mirror of https://github.com/cc65/cc65.git
493 lines
14 KiB
ArmAsm
493 lines
14 KiB
ArmAsm
;
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; Extended memory driver for the Atari 130XE memory standard
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; Shawn Jefferson, 2012-08-11
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;
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; Banking Register $D301:
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; Bit 7: Self-Test on/off
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; Bit 6: Unused
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; Bit 5: Antic sees bank
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; Bit 4: CPU sees bank
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; Bit 3: bank control
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; Bit 2: bank control
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; Bit 1: BASIC on/off
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; Bit 0: OS RAM on/off
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;
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; Masks: %11100011 $E3 Bank 0
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; %11100111 $E7 Bank 1
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; %11101011 $EB Bank 2
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; %11101111 $EF Bank 3
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; %11111111 $FF Off
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;
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; Based on the Extended memory driver for the Apple II auxiliary memory
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; by
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; Stefan Haubenthal, 2003-12-12
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; Ullrich von Bassewitz, 2002-12-02
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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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.ifdef __ATARIXL__
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module_header _atrx130_emd
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.else
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module_header _atr130_emd
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.endif
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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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BANK = $4000 ; bank window
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STACK = $0100 ; stack location
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PAGES = 256 ; 4 x 16k banks
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; ------------------------------------------------------------------------
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; Data.
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.rodata
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banks: .byte $E3,$E7,$EB,$EF ; 130XE banks for cpu banking
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stacktest: sei
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ldy banks
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sty $D301
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tax ; A is set by caller
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inx
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stx $4000 ; change $4000
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ldy #$FF ; STACK+13
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sty $D301
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cmp $4000 ; changed?
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beq @1
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sec ; error
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bcs @2
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@1: clc
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@2: sta $4000 ; restore
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cli
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rts
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stacktest_end:
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stackcopy: sei ; disable interrupts
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@1: dex ; pre-decrement (full page x=0)
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ldy #$FF ; this will be replaced STACK+3
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sty $D301 ; set bank
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lda $FF00,x ; address to copy from STACK+8,+9
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ldy #$FF ; this will be replaced STACK+11
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sty $D301
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sta $FF00,x ; address to copy to STACK+16,+17
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cpx #0
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bne @1
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ldy #$FF ; portb_save STACK+23
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sty $D301
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cli ; enable interrupts
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rts
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stackcopy_end:
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stackcopy_byte: sei
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ldy #$FF ; STACK+2
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sty $D301
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lda $FFFF ; STACK+7 +8
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ldy #$FF ; STACK+10
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sty $D301
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sta $FFFF ; STACK+15 +16
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ldy #$FF ; STACK+18
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sty $D301
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cli
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rts
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stackcopy_byte_end:
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.data
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curpage: .byte $FF ; Current page number in bank (invalid)
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curbank: .byte $FF ; Current bank number
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.bss
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window: .res 256 ; Memory "window"
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portb_save: .res 1 ; portb state
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.code
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install_transfer:
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ldx #stackcopy_end - stackcopy - 1
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@1: lda stackcopy,x
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sta STACK,x
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dex
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bpl @1
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rts
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install_byte_transfer:
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ldx #stackcopy_byte_end - stackcopy_byte - 1
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@2: lda stackcopy_byte,x
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sta STACK,x
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dex
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bpl @2
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rts
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install_test:
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ldx #stacktest_end - stacktest - 1
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@3: lda stacktest,x
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sta STACK,x
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dex
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bpl @3
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rts
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setpage:
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tax ; save page
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and #$C0 ; mask out bank
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clc
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ror
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ror ; divide by 64
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ror ; 64 pages in each bank
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ror
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ror
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ror
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sta curbank ; Remember the new bank
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txa ; bring back page
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and #$3F ; mask out page
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sta curpage ; curpage in bank
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rts
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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 $D301 ; save state of portb
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sta portb_save
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tay
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jsr install_test ; doesn't touch Y
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sty STACK+13
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lda $4000 ; test for extended memory
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jsr STACK
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bcs @1
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lda #EM_ERR_OK
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rts
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@1: lda #EM_ERR_NO_DEVICE
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rts
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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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; 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: jsr setpage ; extract the bank/page
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add #>BANK ; $4000 + page (carry is cleared)
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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 install_transfer ; Transfer one page
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ldx curbank
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lda banks,x
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sta STACK+3 ; set bank to copy from
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; lda ptr1
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; sta STACK+8
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lda ptr1+1
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sta STACK+9 ; set copy from address
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lda portb_save
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sta STACK+11 ; set portb restore
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sta STACK+23 ; set final portb restore
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lda ptr2
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sta STACK+16
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lda ptr2+1
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sta STACK+17 ; set copy to address
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ldx #0 ; full page copy
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jsr STACK ; do the copy!
