New fast decompressor for LZSA2 (-6 bytes, +1% speed)

This commit is contained in:
specke 2022-04-08 13:34:56 +01:00
parent 120bd71ed9
commit b1a87b55da

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@ -1,5 +1,5 @@
;
; Speed-optimized LZSA2 decompressor by spke & uniabis (216 bytes)
; 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);
@ -8,7 +8,8 @@
; 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.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:
@ -57,8 +58,7 @@
; 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
; DEFINE HD64180 ; uncomment for systems using Hitachi HD64180
; DEFINE BACKWARD_DECOMPRESS ; uncomment for data compressed with option -b (+5 bytes, -3.2% speed)
IFNDEF BACKWARD_DECOMPRESS
@ -67,7 +67,7 @@
ENDM
MACRO ADD_OFFSET
ex de,hl : add hl,de
add hl,de
ENDM
MACRO COPY1
@ -85,8 +85,9 @@
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
; 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
@ -99,37 +100,15 @@
ENDIF
IFNDEF HD64180
MACRO LD_IX_DE
ld ixl,e : ld ixh,d
ENDM
MACRO LD_DE_IX
ld e,ixl : ld d,ixh
ENDM
ELSE
MACRO LD_IX_DE
push de : pop ix
ENDM
MACRO LD_DE_IX
push ix : pop de
ENDM
ENDIF
@DecompressLZSA2:
; A' stores next nibble as %1111.... or assumed to contain trash
; B is assumed to be 0
; 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,CopyLiterals
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
@ -140,23 +119,31 @@ ManyLiterals: ld a,18 : add (hl) : NEXT_HL : jr nc,CopyLiterals
MoreLiterals: ld b,(hl) : NEXT_HL
scf : exa : jr nc,.noUpdate
ld a,(hl) : or #F0 : exa
ld a,(hl) : NEXT_HL : or #0F
; 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 ;sub #F0-3 : cp 15+3 : jr z,ManyLiterals
.noUpdate or #F0
;sub #F0-3 : cp 15+3 : jr z,ManyLiterals
inc a : jr z,ManyLiterals : sub #F0-3+1
CopyLiterals: ld c,a : ld a,b : ld b,0
CopyMoreLiterals: ld c,a : ld a,b : ld b,0
COPY1
COPY1
COPYBC
push de : or a : jp p,CASE0xx ;: jr CASE1xx
or a : jp p,CASE0xx
cp %11000000 : jr c,CASE10x
CASE11x cp %11100000 : jr c,CASE110
; "111": repeated offset
CASE111: LD_DE_IX : jr MatchLen
CASE11x cp %11100000 : jr nc,MatchLen
; "110": 16-bit offset
CASE110: ld b,(hl) : NEXT_HL : jr ReadOffsetC
@ -166,23 +153,24 @@ 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
push de : jp m,CASE1xx
jp m,CASE1xx
; short (5 or 9 bit long) offsets
CASE0xx ld d,#FF : cp %01000000 : jr c,CASE00x
CASE0xx cp %01000000 : jr c,CASE00x
; "01x": the case of the 9-bit offset
CASE01x: cp %01100000 : rl d
CASE01x: dec b : cp %01100000 : rl b
ReadOffsetE ld e,(hl) : NEXT_HL
ReadOffsetC ld c,(hl) : NEXT_HL
SaveOffset: LD_IX_DE
SaveOffset ld (CopyMatch.PrevOffset),bc : ld b,0
MatchLen: inc a : and %00000111 : jr z,LongerMatch : inc a
MatchLen inc a : and %00000111 : jr z,LongerMatch : inc a
CopyMatch: ld c,a
.useC ex (sp),hl ; BC = len, DE = offset, HL = dest, SP ->[dest,src]
ADD_OFFSET ; BC = len, DE = dest, HL = dest-offset, SP->[src]
.useC push hl
.PrevOffset EQU $+1 : ld hl,0
ADD_OFFSET
COPY1
COPYBC
.popSrc pop hl
@ -198,37 +186,33 @@ ReadToken: ld a,(hl) : and %00011000 : jp pe,Literals0011 ; process the cases 0
COPYBC
; the token and literals are followed by the offset
push de : or a : jp p,CASE0xx
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 #F0 : exa
ld a,(hl) : NEXT_HL : or #0F
ld a,(hl) : or a : exa
ld a,(hl) : NEXT_HL
rrca : rrca : rrca : rrca
.noUpdate ld d,a : ld a,c
cp %10100000 : dec d : rl d : jr ReadOffsetE
; "110": 16-bit offset
CASE110: ld d,(hl) : NEXT_HL : jr ReadOffsetE
.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 c,a : exa : jr nc,.noUpdate
CASE00x: ld b,a : exa : jr nc,.noUpdate
ld a,(hl) : or #F0 : exa
ld a,(hl) : NEXT_HL : or #0F
ld a,(hl) : or a : exa
ld a,(hl) : NEXT_HL
rrca : rrca : rrca : rrca
.noUpdate ld e,a : ld a,c
cp %00100000 : rl e : jp SaveOffset
.noUpdate or #F0 : ld c,a : ld a,b
cp %00100000 : rl c
ld b,#FF : jr SaveOffset
@ -236,27 +220,27 @@ CASE00x: ld c,a : exa : jr nc,.noUpdate
LongerMatch: scf : exa : jr nc,.noUpdate
ld a,(hl) : or #F0 : exa
ld a,(hl) : NEXT_HL : or #0F
ld a,(hl) : or a : exa
ld a,(hl) : NEXT_HL
rrca : rrca : rrca : rrca
.noUpdate sub #F0-9 : cp 15+9 : jr c,CopyMatch
.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
pop de : ret
ret
ELSE
LongMatch: add (hl) : NEXT_HL : jr c,VeryLongMatch
ld c,a
.useC ex (sp),hl
.useC push hl
ld hl,(CopyMatch.PrevOffset)
ADD_OFFSET
COPY1
; this is an unrolled equivalent of LDIR
xor a : sub c
@ -271,7 +255,7 @@ LongMatch: add (hl) : NEXT_HL : jr c,VeryLongMatch
VeryLongMatch: ld c,(hl) : NEXT_HL
ld b,(hl) : NEXT_HL : jr nz,LongMatch.useC
pop de : ret
ret
ENDIF