lzsa/asm/z80/unlzsa1_fast.asm
2019-09-26 11:42:52 +02:00

164 lines
5.0 KiB
NASM

;
; Speed-optimized LZSA1 decompressor by spke & uniabis (111 bytes)
;
; ver.00 by spke for LZSA 0.5.4 (03-24/04/2019, 134 bytes);
; ver.01 by spke for LZSA 0.5.6 (25/04/2019, 110(-24) bytes, +0.2% speed);
; ver.02 by spke for LZSA 1.0.5 (24/07/2019, added support for backward decompression);
; ver.03 by uniabis (30/07/2019, 109(-1) bytes, +3.5% speed);
; ver.04 by spke (31/07/2019, small re-organization of macros);
; ver.05 by uniabis (22/08/2019, 107(-2) bytes, same speed);
; ver.06 by spke for LZSA 1.0.7 (27/08/2019, 111(+4) bytes, +2.1% speed);
; ver.07 by spke for LZSA 1.1.0 (25/09/2019, added full revision history)
;
; The data must be compressed using the command line compressor by Emmanuel Marty
; The compression is done as follows:
;
; lzsa.exe -f1 -r <sourcefile> <outfile>
;
; 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 DecompressLZSA1
;
; Backward compression is also supported; you can compress files backward using:
;
; lzsa.exe -f1 -r -b <sourcefile> <outfile>
;
; and decompress the resulting files using:
;
; ld hl,LastByteOfCompressedData
; ld de,LastByteOfMemoryForDecompressedData
; call DecompressLZSA1
;
; (do not forget to uncomment the BACKWARD_DECOMPRESS option in the decompressor).
;
; Of course, LZSA 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 BACKWARD_DECOMPRESS
IFNDEF BACKWARD_DECOMPRESS
MACRO NEXT_HL
inc hl
ENDM
MACRO ADD_OFFSET
ex de,hl : add hl,de
ENDM
MACRO COPY_MATCH
ldi : ldi : ldir
ENDM
MACRO BLOCKCOPY
ldir
ENDM
ELSE
MACRO NEXT_HL
dec hl
ENDM
MACRO ADD_OFFSET
ex de,hl : ld a,e : sub l : ld l,a
ld a,d : sbc h : ld h,a ; 4*4+3*4 = 28t / 7 bytes
ENDM
MACRO COPY_MATCH
ldd : ldd : lddr
ENDM
MACRO BLOCKCOPY
lddr
ENDM
ENDIF
@DecompressLZSA1:
ld b,0 : jr ReadToken
NoLiterals: xor (hl)
push de : NEXT_HL : ld e,(hl) : jp m,LongOffset
; short matches have length 0+3..14+3
ShortOffset: ld d,#FF : add 3 : cp 15+3 : jr nc,LongerMatch
; placed here this saves a JP per iteration
CopyMatch: ld c,a
.UseC NEXT_HL : ex (sp),hl ; BC = len, DE = offset, HL = dest, SP ->[dest,src]
ADD_OFFSET ; BC = len, DE = dest, HL = dest-offset, SP->[src]
COPY_MATCH : pop hl ; BC = 0, DE = dest, HL = src
ReadToken: ; first a byte token "O|LLL|MMMM" is read from the stream,
; where LLL is the number of literals and MMMM is
; a length of the match that follows after the literals
ld a,(hl) : and #70 : jr z,NoLiterals
cp #70 : jr z,MoreLiterals ; LLL=7 means 7+ literals...
rrca : rrca : rrca : rrca ; LLL<7 means 0..6 literals...
ld c,a : ld a,(hl)
NEXT_HL : BLOCKCOPY
; next we read the first byte of the offset
push de : ld e,(hl)
; the top bit of token is set if the offset contains two bytes
and #8F : jp p,ShortOffset
LongOffset: ; read second byte of the offset
NEXT_HL : ld d,(hl)
add -128+3 : cp 15+3 : jp c,CopyMatch
; MMMM=15 indicates a multi-byte number of literals
LongerMatch: NEXT_HL : add (hl) : jr nc,CopyMatch
; the codes are designed to overflow;
; the overflow value 1 means read 1 extra byte
; and overflow value 0 means read 2 extra bytes
.code1 ld b,a : NEXT_HL : ld c,(hl) : jr nz,CopyMatch.UseC
.code0 NEXT_HL : ld b,(hl)
; the two-byte match length equal to zero
; designates the end-of-data marker
ld a,b : or c : jr nz,CopyMatch.UseC
pop de : ret
MoreLiterals: ; there are three possible situations here
xor (hl) : exa
ld a,7 : NEXT_HL : add (hl) : jr c,ManyLiterals
CopyLiterals: ld c,a
.UseC NEXT_HL : BLOCKCOPY
push de : ld e,(hl)
exa : jp p,ShortOffset : jr LongOffset
ManyLiterals:
.code1 ld b,a : NEXT_HL : ld c,(hl) : jr nz,CopyLiterals.UseC
.code0 NEXT_HL : ld b,(hl) : jr CopyLiterals.UseC