417 lines
12 KiB
Plaintext
417 lines
12 KiB
Plaintext
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;
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; LZ4FH uncompression for 6502
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; By Andy McFadden
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; Version 1.0.1, August 2015
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;
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; Refactored for size & speed
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; by Peter Ferrie.
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;
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; Developed with Merlin-16
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; Ported to DASM by Steven Hugg
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; Apache 2.0 license
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; http://www.apache.org/licenses/LICENSE-2.0
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;
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processor 6502
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org $0803
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;
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; Constants
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;
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lz4fh_magic equ $66 ;ascii 'f'
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tok_empty equ 253
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tok_eod equ 254
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;
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; Variable storage
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;
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srcptr equ $3c ;2b a1l
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dstptr equ $3e ;2b a1h
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copyptr equ $00 ;2b
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savmix equ $02 ;1b
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savlen equ $03 ;1b
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;
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; ROM routines
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;
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bell equ $ff3a
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monitor equ $ff69
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entry
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sta $c050
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sta $c052
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sta $c057
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jsr ClrScr
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jsr UnpackLZ4FH
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.endless
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jmp .endless
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UnpackLZ4FH:
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lda #<LZDATA ;copy source address to zero page
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sta srcptr
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lda #>LZDATA
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sta srcptr+1
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lda #0 ;copy destination address to zero page
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sta dstptr
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lda #$20
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sta dstptr+1
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sta _desthi+1
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ldy #$00
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lda (srcptr),y
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cmp #lz4fh_magic ;does magic match?
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beq goodmagic
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fail
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jsr bell
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jmp monitor
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; These stubs increment the high byte and then jump
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; back. This saves a cycle because branch-not-taken
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; becomes the common case. We assume that we're not
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; unpacking data at $FFxx, so BNE is branch-always.
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hi2
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inc srcptr+1
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bne nohi2
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hi3
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inc srcptr+1
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clc
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bcc nohi3
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hi4
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inc dstptr+1
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bne nohi4
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notempty
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cmp #tok_eod
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bne fail
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rts ;success!
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; handle "special" match values (value in A)
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specialmatch
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cmp #tok_empty
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bne notempty
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tya ;empty match, advance srcptr
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adc srcptr ; past and jump to main loop
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sta srcptr
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bcc mainloop
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inc srcptr+1
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bne mainloop
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hi5
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inc srcptr+1
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clc
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bcc nohi5
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goodmagic
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inc srcptr
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bne mainloop
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inc srcptr+1
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mainloop
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; Get the mixed-length byte and handle the literal.
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ldy #$00
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lda (srcptr),y ;get mixed-length byte
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sta savmix
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lsr ;get the literal length
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lsr
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lsr
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lsr
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beq noliteral
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cmp #$0f ;sets carry for >= 15
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bne shortlit
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inc srcptr
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beq hi2
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nohi2
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lda (srcptr),y ;get length extension
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adc #14 ;(carry set) add 15 - will not exceed 255
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; at this point, srcptr holds the address of the "mix"
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; word or the length extension, and dstptr holds the
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; address of the next output location. So we want to
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; read from (srcptr),y+1 and write to (dstptr),y.
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; we can do this by sticking the DEY between the LDa
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; and STa.
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;
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; We could save a couple of cycles by substituting
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; addr,y in place of (dp),y, but the added setup cost
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; would only benefit longer literal strings.
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shortlit tax
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tay
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.litloop
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lda (srcptr),y ;5
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dey ;2 if len is 255, copy 0-254
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sta (dstptr),y ;6
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bne .litloop ;3 -> 16 cycles/byte
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; advance srcptr by savlen+1, and dstptr by savlen
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txa
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sec ;this gets us the +1
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adc srcptr
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sta srcptr
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bcs hi3
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nohi3 ;carry cleared by hi3
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txa
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adc dstptr
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sta dstptr
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bcs hi4
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nohi4
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dey ;Y=0; DEY so next INY goes to 0
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; Handle match. Y holds an offset into srcptr such
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; that we need to increment it once to get the next
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; interesting byte.
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noliteral
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lda savmix
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and #$0f
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cmp #$0f
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bcc .shortmatch ;BCC
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iny
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lda (srcptr),y ;get length extension
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cmp #237 ;"normal" values are 0-236
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bcs specialmatch ;BCS
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adc #15 ;will not exceed 255
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; Put the destination address into copyptr.
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.shortmatch
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adc #4 ;min match; won't exceed 255
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sta savlen ;save match len for later
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tax ;and keep it in X
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iny
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lda (srcptr),y ;match offset, lo
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sta copyptr
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iny
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lda (srcptr),y ;match offset, hi
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_desthi ora #$00 ;OR in hi-res page
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sta copyptr+1
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; advance srcptr past the encoded match while we still
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; remember how many bytes it took to encode. Y is
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; indexing the last value used, so we want to go
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; advance srcptr by Y+1.
