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dbrochart |
######################################################################
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#### ####
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#### trellis.py ####
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#### ####
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#### This file is part of the turbo decoder IP core project ####
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#### http://www.opencores.org/projects/turbocodes/ ####
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#### ####
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#### Author(s): ####
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#### - David Brochart(dbrochart@opencores.org) ####
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#### ####
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#### All additional information is available in the README.txt ####
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#### file. ####
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#### ####
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######################################################################
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#### ####
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#### Copyright (C) 2005 Authors ####
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#### ####
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#### This source file may be used and distributed without ####
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#### restriction provided that this copyright statement is not ####
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#### removed from the file and that any derivative work contains ####
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#### the original copyright notice and the associated disclaimer. ####
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#### ####
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#### This source file is free software; you can redistribute it ####
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#### and/or modify it under the terms of the GNU Lesser General ####
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#### Public License as published by the Free Software Foundation; ####
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#### either version 2.1 of the License, or (at your option) any ####
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#### later version. ####
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#### ####
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#### This source is distributed in the hope that it will be ####
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#### useful, but WITHOUT ANY WARRANTY; without even the implied ####
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#### warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ####
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#### PURPOSE. See the GNU Lesser General Public License for more ####
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#### details. ####
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#### ####
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#### You should have received a copy of the GNU Lesser General ####
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#### Public License along with this source; if not, download it ####
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#### from http://www.opencores.org/lgpl.shtml ####
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#### ####
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######################################################################
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from myhdl import Signal, posedge, negedge, intbv, always
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trans2state = [[0, 6, 1, 7], [2, 4, 3, 5], [5, 3, 4, 2], [7, 1, 6, 0], [1, 7, 0, 6], [3, 5, 2, 4], [4, 2, 5, 3], [6, 0, 7, 1]]
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state2trans = [[0, 2, 1, 3], [1, 3, 0, 2], [2, 0, 3, 1], [3, 1, 2, 0], [2, 0, 3, 1], [3, 1, 2, 0], [0, 2, 1, 3], [1, 3, 0, 2]]
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def trellis1(clk, rst, selState, selTrans, selStateL2, selStateL1, stateL1, selTransL2, l = 20):
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""" First trellis.
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l -- first trellis length
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clk, rst -- in : clock and negative reset
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selState -- in : selected state at time 0
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selTrans -- in : 8 selected transitions (1 per state) at time 0
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selStateL2 -- out : selected state at time (l - 2)
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selStateL1 -- out : selected state at time (l - 1)
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stateL1 -- out : 4 possible states at time (l - 1)
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selTransL2 -- out : selected transition at time (l - 2)
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"""
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reg = [[Signal(intbv(0, 0, 4)) for i in range(8)] for j in range(l)]
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free = intbv(255, 0, 256)
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freeBeg = [bool(1) for i in range(8)]
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pastState = [intbv(0, 0, 8) for i in range(8)]
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pathIdReg = [Signal(intbv(i, 0, 8)) for i in range(8)]
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pathId = [intbv(0, 0, 8) for i in range(8)]
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freePathId = intbv(0, 0, 8)
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current_state = intbv(0, 0, 8)
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outState_l2 = intbv(0, 0, 8)
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outState_l1 = intbv(0, 0, 8)
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state_l3 = intbv(0, 0, 4)
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state_l2 = intbv(0, 0, 4)
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state_l1 = intbv(0, 0, 4)
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@always(clk.posedge, rst.negedge)
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def trellis1Logic():
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if rst.val == 0:
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for i in range(4):
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stateL1[i].next = 0
