TAP.py

# Copyright (C) 2011 by fpgaminer <fpgaminer@bitcoin-mining.com>
#                       fizzisist <fizzisist@fpgamining.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

class TAPStateError(Exception):
	def __init__(self, current, destination):
		self.current = TAP.STR_TRANSLATE[current]
		self.destination = TAP.STR_TRANSLATE[destination]
	def __str__(self):
		return self.current + " -> " + self.destination

class TAP:
	TLR = 0
	IDLE = 1
	SELECT_DR = 2
	CAPTURE_DR = 3
	SHIFT_DR = 4
	EXIT1_DR = 5
	PAUSE_DR = 6
	EXIT2_DR = 7
	UPDATE_DR = 8
	SELECT_IR = 9
	CAPTURE_IR = 10
	SHIFT_IR = 11
	EXIT1_IR = 12
	PAUSE_IR = 13
	EXIT2_IR = 14
	UPDATE_IR = 15

	STR_TRANSLATE = ['TLR','IDLE','SELECT_DR','CAPTURE_DR','SHIFT_DR','EXIT1_DR','PAUSE_DR','EXIT2_DR','UPDATE_DR','SELECT_IR','CAPTURE_IR','SHIFT_IR','EXIT1_IR','PAUSE_IR','EXIT2_IR','UPDATE_IR']

	TRANSITIONS = {
		TLR: [IDLE, TLR],
		IDLE: [IDLE, SELECT_DR],
		SELECT_DR: [CAPTURE_DR, SELECT_IR],
		CAPTURE_DR: [SHIFT_DR, EXIT1_DR],
		SHIFT_DR: [SHIFT_DR, EXIT1_DR],
		EXIT1_DR: [PAUSE_DR, UPDATE_DR],
		PAUSE_DR: [PAUSE_DR, EXIT2_DR],
		EXIT2_DR: [SHIFT_DR, UPDATE_DR],
		UPDATE_DR: [IDLE, SELECT_DR],
		SELECT_IR: [CAPTURE_IR, TLR],
		CAPTURE_IR: [SHIFT_IR, EXIT1_IR],
		SHIFT_IR: [SHIFT_IR, EXIT1_IR],
		EXIT1_IR: [PAUSE_IR, UPDATE_IR],
		PAUSE_IR: [PAUSE_IR, EXIT2_IR],
		EXIT2_IR: [SHIFT_IR, UPDATE_IR],
		UPDATE_IR: [IDLE, SELECT_DR]
	}

	def __init__(self, jtagClock):
		self.jtagClock = jtagClock
		self.state = None
		self.debug = 0
	
	def reset(self):
		for i in range(6):
			self.jtagClock(tms=1)

		self.state = TAP.TLR
	
	def clocked(self, tms):
		if self.state is None:
			if self.debug:
				print "TAP-DEBUG: TMS clocked, but state is Unknown."
			return
		
		state = self.state
		self.state = TAP.TRANSITIONS[self.state][tms]

		if self.debug:
			print "TAP-DEBUG: Transitioned (%i) from %s to %s." % (tms, TAP.STR_TRANSLATE[state], TAP.STR_TRANSLATE[self.state])

	
	# When goto is called, we look at where we want to go and where we are.
	# Based on that we choose where to clock TMS low or high.
	# After that we see if we've reached our goal. If not, call goto again.
	# This recursive behavior keeps the function simple.
	def goto(self, state):
		# If state is Unknown, reset.
		if self.state is None:
			if self.debug:
				print "TAP-DEBUG: goto called, but state is Unknown. Resetting."
			self.reset()
		elif state == TAP.TLR:
			self.jtagClock(tms=1)
		elif self.state == TAP.TLR:
			self.jtagClock(tms=0)
		elif state == TAP.SELECT_DR:
			if self.state != TAP.IDLE:
				raise TAPStateError(self.state, state)

			self.jtagClock(tms=1)
		elif state == TAP.SELECT_IR:
			if self.state != TAP.IDLE:
				raise TAPStateError(self.state, state)

			self.jtagClock(tms=1)
			self.jtagClock(tms=1)
		elif state == TAP.SHIFT_DR:
			if self.state != TAP.SELECT_DR:
				raise TAPStateError(self.state, state)

			self.jtagClock(tms=0)
			self.jtagClock(tms=0)
		elif state == TAP.SHIFT_IR:
			if self.state != TAP.SELECT_IR:
				raise TAPStateError(self.state, state)

			self.jtagClock(tms=0)
			self.jtagClock(tms=0)
		elif state == TAP.IDLE:
			if self.state == TAP.IDLE:
				self.jtagClock(tms=0)
			elif self.state == TAP.EXIT1_DR or self.state == TAP.EXIT1_IR:
				self.jtagClock(tms=1)
				self.jtagClock(tms=0)
			else:
				raise TAPStateError(self.state, state)
		else:
			raise TAPStateError(self.state, state)


		if self.state != state:
			self.goto(state)