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5c5d01d84a
in the distribution. Added --forget-inc-paths to the command line of the assembler in the Makefiles, because the assembler does now have builtin paths and will find include files from an installation first. Hopefully fixed any problems that arose from the two changes. git-svn-id: svn://svn.cc65.org/cc65/trunk@4223 b7a2c559-68d2-44c3-8de9-860c34a00d81
270 lines
6.6 KiB
ArmAsm
270 lines
6.6 KiB
ArmAsm
;
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; Extended memory driver for the C16 hidden RAM. Driver works without
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; problems when statically linked.
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;
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; Ullrich von Bassewitz, 2003-12-15
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;
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.include "zeropage.inc"
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.include "em-kernel.inc"
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.include "em-error.inc"
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.include "plus4.inc"
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.macpack generic
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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.segment "JUMPTABLE"
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; Driver signature
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.byte $65, $6d, $64 ; "emd"
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.byte EMD_API_VERSION ; EM API version number
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; Jump table.
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.word INSTALL
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.word UNINSTALL
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.word PAGECOUNT
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.word MAP
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.word USE
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.word COMMIT
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.word COPYFROM
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.word COPYTO
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; ------------------------------------------------------------------------
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; Constants
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BASE = $8000
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; ------------------------------------------------------------------------
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; Data.
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.bss
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pages: .res 1 ; Number of pages
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curpage: .res 1 ; Current page number
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window: .res 256 ; Memory "window"
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.code
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; ------------------------------------------------------------------------
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; INSTALL routine. Is called after the driver is loaded into memory. If
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; possible, check if the hardware is present and determine the amount of
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; memory available.
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; Must return an EM_ERR_xx code in a/x.
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;
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INSTALL:
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; Determine how much memory is available. We will use all memory above
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; $8000 up to MEMTOP
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sec
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jsr $FF99 ; MEMTOP: Get top memory into Y/X
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tya
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sub #>BASE ; Low 32 K are used
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bcc nomem
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beq nomem ; Offering zero pages is a bad idea
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sta pages
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ldx #$FF
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stx curpage ; Invalidate the current page
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inx ; X = 0
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txa ; A = X = EM_ERR_OK
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rts
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nomem: ldx #>EM_ERR_NO_DEVICE
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lda #<EM_ERR_NO_DEVICE
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; rts ; Run into UNINSTALL instead
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; ------------------------------------------------------------------------
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; UNINSTALL routine. Is called before the driver is removed from memory.
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; Can do cleanup or whatever. Must not return anything.
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;
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UNINSTALL:
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rts
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; ------------------------------------------------------------------------
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; PAGECOUNT: Return the total number of available pages in a/x.
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;
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PAGECOUNT:
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lda pages
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ldx #$00 ; 128 pages max
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rts
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; ------------------------------------------------------------------------
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; MAP: Map the page in a/x into memory and return a pointer to the page in
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; a/x. The contents of the currently mapped page (if any) may be discarded
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; by the driver.
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;
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MAP: sta curpage ; Remember the new page
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add #>BASE
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sta ptr1+1
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ldy #$00
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sty ptr1
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lda #<window
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sta ptr2
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lda #>window
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sta ptr2+1
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; Transfer one page
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jsr transfer ; Transfer one page
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; Return the memory window
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lda #<window
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ldx #>window ; Return the window address
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rts
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; ------------------------------------------------------------------------
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; USE: Tell the driver that the window is now associated with a given page.
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USE: sta curpage ; Remember the page
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lda #<window
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ldx #>window ; Return the window
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rts
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; ------------------------------------------------------------------------
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; COMMIT: Commit changes in the memory window to extended storage.
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COMMIT: lda curpage ; Get the current page
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bmi done ; Jump if no page mapped
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add #>BASE
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sta ptr2+1
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ldy #$00
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sty ptr2
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lda #<window
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sta ptr1
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lda #>window
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sta ptr1+1
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; Transfer one page. Y must be zero on entry. Because we bank out the
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; kernal, we will run the routine with interrupts disabled but leave
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; short breath times. Unroll the following loop to make it somewhat faster.
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transfer:
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sei
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sta ENABLE_RAM
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.repeat 8
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lda (ptr1),y
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sta (ptr2),y
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iny
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.endrepeat
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sta ENABLE_ROM
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cli
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bne transfer
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; Done
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done: rts
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; ------------------------------------------------------------------------
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; COPYFROM: Copy from extended into linear memory. A pointer to a structure
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; describing the request is passed in a/x.
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; The function must not return anything.
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;
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COPYFROM:
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sta ptr3
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stx ptr3+1 ; Save the passed em_copy pointer
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ldy #EM_COPY::OFFS
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lda (ptr3),y
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sta ptr1
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ldy #EM_COPY::PAGE
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lda (ptr3),y
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add #>BASE
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sta ptr1+1 ; From
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ldy #EM_COPY::BUF
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lda (ptr3),y
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sta ptr2
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iny
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lda (ptr3),y
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sta ptr2+1 ; To
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common: ldy #EM_COPY::COUNT+1
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lda (ptr3),y ; Get number of pages
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beq @L2 ; Skip if no full pages
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sta tmp1
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; Copy full pages allowing interrupts after each page copied
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ldy #$00
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@L1: jsr transfer
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inc ptr1+1
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inc ptr2+1
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dec tmp1
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bne @L1
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; Copy the remainder of the page
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@L2: ldy #EM_COPY::COUNT
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lda (ptr3),y ; Get bytes in last page
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beq @L4
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tax
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sei ; Disable ints
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sta ENABLE_RAM ; Bank out the ROM
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; Transfer the bytes in the last page
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ldy #$00
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@L3: lda (ptr1),y
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sta (ptr2),y
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iny
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dex
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bne @L3
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; Restore the old memory configuration, allow interrupts
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sta ENABLE_ROM
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cli
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; Done
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@L4: rts
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; ------------------------------------------------------------------------
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; COPYTO: Copy from linear into extended memory. A pointer to a structure
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; describing the request is passed in a/x.
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; The function must not return anything.
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;
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COPYTO: sta ptr3
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stx ptr3+1 ; Save the passed em_copy pointer
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ldy #EM_COPY::OFFS
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lda (ptr3),y
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sta ptr2
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ldy #EM_COPY::PAGE
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lda (ptr3),y
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add #>BASE
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sta ptr2+1 ; To
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ldy #EM_COPY::BUF
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lda (ptr3),y
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sta ptr1
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iny
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lda (ptr3),y
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sta ptr1+1 ; From
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jmp common
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