?? lookup_methods.adb
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---------------------------------------------------------------------------------- ---- File : lookup_methods.adb $Revision: 1.5 $ ---- Abstract: ---- Simple lookup algorithms used in the S-Function ada_direct_lookup ---- See the description in simple_lookup.adb for more deltails. ---- ---- Author : Murali Yeddanapudi, 15-Aug-1999 ---- ---- Copyright 1990-2002 The MathWorks, Inc.-- ----------------------------------------------------------------------------------package body Lookup_Methods is -- Procedure: Left_Continuous_Lookup ---------------------------------------- -- Abstract:: -- This procedure implements the following simple left continuous -- table lookup algorithm: -- -- InpSig <= XValues(1) => OutSig = YValues(0) -- OutIdx = 0 -- XValues(1) < InpSig <= XValues(2) => OutSig = YValues(1) -- OutIdx = 1 -- XValues(2) < InpSig <= XValues(3) => OutSig = YValues(2) -- OutIdx = 2 -- : -- : -- XValues(n-1) < InpSig <= XValues(n) => OutSig = YValues(n-1) -- OutIdx = n-1 -- XValues(n) < InpSig OutSig = YValues(n) -- OutIdx = n -- procedure Left_Continuous_Lookup(InpSig : in Dbl_Array; OutSig : out Dbl_Array; OutIdx : in out Int_Array; XValues : in Dbl_Array; YValues : in Dbl_Array) is SigWidth : Integer := InpSig'Length; TableLen : Integer := XValues'Length; begin for I in 0 .. SigWidth-1 loop declare U : Standard.Long_Float := InpSig(I); Idx : Integer := OutIdx(I); Done : Boolean := FALSE; begin if Idx = 0 then Idx := 1; elsif Idx = TableLen then Idx := TableLen-1; end if; while not(Done) loop if U <= XValues(Idx) then Idx := Idx-1; if Idx = 0 then Done := TRUE; end if; elsif U > XValues(Idx+1) then Idx := Idx+1; if Idx = TableLen then Done := TRUE; end if; else Done := TRUE; end if; end loop; OutIdx(I) := Idx; OutSig(I) := YValues(Idx); if Idx = 0 then if U > XValues(1) then raise Algorithm_Error; end if; elsif Idx < TableLen then if not( XValues(Idx) < U and U <= XValues(Idx+1) ) then raise Algorithm_Error; end if; elsif Idx = TableLen then if U <= XValues(TableLen) then raise Algorithm_Error; end if; else raise Algorithm_Error; end if; end; end loop; end Left_Continuous_Lookup; ------------------------------------------------- -- Procedure: Right_Continuous_Lookup --------------------------------------- -- Abstract:: -- This procedure implements the following simple right continuous -- table lookup algorithm: -- -- InpSig < XValues(1) => OutSig = YValues(0) -- OutIdx = 0 -- XValues(1) <= InpSig < XValues(2) => OutSig = YValues(1) -- OutIdx = 1 -- XValues(2) <= InpSig < XValues(3) => OutSig = YValues(2) -- OutIdx = 2 -- : -- : -- XValues(n-1) <= InpSig < XValues(n) => OutSig = YValues(n-1) -- OutIdx = n-1 -- XValues(n) <= InpSig OutSig = YValues(n) -- OutIdx = n -- procedure Right_Continuous_Lookup(InpSig : in Dbl_Array; OutSig : out Dbl_Array; OutIdx : in out Int_Array; XValues : in Dbl_Array; YValues : in Dbl_Array) is SigWidth : Integer := InpSig'Length; TableLen : Integer := XValues'Length; begin for I in 0 .. SigWidth-1 loop declare U : Standard.Long_Float := InpSig(I); Idx : Integer := OutIdx(I); Done : Boolean := FALSE; begin if Idx = 0 then Idx := 1; elsif Idx = TableLen then Idx := TableLen-1; end if; while not(Done) loop if U < XValues(Idx) then Idx := Idx-1; if Idx = 0 then Done := TRUE; end if; elsif U >= XValues(Idx+1) then Idx := Idx+1; if Idx = TableLen then Done := TRUE; end if; else Done := TRUE; end if; end loop; OutIdx(I) := Idx; OutSig(I) := YValues(Idx); if Idx = 0 then if U >= XValues(1) then raise Algorithm_Error; end if; elsif Idx < TableLen then if not( XValues(Idx) <= U and U < XValues(Idx+1) ) then raise Algorithm_Error; end if; elsif Idx = TableLen then if U < XValues(TableLen) then raise Algorithm_Error; end if; else raise Algorithm_Error; end if; end; end loop; end Right_Continuous_Lookup; ------------------------------------------------end Lookup_Methods;-- EOF: lookup_methods.adb?? 快捷鍵說明
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