src/arch/micro_asm.py - public/gem5 - Git at Google

 # Copyright (c) 2003-2005 The Regents of The University of Michigan
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met: redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer;
 # redistributions in binary form must reproduce the above copyright
 # notice, this list of conditions and the following disclaimer in the
 # documentation and/or other materials provided with the distribution;
 # neither the name of the copyright holders nor the names of its
 # contributors may be used to endorse or promote products derived from
 # this software without specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 import os
 import sys
 import re
 import traceback
 # get type names
 from types import *

 from ply import lex
 from ply import yacc

 ##########################################################################
 #
 # Base classes for use outside of the assembler
 #
 ##########################################################################

 class Micro_Container(object):
     def __init__(self, name):
         self.microops = []
         self.name = name
         self.directives = {}
         self.micro_classes = {}
         self.labels = {}

     def add_microop(self, mnemonic, microop):
         self.microops.append(microop)

     def __str__(self):
         string = "%s:\n" % self.name
         for microop in self.microops:
             string += "  %s\n" % microop
         return string

 class Combinational_Macroop(Micro_Container):
     pass

 class Rom_Macroop(object):
     def __init__(self, name, target):
         self.name = name
         self.target = target

     def __str__(self):
         return "%s: %s\n" % (self.name, self.target)

 class Rom(Micro_Container):
     def __init__(self, name):
         super().__init__(name)
         self.externs = {}

 ##########################################################################
 #
 # Support classes
 #
 ##########################################################################

 class Label(object):
     def __init__(self):
         self.extern = False
         self.name = ""

 class Block(object):
     def __init__(self):
         self.statements = []

 class Statement(object):
     def __init__(self):
         self.is_microop = False
         self.is_directive = False
         self.params = ""

 class Microop(Statement):
     def __init__(self):
         super().__init__()
         self.mnemonic = ""
         self.labels = []
         self.is_microop = True

 class Directive(Statement):
     def __init__(self):
         super().__init__()
         self.name = ""
         self.is_directive = True

 ##########################################################################
 #
 # Functions that handle common tasks
 #
 ##########################################################################

 def print_error(message):
     print()
     print("*** %s" % message)
     print()

 def handle_statement(parser, container, statement):
     if statement.is_microop:
         if statement.mnemonic not in parser.microops.keys():
             raise Exception("Unrecognized mnemonic: {}".format(
                 statement.mnemonic))
         parser.symbols["__microopClassFromInsideTheAssembler"] = \
             parser.microops[statement.mnemonic]
         try:
             microop = eval('__microopClassFromInsideTheAssembler(%s)' %
                     statement.params, {}, parser.symbols)
         except:
             print_error("Error creating microop object with mnemonic %s." % \
                     statement.mnemonic)
             raise
         try:
             for label in statement.labels:
                 container.labels[label.text] = microop
                 if label.is_extern:
                     container.externs[label.text] = microop
             container.add_microop(statement.mnemonic, microop)
         except:
             print_error("Error adding microop.")
             raise
     elif statement.is_directive:
         if statement.name not in container.directives.keys():
             raise Exception("Unrecognized directive: {}".format(
                 statement.name))
         parser.symbols["__directiveFunctionFromInsideTheAssembler"] = \
             container.directives[statement.name]
         try:
             eval('__directiveFunctionFromInsideTheAssembler(%s)' %
                     statement.params, {}, parser.symbols)
         except:
             print_error("Error executing directive.")
             print(container.directives)
             raise
     else:
         raise Exception("Didn't recognize the type of statement {}".format(
             statement))

 ##########################################################################
 #
 # Lexer specification
 #
 ##########################################################################