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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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jsr setpage ; extract bank/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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cmp #$FF
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beq commit_done ; Jump if no page mapped
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clc
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add #>BANK
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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/all bytes
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jsr install_transfer ; Transfer one page
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lda portb_save
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sta STACK+3 ; set bank to copy from
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sta STACK+23 ; set final portb restore
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lda ptr1
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sta STACK+8
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lda ptr1+1
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sta STACK+9 ; set copy from address
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ldx curbank
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lda banks,x
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sta STACK+11 ; set bank to copy to
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;lda ptr2
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;sta STACK+16
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lda ptr2+1
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sta STACK+17 ; set copy to address
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ldx #0 ; full page copy
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jsr STACK ; do the copy!
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commit_done:
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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 ptr3
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stx ptr3+1 ; Save the passed em_copy pointer
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jsr install_byte_transfer ; install the stack copy routine
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ldy #EM_COPY::OFFS
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lda (ptr3),y
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sta STACK+7 ; offset goes into BANK low
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ldy #EM_COPY::PAGE
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lda (ptr3),y
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sta tmp1 ; save page for later
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;add #>BANK
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;sta STACK+8 ; BANK + page goes into BANK high
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ldy #EM_COPY::BUF
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lda (ptr3),y
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sta STACK+15 ; buffer goes into dest low
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iny
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lda (ptr3),y
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sta STACK+16 ; buffer goes into dest high
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ldy #EM_COPY::COUNT
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lda (ptr3),y ; Get bytes in last page
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sta ptr4
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iny
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lda (ptr3),y ; Get number of pages
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sta ptr4+1
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lda tmp1 ; extract bank/page
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jsr setpage ; sets curbank/curpage
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lda curpage
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add #>BANK ; add to BANK address
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sta STACK+8 ; current page in bank
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ldx curbank
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lda banks,x
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sta STACK+2 ; set bank in stack
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lda portb_save
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sta STACK+10 ; set bank restore in stack
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sta STACK+18 ; set final restore too
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copyfrom_copy:
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lda ptr4 ; check if count is zero
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bne @4
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lda ptr4+1
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beq done
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@4: jsr STACK ; copy one byte
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sec
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lda ptr4
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sub #1
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sta ptr4
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bcs @1
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lda ptr4+1
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beq @1
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sub #1
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sta ptr4+1
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@1: inc STACK+7 ; increment address in BANK
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bne @2
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inc STACK+8
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lda STACK+8
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cmp #$80 ; we stepped outside bank
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bne @2
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inc curbank ; get next bank
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ldx curbank
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lda banks,x
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sta STACK+2 ; set new bank
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lda #$40 ; set address back to $4000
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sta STACK+8
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@2: inc STACK+15 ; increment buffer address
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bne @3
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inc STACK+16
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@3: jmp copyfrom_copy ; copy another byte
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done:
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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:
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sta ptr3
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stx ptr3+1 ; Save the passed em_copy pointer
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jsr install_byte_transfer ; install the stack copy routine
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ldy #EM_COPY::OFFS
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lda (ptr3),y
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sta STACK+15 ; offset goes into BANK low
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ldy #EM_COPY::PAGE
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lda (ptr3),y
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sta tmp1 ; save page for later
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;add #>BANK
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;sta STACK+16 ; BANK + page goes into BANK high
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ldy #EM_COPY::BUF
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lda (ptr3),y
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sta STACK+7 ; buffer goes into dest low
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iny
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lda (ptr3),y
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sta STACK+8 ; buffer goes into dest high
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ldy #EM_COPY::COUNT
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lda (ptr3),y ; Get bytes in last page
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sta ptr4
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iny
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lda (ptr3),y ; Get number of pages
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sta ptr4+1
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lda tmp1 ; extract bank/page
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jsr setpage ; sets curbank/curpage
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lda curpage
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add #>BANK ; add to BANK address
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sta STACK+16 ; current page in bank
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ldx curbank
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lda banks,x
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sta STACK+10 ; set bank in stack
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lda portb_save
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sta STACK+2 ; set bank restore in stack
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sta STACK+18 ; set final restore too
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copyto_copy:
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lda ptr4 ; check if count is zero
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bne @4
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lda ptr4+1
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beq done
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@4: jsr STACK ; copy one byte
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sec
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lda ptr4
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sub #1
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sta ptr4
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bcs @1
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lda ptr4+1
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beq @1
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sub #1
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sta ptr4+1
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@1: inc STACK+15 ; increment address in BANK
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bne @2
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inc STACK+16
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lda STACK+16
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cmp #$80 ; we stepped outside bank
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bne @2
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inc curbank ; get next bank
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ldx curbank
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lda banks,x
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sta STACK+10 ; set new bank
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lda #$40 ; set address back to $4000
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sta STACK+16
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@2: inc STACK+7 ; increment buffer address
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bne @3
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inc STACK+8
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@3: jmp copyto_copy ; copy another byte
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