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Update LZSA2 6502 and 8088 depackers

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Emmanuel Marty 2019-06-07 23:22:34 +02:00 committed by GitHub
parent 62003a82c2
commit 272f2e7a29
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 27 additions and 30 deletions
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43
asm/6502/decompress_v2.asm
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@ -56,8 +56,9 @@ DECODE_TOKEN
BNE PREPARE_COPY_LITERALS ; if less, literals count is complete
JSR GETSRC ; get extra byte of variable literals count
TAX ; non-zero?
BNE PREPARE_COPY_LITERALS_HIGH ; if so, literals count is complete
CLC
ADC #$12 ; overflow?
BCC PREPARE_COPY_LITERALS ; if not, literals count is complete
; handle 16 bits literals count
; literals count = directly these 16 bits
@ -96,23 +97,21 @@ NO_LITERALS
AND #$10
STA FIXUP
LDA #$0FF ; set offset bits 15-8 to 1
STA OFFSHI
JSR GETNIBBLE ; get nibble for offset bits 0-3
ORA FIXUP ; merge offset bit 4
ORA #$E0 ; set offset bits 7-5 to 1
TAX ; store low byte of match offset
LDA #$0FF ; set offset bits 15-8 to 1
BNE GOT_OFFSET ; (*same as JMP GOT_OFFSET but shorter)
JMP GOT_OFFSET_LO ; go store low byte of match offset and prepare match
OFFSET_9_BIT ; 01Z: 9 bit offset
ASL ; shift Z (offset bit 8) in place
ROL
ROL
ORA #$FE ; set offset bits 15-9 to 1
STA OFFSHI
JSR GETSRC ; get offset bits 0-7 from stream in A
TAX ; store low byte of match offset
JMP GOT_OFFSET_LO ; go prepare match
BNE GOT_OFFSET_HI ; go store high byte, read low byte of match offset and prepare match
; (*same as JMP GOT_OFFSET_HI but shorter)
REPMATCH_OR_LARGE_OFFSET
ASL ; 13 bit offset?
@ -125,26 +124,24 @@ REPMATCH_OR_LARGE_OFFSET
AND #$10
STA FIXUP
JSR GETSRC ; get offset bits 0-7 from stream in A
TAX ; store low byte of match offset
JSR GETNIBBLE ; get nibble for offset bits 8-11
ORA FIXUP ; merge offset bit 12
CLC
ADC #$DE ; set bits 13-15 to 1 and substract 2 (to substract 512)
BNE GOT_OFFSET ; go prepare match (*same as JMP GOT_OFFSET but shorter)
BNE GOT_OFFSET_HI ; go store high byte, read low byte of match offset and prepare match
; (*same as JMP GOT_OFFSET_HI but shorter)
REPMATCH_OR_16_BIT ; rep-match or 16 bit offset
ASL ; XYZ=111?
BMI REP_MATCH ; reuse previous offset if so (rep-match)
; 110: handle 16 bit offset
JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A
GOT_OFFSET
STA OFFSHI ; store final match offset
JSR GETSRC ; grab high 8 bits
GOT_OFFSET_HI
STA OFFSHI ; store high byte of match offset
JSR GETSRC ; grab low 8 bits
GOT_OFFSET_LO
STX OFFSLO
STA OFFSLO ; store low byte of match offset
REP_MATCH
CLC ; add dest + match offset
@ -169,14 +166,14 @@ REP_MATCH
BNE PREPARE_COPY_MATCH ; if less, match length is complete
JSR GETSRC ; get extra byte of variable match length
TAX ; non-zero?
BNE PREPARE_COPY_MATCH_Y ; if so, the match length is complete
CLC
ADC #$18 ; overflow?
BCC PREPARE_COPY_MATCH ; if not, the match length is complete
BEQ DECOMPRESSION_DONE ; if EOD code, bail
; Handle 16 bits match length
JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A
TAY ; put high 8 bits in Y
; large match length with zero high byte?
BEQ DECOMPRESSION_DONE ; if so, this is the EOD code, bail
TXA
PREPARE_COPY_MATCH

14
asm/8088/decompress_small_v2.S
View File

@ -56,8 +56,8 @@ lzsa2_decompress:
jne .got_literals ; if not, we have the full literals count, go copy
lodsb ; grab extra length byte
test al,al ; zero?
jne .got_literals ; if not, we have the full literals count, go copy
add al,012H ; overflow?
jnc .got_literals ; if not, we have the full literals count, go copy
lodsw ; grab 16-bit extra length
@ -96,7 +96,6 @@ lzsa2_decompress:
jnb .rep_match_or_16_bit
; 13 bit offset
lodsb ; load match offset bits 0-7
mov ah,020H ; shift Z (offset bit 12) in place
and ah,dl
@ -105,6 +104,7 @@ lzsa2_decompress:
or ah,cl ; merge nibble
or ah,0E0H ; set offset bits 15-13 to 1
sub ah,2 ; substract 512
lodsb ; load match offset bits 0-7
jmp short .get_match_length
.rep_match_or_16_bit:
@ -113,6 +113,7 @@ lzsa2_decompress:
; 16 bit offset
lodsw ; Get 2-byte match offset
xchg ah,al
.get_match_length:
mov bp,ax ; bp: offset
@ -130,12 +131,11 @@ lzsa2_decompress:
jne .got_matchlen ; no, we have the full match length from the token, go copy
lodsb ; grab extra length byte
test al,al ; zero?
jne .got_matchlen ; if not, we have the entire length
add al,018H ; overflow?
jnc .got_matchlen ; if not, we have the entire length
je short .done_decompressing ; detect EOD code
lodsw ; grab 16-bit length
test ax,ax ; bail if we hit EOD
je short .done_decompressing
.got_matchlen:
xchg cx,ax ; copy match length into cx