; v016 ; LZ48 cruncher by roudoudou / Flower Corp. ; inspired by LZ4 block format (Yann Collet) ; ; modifications ; - first byte in the encoded flux is a literal out of block sequence ; - no literal byte minimum in the first block instead of 4 ; - end of file comes with offset zero instead of minimum 5 literals and zero offset ; - offsets are 8bits instead of 16btis ; - offset are encoded 'value-1' to optimise decrunch ; - can crunch data of less than 4 bytes ; ; ; known limitations ; - data adress to crunch must be > #100 ; org #9000 ; CALL #9000,adresse,taille ; init di ; push_byte init ld a,#C4 ld (push_bank),a ld hl,#4000 ld (push_offset),hl ; parameters ld h,(ix+3) ld l,(ix+2) ld d,(ix+1) ld e,(ix+0) ; first byte is always literal but ouf of block sequence ld (startadr_cpy1+1),hl ld (startadr_cpy2+1),hl ld a,(hl) inc hl dec de call LZ48_push_byte ld (curadr),hl ld (curliteraladr),hl ld (curlength),de add hl,de ld (endadrcpy+1),hl ld (endadrcpy2+1),hl ; endadress is a constant dec hl dec hl dec hl ld (endadrcpy1m3+1),hl inc d dec d jr nz,bigsizetocrunch ld a,e cp 5 jr nc,bigsizetocrunch ; want to crunch less than 5 bytes data! OK boy! ld a,e add a add a add a add a call LZ48_push_byte smallcrunch ld a,(hl) inc hl call LZ48_push_byte dec e jr nz,smallcrunch ld a,#FF call LZ48_push_byte ret bigsizetocrunch xor a ld (lz48_failed),a ld hl,0 ld (literal),hl ;------------- inner compression loop ------ crunch_data ; do we have a match? call LZ48_get_match or a jr nz,encode_block ; no! raise literral counter ld hl,(literal) inc hl ld (literal),hl ld hl,(curadr) inc hl ld (curadr),hl endadrcpy1m3: ld de,#1234 xor a sbc hl,de jr z,encode_block3 ; force encode block because end of file jr crunch_data ; LZ48 block is (similar to LZ4 format) ; 1 byte descriptor ; n byte for extended lenght of literals ; n byte for literals ; 1 byte special offset (instead of 2 for LZ4) ; n byte for extended length of copy encode_block3 ld hl,(literal) inc hl inc hl inc hl ld (literal),hl encode_block call LZ48_newblock ; encode block with litterals+offset ld hl,(literal) inc h dec h jr nz,literal_extended ld a,l cp 15 jr nc,literal_extended add a add a add a add a call LZ48_blockheaderfusion inc l dec l jr z,encode_block_offset ; no literal to encode jr push_literals literal_extended xor a ld de,15 sbc hl,de ld a,#F0 call LZ48_blockheaderfusion literal_extended_redo ; is hl>255? inc h dec h jr z,literal_extended_last_byte ld de,255 xor a sbc hl,de ld a,255 call LZ48_push_byte jr literal_extended_redo literal_extended_last_byte ld a,l cp 255 jr nz,really_the_last_extended call LZ48_push_byte xor a really_the_last_extended call LZ48_push_byte push_literals ld de,(literal) ld hl,(curliteraladr) push_literals_loop ld a,(hl) inc hl call LZ48_push_byte dec de ld a,d or e jr nz,push_literals_loop ;--- encode offset length in block --- encode_block_offset encode_offsetlength ld a,lx or a jr z,encode_block_end ; nothing to do for the last block ; length of copy ld hl,(maxmatch+1) dec hl dec hl dec hl inc h dec h jr nz,encode_offsetlength_extended ld a,l cp 15 jr nc,encode_offsetlength_extended call LZ48_blockheaderfusion jr encode_offset encode_offsetlength_extended xor a ld de,15 sbc hl,de ld a,#F call LZ48_blockheaderfusion encode_offsetlength_redo ; is hl>255? inc h dec h jr z,encode_offsetlength_last_byte ld de,255 xor a sbc hl,de ld a,255 call LZ48_push_byte jr encode_offsetlength_redo encode_offsetlength_last_byte ld a,l cp 255 jr nz,really_the_last call LZ48_push_byte xor a really_the_last call LZ48_push_byte ;--- encode offset translation in block --- encode_offset ld hl,(curadr) maxoffset: ld de,#1234 xor a sbc hl,de ld a,l dec a ; special byte offset FF->EOF call LZ48_push_byte ; add offset to current adress ld hl,(maxmatch+1) ld de,(curadr) add hl,de ld (curadr),hl ; reset counters xor a ld h,a ld l,a ld (literal),hl ; again? ld hl,(curadr) ld (curliteraladr),hl ; reset literal position endadrcpy2: ld de,#1234 sbc hl,de jp nz,crunch_data jr lastpushbyte ; ; if last byte is literal, offset to zero [coded #FF) mean EOF ; else we need to add two extra bytes to encode zero literal and offset 0 ; encode_block_end ld a,#FF call LZ48_push_byte jr lz48end lastpushbyte ld a,#12 inc a jr z,lz48end xor a call LZ48_push_byte dec a call LZ48_push_byte lz48end ld hl,msgout ld a,(hl) displayendmsg inc hl call #BB5A ld a,(hl) or a jr