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tya
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sec
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adc srcptr
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sta srcptr
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bcs hi5
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nohi5 ;hi5 clears carry
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; Copy the match. The length is in X. Note this
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; must be a forward copy so overlapped data works.
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;
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; We know the match is at least 4 bytes long, so
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; we could save a few cycles by not doing the
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; aDC #4 earlier, and unrolling the first 4
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; load/store operations here.
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ldy #$00
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.copyloop
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lda (copyptr),y ;5
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sta (dstptr),y ;6
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iny ;2
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dex ;2
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bne .copyloop ;3 -> 18 cycles/byte
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; advance dstptr past copied data
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lda dstptr
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adc savlen ;carry is clear
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sta dstptr
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bcc mainloop
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inc dstptr+1
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bne mainloop ;always (not unpacking at $FFxx)
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ClrScr:
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lda #$20
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sta .clrloop+2
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ldy #0
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lda #0
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.clrloop sta $2000,y
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iny
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bne .clrloop
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inc .clrloop+2
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ldx .clrloop+2
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cpx #$40
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bne .clrloop
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rts
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LZDATA:
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; WORLDMAP file
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hex 661f7f1400002001002900b040014019
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hex 0000007c000008290041030600032a00
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hex 43065433002900980000403f00002603
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hex 0059005102000000202a000668000249
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hex 002f0100128100134080001536770011
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hex 042900213c6429001a0f9f006760004b
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hex 0000025900536000000008e2002f3066
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hex 27740025043c5900170ca30083106040
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hex 1370472102a5005a1000000018810014
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hex 0357014f0600071c2674005844780300
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hex 007800140ce0004510000004a3005a20
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hex 781f0030810014017f003f0818000e73
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hex 00430c003010350137700106a2000958
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hex 00576003044003f201420a607c0fa600
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hex 121e290017059d000a2c020875001030
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hex 6e0134000e075900617c7f01007c0157
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hex 011306590010222c005a0e0c20030c9a
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hex 002270063d021220400192030c000440
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hex 01000660d90008ad021b30d8010f0176
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hex 00f2031e18400100400700067f1f6a38
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hex 0c4001000f630150387e00002c0c034a
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hex 39005000810022700f3f0014014a005f
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hex 604001000c017e004f330000600ceb02
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hex 2400042c026230005c1b00422802162c
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hex 49002d1f0380001403bc0113082a021f
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hex 401580000f2178005001006000403800
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hex 133e5601223e029b02477805541fa100
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hex 6f7e03007e0702425a002a3200b10021
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hex 204428001a079f007a30004e00000208
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hex 6d0204ea002f1c22267400260e06ad02
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hex 04ea000141016830003f647c204c013a
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hex 1000005a00190885030f1077002d7001
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hex 9c0029047cdc0104c404762038007031
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hex 0006cb012c0e30570523016080002f78
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hex 0f0ef20153381800781fb50037304003
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hex a20019092e024702040001f201750e40
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hex 1738004001c3002770079d002f400105
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hex 6902581f0000637109027702407b7f07
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hex 0010c304aa3360034001023860000e9a
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hex 00130f210212234001210206cd021a02
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hex d8000440050a9b000f01770012707f00
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hex a37c71004f2008400040014803401e00
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hex 00070c031d332c034630060006c20412
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hex 404c001f08017e001f3e0ee802340660
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hex 07a700621800761e004e7b0016244900
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hex 5c0703011800d90124003cc2032f4001
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hex 4ccc0311402c04210c03c40012303606
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hex 22000cec052a7400a10038380f0a5900
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hex 110691030348030f2973001c13b00424
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hex 7c01b500431e704301a6007a10004c01
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hex 0000049d00130c6b001f0627f3043a0a
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hex 030c300513303f057f10006e07002006
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hex 094d05140cb3001f021373004d401f7f
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hex 019d051a0cb303250001330535730f03
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hex a3006a6003600018009b001f3017e903
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hex 537830037801350136607101a2002a40
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hex 0d59001706df006200001c0033604e00
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hex 0288022850015c060f06e80267010060
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hex 3f5f038103857f466a7d0d001000d800
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hex ba4013205e4101037840010e81002518
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hex 3c9e0200e3022f420307cd061f1810e8
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hex 0634400107df00523078410070d10060
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hex 40471f0000034f001d132c0346600700
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hex 0cd60212604c004f180040011fd60373
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hex 40073000400118c20343460300789a07
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hex 151e4a005a0e420108039b0045030000
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hex 68c2071f004fcc074240134004750002
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hex 72080367054a481b0700a10038000e08
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hex 590014045501000c030f2973002a1100