 # Error handler.  Just call exit.  Output formatted to work under
 # Emacs compile-mode.  Optional 'print_traceback' arg, if set to True,
 # prints a Python stack backtrace too (can be handy when trying to
 # debug the parser itself).
 def error(lineno, string, print_traceback = False):
     # Print a Python stack backtrace if requested.
     if (print_traceback):
         traceback.print_exc()
     if lineno != 0:
         line_str = "%d:" % lineno
     else:
         line_str = ""
     sys.exit("%s %s" % (line_str, string))

 reserved = ('DEF', 'MACROOP', 'ROM', 'EXTERN')

 tokens = reserved + (
         # identifier
         'ID',
         # arguments for microops and directives
         'PARAMS',

         'LPAREN', 'RPAREN',
         'LBRACE', 'RBRACE',
         'COLON', 'SEMI', 'DOT',
         'NEWLINE'
         )

 # New lines are ignored at the top level, but they end statements in the
 # assembler
 states = (
     ('asm', 'exclusive'),
     ('params', 'exclusive'),
 )

 reserved_map = { }
 for r in reserved:
     reserved_map[r.lower()] = r

 # Ignore comments
 def t_ANY_COMMENT(t):
     r'\#[^\n]*(?=\n)'

 def t_ANY_MULTILINECOMMENT(t):
     r'/\*([^/]|((?<!\*)/))*\*/'

 # A colon marks the end of a label. It should follow an ID which will
 # put the lexer in the "params" state. Seeing the colon will put it back
 # in the "asm" state since it knows it saw a label and not a mnemonic.
 def t_params_COLON(t):
     r':'
     t.lexer.begin('asm')
     return t

 # Parameters are a string of text which don't contain an unescaped statement
 # statement terminator, ie a newline or semi colon.
 def t_params_PARAMS(t):
     r'([^\n;\\]|(\\[\n;\\]))+'
     t.lineno += t.value.count('\n')
     unescapeParamsRE = re.compile(r'(\\[\n;\\])')
     def unescapeParams(mo):
         val = mo.group(0)
         return val[1]
     t.value = unescapeParamsRE.sub(unescapeParams, t.value)
     t.lexer.begin('asm')
     return t

 # An "ID" in the micro assembler is either a label, directive, or mnemonic
 # If it's either a directive or a mnemonic, it will be optionally followed by
 # parameters. If it's a label, the following colon will make the lexer stop
 # looking for parameters.
 def t_asm_ID(t):
     r'[A-Za-z_]\w*'
     t.type = reserved_map.get(t.value, 'ID')
     # If the ID is really "extern", we shouldn't start looking for parameters
     # yet. The real ID, the label itself, is coming up.
     if t.type != 'EXTERN':
         t.lexer.begin('params')
     return t

 # If there is a label and you're -not- in the assembler (which would be caught
 # above), don't start looking for parameters.
 def t_ANY_ID(t):
     r'[A-Za-z_]\w*'
     t.type = reserved_map.get(t.value, 'ID')
     return t

 # Braces enter and exit micro assembly
 def t_INITIAL_LBRACE(t):
     r'\{'
     t.lexer.begin('asm')
     return t

 def t_asm_RBRACE(t):
     r'\}'
     t.lexer.begin('INITIAL')
     return t

 # At the top level, keep track of newlines only for line counting.
 def t_INITIAL_NEWLINE(t):
     r'\n+'
     t.lineno += t.value.count('\n')

 # In the micro assembler, do line counting but also return a token. The
 # token is needed by the parser to detect the end of a statement.
 def t_asm_NEWLINE(t):
     r'\n+'
     t.lineno += t.value.count('\n')
     return t

 # A newline or semi colon when looking for params signals that the statement
 # is over and the lexer should go back to looking for regular assembly.
 def t_params_NEWLINE(t):
     r'\n+'
     t.lineno += t.value.count('\n')
     t.lexer.begin('asm')
     return t

 def t_params_SEMI(t):
     r';'
     t.lexer.begin('asm')
     return t

 # Basic regular expressions to pick out simple tokens
 t_ANY_LPAREN = r'\('
 t_ANY_RPAREN = r'\)'
 t_ANY_SEMI   = r';'
 t_ANY_DOT    = r'\.'

