; ; Speed-optimized LZSA2 decompressor by spke & uniabis (210 bytes) ; ; ver.00 by spke for LZSA 1.0.0 (02-07/06/2019, 218 bytes); ; ver.01 by spke for LZSA 1.0.5 (24/07/2019, added support for backward decompression); ; ver.02 by spke for LZSA 1.0.6 (27/07/2019, fixed a bug in the backward decompressor); ; ver.03 by uniabis (30/07/2019, 213(-5) bytes, +3.8% speed and support for Hitachi HD64180); ; ver.04 by spke for LZSA 1.0.7 (01/08/2019, 214(+1) bytes, +0.2% speed and small re-organization of macros); ; ver.05 by spke (27/08/2019, 216(+2) bytes, +1.1% speed); ; ver.06 by spke for LZSA 1.1.0 (26/09/2019, added full revision history); ; ver.07 by spke for LZSA 1.1.1 (10/10/2019, +0.2% speed and an option for unrolled copying of long matches); ; ver.08 by spke (07-08/04/2022, 210(-6) bytes, +1.7% speed, using self-modifying code by default) ; ; The data must be compressed using the command line compressor by Emmanuel Marty ; The compression is done as follows: ; ; lzsa.exe -f2 -r ; ; where option -r asks for the generation of raw (frame-less) data. ; ; The decompression is done in the standard way: ; ; ld hl,FirstByteOfCompressedData ; ld de,FirstByteOfMemoryForDecompressedData ; call DecompressLZSA2 ; ; Backward compression is also supported; you can compress files backward using: ; ; lzsa.exe -f2 -r -b ; ; and decompress the resulting files using: ; ; ld hl,LastByteOfCompressedData ; ld de,LastByteOfMemoryForDecompressedData ; call DecompressLZSA2 ; ; (do not forget to uncomment the BACKWARD_DECOMPRESS option in the decompressor). ; ; Of course, LZSA2 compression algorithms are (c) 2019 Emmanuel Marty, ; see https://github.com/emmanuel-marty/lzsa for more information ; ; Drop me an email if you have any comments/ideas/suggestions: zxintrospec@gmail.com ; ; This software is provided 'as-is', without any express or implied ; warranty. In no event will the authors be held liable for any damages ; arising from the use of this software. ; ; Permission is granted to anyone to use this software for any purpose, ; including commercial applications, and to alter it and redistribute it ; freely, subject to the following restrictions: ; ; 1. The origin of this software must not be misrepresented; you must not ; claim that you wrote the original software. If you use this software ; in a product, an acknowledgment in the product documentation would be ; appreciated but is not required. ; 2. Altered source versions must be plainly marked as such, and must not be ; misrepresented as being the original software. ; 3. This notice may not be removed or altered from any source distribution. ; DEFINE UNROLL_LONG_MATCHES ; uncomment for faster decompression of very compressible data (+38 bytes) ; DEFINE BACKWARD_DECOMPRESS ; uncomment for data compressed with option -b (+5 bytes, -3.2% speed) IFNDEF BACKWARD_DECOMPRESS MACRO NEXT_HL inc hl ENDM MACRO ADD_OFFSET add hl,de ENDM MACRO COPY1 ldi ENDM MACRO COPYBC ldir ENDM ELSE MACRO NEXT_HL dec hl ENDM MACRO ADD_OFFSET ; HL = DE - HL ld a,e : sub l : ld l,a ld a,d : sbc