Merge pull request #32 from specke/master

Slightly faster unlzsa2_fast.asm for Z80

asm/z80/unlzsa2_fast.asm

@@ -7,7 +7,8 @@
 ;  ver.03 by uniabis (30/07/2019, 213(-5) bytes, +3.8% speed and support for Hitachi HD64180);
 ;  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.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)
 ;
 ;  The data must be compressed using the command line compressor by Emmanuel Marty
 ;  The compression is done as follows:
@@ -55,6 +56,7 @@
 ;     misrepresented as being the original software.
 ;  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
 
@@ -68,12 +70,12 @@
 		ex de,hl : add hl,de
 		ENDM
 
-		MACRO BLOCKCOPY
-		ldir
+		MACRO COPY1
+		ldi
 		ENDM
 
-		MACRO COPY_MATCH
-		ldi : ldir
+		MACRO COPYBC
+		ldir
 		ENDM
 
 	ELSE
@@ -87,12 +89,12 @@
 		ld a,d : sbc h : ld h,a						; 4*4+3*4 = 28t / 7 bytes
 		ENDM
 
-		MACRO BLOCKCOPY
-		lddr
+		MACRO COPY1
+		ldd
 		ENDM
 
-		MACRO COPY_MATCH
-		ldd : lddr
+		MACRO COPYBC
+		lddr
 		ENDM
 
 	ENDIF
@@ -146,7 +148,7 @@ MoreLiterals:	ld b,(hl) : NEXT_HL
 		inc a : jr z,ManyLiterals : sub #F0-3+1
 
 CopyLiterals:	ld c,a : ld a,b : ld b,0
-		BLOCKCOPY
+		COPYBC
 		push de : or a : jp p,CASE0xx ;: jr CASE1xx
 
 		cp %11000000 : jr c,CASE10x
@@ -181,7 +183,9 @@ 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]
-		COPY_MATCH : pop hl
+		COPY1
+		COPYBC
+.popSrc		pop hl
 
 		; compressed data stream contains records
 		; each record begins with the byte token "XYZ|LL|MMM"
@@ -191,14 +195,14 @@ ReadToken:	ld a,(hl) : and %00011000 : jp pe,Literals0011		; process the cases 0
 
 		ld c,a : ld a,(hl)					; token is re-read for further processing
 .NEXTHLuseBC	NEXT_HL
-		BLOCKCOPY
+		COPYBC
 
 		; the token and literals are followed by the offset
 		push de : or a : jp p,CASE0xx
 
 CASE1xx		cp %11000000 : jr nc,CASE11x
 
-		; "10x": the case of the 5-bit offset
+		; "10x": the case of the 13-bit offset
 CASE10x:	ld c,a : exa : jr nc,.noUpdate
 
 			ld a,(hl) : or #F0 : exa
@@ -206,8 +210,7 @@ CASE10x:	ld c,a : exa : jr nc,.noUpdate
 			rrca : rrca : rrca : rrca
 
 .noUpdate	ld d,a : ld a,c
-		cp %10100000 : rl d
-		dec d : dec d : jr ReadOffsetE
+		cp %10100000 : dec d : rl d : jr ReadOffsetE
 
 
 		
@@ -225,7 +228,7 @@ CASE00x:	ld c,a : exa : jr nc,.noUpdate
 			rrca : rrca : rrca : rrca
 
 .noUpdate	ld e,a : ld a,c
-		cp %00100000 : rl e : jr SaveOffset
+		cp %00100000 : rl e : jp SaveOffset
 
 
 
@@ -239,16 +242,38 @@ LongerMatch:	scf : exa : jr nc,.noUpdate
 
 .noUpdate	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
 
-
-
-
-
-
+	ELSE
+
+LongMatch:	add (hl) : NEXT_HL : jr c,VeryLongMatch
+
+		ld c,a
+.useC		ex (sp),hl
+		ADD_OFFSET
+		COPY1
+
+		; this is an unrolled equivalent of LDIR
+		xor a : sub c
+		and 8-1 : add a
+		ld (.jrOffset),a : jr nz,$+2
+.jrOffset	EQU $-1
+.fastLDIR	DUP 8
+		COPY1
+		EDUP
+		jp pe,.fastLDIR
+		jp CopyMatch.popSrc
+
+VeryLongMatch:	ld c,(hl) : NEXT_HL
+		ld b,(hl) : NEXT_HL : jr nz,LongMatch.useC
+		pop de : ret
+
+	ENDIF