 t_ANY_ignore = ' \t\x0c'

 def t_ANY_error(t):
     error(t.lineno, "illegal character '%s'" % t.value[0])
     t.skip(1)

 ##########################################################################
 #
 # Parser specification
 #
 ##########################################################################

 # Start symbol for a file which may have more than one macroop or rom
 # specification.
 def p_file(t):
     'file : opt_rom_or_macros'

 def p_opt_rom_or_macros_0(t):
     'opt_rom_or_macros : '

 def p_opt_rom_or_macros_1(t):
     'opt_rom_or_macros : rom_or_macros'

 def p_rom_or_macros_0(t):
     'rom_or_macros : rom_or_macro'

 def p_rom_or_macros_1(t):
     'rom_or_macros : rom_or_macros rom_or_macro'

 def p_rom_or_macro_0(t):
     '''rom_or_macro : rom_block
                     | macroop_def'''

 # Defines a section of microcode that should go in the current ROM
 def p_rom_block(t):
     'rom_block : DEF ROM block SEMI'
     if not t.parser.rom:
         print_error("Rom block found, but no Rom object specified.")
         raise TypeError("Rom block found, but no Rom object was specified.")
     for statement in t[3].statements:
         handle_statement(t.parser, t.parser.rom, statement)
     t[0] = t.parser.rom

 # Defines a macroop that jumps to an external label in the ROM
 def p_macroop_def_0(t):
     'macroop_def : DEF MACROOP ID LPAREN ID RPAREN SEMI'
     if not t.parser.rom_macroop_type:
         print_error("ROM based macroop found, but no ROM macroop " +
             "class was specified.")
         raise TypeError("ROM based macroop found, but no ROM macroop " +
             "class was specified.")
     macroop = t.parser.rom_macroop_type(t[3], t[5])
     t.parser.macroops[t[3]] = macroop


 # Defines a macroop that is combinationally generated
 def p_macroop_def_1(t):
     'macroop_def : DEF MACROOP ID block SEMI'
     try:
         curop = t.parser.macro_type(t[3])
     except TypeError:
         print_error("Error creating macroop object.")
         raise
     for statement in t[4].statements:
         handle_statement(t.parser, curop, statement)
     t.parser.macroops[t[3]] = curop

 # A block of statements
 def p_block(t):
     'block : LBRACE statements RBRACE'
     block = Block()
     block.statements = t[2]
     t[0] = block

 def p_statements_0(t):
     'statements : statement'
     if t[1]:
         t[0] = [t[1]]
     else:
         t[0] = []

 def p_statements_1(t):
     'statements : statements statement'
     if t[2]:
         t[1].append(t[2])
     t[0] = t[1]

 def p_statement(t):
     'statement : content_of_statement end_of_statement'
     t[0] = t[1]

 # A statement can be a microop or an assembler directive
 def p_content_of_statement_0(t):
     '''content_of_statement : microop
                             | directive'''
     t[0] = t[1]

 # Ignore empty statements
 def p_content_of_statement_1(t):
     'content_of_statement : '
     pass

 # Statements are ended by newlines or a semi colon
 def p_end_of_statement(t):
     '''end_of_statement : NEWLINE
                         | SEMI'''
     pass

 # Different flavors of microop to avoid shift/reduce errors
 def p_microop_0(t):
     'microop : labels ID'
     microop = Microop()
     microop.labels = t[1]
     microop.mnemonic = t[2]
     t[0] = microop

 def p_microop_1(t):
     'microop : ID'
     microop = Microop()
     microop.mnemonic = t[1]
     t[0] = microop

 def p_microop_2(t):
     'microop : labels ID PARAMS'
     microop = Microop()
     microop.labels = t[1]
     microop.mnemonic = t[2]
     microop.params = t[3]
     t[0] = microop

 def p_microop_3(t):
     'microop : ID PARAMS'
     microop = Microop()
     microop.mnemonic = t[1]
     microop.params = t[2]
     t[0] = microop