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selStateL1.next = 0
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selStateL2.next = 0
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selTransL2.next = 0
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for i in range(8):
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pathIdReg[i].next = i
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for j in range(l):
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reg[j][i].next = 0
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else:
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free = intbv(255)
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for i in range(8):
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pastState[i] = trans2state[i][int(selTrans[i].val)]
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pathId[i] = pathIdReg[pastState[i]].val
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free[int(pathId[i])] = 0
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freeBeg = [bool(1) for i in range(8)]
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for i in range(8):
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current_state = intbv(i)
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if freeBeg[int(pathId[int(current_state)])] == 1:
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reg[0][int(pathId[int(current_state)])].next = current_state[2:0]
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freeBeg[int(pathId[i])] = 0
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pathIdReg[int(current_state)].next = pathId[int(current_state)]
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for j in range(l - 1):
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reg[j + 1][int(pathId[int(current_state)])].next = reg[j][int(pathId[int(current_state)])].val
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else:
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if free[0] == 1:
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freePathId = 0
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if free[2:0] == 2:
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freePathId = 1
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if free[3:0] == 4:
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freePathId = 2
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if free[4:0] == 8:
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freePathId = 3
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if free[5:0] == 16:
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freePathId = 4
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if free[6:0] == 32:
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freePathId = 5
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if free[7:0] == 64:
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freePathId = 6
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if free[8:0] == 128:
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freePathId = 7
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reg[0][freePathId].next = current_state[2:0]
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free[freePathId] = 0
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pathIdReg[int(current_state)].next = freePathId
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for j in range(l - 1):
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reg[j + 1][freePathId].next = reg[j][int(pathId[int(current_state)])].val
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state_l3 = reg[l - 3][int(pathId[int(selState.val)])].val
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state_l2 = reg[l - 2][int(pathId[int(selState.val)])].val
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state_l1 = reg[l - 1][int(pathId[int(selState.val)])].val
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outState_l2[2] = state_l3[1] ^ (state_l3[0] ^ state_l2[1])
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outState_l2[2:0] = state_l2
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outState_l1[2] = state_l2[1] ^ (state_l2[0] ^ state_l1[1])
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outState_l1[2:0] = state_l1
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selStateL1.next = outState_l1
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selStateL2.next = outState_l2
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selTransL2.next = state2trans[int(outState_l2)][int(state_l1)]
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for i in range(4):
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stateL1[i].next = trans2state[int(outState_l2)][i]
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if __debug__:
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# Monitor: checks that in the first trellis, from each of the 8 states (trellis' beginning) we arrive at the same state (trellis' end).
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# (Ignore this message until every iteration is fully started)
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diff = 0
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ref = intbv(0)
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tmp = intbv(0)
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state_l2_deb = reg[l - 2][int(pathId[7])].val
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state_l1_deb = reg[l - 1][int(pathId[7])].val
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ref[2] = state_l2_deb[1] ^ (state_l2_deb[0] ^ state_l1_deb[1])
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ref[2:0] = state_l1_deb
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for i in range(7):
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state_l2_deb = reg[l - 2][int(pathId[i])].val
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state_l1_deb = reg[l - 1][int(pathId[i])].val
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tmp[2] = state_l2_deb[1] ^ (state_l2_deb[0] ^ state_l1_deb[1])
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tmp[2:0] = state_l1_deb
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if ref != tmp:
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diff = 1
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if diff == 1:
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print "WARNING: all paths don't arrive at same state at end of first trellis (you should think about increasing its length)"
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return trellis1Logic
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def trellis2(clk, rst, selState, state, selTrans, weight, llr0, llr1, llr2, llr3, a, b, m = 10, q = 8):
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""" Second trellis and revision logic.
