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Added an option for unrolling long match copying
Usually useless and costing +57 bytes, this option can bring dramatic performance improvements on very compressible data dominated by long matches
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@ -8,7 +8,8 @@
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; ver.04 by spke (31/07/2019, small re-organization of macros);
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; ver.05 by uniabis (22/08/2019, 107(-2) bytes, same speed);
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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.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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;
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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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@ -56,6 +57,7 @@
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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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IFNDEF BACKWARD_DECOMPRESS
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@ -68,11 +70,11 @@
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ex de,hl : add hl,de
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ENDM
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MACRO COPY_MATCH
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ldi : ldi : ldir
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MACRO COPY1
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ldi
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ENDM
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MACRO BLOCKCOPY
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MACRO COPYBC
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ldir
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ENDM
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@ -87,11 +89,11 @@
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ld a,d : sbc h : ld h,a ; 4*4+3*4 = 28t / 7 bytes
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ENDM
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MACRO COPY_MATCH
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ldd : ldd : lddr
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MACRO COPY1
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ldd
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ENDM
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MACRO BLOCKCOPY
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MACRO COPYBC
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lddr
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ENDM
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@ -110,7 +112,8 @@ ShortOffset: ld d,#FF : add 3 : cp 15+3 : jr nc,LongerMatch
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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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COPY_MATCH : pop hl ; BC = 0, DE = dest, HL = 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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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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@ -121,7 +124,7 @@ ReadToken: ; first a byte token "O|LLL|MMMM" is read from the stream,
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rrca : rrca : rrca : rrca ; LLL<7 means 0..6 literals...
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ld c,a : ld a,(hl)
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NEXT_HL : BLOCKCOPY
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NEXT_HL : COPYBC
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; next we read the first byte of the offset
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push de : ld e,(hl)
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@ -132,6 +135,8 @@ LongOffset: ; read second byte of the offset
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NEXT_HL : ld d,(hl)
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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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@ -146,12 +151,46 @@ LongerMatch: NEXT_HL : add (hl) : jr nc,CopyMatch
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ld a,b : or c : jr nz,CopyMatch.UseC
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pop de : 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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ld c,a
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.UseC NEXT_HL : ex (sp),hl
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ADD_OFFSET
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COPY1 : COPY1
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; this is an unrolled equivalent of LDIR
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xor a : sub c
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and 16-1 : add a
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ld (.jrOffset),a : jr nz,$+2
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.jrOffset EQU $-1
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.fastLDIR DUP 16
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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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VeryLongMatch: ; 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,LongerMatch.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,LongerMatch.UseC
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pop de : ret
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ENDIF
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MoreLiterals: ; there are three possible situations here
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xor (hl) : exa
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ld a,7 : NEXT_HL : add (hl) : jr c,ManyLiterals
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CopyLiterals: ld c,a
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.UseC NEXT_HL : BLOCKCOPY
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.UseC NEXT_HL : COPYBC
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push de : ld e,(hl)
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exa : jp p,ShortOffset : jr LongOffset
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