h : ld h,a ; 6*4 = 24t / 6 bytes ENDM MACRO COPY1 ldd ENDM MACRO COPYBC lddr ENDM ENDIF @DecompressLZSA2: ; A' stores next nibble as %1111.... or assumed to contain trash ; B is assumed to be 0 in many places ld b,0 : scf : exa : jr ReadToken ManyLiterals: ld a,18 : add (hl) : NEXT_HL : jr nc,CopyMoreLiterals ld c,(hl) : NEXT_HL ld a,b : ld b,(hl) jr ReadToken.NEXTHLuseBC MoreLiterals: ld b,(hl) : NEXT_HL scf : exa : jr nc,.noUpdate ; nibbles are read left-to-right; spare nibbles are kept in AF' ; and flag NC indicates that a nibble is available ld a,(hl) : or a : exa ld a,(hl) : NEXT_HL rrca : rrca : rrca : rrca .noUpdate or #F0 ;sub #F0-3 : cp 15+3 : jr z,ManyLiterals inc a : jr z,ManyLiterals : sub #F0-3+1 CopyMoreLiterals: ld c,a : ld a,b : ld b,0 COPY1 COPY1 COPYBC or a : jp p,CASE0xx cp %11000000 : jr c,CASE10x ; "111": repeated offset CASE11x cp %11100000 : jr nc,MatchLen ; "110": 16-bit offset CASE110: ld b,(hl) : NEXT_HL : jr ReadOffsetC Literals0011: jr nz,MoreLiterals ; if "LL" of the byte token is equal to 0, ; there are no literals to copy NoLiterals: or (hl) : NEXT_HL jp m,CASE1xx ; short (5 or 9 bit long) offsets CASE0xx cp %01000000 : jr c,CASE00x ; "01x": the case of the 9-bit offset CASE01x: dec b : cp %01100000 : rl b ReadOffsetC ld c,(hl) : NEXT_HL SaveOffset ld (CopyMatch.PrevOffset),bc : ld b,0 MatchLen inc a : and %00000111 : jr z,LongerMatch : inc a CopyMatch: ld c,a .useC push hl .PrevOffset EQU $+1 : ld hl,0 ADD_OFFSET COPY1 COPYBC .popSrc pop hl ; compressed data stream contains records ; each record begins with the byte token "XYZ|LL|MMM" ReadToken: ld a,(hl) : and %00011000 : jp pe,Literals0011 ; process the cases 00 and 11 separately rrca : rrca : rrca ld c,a : ld a,(hl) ; token is re-read for further processing .NEXTHLuseBC NEXT_HL COPYBC ; the token and literals are followed by the offset or a : jp p,CASE0xx CASE1xx cp %11000000 : jr nc,CASE11x ; "10x": the case of the 13-bit offset CASE10x: ld c,a : exa : jr nc,.noUpdate ld a,(hl) : or a : exa ld a,(hl) : NEXT_HL rrca : rrca : rrca : rrca .noUpdate or #F0 : ld b,a : ld a,c cp %10100000 : dec b : rl b : jr ReadOffsetC ; "00x": the case of the 5-bit offset CASE00x: ld b,a : exa : jr nc,.noUpdate ld a,(hl) : or a : exa ld a,(hl) : NEXT_HL rrca : rrca : rrca : rrca .noUpdate or #F0 : ld c,a : ld a,b cp %00100000 : rl c ld b,#FF : jr SaveOffset LongerMatch: scf : exa : jr nc,.noUpdate ld a,(hl) : or a : exa ld a,(hl) : NEXT_HL rrca : rrca : rrca : rrca .noUpdate or #F0 : sub #F0-9 : cp 15+9 : jr c,CopyMatch IFNDEF UNROLL_LONG_MATCHES LongMatch: add (hl) : NEXT_HL : jr nc,CopyMatch ld c,(hl) : NEXT_HL ld b,(hl) : NEXT_HL : jr nz,CopyMatch.useC ret ELSE LongMatch: add (hl) : NEXT_HL : jr c,VeryLongMatch ld c,a .useC push hl ld hl,(CopyMatch.PrevOffset) ADD_OFFSET ; this is an unrolled equivalent of LDIR xor a : sub c and 8-1 : add a ld (.jrOffset),a : jr nz,$+2 .jrOffset EQU $-1 .fastLDIR DUP 8 COPY1 EDUP jp pe,.fastLDIR jp CopyMatch.popSrc VeryLongMatch: ld c,(hl) : NEXT_HL ld b,(hl) : NEXT_HL : jr nz,LongMatch.useC ret ENDIF