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|
;
; LZ48 decrunch
;
; In ; HL=compressed data address
; ; DE=output data address
; Out ; HL last address of compressed data read (you must inc once for LZ48 stream)
; ; DE last address of decrunched data write +1
; ; BC always 3
; ; A always zero
; ; IXL undetermined
; ; flags (inc a -> 0)
; Modif ; AF, BC, DE, HL, IXL
LZ48_decrunch
ldi
ld b,0
nextsequence
ld a,(hl)
inc hl
cp #10
jr c,lzunpack ; no literal bytes
ld ixl,a
and #f0
rrca
rrca
rrca
rrca
cp 15 ; more bytes for literal length?
jr nz,copyliteral
getadditionallength
ld c,(hl) ; get additional literal length byte
inc hl
add a,c ; compute literal length total
jr nc,lengthNC
inc b
lengthNC
inc c
jr z,getadditionallength ; if last literal length byte was 255, we have more bytes to process
copyliteral
ld c,a
ldir
ld a,ixl
and #F
lzunpack
add 3
cp 18 ; more bytes for match length?
jr nz,readoffset
getadditionallengthbis
ld c,(hl) ; get additional match length byte
inc hl
add a,c ; compute match length size total
jr nc,lengthNCbis
inc b
lengthNCbis
inc c
jr z,getadditionallengthbis ; if last match length byte was 255, we have more bytes to process
readoffset
ld c,a
; read encoded offset
ld a,(hl)
inc a
ret z ; LZ48 end with zero offset
inc hl
push hl
; source=dest-copyoffset
; A != 0 here
neg
ld l,a
ld h,#ff
add hl,de
copykey
ldir
pop hl
jr nextsequence
|
