A2osX/SHARED/X.UNARC.S.txt

NEW
  AUTO 3,1
*--------------------------------------
* ZPInBufPtr = Ptr to Shunk Data
* ZPOutBufPtr = Ptr to Uncompressed Data
*--------------------------------------
* ZPnCnt = !ZPULen
* ZPPtr1
* ZPPtr2
* ZPInMask
* ZPSTRLenBits
* ZPBLLenBits
* ZPBLOfsLBits
* ZPBLOfsHBits
* ZPTOPCnt
*--------------------------------------
X.UnArc			jsr X.UnArc.GetByte		ULEN LO
				eor #$ff
				sta ZPnCnt

				jsr X.UnArc.GetByte		ULEN HI
				eor #$ff
				sta ZPnCnt+1

				jsr X.UnArc.GetByte		TBLBITS LO
				sta ZPPtr1

				jsr X.UnArc.GetByte		TBLBITS HI
				sta ZPPtr1+1
				ora ZPPtr1
				bne X.UnArc.ARC
*--------------------------------------
X.UnArc.STORE	ldx ZPnCnt				!LEN LO

				ldy #0

.1				inx
				bne .2

				inc ZPnCnt+1
				beq .8

.2				lda (ZPInBufPtr),y
				sta (ZPOutBufPtr),y
				iny
				bne .1

				inc ZPInBufPtr+1
				inc ZPOutBufPtr+1

				bra .1

.8				clc
				rts
*--------------------------------------
X.UnArc.ARC		lda #$80
				sta ZPTOPCnt			Default to no TOP bytes...
				sta ZPSTRLenBits		...and no long length for STR...
				sta ZPBLLenBits			...and BL
				sta ZPInMask			Init Bit shifter

				lda ZPPtr1+1
				and #%01111111			-llloooo
				beq  .13				no BL/STR

				lsr
				lsr
				lsr
				lsr
				sta ZPBLLenBits			lll

				lda ZPPtr1+1			----oooo
				and #%00001111

				ldx #0
				cmp #8
				bcc .10

*				sec
				sbc #8
				tax
				lda #8

.10				sta ZPBLOfsLBits
				stx ZPBLOfsHBits

				lda ZPPtr1				sss-----

				lsr
				lsr
				lsr
				lsr
				lsr
				beq .13

				sta ZPSTRLenBits

.13				lda ZPPtr1+1			c-------
				asl
				lda ZPPtr1				---ccccc
				and #%00011111
				rol
				beq X.UnArc.ARC.LOOP

				sta ZPTOPCnt

				ldx ZPInBufPtr			ZPPtr1 = TOP table
				stx ZPPtr1
				ldx ZPInBufPtr+1
				stx ZPPtr1+1

				clc
				adc ZPInBufPtr			skip TOP table
				sta ZPInBufPtr
				bcc X.UnArc.ARC.LOOP

				inc ZPInBufPtr+1
*--------------------------------------
X.UnArc.ARC.LOOP
				bit ZPSTRLenBits
				bpl X.UnArc.ARC.LOOPBL

.1				jsr X.UnArc.Single
				bne .1

				clc
				rts
*--------------------------------------
X.UnArc.ARC.LOOPBL
				jsr X.UnArc.GetBitInC
				bcs .60					-> STRBL	

				jsr X.UnArc.Single
				bne X.UnArc.ARC.LOOPBL

				clc
				rts				
*--------------------------------------
* STRBL
*--------------------------------------
.60				jsr X.UnArc.GetBitInC
				bcs .70					-> BL
*--------------------------------------
* STR
*--------------------------------------
*				bit ZPSTRLenBits
*				bmi .63					no long len

				jsr X.UnArc.GetBitInC
				bcs .61					-> Long Len

.63				ldx #ARC.B.SHORTSTR.W
				jsr X.UnArc.GetXBitInA

				clc
				adc #STR.MIN
				bra .62

.61				ldx ZPSTRLenBits
				jsr X.UnArc.GetXBitInA

				clc
				adc #STR.MID

.62				pha						STR len

				jsr X.UnArc.Single

				pla
				dec
				bne .62

.81				bra .80
*--------------------------------------
* BL
*--------------------------------------
.70				bit ZPBLLenBits
				bmi .73					no long len

				jsr X.UnArc.GetBitInC
				bcs .71					-> Long Len

.73				ldx #ARC.B.SHORTBLL.W
				jsr X.UnArc.GetXBitInA

				clc
				adc #BLL.MIN
				bra .72
*--------------------------------------
.71				ldx ZPBLLenBits
				jsr X.UnArc.GetXBitInA

				clc
				adc #BLL.MID

.72				sta ZPPtr2				save BL Len....

