268 lines
3 KiB
NASM
268 lines
3 KiB
NASM
.BANK 0 SLOT 0
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.ORG 0
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.SECTION "Decompression"
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;decompReq SRC, DST
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;Source must be in ROM, IRAM, BWRAM
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;Destination must be in IRAM, BWRAM
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.MACRO decompReq
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ldx.W \1
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stx $3011
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lda.B :\1
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sta $3013
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ldx.W \2
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stx $3014
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lda.B :\2
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sta $3016
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lda #$02
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sta $3010
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lda #$0F
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sta $2200
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lda #$01
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jsl WaitForSA1
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.ENDM
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Decomp:
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php
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phb
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sep #$20
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rep #$10
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lda $13
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pha
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plb
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stz $18
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ldy #$0000
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MainDecompLoop:
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phx
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ldx $11
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lda $0000,X
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inx
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bne DC_NoOF1
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jsr SBOF_Correction
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DC_NoOF1:
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stx $11
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plx
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sta $19
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cmp #$FF ;End of File?
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bne DC_Cont
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stz $00
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lda #$01
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sta $2209
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plb
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plp
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ply
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plx
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pla
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rtl
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DC_Cont:
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and #$E0
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cmp #$E0
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bne DC_NormalCommand
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;Command 111: Extended
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lda $19 ;Get Byte Value
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asl
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asl
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asl ;Shift out command
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and #$E0
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pha
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lda $19
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and #$03
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xba ;B=High bits of length
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phx
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ldx $11
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lda $0000,X
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inx
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bne DC_NoOF2
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jsr SBOF_Correction
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DC_NoOF2:
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stx $11
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plx
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bra DC_Main
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DC_NormalCommand:
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pha
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lda #$00
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xba ;B=0
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lda $19
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and #$1F
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DC_Main:
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tax
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inx ;X=Counter+1
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pla ;A=Command
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cmp #$00
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bpl DCC_plus
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jmp DCC_minus
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DCC_plus:
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cmp #$20
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beq DCC_Bytefill
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cmp #$40
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beq DCC_Wordfill
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cmp #$60
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beq DCC_Incfill
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DCC_Copy:
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phx
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ldx $11
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lda $0000,X
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inx
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bne DC_NoOF3
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jsr SBOF_Correction
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DC_NoOF3:
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stx $11
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plx
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sta [$14],Y
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iny ;Destination++=A
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dex
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bne DCC_Copy
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beq MainDecompLoop ;Next!
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DCC_Bytefill:
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phx
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ldx $11
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lda $0000,X
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inx
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bne DC_NoOF4
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jsr SBOF_Correction
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DC_NoOF4:
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stx $11
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plx
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DCC_Bytefill_Loop:
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sta [$14],Y
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iny
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dex
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bne DCC_Bytefill_Loop
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jmp MainDecompLoop
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DCC_Wordfill:
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phx
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ldx $11
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lda $0000,X
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inx
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bne DC_NoOF5
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jsr SBOF_Correction
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DC_NoOF5:
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xba
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lda $0000,X
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inx
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bne DC_NoOF6
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jsr SBOF_Correction
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DC_NoOF6:
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stx $11
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plx
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xba
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DCC_Wordfill_Loop:
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sta [$14],Y
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xba
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iny
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dex
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beq DCC_Wordfill_Out
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sta [$14],Y
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xba
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iny
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dex
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bne DCC_Wordfill_Loop
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DCC_Wordfill_Out:
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jmp MainDecompLoop
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DCC_Incfill:
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phx
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ldx $11
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lda $0000,X
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inx
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bne DC_NoOF7
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jsr SBOF_Correction
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DC_NoOF7:
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stx $11
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plx
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DCC_Incfill_Loop:
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sta [$14],Y
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ina
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iny
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dex
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bne DCC_Incfill_Loop
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jmp MainDecompLoop
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DCC_minus:
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cmp #$C0
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bcs DCC_C0plus
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DictionaryCopy:
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and #$20
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sta $18 ;Inverted bit
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phx
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ldx $11
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lda $0000,X
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inx
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bne DC_NoOF8
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jsr SBOF_Correction
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DC_NoOF8:
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sta $19
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lda $0000,X
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inx
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bne DC_NoOF9
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jsr SBOF_Correction
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DC_NoOF9:
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stx $11
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plx
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sta $1A
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DictionaryCopyStart:
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sep #$20
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DictionaryCopyLoop:
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phx
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phy
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ldy $19
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lda [$14],Y
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iny
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sty $19
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ply
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xba
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lda $18
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beq DictionaryCopyNoInvert
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xba
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eor #$FF
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xba
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DictionaryCopyNoInvert:
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xba
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sta [$14],Y
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iny
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plx
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dex
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bne DictionaryCopyLoop
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jmp MainDecompLoop
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DCC_C0plus:
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and #$20
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sta $18 ;Inverted bit
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phx
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ldx $11
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lda $0000,X
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inx
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bne DC_NoOF10
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jsr SBOF_Correction
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DC_NoOF10:
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stx $11
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plx
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sta $19
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stz $1A
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rep #$20
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tya
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sec
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sbc $4A
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sta $4A
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bra DictionaryCopyStart
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SBOF_Correction:
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pha
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phb
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pla
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cmp #$3F
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bmi BOF_case1
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beq BOF_case2
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cmp #$BF
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bmi BOF_case1
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ina
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ldx #$0000
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BOF_back:
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pha
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plb
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pla
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rts
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BOF_case1:
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ina
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ldx #$8000
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bra BOF_back
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BOF_case2:
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lda #$80
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ldx #$8000
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bra BOF_back
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.ENDS
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