[quirks-uvm-devel] query on quirks examples

[Bhavani M. <bha...@ya...>]

> Date: Thu, 28 Mar 2002 14:00:09 -0800 (PST)
> From: bhavmus m <bh...@ya...>
> Subject: query on quirks examples
> To: qui...@li...
> 
> 
> Hi,
> 
>       I have got the following questions after going
> through the simple example.
> 
> 
> 1. usage of fp[0], fp[1] is little bit confusing. I
> am thinking these are the procedure parameters and
> can be used for procedure INPUT or OUTPUT
> 2. why can not we declare the ct value in the 
> fact.ua file? 
> 3. I am able to understand the declaration of
> registers, but not the actual mapping done below.
>  map is
>   (auMul[1], lv[1])  (auMul[0], fp[0])   (auMul[2],
> fp[1])
>  end map;
> 4. I want to have some more explanation for *act
> command.
> 
> 5. I have gone through the fibonacci example too. it
> is easy compared to factorial. In this example also
> I did n't get the
> purpose of mapping lv[3] twice. Why do we need auSum
> register, even though we have the actual result in
> lv[2]?
> 
> 
> procedure :Fibonacci is
>  lv is <int32/inout int32/inout int32/inout
> int32/inout stu>;
> 
>  declare map
>     auInc is <int32/out int32/in stu>;
>     auSum is <int32/in int32/in int32/out stu>;
>  map is
>   (lv[3],auInc[0])
>   (lv[3],auInc[1])
>   (lv[0],auSum[0])
>   (lv[1],auSum[1])
>   (lv[2],auSum[2])
>  end map;
> begin
>  lv[3] <- fp[0];
>  lv[0] <- ct[0];
>  lv[1] <- ct[1];
> 
>  loop
>     * auInc;
>      lv[0] <- lv[1];
>     lv[1] <- lv[2];
>  until not lv[3];
> 
>  fp[1] <- lv[2];
> 
> end :Fibonacci;
> 
> 
>  
> 
>  
> 
> procedure :fact is
>  -- Make two 32 bit local registers.
>  -- Each register is both writeable and readable.
>  lv is <int32/inout int32/inout stu>;
>  
>  declare map
>   -- Get access to two registers of
> incrementer/decrementer
>   auInc is <int32/out int32/in stu>;
> 
>   -- Make two virtual registers (they are simple
> "ports"
>   -- and now they are attached to nothing).
>   dx1 is <int32/in int32/out stu>;
>   
>   -- Three ports of multiplier
>   auMul is <int32/in int32/in int32/out stu>;
>  map is
>   -- Attach fp[0] (it is the first of registers -
> parameters
>   -- of this procedure) to the input register of
> incr/decr.
>   -- The output register of incr/decr attach to the
> first local
>   -- register.
>   (auInc[0], lv[0])  (auInc[1], fp[0])
> 
>   -- The first local register will contain n-1,
>   -- the second one will contain the result of
> recursive call.
>   (lv[0], dx1[0])    (lv[1], dx1[1])
> 
>   -- This attach the output of our multiplier (n *
> fact (n-1))
>   -- to fp[1]. Really fp[x] it is either a memory
> cell
>   -- in the caller stack or a register if our
> optimizer is 
>   -- a lassie. It is why it is named "secondary (or
> virtual)"
>   -- selector. Any virtual register is like a
> deference.
>   (auMul[1], lv[1])  (auMul[0], fp[0])   (auMul[2],
> fp[1])
>  end map;
> begin
>  if fp[0] then
>   -- It is imperfection of current machine - we need
>   -- awake decrementor to make its outputs updated.
>   * auInc;
> 
>   -- dx1 will be substituted by fp when th procedure
> calls.
>   -- Theses lv and dx1 will not be able to access
> there.
>   call dx1, :fact;
> 
>   -- Synchronize impuls to multiplier
>   * auMul;
>  else
>   -- This branch is for the case of fact(0) = 1.
>   -- Moves '1' into a register which is "hided"
> behind
>   -- the virtual fp[1].
>   fp[1] <- ct[0];
>  end if;
> 
> end :fact;
> 


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