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hex b100246001b40044701b1066cd083a18
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hex 0000d80805d70c4f4000000227f30436
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hex 3b010cb30a02d10804e10a5766050020
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hex 044d011c3059051f04186a097f607f7f
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hex 417f00400b9c09044c0902e700451e78
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hex 0160cc095a00400008006b021f1007e9
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hex 021c1c2e0b4460030e0f350d205b0310
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hex 0603ce090aad06560606600300c00242
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hex 140020204e0002580018589c091f6009
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hex 680a45010f037c58006966434f3a6d39
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hex 970a8c19307e4001014000ac0a227020
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hex 49001223e100226300cd020f01d3061f
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hex 0c11e80324410fdf0280103c41001c00
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hex 7e016900137f4b004c200f6071810012
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hex 04980b2418783a096f40010010004020
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hex d50382600c1f0000077c1f900723043a
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hex c30235016c1f4a00241e42ef0508b503
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hex 234007d10c1f604dcb0b00e805101653
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hex 0a1570240a0367013a685101a0002c38
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hex 3006020336001340640e0f2477003a40
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hex 1104b1002238033401644003100c1027
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hex cd084d0f000003b0071f062feb0c1725
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hex ac0a17303a0d5a300840630f4a0d1c20
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hex 5905140633010f107205933f00784118
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hex 007041038e071403a6051a005b10255e
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hex 013301560c40006001a5105f070c0040
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hex 0114dc0d2a76012e0200390a14073501
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hex 01ad06102e2d004a03003c0e310f3704
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hex 700f3f0e303c0020a50605bd0c186cdb
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hex 001f2006e8021107290d2506065f0786
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hex 0f583f0f60007000d800321f103ea70e
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hex 2a1c009a0018273e0a40003f00001703
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hex 1f0400d3062f300410e8032438479c02
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hex 901c1c644101060003011e06133a4b00
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hex 4e300b30012e0f01a70033704f0f5101
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hex 0027132f006020d50382266c0100002f
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hex 3c70d10823042e590026314821065d3c
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hex 5e007818b00723000c3a091f204dcb0b
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hex 1178470e560320000400c80311100f06
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hex 2a7300a0002a6e388100150867104f01
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hex 0040702774003a601807b100237c0145
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hex 066306101c506101ce0900e7100acf03
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hex 23010071091f0129f1083567010b5900
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hex 17203a0d8f607f1f0378066006094d11
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hex 1302ea012f40010e7300406001004e22
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hex 0f137f58002f4c0701a6115638007833
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hex 01b3004640072001a5002a0404fe0a2f
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hex 001c06e902393803073103775e61637e
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hex 037f01d702aa403b0040016002600700
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hex 0702370c071f3f0e31680020d7143260
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hex 677daa000759001f2007e70201210270
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hex 6a037c07001c003d1292180e106c0c40
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hex 036001520e70601f00007c300ea70e4a
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hex 030138008100192c71024f7301000804
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hex cf123f600c0e0fe903246c44db04e37e
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hex 040c000102004101001860033e4b003d
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hex 700a1880004506000003340d13184803
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hex 2f38301fd503307c3f361006023c0242
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hex 10000c66290036033f0c210a5e287000
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hex 7870b0131338c0020f4eca1300571430
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hex 3440011b0f069902121c9f120a9f003a
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hex 404f28a911181867141f582774003a20
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hex 7801b1001236380364037e0c187070cc
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hex 1116306d1106780023600362012f0432
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hex 2674003946410ddd00240018b5066710
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hex 0040074003cd180f0758150f0ff20121
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hex 7c0332182340738b02147da515190631
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hex 0323000ce805022b1636072003a50058
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hex 3c0700000f5c021f0605690220406f2e
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hex 0d163d3403517347637f01c504160836
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hex 0379400130062003007800471848055c
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hex bf0231580130cd0231387c4728001812
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hex 5b161f100b6816f3040e00000c703f00
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hex 1c780770030630587c030660cd08613c
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hex 700300602fa6124a4701280081003728
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hex 7003a300511e01000841d0121d039700
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hex 1f0810e803244747c600606f7c180001
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hex 03210f440e70011c4703131fa0170a5b
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hex 002406003a0d130c6c0c2f6f1f1fd503
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hex 1106591a232006650804701948062c64
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hex 0122142a60438000140167001f6050c8
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hex 1313002c1808b3002f783f0241182a40
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hex 69d602173067102f604c2774003a3c28
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hex 00b1001203400177406319184021034d
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hex 013a080002db011530610d1f1627f418
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hex 2a61069e001708e00d07ca010e551114
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hex 032c022f08700ff201430403601fd10c
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hex 64707f03007818a5001a02ae19053c02
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hex 1103c20023201ea5005906000078012b
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hex 0a3f4000020569022060063801263f03
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hex 5e0146076307011b1200510410018b0b
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hex 490420070c7800577058044006c00221
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hex 0118cd02410c70010306030f135b1a14
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hex 040c0ad0130e0007007c1c7e7f215e3b
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hex 0e3c0612786c01500e407f793ca70e3d
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hex 6d00780406277e017c0032010078cf1a
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hex 0d80000030001f300d6b031406ac0662
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hex 6039403c0003a81d157849003f401706
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hex 012d1b1504340d1f0628cc0331030013
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hex c21821000cbc0c130c711536047c6621
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hex 0a005a062c0343b1031a006a000f1500
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hex 000ffe
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