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https://github.com/cc65/cc65.git
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377 lines
10 KiB
ArmAsm
377 lines
10 KiB
ArmAsm
;
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; Extended memory driver for 65816 based extra RAM. Driver works without
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; problems when statically linked.
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;
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; Marco van den Heuvel, 2015-12-01
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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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.macpack module
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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module_header _c64_65816_emd
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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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; Data.
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.bss
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isnotscpu: .res 1 ; SuperCPU not present
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curpage: .res 1 ; Current page number
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curbank: .res 1 ; Current bank number (+1)
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bankcount: .res 1 ; Number of available banks (pages = banks * 256)
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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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sei
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clc
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sed
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lda #$99
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adc #$01 ; on 65C02, 65SC02, 65CE02, 65802 and 65816 sets the zero flag correctly
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cld
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bne @not_present
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clc
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.P816
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sep #$01 ; nop #$01 on 65C02/65SC02 and lda ($01,s),y on 65CE02
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.P02
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bcc @not_present
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lda $d0bc
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and #$80
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sta isnotscpu
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lda $07e8
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pha ; save value incase it was used somewhere else
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ldx #$ff
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@fillloop: ; fill from top (bank 255) to bottom
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txa
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pha
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.P816
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plb ; pull dbr
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.P02
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stx $07e8
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dex
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cpx #$ff
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bne @fillloop
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inx
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@compareloop: ; check from bottom to top
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txa
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pha
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.P816
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plb
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.P02
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cmp $07e8
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bne @found_pages
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.P816
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inc
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.P02
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sta $07e8
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cmp $07e8
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bne @found_pages
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inx
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bne @compareloop
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@found_pages:
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dex
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lda #$00
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pha
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.P816
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plb
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.P02
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pla
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sta $07e8
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cli
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lda isnotscpu
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bne @noextradex
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dex
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@noextradex:
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stx bankcount
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lda #<EM_ERR_OK
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ldx #>EM_ERR_OK
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rts
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@not_present:
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cli
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lda #<EM_ERR_NO_DEVICE
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ldx #>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 #$00 ; a whole bank is either usable or not
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ldx bankcount
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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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stx curbank ; Remember the new bank
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sta ptr2+1 ; src address low
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lda #$00
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sta ptr2 ; src address high
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inx
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ldy isnotscpu ; check if not scpu
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bne @notscpu
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inx
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@notscpu:
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stx tmp2 ; src bank
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sta tmp1 ; dst bank
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sta ptr3+1 ; length high
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lda #$ff
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sta ptr3 ; length low
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lda #<window
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sta ptr1 ; dst address low
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ldx #>window
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stx ptr1+1 ; dst address high
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jsr transfer
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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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stx curbank ; Remember the bank
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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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sta ptr1+1 ; dst high
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ldx #$00
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stx ptr1 ; dst low
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lda #<window
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sta ptr2 ; src low
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lda #>window
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sta ptr2+1 ; src high
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stx ptr3+1 ; length high
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lda #$ff
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sta ptr3 ; length low
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stx tmp2 ; src bank
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ldy curbank ; Get the current bank
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iny
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ldx isnotscpu
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bne @notascpu
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iny
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@notascpu:
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sty tmp1 ; dst bank
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jsr transfer
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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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sta ptr4
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stx ptr4+1 ; Save the passed em_copy pointer
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ldy #EM_COPY::COUNT+1 ; start at the end of the struct
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lda (ptr4),y ; get high byte of count
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tax
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dey
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lda (ptr4),y ; get low byte of count
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bne @nodex
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dex
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@nodex:
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.P816
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dec
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.P02
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sta ptr3 ; length low
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stx ptr3+1 ; length high
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dey
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lda (ptr4),y ; get bank
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.P816
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inc
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.P02
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ldx isnotscpu
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bne @notscpu64
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.P816
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inc
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.P02
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@notscpu64:
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sta tmp2 ; src bank
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dey
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lda (ptr4),y ; get page
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sta ptr2+1 ; src high
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dey
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lda (ptr4),y ; get offset in page
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sta ptr2 ; src low
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dey
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lda (ptr4),y ; get memory buffer high
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sta ptr1+1 ; dst high
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dey
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lda (ptr4),y ; get memory buffer low
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sta ptr1 ; dst low
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lda #$00
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sta tmp1 ; dst bank
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jsr transfer
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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 ptr4
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stx ptr4+1 ; Save the passed em_copy pointer
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ldy #EM_COPY::COUNT+1 ; start at the end of the struct
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lda (ptr4),y ; get high byte of count
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tax
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dey
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lda (ptr4),y ; get low byte of count
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bne @nodex2
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dex
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@nodex2:
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.P816
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dec
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.P02
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sta ptr3 ; length low
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txa
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sta ptr3+1 ; length high
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dey
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lda (ptr4),y ; get bank
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.P816
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inc
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.P02
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ldx isnotscpu
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bne @notascpu64
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.P816
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inc
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.P02
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@notascpu64:
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sta tmp1 ; dst bank
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dey
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lda (ptr4),y ; get page
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sta ptr1+1 ; dst high
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dey
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lda (ptr4),y ; get page offset
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sta ptr1 ; dst low
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dey
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lda (ptr4),y ; get memory buffer high
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sta ptr2+1 ; src low
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dey
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lda (ptr4),y ; get memory buffer low
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sta ptr2 ; src high
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lda #$00
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sta tmp2 ; src bank
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jsr transfer
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rts
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; ------------------------------------------------------------------------
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; Helper function for moving a block, the following is used:
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; ptr1: dst
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; ptr2: src
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; ptr3: length
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; tmp1: dst bank
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; tmp2: src bank
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transfer:
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.P816
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.A8
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.I8
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sei
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pha
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phx
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phy
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ldx tmp1 ; load srcbank
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stx @move+1 ; store srcbank in move + 1
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ldy tmp2 ; load dstbank
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sty @move+2 ; store dstbank in move + 2
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clc ; switch to native mode
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xce
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php ; save status bits
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rep #%00110000 ; set A and index to 16bit
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.A16
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.I16
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ldy ptr1
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ldx ptr2
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lda ptr3
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@move:
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mvn 0,0
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plp ; restore status bits
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.A8
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.I8
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lda #$00
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pha
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plb ; restore dbr
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sec
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xce ; switch to emul mode
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ply
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plx
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pla
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cli
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rts
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.P02
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