mirror of
https://github.com/nathanriggs/AppleIIAsm-Collection.git
synced 2024-12-01 06:49:59 +00:00
12a0b19398
- added some error control - added initial jump table - fixed a few minor bugs - separated common library into separate subroutine files
211 lines
5.4 KiB
Plaintext
211 lines
5.4 KiB
Plaintext
*
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*``````````````````````````````*
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* MEMMOVE :: MOVE MEM BLOCK *
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*- -*
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* MOVES A SPECIFIED BLOCK OF *
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* MEMORY FROM A SOURCE ADDRESS *
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* TO A DESTINATION ADDRESS *
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* RANGE. *
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*- -*
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* CLOBBERS: *
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* *
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* FLAGS: ????---- REG: AXYM *
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*- -*
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* CYCLES: ??? *
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* SIZE: *
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*- -*
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* USAGE: *
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* *
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* LDA #>$6A00 *
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* PHA *
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* LDA #<$6A00 *
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* PHA *
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* LDA #>$7000 ; DEST *
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* PHA *
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* LDA #<$7000 *
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* PHA *
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* LDA #>1024 *
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* PHA *
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* LDA #<1024 *
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* PHA *
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* JSR MEMMOVE *
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*- -*
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* ENTRY *
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* *
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* TOP OF STACK *
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* *
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* LOW BYTE OF RETURN ADDRESS *
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* HI BYTE OF RETURN ADDRESS *
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* NUMBER OF BYTES TO MOVE *
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* LOW BYTE OF DESTINATION *
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* HIGH BYTE OF DESTINATION *
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* LOW BYTE OF SOURCE ADDRESS *
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* HIGH BYTE OF SOURCE ADDRESS *
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*- -*
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* EXIT *
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* *
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* TOP OF STACK *
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* *
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* LOW BYTE OF RETURN ADDRESS *
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* HI BYTE OF RETURN ADDRESS *
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* *
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* Y = COUNTER; TRASH *
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* X = COUNTER; TRASH *
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* A = LOW BYTE OF RET ADDR *
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*- -*
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* ADAPTED FROM LEVANTHAL AND *
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* WINTHROP'S /6502 ASSEMBLY *
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* LANGUAGE ROUTINES/. *
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*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
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*
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MEMMOVE
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*
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** SAVE RETURN ADDRESS
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*
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PLA
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STA RETADR
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PLA
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STA RETADR+1
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*
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** GET PARAMETERS
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*
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PLA
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STA :MVELEN
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PLA
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STA :MVELEN+1
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PLA
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STA ADDR2 ; ZERO PAGE POINTER
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PLA
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STA ADDR2+1
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PLA
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STA ADDR1
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PLA
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STA ADDR1+1
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*
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** DETERMINE IF DEST AREA IS
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** ABOVE SRC AREA BUT OVERLAPS
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** IT. REMEMBER, OVERLAP CAN BE
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** MOD 64K. OVERLAP OCCURS IF
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** STARTING DEST ADDRESS MINUS
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** STARTING SRC ADDRESS (MOD
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** 64K) IS LESS THAN NUMBER
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** OF BYTES TO MOVE.
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*
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LDA ADDR2 ;CALC DEST-SRC
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SEC
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SBC ADDR1
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TAX
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LDA ADDR2+1
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SBC ADDR1+1 ; MOD 64K AUTOMATIC
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; -- DISCARD CARRY
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TAY
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TXA ; CMP WITH # OF BYTES TO MOVE
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CMP :MVELEN
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TYA
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SBC :MVELEN+1
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BCS :DOLEFT ; BRANCH IF NO OVERLAP
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*
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** DEST AREA IS ABOVE SRC AREA
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** BUT OVERLAPS IT.
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** MOVE FROM HIGHEST ADDR TO
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** AVOID DESTROYING DATA
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*
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JSR :MVERHT
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JMP :EXIT
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*
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** NO PROB DOING ORDINARY MOVE
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** STARTING AT LOWEST ADDR
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*
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:DOLEFT
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JSR :MVELEFT
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:EXIT
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JMP :MREXIT
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*
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********************************
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* SUBROUTINE: MVELEFT *
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********************************
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*
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:MVELEFT
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LDY #0 ; ZERO INDEX
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LDX :MVELEN+1 ; X=# OF FULL PP TO MOVE
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BEQ :MLPART ; IF X=0, DO PARTIAL PAGE
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:MLPAGE
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LDA (ADDR1),Y
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STA (ADDR2),Y ;MOVE ONE BYTE
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INY ; NEXT BYTE
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BNE :MLPAGE ; CONT UNTIL 256B MOVED
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INC ADDR1+1 ; ADV TO NEXT SRC PAGE
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INC ADDR2+1 ; ADV NEXT DEST PAGE
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DEX ; DEC PAGE COUNT
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BNE :MLPAGE ; CONT UNTIL ALL FULL
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; PAGES ARE MOVED
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:MLPART
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LDX :MVELEN ; GET LENGTH OF LAST PAGE
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BEQ :MLEXIT ; BR IF LENGTH OF LAST
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; PAGE = 0
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; REG Y IS 0
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:MLLAST
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LDA (ADDR1),Y
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STA (ADDR2),Y ; MOVE BYTE
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INY ; NEXT BYTE
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DEX ; DEC COUNTER
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BNE :MLLAST ; CONT UNTIL LAST P DONE
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:MLEXIT
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JMP :MREXIT
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*
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********************************
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* SUBROUTINE: MVERHT *
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********************************
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*
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:MVERHT
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*
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** MOVE THE PARTIAL PAGE FIRST
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*
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LDA :MVELEN+1
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CLC
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ADC ADDR1+1
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STA ADDR1+1 ;POINT TO LAST P OF SRC
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LDA :MVELEN+1
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CLC
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ADC ADDR2+1
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STA ADDR2+1 ; POINT TO LAST P OF DEST
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*
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** MOVE THE LAST PARTIAL PAGE FIRST
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*
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LDY :MVELEN ;GET LENGTH OF LAST PAGE
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BEQ :MRPAGE ; IF Y=0 DO THE FULL PAGES
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:MR0
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DEY ; BACK UP Y TO NEXT BYTE
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LDA (ADDR1),Y
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STA (ADDR2),Y ; MOVE BYTE
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CPY #0
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BNE :MR0 ; BR IF NOT DONE W LAST P
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:MRPAGE
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LDX :MVELEN+1 ; GET BYTE OF COUNT AS P CT
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BEQ :MREXIT ; BR IF HYBYTE = 0 (NO FULL P)
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:MR1
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DEC ADDR1+1 ; BACK UP TO PREV SRC PAGE
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DEC ADDR2+1 ; AND DEST
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:MR2
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DEY ; BACK UP Y TO NEXT BYTE
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LDA (ADDR1),Y
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STA (ADDR2),Y ; MOVE BYTE
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CPY #0
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BNE :MR2 ; BR IF NOT DONE W THIS PAGE
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DEX
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BNE :MR1 ; BR IF NOT ALL PAGES MOVED
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:MREXIT
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*
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** RESTORE RETURN ADDRESS
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*
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LDA RETADR+1
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PHA
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LDA RETADR
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PHA
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RTS
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*
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** DATA
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*
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:MVELEN DS 2
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*
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