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d6c3bd29ac
This change was suppsed to fix the issue that the former JUMPTABLE is merked as 'ro' while it is actually written to in several scenarios. When drivers are converted using co65 and then compiled into ROMs the JUMPTABLE isn't copied to RAM and therefore the write operations in question fail. However unfortunately I didn't succeed in changing that :-( Just setting the former JUMPTABLE to 'rw' broke the drivers. So I placed the DATA segment directly after the former JUMPTABLE segment. This made the drivers converted with co65 work again - obviously after changing libsrc/Makefile:235 from '--code-label' to '--data-label'. But the actual dynamic drivers still didn't work as the former JUMPTABLE wasn't placed as the beginning of the loaded file anymore. That effect could be changed by exchanging src/ld65/o65.c:1391 with src/ld65/o65.c:1394 but doing so broke the drivers again :-((
275 lines
6.1 KiB
ArmAsm
275 lines
6.1 KiB
ArmAsm
;
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; Extended memory driver for the ISEPIC cartridge.
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; Marco van den Heuvel, 2010-01-24
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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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.macpack generic
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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.segment "HEADER"
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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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; Library reference
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.addr $0000
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; Jump table
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.addr INSTALL
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.addr UNINSTALL
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.addr PAGECOUNT
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.addr MAP
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.addr USE
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.addr COMMIT
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.addr COPYFROM
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.addr COPYTO
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; ------------------------------------------------------------------------
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; Constants
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IP_WINDOW = $DF00 ; Address of ISEPIC window
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IP_CTRL_BASE = $DE00
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PAGES = 8
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; ------------------------------------------------------------------------
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; Code.
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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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lda #0
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sta IP_CTRL_BASE
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ldx IP_WINDOW
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cpx IP_WINDOW
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bne @notpresent
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inc IP_WINDOW
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cpx IP_WINDOW
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beq @notpresent
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ldx IP_WINDOW
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sta IP_CTRL_BASE+1
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inx
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stx IP_WINDOW
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dex
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sta IP_CTRL_BASE
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cpx IP_WINDOW
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beq @setok
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@notpresent:
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lda #<EM_ERR_NO_DEVICE
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ldx #>EM_ERR_NO_DEVICE
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rts
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@setok:
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lda #<EM_ERR_OK
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ldx #>EM_ERR_OK
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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 #>PAGES
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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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; The Isepic cartridge does not copy but actually map the window, so USE is
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; identical to MAP.
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USE := MAP
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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:
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tax
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sta IP_CTRL_BASE,x
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lda #<IP_WINDOW
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ldx #>IP_WINDOW
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; Use the RTS from COMMIT below to save a precious byte of storage
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; ------------------------------------------------------------------------
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; COMMIT: Commit changes in the memory window to extended storage.
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COMMIT:
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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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jsr setup
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; Setup is:
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;
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; - ptr1 contains the struct pointer
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; - ptr2 contains the linear memory buffer
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; - ptr3 contains -(count-1)
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; - tmp1 contains the low page register value
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; - X contains the page offset
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; - Y contains zero
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jmp @L5
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@L1:
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lda IP_WINDOW,x
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sta (ptr2),y
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iny
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bne @L2
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inc ptr2+1
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@L2:
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inx
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beq @L4
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; Bump count and repeat
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@L3:
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inc ptr3
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bne @L1
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inc ptr3+1
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bne @L1
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rts
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; Bump page register
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@L4:
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inc tmp1 ; Bump low page register
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@L5:
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stx tmp2
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ldx tmp1
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sta IP_CTRL_BASE,x
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ldx tmp2
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jmp @L3
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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:
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jsr setup
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; Setup is:
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;
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; - ptr1 contains the struct pointer
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; - ptr2 contains the linear memory buffer
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; - ptr3 contains -(count-1)
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; - tmp1 contains the low page register value
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; - X contains the page offset
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; - Y contains zero
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jmp @L5
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@L1:
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lda (ptr2),y
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sta IP_WINDOW,x
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iny
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bne @L2
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inc ptr2+1
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@L2:
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inx
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beq @L4
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; Bump count and repeat
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@L3:
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inc ptr3
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bne @L1
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inc ptr3+1
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bne @L1
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rts
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; Bump page register
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@L4:
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inc tmp1 ; Bump page register
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@L5:
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stx tmp2
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ldx tmp1
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sta IP_CTRL_BASE,x
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ldx tmp2
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jmp @L3
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; ------------------------------------------------------------------------
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; Helper function for COPYFROM and COPYTO: Store the pointer to the request
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; structure and prepare data for the copy
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setup:
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sta ptr1
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stx ptr1+1 ; Save passed pointer
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; Get the page number from the struct and remember it.
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ldy #EM_COPY::PAGE
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lda (ptr1),y
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sta tmp1
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; Get the buffer pointer into ptr2
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ldy #EM_COPY::BUF
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lda (ptr1),y
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sta ptr2
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iny
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lda (ptr1),y
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sta ptr2+1
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; Get the count, calculate -(count-1) and store it into ptr3
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ldy #EM_COPY::COUNT
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lda (ptr1),y
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eor #$FF
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sta ptr3
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iny
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lda (ptr1),y
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eor #$FF
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sta ptr3+1
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; Get the page offset into X and clear Y
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ldy #EM_COPY::OFFS
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lda (ptr1),y
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tax
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ldy #0
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; Done
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rts
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