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m -- second trellis length
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q -- accumulated distance width
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clk, rst -- in : clock and negative reset
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selState -- in : selected state at time (l - 1)
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state -- in : 4 possible states at time (l - 1)
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selTrans -- in : 8 selected transitions (1 per state) at time (l - 1)
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weight -- in : four weights sorted by transition code at time (l - 1)
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llr0 -- out : LLR for (a, b) = (0, 0) at time (l + m - 1)
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llr1 -- out : LLR for (a, b) = (0, 1) at time (l + m - 1)
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llr2 -- out : LLR for (a, b) = (1, 0) at time (l + m - 1)
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llr3 -- out : LLR for (a, b) = (1, 1) at time (l + m - 1)
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a, b -- out : decoded values of (a, b) at time (l + m - 1)
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"""
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reg = [[Signal(intbv(0, 0, 4)) for i in range(8)] for j in range(m)]
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free = intbv(255, 0, 256)
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freeBeg = [bool(1) for i in range(8)]
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pastState = [intbv(0, 0, 8) for i in range(8)]
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pathIdReg = [Signal(intbv(i, 0, 8)) for i in range(8)]
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pathId = [intbv(0, 0, 8) for i in range(8)]
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freePathId = intbv(0, 0, 8)
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revWeight = [[Signal(intbv(0, 0, 2**q)) for i in range(m)] for j in range(4)]
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revWeightTmp = [[intbv(0, 0, 2**q) for i in range(m)] for j in range(4)]
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revWeightFilt = [intbv(0, 0, 2**q) for j in range(3)]
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op = [intbv(0, 0, 2**q) for i in range(4)]
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tmp = [intbv(0, 0, 2**q) for i in range(4)]
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tmp4 = intbv(0, 0, 2**(q+1))
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notZero = [[intbv(0, 0, 4) for i in range(3)] for j in range(2)]
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ind = [[intbv(0, 0, 4) for i in range(3)] for j in range(2)]
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minTmp = [bool(0) for i in range(3)]
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@always(clk.posedge, rst.negedge)
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def trellis2Logic():
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if rst.val == 0:
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for i in range(4):
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for j in range(m):
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revWeight[i][j].next = 0
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a.next = 0
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b.next = 0
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llr0.next = 0
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llr1.next = 0
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llr2.next = 0
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llr3.next = 0
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for i in range(8):
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pathIdReg[i].next = i
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for j in range(m):
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reg[j][i].next = 0
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else:
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free = intbv(255)
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for i in range(8):
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pastState[i] = trans2state[i][int(selTrans[i].val)]
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pathId[i] = pathIdReg[pastState[i]].val
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free[int(pathId[i])] = 0
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freeBeg = [bool(1) for i in range(8)]
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for i in range(8):
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if freeBeg[int(pathId[i])] == 1:
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reg[0][int(pathId[i])].next = selTrans[i].val
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freeBeg[int(pathId[i])] = 0
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pathIdReg[i].next = pathId[i]
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for j in range(m - 1):
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reg[j + 1][int(pathId[i])].next = reg[j][int(pathId[i])].val
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else:
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if free[1:0] == 1:
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freePathId = 0
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if free[2:0] == 2:
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freePathId = 1
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if free[3:0] == 4:
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freePathId = 2
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if free[4:0] == 8:
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freePathId = 3
