ind, self.fixedmask) if self.format: r += ' ' + self.format.name r += ' [\n' for (b, s) in self.subs: r += '{0} {1:08x}:\n'.format(ind, b) r += s.str1(i + 4) + '\n' r += ind + ']' return r def __str__(self): return self.str1(0) def output_code(self, i, extracted, outerbits, outermask): ind = str_indent(i) # If we identified all nodes below have the same format, # extract the fields now. if not extracted and self.base: output(ind, self.base.extract_name(), '(&u.f_', self.base.base.name, ', insn);\n') extracted = True # Attempt to aid the compiler in producing compact switch statements. # If the bits in the mask are contiguous, extract them. sh = is_contiguous(self.thismask) if sh > 0: # Propagate SH down into the local functions. def str_switch(b, sh=sh): return '(insn >> {0}) & 0x{1:x}'.format(sh, b >> sh) def str_case(b, sh=sh): return '0x{0:x}'.format(b >> sh) else: def str_switch(b): return 'insn & 0x{0:08x}'.format(b) def str_case(b): return '0x{0:08x}'.format(b) output(ind, 'switch (', str_switch(self.thismask), ') {\n') for b, s in sorted(self.subs): assert (self.thismask & ~s.fixedmask) == 0 innermask = outermask | self.thismask innerbits = outerbits | b output(ind, 'case ', str_case(b), ':\n') output(ind, ' /* ', str_match_bits(innerbits, innermask), ' */\n') s.output_code(i + 4, extracted, innerbits, innermask) output(ind, '}\n') output(ind, 'return false;\n') # end Tree def build_tree(pats, outerbits, outermask): # Find the intersection of all remaining fixedmask. innermask = ~outermask for i in pats: innermask &= i.fixedmask if innermask == 0: pnames = [] for p in pats: pnames.append(p.name + ':' + str(p.lineno)) error(pats[0].lineno, 'overlapping patterns:', pnames) fullmask = outermask | innermask # Sort each element of pats into the bin selected by the mask. bins = {} for i in pats: fb = i.fixedbits & innermask if fb in bins: bins[fb].append(i) else: bins[fb] = [i] # We must recurse if any bin has more than one element or if # the single element in the bin has not been fully matched. t = Tree(fullmask, innermask) for b, l in bins.items(): s = l[0] if len(l) > 1 or s.fixedmask & ~fullmask != 0: s = build_tree(l, b | outerbits, fullmask) t.subs.append((b, s)) return t # end build_tree def prop_format(tree): """Propagate Format objects into the decode tree""" # Depth first search. for (b, s) in tree.subs: if isinstance(s, Tree): prop_format(s) # If all entries in SUBS have the same format, then # propagate that into the tree. f = None for (b, s) in tree.subs: if f is None: f = s.base if f is None: return if f is not s.base: return tree.base = f # end prop_format def main(): global arguments global formats global patterns global translate_scope global translate_prefix global output_fd global output_file global input_file global insnwidth global insntype decode_function = 'decode' decode_scope = 'static ' long_opts = ['decode=', 'translate=', 'output=', 'insnwidth='] try: (opts, args) = getopt.getopt(sys.argv[1:], 'o:w:', long_opts) except getopt.GetoptError as err: error(0, err) for o, a in opts: if o in ('-o', '--output'): output_file = a elif o == '--decode': decode_function = a decode_scope = '' elif o == '--translate': translate_prefix = a translate_scope = '' elif o in ('-w', '--insnwidth'): insnwidth = int(a) if insnwidth == 16: insntype = 'uint16_t' insnmask = 0xffff elif insnwidth != 32: error(0, 'cannot handle insns of width', insnwidth) else: assert False, 'unhandled option' if len(args) < 1: error(0, 'missing input file') input_file = args[0] f = open(input_file, 'r') parse_file(f) f.close() t = build_tree(patterns, 0, 0) prop_format(t) if output_file: output_fd = open(output_file, 'w') else: output_fd = sys.stdout output_autogen() for n in sorted(arguments.keys()): f = arguments[n] f.output_def() # A single translate function can be invoked for different patterns. # Make sure that the argument sets are the same, and declare the # function only once. out_pats = {} for i in patterns: if i.name in out_pats: p = out_pats[i.name] if i.base.base != p.base.base: error(0, i.name, ' has conflicting argument sets') else: i.output_decl() out_pats[i.name] = i output('\n') for n in sorted(formats.keys()): f = formats[n] f.output_extract() output(decode_scope, 'bool ', decode_function, '(DisasContext *ctx, ', insntype, ' insn)\n{\n') i4 = str_indent(4) output(i4, 'union {\n') for n in sorted(arguments.keys()): f = arguments[n] output(i4, i4, f.struct_name(), ' f_', f.name, ';\n') output(i4, '} u;\n\n') t.output_code(4, False, 0, 0) output('}\n') if output_file: output_fd.close() # end main if __name__ == '__main__': main()