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import: BrutalDeluxe LZ4 decompressor

This commit is contained in:
dwsJason 2018-07-16 20:31:40 -04:00
parent 7c2a655fe9
commit 4daa62fde9
1 changed files with 80 additions and 0 deletions
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asm/LZ4.s Normal file
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MX %00
*-------------------------------------------------------------------------------
LZ4_Unpack STA LZ4_Literal_3+1 ; Uncompress a LZ4 Packed Data buffer (64 KB max)
SEP #$20 ; A = Bank Src,Bank Dst
STA LZ4_Match_5+1 ; X = Header Size = 1st Packed Byte offset
STA LZ4_Match_5+2 ; Y = Pack Data Size
XBA ; => Return in A the length of unpacked Data
STA LZ4_ReadToken+3
STA LZ4_Match_1+3
STA LZ4_GetLength_1+3
REP #$30
STY LZ4_Limit+1
*--
LDY #$0000 ; Init Target unpacked Data offset
LZ4_ReadToken LDAL $AA0000,X ; Read Token Byte
INX
STA LZ4_Match_2+1
*----------------
LZ4_Literal AND #$00F0 ; >>> Process Literal Bytes <<<
BEQ LZ4_Limit ; No Literal
CMP #$00F0
BNE LZ4_Literal_1
JSR LZ4_GetLengthLit ; Compute Literal Length with next bytes
BRA LZ4_Literal_2
LZ4_Literal_1 LSR ; Literal Length use the 4 bit
LSR
LSR
LSR
*--
LZ4_Literal_2 DEC ; Copy A+1 Bytes
LZ4_Literal_3 MVN $AA,$BB ; Copy Literal Bytes from packed data buffer
PHK ; X and Y are auto incremented
PLB
*----------------
LZ4_Limit CPX #$AAAA ; End Of Packed Data buffer ?
BEQ LZ4_End
*----------------
LZ4_Match TYA ; >>> Process Match Bytes <<<
SEC
LZ4_Match_1 SBCL $AA0000,X ; Match Offset
INX
INX
STA LZ4_Match_4+1
*--
LZ4_Match_2 LDA #$0000 ; Current Token Value
AND #$000F
CMP #$000F
BNE LZ4_Match_3
JSR LZ4_GetLengthMat ; Compute Match Length with next bytes
LZ4_Match_3 CLC
ADC #$0003 ; Minimum Match Length is 4 (-1 for the MVN)
*--
PHX
LZ4_Match_4 LDX #$AAAA ; Match Byte Offset
LZ4_Match_5 MVN $BB,$BB ; Copy Match Bytes from unpacked data buffer
PHK ; X and Y are auto incremented
PLB
PLX
*----------------
BRA LZ4_ReadToken
*----------------
LZ4_GetLengthLit LDA #$000F ; Compute Variable Length (Literal or Match)
LZ4_GetLengthMat STA LZ4_GetLength_2+1
LZ4_GetLength_1 LDAL $AA0000,X ; Read Length Byte
INX
AND #$00FF
CMP #$00FF
BNE LZ4_GetLength_3
CLC
LZ4_GetLength_2 ADC #$000F
STA LZ4_GetLength_2+1
BRA LZ4_GetLength_1
LZ4_GetLength_3 ADC LZ4_GetLength_2+1
RTS
*----------------
LZ4_End TYA ; A = Length of Unpack Data
RTS
*-------------------------------------------------------------------------------