TITLE      Barrel Shifter
DATE       Oct 7, 2003
REVISION   1.0
PATTERN    alpha
Author     Lhamon
Company    U.K.
CHIP DEVICE PALCE22V10H

;  This device is a three bit barrel shifter with both LOAD and 
;  HOLD. RESET is dome synchronously. The design is built around
;  a basic 4-TO-1 MUX element.  The design was not minimized to
;  aid in the readability of the design.  The optimizer will help
;  reduce the equations.
;

;  Inputs                     
Pin 1  CLOCK                  ; CLOCK may be free running.    
Pin 2  IN0                    ; LOAD input 0  
Pin 3  IN1                    ; LOAD input 1
Pin 4  IN2                    ; LOAD input 2 
Pin 5  MODA                   ; MOD selection inputs. 
Pin 6  MODB                   
Pin 19 RESET                  ; Note that Pin 19 is an input       

;  Outputs 
Pin 14  Q0  REGISTERED        ; Output 0 
Pin 15  Q1  REGISTERED        ; Output 1
Pin 16  Q2  REGISTERED        ; Output 2 

EQUATIONS
; Logic Equations 

Q0 := /RESET * (( /MODB * /MODA) * IN0) + (( /MODB * MODA) * Q2) 
             + ((  MODB * /MODA) *  Q1) + ((  MODB * MODA) * Q0)

Q1 := /RESET * (( /MODB * /MODA) * IN1) + (( /MODB * MODA) * Q0) 
             + ((  MODB * /MODA) *  Q2) + ((  MODB * MODA) * Q1)

Q2 := /RESET * (( /MODB * /MODA) * IN2) + (( /MODB * MODA) * Q1) 
             + ((  MODB * /MODA) *  Q0) + ((  MODB * MODA) * Q2)

SIMULATION
TRACE_ON CLOCK RESET MODA MODB IN0 IN1 IN2 Q0 Q1 Q2
SETF RESET /MODA /MODB /IN0 /IN1 /IN2
CLOCKF CLOCK
SETF /RESET
SETF IN0 /IN1 IN2
CLOCKF CLOCK
SETF /MODB MODA
CLOCKF CLOCK
CLOCKF CLOCK
CLOCKF CLOCK
CLOCKF CLOCK
SETF MODB /MODA
CLOCKF CLOCK
CLOCKF CLOCK
CLOCKF CLOCK
CLOCKF CLOCK
SETF MODB MODA
CLOCKF CLOCK
CLOCKF CLOCK
CLOCKF CLOCK
CLOCKF CLOCK
TRACE_OFF