110 lines
1.3 KiB
ArmAsm
110 lines
1.3 KiB
ArmAsm
;LZ4 data decompressor for Apple II
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;Peter Ferrie (peter.ferrie@gmail.com)
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;
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;from http://pferrie.host22.com/misc/appleii.htm
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;Converted to ATasm by Rob McMullen
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;unpacker variables, set in main.s
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; src = $0 ; source packed data
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; dst = $2 ; destination unpacked data
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; end = $4 ; end of source packed data
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; count = $6 ; temporary variable
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; delta = $8 ; temporary variable
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unpack_lz4 ldy #0
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parsetoken
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jsr getsrc
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pha
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lsr
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lsr
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lsr
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lsr
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beq copymatches
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jsr buildcount
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tax
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jsr docopy
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lda src
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cmp end
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lda src+1
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sbc end+1
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bcs done
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copymatches
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jsr getsrc
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sta delta
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jsr getsrc
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sta delta+1
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pla
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and #$0f
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jsr buildcount
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clc
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adc #4
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tax
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bcc ?1
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inc count+1
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?1 lda src+1
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pha
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lda src
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pha
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sec
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lda dst
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sbc delta
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sta src
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lda dst+1
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sbc delta+1
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sta src+1
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jsr docopy
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pla
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sta src
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pla
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sta src+1
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jmp parsetoken
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done
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pla
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rts
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docopy
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jsr getput
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dex
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bne docopy
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dec count+1
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bne docopy
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rts
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buildcount
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ldx #1
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stx count+1
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cmp #$0f
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bne ?3
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?1 sta count
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jsr getsrc
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tax
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clc
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adc count
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bcc ?2
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inc count+1
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?2 inx
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beq ?1
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?3 rts
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getput
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jsr getsrc
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putdst
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sta (dst), y
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inc dst
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beq ?1
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rts
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?1 inc dst+1
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rts
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getsrc
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lda (src), y
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inc src
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beq ?1
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rts
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?1 inc src+1
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rts
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