 # Labels in the microcode
 def p_labels_0(t):
     'labels : label'
     t[0] = [t[1]]

 def p_labels_1(t):
     'labels : labels label'
     t[1].append(t[2])
     t[0] = t[1]

 # labels on lines by themselves are attached to the following instruction.
 def p_labels_2(t):
     'labels : labels NEWLINE'
     t[0] = t[1]

 def p_label_0(t):
     'label : ID COLON'
     label = Label()
     label.is_extern = False
     label.text = t[1]
     t[0] = label

 def p_label_1(t):
     'label : EXTERN ID COLON'
     label = Label()
     label.is_extern = True
     label.text = t[2]
     t[0] = label

 # Directives for the macroop
 def p_directive_0(t):
     'directive : DOT ID'
     directive = Directive()
     directive.name = t[2]
     t[0] = directive

 def p_directive_1(t):
     'directive : DOT ID PARAMS'
     directive = Directive()
     directive.name = t[2]
     directive.params = t[3]
     t[0] = directive

 # Parse error handler.  Note that the argument here is the offending
 # *token*, not a grammar symbol (hence the need to use t.value)
 def p_error(t):
     if t:
         error(t.lineno, "syntax error at '%s'" % t.value)
     else:
         error(0, "unknown syntax error", True)

 class MicroAssembler(object):

     def __init__(self, macro_type, microops,
             rom = None, rom_macroop_type = None):
         self.lexer = lex.lex()
         self.parser = yacc.yacc()
         self.parser.macro_type = macro_type
         self.parser.macroops = {}
         self.parser.microops = microops
         self.parser.rom = rom
         self.parser.rom_macroop_type = rom_macroop_type
         self.parser.symbols = {}
         self.symbols = self.parser.symbols

     def assemble(self, asm):
         self.parser.parse(asm, lexer=self.lexer)
         macroops = self.parser.macroops
         self.parser.macroops = {}
         return macroops
	# Copyright (c) 2003-2005 The Regents of The University of Michigan
	# All rights reserved.
	#
	# Redistribution and use in source and binary forms, with or without
	# modification, are permitted provided that the following conditions are
	# met: redistributions of source code must retain the above copyright
	# notice, this list of conditions and the following disclaimer;
	# redistributions in binary form must reproduce the above copyright
	# notice, this list of conditions and the following disclaimer in the
	# documentation and/or other materials provided with the distribution;
	# neither the name of the copyright holders nor the names of its
	# contributors may be used to endorse or promote products derived from
	# this software without specific prior written permission.
	#
	# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

	import os
	import sys
	import re
	import traceback
	# get type names
	from types import *

	from ply import lex
	from ply import yacc

	##########################################################################
	#
	# Base classes for use outside of the assembler
	#
	##########################################################################

	class Micro_Container(object):
	def __init__(self, name):
	self.microops = []
	self.name = name
	self.directives = {}
	self.micro_classes = {}
	self.labels = {}

	def add_microop(self, mnemonic, microop):
	self.microops.append(microop)

	def __str__(self):
	string = "%s:\n" % self.name
	for microop in self.microops:
	string += " %s\n" % microop
	return string

	class Combinational_Macroop(Micro_Container):
	pass

	class Rom_Macroop(object):
	def __init__(self, name, target):
	self.name = name
	self.target = target

	def __str__(self):
	return "%s: %s\n" % (self.name, self.target)

	class Rom(Micro_Container):
	def __init__(self, name):
	super().__init__(name)
	self.externs = {}

	##########################################################################
	#
	# Support classes
	#
	##########################################################################

	class Label(object):
	def __init__(self):
	self.extern = False
	self.name = ""

	class Block(object):
	def __init__(self):
	self.statements = []

	class Statement(object):
	def __init__(self):
	self.is_microop = False
	self.is_directive = False
	self.params = ""

	class Microop(Statement):
	def __init__(self):
	super().__init__()
	self.mnemonic = ""
	self.labels = []
	self.is_microop = True

	class Directive(Statement):
	def __init__(self):
	super().__init__()
	self.name = ""
	self.is_directive = True