nz,displayendmsg ld hl,(push_offset) ld de,#4000 xor a sbc hl,de ld a,(push_bank) sub #C4 add a add a add a add a add a add a add h call displayhexdigit ld a,l call displayhexdigit ld a,10 call #bb5A ld a,13 call #bb5A ei ret digit16 defw 0 displayhexdigit push af and #F0 rrca rrca rrca rrca cp 10 jr c,putdigit add 'A'-10 call #BB5A jr lowhexdigit putdigit add '0' call #BB5A lowhexdigit pop af and #F cp 10 jr c,putdigit2 add 'A'-10 call #BB5A ret putdigit2 add '0' call #BB5A ret ;------------------- END - msgout defb 'compressed in #',0 curadr defw 0 ; current adress of data curlength defw 0 ; lenght of data ; literal defw 0 ; counter of literal data to push curliteraladr defw 0 ; adress of first literal data ; ; ; key scan from current adress -255 bytes to current adress -1 byte ; LZ48_get_match xor a ld h,a ld l,a ld (maxmatch+1),hl ld lx,a ; matchflag ld hl,(curadr) ld de,255 sbc hl,de ld (startscan+1),hl startadr_cpy1:ld de,#1234 sbc hl,de jr nc,LZ4_get_match_compute_start jr z,LZ4_get_match_compute_start startadr_cpy2:ld hl,#1234 ld (startscan+1),hl LZ4_get_match_compute_start ld hl,(curadr) ld (curadrcpy+1),hl ld (curadrcpy2+1),hl endadrcpy: ld hl,#1234 ld a,l ld (matchcp1+1),a ld a,h ld (matchcp2+1),a xor a ;------------- looking for 3 repetitions or more ------------------------ LZ48_get_match_rescan ld bc,3 startscan: ld de,#1234 curadrcpy: ld hl,#1234 ; we are looking for a key with 3 repetitions or more ld a,(de) cp (hl) jr nz,LZ48_get_match_inc_scan inc hl inc de ld a,(de) cp (hl) jr nz,LZ48_get_match_inc_scan inc hl inc de ld a,(de) cp (hl) jr nz,LZ48_get_match_inc_scan inc hl inc de LZ48_get_match_scan ld a,(de) cp (hl) jr nz,LZ48_get_match_scan_is_best inc bc inc hl inc de ld a,l matchcp1:cp #12 jr nz,LZ48_get_match_scan ; until the end of data, if data match! ld a,h matchcp2:cp #12 jr nz,LZ48_get_match_scan ; until the end of data, if data match! ;-------------------- LZ48_get_match_scan_is_best ; found something? maxmatch:ld hl,#1234 xor a sbc hl,bc jr nc,LZ48_get_match_inc_scan ; this is the best match so far ld (maxmatch+1),bc ld hl,(startscan+1) ld (maxoffset+1),hl jr LZ48_get_match_inc_scan_next LZ48_get_match_inc_scan ld hl,(startscan+1) LZ48_get_match_inc_scan_next inc hl ld (startscan+1),hl xor a curadrcpy2:ld de,#1234 sbc hl,de jr nz,LZ48_get_match_rescan ; until we reach the current adress ; do we have a match? ld hl,(maxmatch+1) ld a,h or l ret z ; yes! set match flag / A is already != 0 inc lx ret lz48_failed defb 0 push_bank defb 0 push_offset defw 0 blockadr defw 0 blockbnk defb 0 ; save memory position and push 0 LZ48_newblock push af push bc push hl ld a,(push_bank) ld (blockbnk),a ld hl,(push_offset) ld (blockadr),hl xor a call LZ48_push_byte pop hl pop bc pop af ret LZ48_blockheaderfusion push bc push hl push af ld b,#7F ld a,(blockbnk) out (c),a pop af ld hl,(blockadr) or (hl) ld (hl),a ld c,#C0 out (c),c pop hl pop bc ret LZ48_push_byte push af push bc push hl push af ld a,(push_bank) ld b,#7F out (c),a ld hl,(push_offset) pop af ld (hl),a ld (lastpushbyte+1),a inc hl ld a,h cp #80 jr nz,push_lz48_byte_exit ld hl,#4000 ld a,(push_bank) inc a cp #C8 call z,LZ48_overmem ld (push_bank),a push_lz48_byte_exit ld (push_offset),hl ; central ram again ld bc,#7FC0 out (c),c pop hl pop bc pop af ret LZ48_overmem ld a,1 ld (lz48_failed),a ld a,#C4 ret

; v006 ; LZ48 decrunch ; ; hl compressed data adress ; de output adress of data ; org #8000 ; CALL #8000,source,destination di ; parameters ld h,(ix+3) ld l,(ix+2) ld d,(ix+1) ld e,(ix+0) call LZ48_decrunch ei ret LZ48_decrunch ldi ld b,0 nextsequence ld a,(hl) inc hl ld lx,a and #F0 jr z,lzunpack ; no litteral bytes rrca rrca rrca rrca ld c,a cp 15 ; more bytes for length? jr nz,copyliteral getadditionallength ld a,(hl) inc hl inc a jr nz,lengthnext inc b dec bc jr getadditionallength lengthnext dec a add a,c ld c,a ld a,b adc a,0 ld b,a ; bc=length copyliteral ldir lzunpack ld a,lx and #F add 3 ld c,a cp 18 ; more bytes for length? jr nz,readoffset getadditionallengthbis ld a,(hl) inc hl inc a jr nz,lengthnextbis inc b dec bc jr getadditionallengthbis lengthnextbis dec a add a,c ld c,a ld a,b adc a,0 ld b,a ; bc=length readoffset ; read encoded offset ld a,(hl) inc a ret z ; LZ48 end with zero offset inc hl push hl ld l,a ld a,e sub l ld l,a ld a,d sbc a,0 ld h,a ; source=dest-copyoffset copykey ldir pop hl jr nextsequence