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2bytes shorter

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uniabis 2019-08-22 12:55:55 +09:00
parent 27d0fe4e83
commit a807344343
1 changed files with 9 additions and 10 deletions
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19
asm/z80/unlzsa1_fast_v1.asm
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@ -1,6 +1,5 @@
;
; Speed-optimized LZSA1 decompressor by spke (v.1 03-25/04/2019, 109 bytes);
; with improvements by uniabis (30/07/2019, -1 byte, +3% speed).
; Speed-optimized LZSA1 decompressor by spke (v.1 03.1-22/08/2019, 107 bytes);
;
; The data must be compressed using the command line compressor by Emmanuel Marty
; The compression is done as follows:
@ -85,14 +84,14 @@
ld b,0 : jr ReadToken
NoLiterals: xor (hl) : NEXT_HL
push de : ld e,(hl) : NEXT_HL : jp m,LongOffset
push de : 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 ex (sp),hl ; BC = len, DE = offset, HL = dest, SP ->[dest,src]
.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]
BLOCKCOPY : pop hl ; BC = 0, DE = dest, HL = src
@ -108,22 +107,22 @@ ReadToken: ; first a byte token "O|LLL|MMMM" is read from the stream,
BLOCKCOPY
; next we read the first byte of the offset
push de : ld e,(hl) : NEXT_HL
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
ld d,(hl) : NEXT_HL
NEXT_HL : ld d,(hl)
add -128+3 : cp 15+3 : jp c,CopyMatch
; MMMM=15 indicates a multi-byte number of literals
LongerMatch: add (hl) : NEXT_HL : jr nc,CopyMatch
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 : ld c,(hl) : NEXT_HL : jr nz,CopyMatch.UseC
.code0 ld b,(hl) : NEXT_HL
.code1 NEXT_HL : ld b,a : 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
@ -137,7 +136,7 @@ MoreLiterals: ; there are three possible situations here
CopyLiterals: ld c,a
.UseC BLOCKCOPY
push de : ld e,(hl) : NEXT_HL
push de : ld e,(hl)
exa : jp p,ShortOffset : jr LongOffset
ManyLiterals: