mirror of
https://github.com/A2osX/A2osX.git
synced 2024-06-01 22:41:29 +00:00
167 lines
3.2 KiB
Plaintext
167 lines
3.2 KiB
Plaintext
NEW
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PREFIX
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AUTO 4,1
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.LIST OFF
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*--------------------------------------
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* Sliding Window = 4096
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*--------------------------------------
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WSIZE .EQ 4096 power of 2
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*--------------------------------------
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* Output BITSTREAM :
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* 0 : Lit (8)
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* 1 : Copy, L (4), P.HI (4), P.LO (8)
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*--------------------------------------
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Pak.LZ jsr Pak.In.Init Init SrcPtr,SrcCnt
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jsr Pak.Out.Init
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* future optimization, make P grows from 2 to 12 while increasing W size
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* lda #2 Ptr width starts at 2 bits
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* sta Pak.LZ.PWidth
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* lda #%00000011 Ptr Mask Starts at %000000000011
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* sta Pak.LZ.PMaskLO
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* stz Pak.LZ.PMaskHI
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lda #$ff
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sta Pak.LZ.WCnt
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sta Pak.LZ.WCnt+1 WCnt=!0
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.1 jsr Pak.In.GetRH Z if EOF
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beq .80
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cmp #3
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bcc .8 no more than 2 bytes left....store
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cmp #19 more than 18 bytes left, limit to 18
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bcc .2
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lda #18
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.2 tax X = Read ahead max size
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lda ZPSrcPtr make ZPSrcWPtr=ZPSrcPtr
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sta ZPSrcWPtr
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lda ZPSrcPtr
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sta ZPSrcWPtr
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lda Pak.LZ.WCnt
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sta ZPCnt
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lda Pak.LZ.WCnt+1
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sta ZPCnt+1
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stz Pak.LZ.BestLen
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.3 inc ZPCnt
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bne .4
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inc ZPCnt+1
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beq .7 reached begining of window....store
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lda ZPSrcWPtr make ZPSrcWPtr-=1
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sec
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sbc #1
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sta ZPSrcWPtr
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bcs .4
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dec ZPSrcWPtr+1
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.4 ldy #0
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phx save Read ahead max size
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.5 lda (ZPSrcPtr),y Try to find a match
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cmp (ZPSrcWPtr),y
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bne .6
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iny
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dex don't exceed 18 or Src Buffer
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bne .5
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.6 plx get back Read ahead max size
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cpy #3 matched a least 3 chars ?
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bcc .3 no....try one char back in Wnd
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cpy Pak.LZ.BestLen better than last match ?
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bcc .3 no....try one char back in Wnd
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sty Pak.LZ.BestLen
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lda ZPSrcWPtr
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sta Pak.LZ.BestPtr
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lda ZPSrcWPtr+1
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sta Pak.LZ.BestPtr+1
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bra .3
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.7 lda Pak.LZ.BestLen do we match something ?
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beq .8
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lda Pak.LZ.BestPtr
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sec
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sbc ZPSrcPtr
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sta Pak.LZ.BestPtr
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lda Pak.LZ.BestPtr+1
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sbc ZPSrcPtr+1
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sta Pak.LZ.BestPtr+1
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tya get len
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dec Adjust range 0-15
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dec
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dec
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ora Pak.LZ.BestPtr+1 merge with P.HI
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sec
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jsr Pak.Out.PutCA Put 9 bits 1+LLLL+PPPP
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bcs .99
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lda Pak.LZ.BestPtr Put 8 bits pppppppp
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jsr Pak.Out.PutA
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bcs .99
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tya
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bra .81
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.8 lda (ZPSrcPtr)
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clc
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jsr Pak.Out.PutCA Put 9 bits 0+xxxxxxxx
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bcs .99
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lda #1
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.81 jsr Pak.In.MoveFWA
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tya
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jsr LZ.MoveWndY
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bra .3
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bra .71
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.80 clc
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.99 rts
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*--------------------------------------
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Unpak.LZ
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clc
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rts
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*--------------------------------------
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LZ.MoveWndY tya
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sec
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sbc Pak.LZ.WCnt
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tax
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lda #0
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sbc Pak.LZ.WCnt+1
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cpx #WSIZE^$FF
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sbc /WSIZE^$FF
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bcs .1
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ldx #WSIZE^$FF
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lda /WSIZE^$FF
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.1 stx Pak.LZ.WCnt
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sta Pak.LZ.WCnt+1
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rts
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*--------------------------------------
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MAN
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SAVE USR/SRC/LIB/LIBPAK.S.LZ
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ASM
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