	##########################################################################
	#
	# Functions that handle common tasks
	#
	##########################################################################

	def print_error(message):
	print()
	print("*** %s" % message)
	print()

	def handle_statement(parser, container, statement):
	if statement.is_microop:
	if statement.mnemonic not in parser.microops.keys():
	raise Exception("Unrecognized mnemonic: {}".format(
	statement.mnemonic))
	parser.symbols["__microopClassFromInsideTheAssembler"] = \
	parser.microops[statement.mnemonic]
	try:
	microop = eval('__microopClassFromInsideTheAssembler(%s)' %
	statement.params, {}, parser.symbols)
	except:
	print_error("Error creating microop object with mnemonic %s." % \
	statement.mnemonic)
	raise
	try:
	for label in statement.labels:
	container.labels[label.text] = microop
	if label.is_extern:
	container.externs[label.text] = microop
	container.add_microop(statement.mnemonic, microop)
	except:
	print_error("Error adding microop.")
	raise
	elif statement.is_directive:
	if statement.name not in container.directives.keys():
	raise Exception("Unrecognized directive: {}".format(
	statement.name))
	parser.symbols["__directiveFunctionFromInsideTheAssembler"] = \
	container.directives[statement.name]
	try:
	eval('__directiveFunctionFromInsideTheAssembler(%s)' %
	statement.params, {}, parser.symbols)
	except:
	print_error("Error executing directive.")
	print(container.directives)
	raise
	else:
	raise Exception("Didn't recognize the type of statement {}".format(
	statement))

	##########################################################################
	#
	# Lexer specification
	#
	##########################################################################

	# Error handler. Just call exit. Output formatted to work under
	# Emacs compile-mode. Optional 'print_traceback' arg, if set to True,
	# prints a Python stack backtrace too (can be handy when trying to
	# debug the parser itself).
	def error(lineno, string, print_traceback = False):
	# Print a Python stack backtrace if requested.
	if (print_traceback):
	traceback.print_exc()
	if lineno != 0:
	line_str = "%d:" % lineno
	else:
	line_str = ""
	sys.exit("%s %s" % (line_str, string))

	reserved = ('DEF', 'MACROOP', 'ROM', 'EXTERN')

	tokens = reserved + (
	# identifier
	'ID',
	# arguments for microops and directives
	'PARAMS',

	'LPAREN', 'RPAREN',
	'LBRACE', 'RBRACE',
	'COLON', 'SEMI', 'DOT',
	'NEWLINE'
	)

	# New lines are ignored at the top level, but they end statements in the
	# assembler
	states = (
	('asm', 'exclusive'),
	('params', 'exclusive'),
	)

	reserved_map = { }
	for r in reserved:
	reserved_map[r.lower()] = r

	# Ignore comments
	def t_ANY_COMMENT(t):
	r'\#[^\n]*(?=\n)'

	def t_ANY_MULTILINECOMMENT(t):
	r'/\([^/]\|((?<!\)/))\/'

	# A colon marks the end of a label. It should follow an ID which will
	# put the lexer in the "params" state. Seeing the colon will put it back
	# in the "asm" state since it knows it saw a label and not a mnemonic.
	def t_params_COLON(t):
	r':'
	t.lexer.begin('asm')
	return t

	# Parameters are a string of text which don't contain an unescaped statement
	# statement terminator, ie a newline or semi colon.
	def t_params_PARAMS(t):
	r'([^\n;\\]\|(\\[\n;\\]))+'
	t.lineno += t.value.count('\n')
	unescapeParamsRE = re.compile(r'(\\[\n;\\])')
	def unescapeParams(mo):
	val = mo.group(0)
	return val[1]
	t.value = unescapeParamsRE.sub(unescapeParams, t.value)
	t.lexer.begin('asm')
	return t

