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;**************************************************************************
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; M16C5x_Tst.ASM
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;
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; This sample program runs on most all PIC devices. To ensure
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; proper execution, replace the processor specified in the LIST directive
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; with your target processor.
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;
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; Program execution starts at location H'50'. The loop routine executes
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; seven times. The routines Reduce and Double execute one time for each
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; loop.
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;
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; After the loop executes seven times, the program repeats execution from
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; the beginning.
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;
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;
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; Variable Initial Description
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; Value
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;--------------------------------------------------------------------------
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; CountDown 255 Decreases to 128 by subtracting Doubler
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; Doubler 1 Increases to 128 by adding to itself
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; OuterLoop 7 Decrements by one to 0
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;
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;
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; The program generates the following values:
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;
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; Cycle # CountDown Doubler OuterLoop
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; 0 255 1 7
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; 1 254 2 6
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; 2 252 4 5
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; 3 248 8 4
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; 4 240 16 3
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; 5 224 32 2
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; 6 192 64 1
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; 7 128 128 0
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;
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;**************************************************************************
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LIST P=16F59, R=DEC
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;--------------------------------------------------------------------------
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; Set ScratchPadRam here. If you are using a PIC16C5X device, use:
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;ScratchPadRam EQU 0x10
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; Otherwise, use:
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;ScratchPadRam EQU 0x20
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;--------------------------------------------------------------------------
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ScratchPadRam EQU 0x10
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;--------------------------------------------------------------------------
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; Variables
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;--------------------------------------------------------------------------
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CountDown EQU ScratchPadRam+0
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Doubler EQU ScratchPadRam+1
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OuterLoop EQU ScratchPadRam+2
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;--------------------------------------------------------------------------
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; Program Code
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;--------------------------------------------------------------------------
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;--------------------------------------------------------------------------
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; Set the reset vector here. If you are using a PIC16C5X device, use:
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; ORG
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; Otherwise, use:
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; ORG 0
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;--------------------------------------------------------------------------
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ORG H'7FF'
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GOTO Start
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;--------------------------------------------------------------------------
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; Main Program
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;--------------------------------------------------------------------------
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ORG H'50'
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Start
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MOVLW 255 ; Initialize the variables to
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MOVWF CountDown ; their starting values.
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MOVLW 1
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MOVWF Doubler
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MOVLW 7
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MOVWF OuterLoop
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Loop
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CALL Reduce ; Perform the inner portion of
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DECFSZ OuterLoop,f ; the loop.
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GOTO Loop
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GOTO Start ; Repeat the whole thing.
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;--------------------------------------------------------------------------
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Reduce
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SWAPF Doubler,f ; Reduce CountDown by the
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SWAPF Doubler,w ; value of Doubler. Then
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SWAPF Doubler,f ; call the doubling routine.
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SUBWF CountDown,f
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CALL Double
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RETLW 0
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;--------------------------------------------------------------------------
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Double
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SWAPF Doubler,f ; Double the value of Doubler
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SWAPF Doubler,w ; by adding it to itself.
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SWAPF Doubler,f
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ADDWF Doubler,f
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RETLW 0
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END
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