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Improved "fast" Z80 decompressor for LZSA1
113(+4) bytes, +5% speed
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introspec
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004db30296
@ -1,5 +1,5 @@
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;
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; Speed-optimized LZSA1 decompressor by spke & uniabis (109 bytes)
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; Speed-optimized LZSA1 decompressor by spke & uniabis (113 bytes)
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;
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; ver.00 by spke for LZSA 0.5.4 (03-24/04/2019, 134 bytes);
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; ver.01 by spke for LZSA 0.5.6 (25/04/2019, 110(-24) bytes, +0.2% speed);
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@ -10,7 +10,8 @@
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; ver.06 by spke for LZSA 1.0.7 (27/08/2019, 111(+4) bytes, +2.1% speed);
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; ver.07 by spke for LZSA 1.1.0 (25/09/2019, added full revision history);
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; ver.08 by spke for LZSA 1.1.2 (22/10/2019, re-organized macros and added an option for unrolled copying of long matches);
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; ver.09 by spke for LZSA 1.2.1 (02/01/2020, 109(-2) bytes, same speed)
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; ver.09 by spke for LZSA 1.2.1 (02/01/2020, 109(-2) bytes, same speed);
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; ver.10 by spke (07/04/2021, 113(+4) bytes, +5% speed)
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;
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; The data must be compressed using the command line compressor by Emmanuel Marty
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; The compression is done as follows:
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@ -58,8 +59,8 @@
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; misrepresented as being the original software.
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; 3. This notice may not be removed or altered from any source distribution.
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; DEFINE UNROLL_LONG_MATCHES ; uncomment for faster decompression of very compressible data (+57 bytes)
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; DEFINE BACKWARD_DECOMPRESS
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; DEFINE UNROLL_LONG_MATCHES ; uncomment for faster decompression of very compressible data (+51 byte)
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; DEFINE BACKWARD_DECOMPRESS ; uncomment to decompress backward compressed data (-3% speed, +5 bytes)
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IFNDEF BACKWARD_DECOMPRESS
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@ -68,7 +69,8 @@
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ENDM
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MACRO ADD_OFFSET
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ex de,hl : add hl,de
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; HL = DE+HL
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add hl,de
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ENDM
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MACRO COPY1
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@ -86,8 +88,9 @@
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ENDM
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MACRO ADD_OFFSET
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ex de,hl : ld a,e : sub l : ld l,a
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ld a,d : sbc h : ld h,a ; 4*4+3*4 = 28t / 7 bytes
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; HL = DE-HL
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ld a,e : sub l : ld l,a
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ld a,d : sbc h : ld h,a ; 6*4 = 24t / 6 bytes
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ENDM
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MACRO COPY1
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@ -103,19 +106,25 @@
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@DecompressLZSA1:
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ld b,0 : jr ReadToken
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IFNDEF UNROLL_LONG_MATCHES
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CopyMatch2: ld c,a
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.UseC ex (sp),hl : jr CopyMatch.UseC
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ENDIF
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NoLiterals: xor (hl) : NEXT_HL : jp m,LongOffset
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ShortOffset: push de : ld e,(hl) : ld d,#FF
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ShortOffset: push hl : ld l,(hl) : ld h,#FF
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; short matches have length 0+3..14+3
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add 3 : cp 15+3 : jr nc,LongerMatch
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; placed here this saves a JP per iteration
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CopyMatch: ld c,a
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.UseC NEXT_HL : ex (sp),hl ; BC = len, DE = offset, HL = dest, SP ->[dest,src]
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ADD_OFFSET ; BC = len, DE = dest, HL = dest-offset, SP->[src]
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CopyMatch: ld c,a ; BC = len, DE = dest, HL = offset, SP -> [src]
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.UseC ADD_OFFSET ; BC = len, DE = dest, HL = dest-offset, SP->[src]
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COPY1 : COPY1 : COPYBC ; BC = 0, DE = dest
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.popSrc pop hl ; HL = src
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.popSrc pop hl : NEXT_HL ; HL = src
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ReadToken: ; first a byte token "O|LLL|MMMM" is read from the stream,
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; where LLL is the number of literals and MMMM is
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@ -132,32 +141,32 @@ ReadToken: ; first a byte token "O|LLL|MMMM" is read from the stream,
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and #8F : jp p,ShortOffset
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LongOffset: ; read second byte of the offset
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push de : ld e,(hl) : NEXT_HL : ld d,(hl)
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ld c,(hl) : NEXT_HL : push hl : ld h,(hl) : ld l,c
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add -128+3 : cp 15+3 : jp c,CopyMatch
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IFNDEF UNROLL_LONG_MATCHES
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; MMMM=15 indicates a multi-byte number of literals
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LongerMatch: NEXT_HL : add (hl) : jr nc,CopyMatch
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LongerMatch: ex (sp),hl : NEXT_HL : add (hl) : jr nc,CopyMatch2
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; the codes are designed to overflow;
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; the overflow value 1 means read 1 extra byte
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; and overflow value 0 means read 2 extra bytes
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.code1 ld b,a : NEXT_HL : ld c,(hl) : jr nz,CopyMatch.UseC
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.code1 ld b,a : NEXT_HL : ld c,(hl) : jr nz,CopyMatch2.UseC
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.code0 NEXT_HL : ld b,(hl)
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; the two-byte match length equal to zero
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; designates the end-of-data marker
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ld a,b : or c : jr nz,CopyMatch.UseC
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pop de : ret
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ld a,b : or c : jr nz,CopyMatch2.UseC
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pop hl : ret
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ELSE
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; MMMM=15 indicates a multi-byte number of literals
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LongerMatch: NEXT_HL : add (hl) : jr c,VeryLongMatch
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LongerMatch: ex (sp),hl : NEXT_HL : add (hl) : jr c,VeryLongMatch
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ld c,a
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.UseC NEXT_HL : ex (sp),hl
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.UseC ex (sp),hl
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ADD_OFFSET
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COPY1 : COPY1
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@ -170,7 +179,7 @@ LongerMatch: NEXT_HL : add (hl) : jr c,VeryLongMatch
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COPY1
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EDUP
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jp pe,.fastLDIR
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jp CopyMatch.popSrc
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jr CopyMatch.popSrc
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VeryLongMatch: ; the codes are designed to overflow;
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; the overflow value 1 means read 1 extra byte
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@ -181,7 +190,7 @@ VeryLongMatch: ; the codes are designed to overflow;
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; the two-byte match length equal to zero
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; designates the end-of-data marker
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ld a,b : or c : jr nz,LongerMatch.UseC
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pop de : ret
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pop hl : ret
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ENDIF
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