	# An "ID" in the micro assembler is either a label, directive, or mnemonic
	# If it's either a directive or a mnemonic, it will be optionally followed by
	# parameters. If it's a label, the following colon will make the lexer stop
	# looking for parameters.
	def t_asm_ID(t):
	r'[A-Za-z_]\w*'
	t.type = reserved_map.get(t.value, 'ID')
	# If the ID is really "extern", we shouldn't start looking for parameters
	# yet. The real ID, the label itself, is coming up.
	if t.type != 'EXTERN':
	t.lexer.begin('params')
	return t

	# If there is a label and you're -not- in the assembler (which would be caught
	# above), don't start looking for parameters.
	def t_ANY_ID(t):
	r'[A-Za-z_]\w*'
	t.type = reserved_map.get(t.value, 'ID')
	return t

	# Braces enter and exit micro assembly
	def t_INITIAL_LBRACE(t):
	r'\{'
	t.lexer.begin('asm')
	return t

	def t_asm_RBRACE(t):
	r'\}'
	t.lexer.begin('INITIAL')
	return t

	# At the top level, keep track of newlines only for line counting.
	def t_INITIAL_NEWLINE(t):
	r'\n+'
	t.lineno += t.value.count('\n')

	# In the micro assembler, do line counting but also return a token. The
	# token is needed by the parser to detect the end of a statement.
	def t_asm_NEWLINE(t):
	r'\n+'
	t.lineno += t.value.count('\n')
	return t

	# A newline or semi colon when looking for params signals that the statement
	# is over and the lexer should go back to looking for regular assembly.
	def t_params_NEWLINE(t):
	r'\n+'
	t.lineno += t.value.count('\n')
	t.lexer.begin('asm')
	return t

	def t_params_SEMI(t):
	r';'
	t.lexer.begin('asm')
	return t

	# Basic regular expressions to pick out simple tokens
	t_ANY_LPAREN = r'\('
	t_ANY_RPAREN = r'\)'
	t_ANY_SEMI = r';'
	t_ANY_DOT = r'\.'

	t_ANY_ignore = ' \t\x0c'

	def t_ANY_error(t):
	error(t.lineno, "illegal character '%s'" % t.value[0])
	t.skip(1)

	##########################################################################
	#
	# Parser specification
	#
	##########################################################################

	# Start symbol for a file which may have more than one macroop or rom
	# specification.
	def p_file(t):
	'file : opt_rom_or_macros'

	def p_opt_rom_or_macros_0(t):
	'opt_rom_or_macros : '

	def p_opt_rom_or_macros_1(t):
	'opt_rom_or_macros : rom_or_macros'

	def p_rom_or_macros_0(t):
	'rom_or_macros : rom_or_macro'

	def p_rom_or_macros_1(t):
	'rom_or_macros : rom_or_macros rom_or_macro'

	def p_rom_or_macro_0(t):
	'''rom_or_macro : rom_block
	\| macroop_def'''

	# Defines a section of microcode that should go in the current ROM
	def p_rom_block(t):
	'rom_block : DEF ROM block SEMI'
	if not t.parser.rom:
	print_error("Rom block found, but no Rom object specified.")
	raise TypeError("Rom block found, but no Rom object was specified.")
	for statement in t[3].statements:
	handle_statement(t.parser, t.parser.rom, statement)
	t[0] = t.parser.rom

	# Defines a macroop that jumps to an external label in the ROM
	def p_macroop_def_0(t):
	'macroop_def : DEF MACROOP ID LPAREN ID RPAREN SEMI'
	if not t.parser.rom_macroop_type:
	print_error("ROM based macroop found, but no ROM macroop " +
	"class was specified.")
	raise TypeError("ROM based macroop found, but no ROM macroop " +
	"class was specified.")
	macroop = t.parser.rom_macroop_type(t[3], t[5])
	t.parser.macroops[t[3]] = macroop


