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dbrochart |
######################################################################
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#### ####
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#### limiter.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, always_comb
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def limiter(a, b, y1, y2, y1Int, y2Int, aLim, bLim, y1Lim, y2Lim, y1IntLim, y2IntLim, n = 4):
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""" Limiter [-2**(n - 1) + 1, 2**(n - 1) - 1].
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n -- number of bits for the coding of the decoder input signals
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a, b, y1, y2, y1Int, y2Int -- in : decoder input signals, coded with n bits
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aLim, bLim, y1Lim, y2Lim, y1IntLim, y2IntLim -- out : limited signals
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"""
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@always_comb
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def limitLogic():
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if a.val <= -2**(n - 1):
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aLim.next = -2**(n - 1) + 1
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elif a.val >= 2**(n - 1):
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aLim.next = 2**(n - 1) - 1
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else:
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aLim.next = a.val
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if b.val <= -2**(n - 1):
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bLim.next = -2**(n - 1) + 1
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elif b.val >= 2**(n - 1):
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bLim.next = 2**(n - 1) - 1
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else:
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bLim.next = b.val
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if y1.val <= -2**(n - 1):
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y1Lim.next = -2**(n - 1) + 1
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elif y1.val >= 2**(n - 1):
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y1Lim.next = 2**(n - 1) - 1
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else:
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y1Lim.next = y1.val
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if y2.val <= -2**(n - 1):
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y2Lim.next = -2**(n - 1) + 1
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elif y2.val >= 2**(n - 1):
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y2Lim.next = 2**(n - 1) - 1
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else:
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y2Lim.next = y2.val
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if y1Int.val <= -2**(n - 1):
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y1IntLim.next = -2**(n - 1) + 1
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elif y1Int.val >= 2**(n - 1):
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y1IntLim.next = 2**(n - 1) - 1
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else:
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y1IntLim.next = y1Int.val
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if y2Int.val <= -2**(n - 1):
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y2IntLim.next = -2**(n - 1) + 1
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elif y2Int.val >= 2**(n - 1):
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y2IntLim.next = 2**(n - 1) - 1
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else:
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y2IntLim.next = y2Int.val
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return limitLogic
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