* BLOFS
				pha

				ldy #0
				ldx ZPBLOfsHBits
				beq .75

				jsr X.UnArc.GetXBitInA

				tay

.75				jsr X.UnArc.Get8BitInA	YA=Offset

				clc
				adc ZPPtr2				ZPPtr2=BL Len+Offset
				sta ZPPtr2
				
				tya
				adc #0
				sta ZPPtr2+1

				lda ZPOutBufPtr
				sec
				sbc ZPPtr2
				sta ZPPtr2

				lda ZPOutBufPtr+1
				sbc ZPPtr2+1
				sta ZPPtr2+1

				plx						Get Back BL Len
				ldy #0

.76				lda (ZPPtr2),y
				jsr X.UnArc.PutByte

				iny
				dex
				bne .76

.80				lda ZPnCnt
				and ZPnCnt+1
				inc
				beq .88

				jmp X.UnArc.ARC.LOOPBL

.88				clc
				rts
*--------------------------------------
X.UnArc.Single	bit ZPTOPCnt
				bmi .1					no TOP Table

				jsr X.UnArc.GetBitInC
				bcs .3					->TOP0
*--------------------------------------
* RAW
*--------------------------------------
.1				jsr X.UnArc.Get8BitInA
				bra X.UnArc.PutByte
*--------------------------------------
.3				jsr X.UnArc.GetBitInC
				bcs .4					->TOP8
*--------------------------------------
* TOP0/4
*--------------------------------------
				ldx #ARC.B.TOP0.W-1
				jsr X.UnArc.GetXBitInA
				bra .51
*--------------------------------------
.4				jsr X.UnArc.GetBitInC
				bcs .5					->TOP16
*--------------------------------------
* TOP8
*--------------------------------------
				ldx #ARC.B.TOP8.W-2
				jsr X.UnArc.GetXBitInA
				ora #%1000
				bra .51
*--------------------------------------
* TOP16
*--------------------------------------
.5				ldx #ARC.B.TOP16.W-2
				jsr X.UnArc.GetXBitInA
				ora #%10000

.51				tay
				lda (ZPPtr1),y
*--------------------------------------
* fall in PutByte
*--------------------------------------
X.UnArc.PutByte	inc ZPnCnt
				bne .1

				inc ZPnCnt+1
				beq .8

.1				sta (ZPOutBufPtr)

				inc ZPOutBufPtr
				bne .8

				inc ZPOutBufPtr+1

.8				rts
*--------------------------------------
X.UnArc.Get8BitInA
				ldx #8
X.UnArc.GetXBitInA
				lda #0

.1				pha
				jsr X.UnArc.GetBitInC
				pla
				rol
				dex
				bne .1

				rts
*--------------------------------------
X.UnArc.GetBitInC
				lda (ZPInBufPtr)
				and ZPInMask
				
				cmp #1					CC if bit=0
				
				php

				lsr ZPInMask
				bcc .8

				ror ZPInMask

				jsr X.UnArc.NextByte

.8				plp
				rts
*--------------------------------------
X.UnArc.GetByte	lda (ZPInBufPtr)
X.UnArc.NextByte
				inc ZPInBufPtr
				bne .8

				inc ZPInBufPtr+1

.8				rts
*--------------------------------------
				.LIST ON
X.UnArc.Size	.EQ *-X.UnArc
				.LIST OFF
*--------------------------------------
MAN
SAVE usr/src/shared/x.unarc.s
LOAD usr/src/bin/unarc.s
ASM