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if free[5:0] == 16:
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freePathId = 4
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if free[6:0] == 32:
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freePathId = 5
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if free[7:0] == 64:
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freePathId = 6
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if free[8:0] == 128:
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freePathId = 7
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reg[0][freePathId].next = selTrans[i].val
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free[freePathId] = 0
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pathIdReg[i].next = freePathId
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for j in range(m - 1):
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reg[j + 1][freePathId].next = reg[j][int(pathId[i])].val
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a.next = reg[m - 1][int(pathId[int(selState.val)])].val[1]
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b.next = reg[m - 1][int(pathId[int(selState.val)])].val[0]
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for i in range(4):
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for j in range(m - 1):
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for k in range(4):
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if reg[j][int(pathId[int(state[k].val)])].val == i and state[k].val != selState.val:
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op[k] = weight[k].val
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else:
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op[k] = (2 ** q) - 1
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if op[0] < op[1]:
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tmp[0] = op[0]
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else:
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tmp[0] = op[1]
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if op[2] < op[3]:
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tmp[1] = op[2]
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else:
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tmp[1] = op[3]
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if tmp[0] < tmp[1]:
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tmp[2] = tmp[0]
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else:
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tmp[2] = tmp[1]
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if tmp[2] < revWeight[i][j].val:
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revWeightTmp[i][j + 1] = tmp[2]
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else:
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revWeightTmp[i][j + 1] = revWeight[i][j].val
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revWeightTmp[i][0] = weight[i].val
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for j in range(2):
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if revWeightTmp[0][j] == 0:
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notZero[j] = [1, 2, 3]
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elif revWeightTmp[1][j] == 0:
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notZero[j] = [0, 2, 3]
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elif revWeightTmp[2][j] == 0:
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notZero[j] = [0, 1, 3]
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elif revWeightTmp[3][j] == 0:
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notZero[j] = [0, 1, 2]
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if revWeightTmp[int(notZero[j][0])][j] <= revWeightTmp[int(notZero[j][1])][j]:
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minTmp[0] = 0
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else:
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minTmp[0] = 1
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if revWeightTmp[int(notZero[j][0])][j] <= revWeightTmp[int(notZero[j][2])][j]:
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minTmp[1] = 0
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else:
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minTmp[1] = 1
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|
|
if revWeightTmp[int(notZero[j][1])][j] <= revWeightTmp[int(notZero[j][2])][j]:
|
| 285 |
|
|
minTmp[2] = 0
|
| 286 |
|
|
else:
|
| 287 |
|
|
minTmp[2] = 1
|
| 288 |
|
|
if minTmp == [0, 0, 0]:
|
| 289 |
|
|
ind[j] = [0, 1, 2]
|
| 290 |
|
|
elif minTmp == [0, 0, 1]:
|
| 291 |
|
|
ind[j] = [0, 2, 1]
|
| 292 |
|
|
elif minTmp == [1, 0, 0]:
|
| 293 |
|
|
ind[j] = [1, 0, 2]
|
| 294 |
|
|
elif minTmp == [0, 1, 1]:
|
| 295 |
|
|
ind[j] = [1, 2, 0]
|
| 296 |
|
|
elif minTmp == [1, 1, 0]:
|
| 297 |
|
|
ind[j] = [2, 0, 1]
|
| 298 |
|
|
elif minTmp == [1, 1, 1]:
|
| 299 |
|
|
ind[j] = [2, 1, 0]
|
| 300 |
|
|
else:
|
| 301 |
|
|
print "ERROR: Configuration does not exist", minTmp
|
| 302 |
|
|
for i in range(3):
|
| 303 |
|
|
tmp[3] = revWeightTmp[int(notZero[0][int(ind[0][i])])][0]
|
| 304 |
|
|
tmp4 = revWeightTmp[int(notZero[1][int(ind[1][i])])][1] + (2 ** (q - 4))
|
| 305 |
|
|
if tmp[3] < tmp4:
|
| 306 |
|
|
revWeightFilt[int(ind[0][i])] = tmp[3]
|
| 307 |
|
|
else:
|
| 308 |
|
|
revWeightFilt[int(ind[0][i])] = intbv(tmp4)[q:0]
|
| 309 |
|
|
for i in range(3):
|
| 310 |
|
|
revWeightTmp[int(notZero[0][i])][0] = revWeightFilt[i]
|
| 311 |
|
|
for i in range(4):
|
| 312 |
|
|
for j in range(m):
|
| 313 |
|
|
revWeight[i][j].next = revWeightTmp[i][j]
|
| 314 |
|
|
llr0.next = revWeight[0][m - 1]
|
| 315 |
|
|
llr1.next = revWeight[1][m - 1]
|
| 316 |
|
|
llr2.next = revWeight[2][m - 1]
|
| 317 |
|
|
llr3.next = revWeight[3][m - 1]
|
| 318 |
|
|
return trellis2Logic
|