	# Defines a macroop that is combinationally generated
	def p_macroop_def_1(t):
	'macroop_def : DEF MACROOP ID block SEMI'
	try:
	curop = t.parser.macro_type(t[3])
	except TypeError:
	print_error("Error creating macroop object.")
	raise
	for statement in t[4].statements:
	handle_statement(t.parser, curop, statement)
	t.parser.macroops[t[3]] = curop

	# A block of statements
	def p_block(t):
	'block : LBRACE statements RBRACE'
	block = Block()
	block.statements = t[2]
	t[0] = block

	def p_statements_0(t):
	'statements : statement'
	if t[1]:
	t[0] = [t[1]]
	else:
	t[0] = []

	def p_statements_1(t):
	'statements : statements statement'
	if t[2]:
	t[1].append(t[2])
	t[0] = t[1]

	def p_statement(t):
	'statement : content_of_statement end_of_statement'
	t[0] = t[1]

	# A statement can be a microop or an assembler directive
	def p_content_of_statement_0(t):
	'''content_of_statement : microop
	\| directive'''
	t[0] = t[1]

	# Ignore empty statements
	def p_content_of_statement_1(t):
	'content_of_statement : '
	pass

	# Statements are ended by newlines or a semi colon
	def p_end_of_statement(t):
	'''end_of_statement : NEWLINE
	\| SEMI'''
	pass

	# Different flavors of microop to avoid shift/reduce errors
	def p_microop_0(t):
	'microop : labels ID'
	microop = Microop()
	microop.labels = t[1]
	microop.mnemonic = t[2]
	t[0] = microop

	def p_microop_1(t):
	'microop : ID'
	microop = Microop()
	microop.mnemonic = t[1]
	t[0] = microop

	def p_microop_2(t):
	'microop : labels ID PARAMS'
	microop = Microop()
	microop.labels = t[1]
	microop.mnemonic = t[2]
	microop.params = t[3]
	t[0] = microop

	def p_microop_3(t):
	'microop : ID PARAMS'
	microop = Microop()
	microop.mnemonic = t[1]
	microop.params = t[2]
	t[0] = microop

	# Labels in the microcode
	def p_labels_0(t):
	'labels : label'
	t[0] = [t[1]]

	def p_labels_1(t):
	'labels : labels label'
	t[1].append(t[2])
	t[0] = t[1]

	# labels on lines by themselves are attached to the following instruction.
	def p_labels_2(t):
	'labels : labels NEWLINE'
	t[0] = t[1]

	def p_label_0(t):
	'label : ID COLON'
	label = Label()
	label.is_extern = False
	label.text = t[1]
	t[0] = label

	def p_label_1(t):
	'label : EXTERN ID COLON'
	label = Label()
	label.is_extern = True
	label.text = t[2]
	t[0] = label

	# Directives for the macroop
	def p_directive_0(t):
	'directive : DOT ID'
	directive = Directive()
	directive.name = t[2]
	t[0] = directive

	def p_directive_1(t):
	'directive : DOT ID PARAMS'
	directive = Directive()
	directive.name = t[2]
	directive.params = t[3]
	t[0] = directive

	# Parse error handler. Note that the argument here is the offending
	# token, not a grammar symbol (hence the need to use t.value)
	def p_error(t):
	if t:
	error(t.lineno, "syntax error at '%s'" % t.value)
	else:
	error(0, "unknown syntax error", True)

	class MicroAssembler(object):

	def __init__(self, macro_type, microops,
	rom = None, rom_macroop_type = None):
	self.lexer = lex.lex()
	self.parser = yacc.yacc()
	self.parser.macro_type = macro_type
	self.parser.macroops = {}
	self.parser.microops = microops
	self.parser.rom = rom
	self.parser.rom_macroop_type = rom_macroop_type
	self.parser.symbols = {}
	self.symbols = self.parser.symbols

	def assemble(self, asm):
	self.parser.parse(asm, lexer=self.lexer)
	macroops = self.parser.macroops
	self.parser.macroops = {}
	return macroops