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Merge pull request #1 from emmanuel-marty/master

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Add backward depackers for 6809
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Doug Masten 2020-06-20 12:03:30 -05:00 committed by GitHub
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109
asm/6809/unlzsa1b.s Normal file
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; unlzsa1b.s - 6809 backward decompression routine for raw LZSA1 - 116 bytes
; compress with lzsa -r -b <original_file> <compressed_file>
;
; in: x = last byte of compressed data
; y = last byte of decompression buffer
; out: y = first byte of decompressed data
;
; Copyright (C) 2020 Emmanuel Marty
;
; This software is provided 'as-is', without any express or implied
; warranty. In no event will the authors be held liable for any damages
; arising from the use of this software.
;
; Permission is granted to anyone to use this software for any purpose,
; including commercial applications, and to alter it and redistribute it
; freely, subject to the following restrictions:
;
; 1. The origin of this software must not be misrepresented; you must not
; claim that you wrote the original software. If you use this software
; in a product, an acknowledgment in the product documentation would be
; appreciated but is not required.
; 2. Altered source versions must be plainly marked as such, and must not be
; misrepresented as being the original software.
; 3. This notice may not be removed or altered from any source distribution.
decompress_lzsa1
leax 1,x
leay 1,y
lz1token ldb ,-x ; load next token into B: O|LLL|MMMM
pshs b ; save it
clra ; clear A (high part of literals count)
andb #$70 ; isolate LLL (embedded literals count) in B
beq lz1nolt ; skip if no literals
cmpb #$70 ; LITERALS_RUN_LEN?
bne lz1declt ; if not, we have the complete count, go unshift
ldb ,-x ; load extra literals count byte
addb #$07 ; add LITERALS_RUN_LEN
bcc lz1gotlt ; if no overflow, we got the complete count, copy
bne lz1midlt
ldd ,--x ; load 16 bit count in D (low part in B, high in A)
bra lz1gotlt ; we now have the complete count, go copy
lz1midlt tfr b,a ; copy high part of literals count into A
ldb ,-x ; load low 8 bits of literals count
bra lz1gotlt ; we now have the complete count, go copy
lz1declt lsrb ; shift literals count into place
lsrb
lsrb
lsrb
lz1gotlt tfr x,u
tfr d,x ; transfer 16-bit count into X
lz1cpylt lda ,-u ; copy literal byte
sta ,-y
leax -1,x ; decrement X and update Z flag
bne lz1cpylt ; loop until all literal bytes are copied
tfr u,x
lz1nolt ldb ,s ; get token again, don't pop it from the stack
tstb ; test O bit (small or large offset)
bmi lz1bigof
ldb ,-x ; O clear: load 8 bit (negative, signed) offset
lda #$ff ; set high 8 bits
bra lz1gotof
lz1bigof ldd ,--x ; O set: load long 16 bit (negative, signed) offset
lz1gotof nega ; reverse sign of offset in D
negb
sbca #0
leau d,y ; put backreference start address in U (dst+offset)
puls b ; restore token
clra ; clear A (high part of match length)
andb #$0F ; isolate MMMM (embedded match length)
addb #$03 ; add MIN_MATCH_SIZE
cmpb #$12 ; MATCH_RUN_LEN?
bne lz1gotln ; no, we have the full match length, go copy
ldb ,-x ; grab extra match length byte
addb #$12 ; add MIN_MATCH_SIZE + MATCH_RUN_LEN
bcc lz1gotln ; if no overflow, we have the full length
bne lz1midln
ldd ,--x ; load 16-bit len in D (low part in B, high in A)
bne lz1gotln ; check if we hit EOD (16-bit length = 0)
rts ; done, bail
lz1midln tfr b,a ; copy high part of len into A
ldb ,-x ; grab low 8 bits of len in B
lz1gotln pshs x ; save source compressed data pointer
tfr d,x ; copy match length to X
lz1cpymt lda ,-u ; copy matched byte
sta ,-y
leax -1,x ; decrement X
bne lz1cpymt ; loop until all matched bytes are copied
puls x ; restore source compressed data pointer
bra lz1token ; go decode next token

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asm/6809/unlzsa2b.s Normal file
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; unlzsa2.s - 6809 backward decompression routine for raw LZSA2 - 189 bytes
; compress with lzsa -f2 -r -b <original_file> <compressed_file>
;
; in: x = last byte of compressed data
; y = last byte of decompression buffer
; out: y = first byte of decompressed data
;
; Copyright (C) 2020 Emmanuel Marty
;
; This software is provided 'as-is', without any express or implied
; warranty. In no event will the authors be held liable for any damages
; arising from the use of this software.
;
; Permission is granted to anyone to use this software for any purpose,
; including commercial applications, and to alter it and redistribute it
; freely, subject to the following restrictions:
;
; 1. The origin of this software must not be misrepresented; you must not
; claim that you wrote the original software. If you use this software
; in a product, an acknowledgment in the product documentation would be
; appreciated but is not required.
; 2. Altered source versions must be plainly marked as such, and must not be
; misrepresented as being the original software.
; 3. This notice may not be removed or altered from any source distribution.
decompress_lzsa2
lsr <lz2nibct,pcr ; reset nibble available flag
leax 1,x
leay 1,y
lz2token ldb ,-x ; load next token into B: XYZ|LL|MMM
pshs b ; save it
clra ; clear A (high part of literals count)
andb #$18 ; isolate LLL (embedded literals count) in B
beq lz2nolt ; skip if no literals
cmpb #$18 ; LITERALS_RUN_LEN_V2?
bne lz2declt ; if not, we have the complete count, go unshift
bsr lz2nibl ; get extra literals length nibble in B
addb #$03 ; add LITERALS_RUN_LEN_V2
cmpb #$12 ; LITERALS_RUN_LEN_V2 + 15 ?
bne lz2gotlt ; if not, we have the full literals count, go copy
ldb ,-x ; load extra literals count byte
addb #$12 ; add LITERALS_RUN_LEN + 15
bcc lz2gotlt ; if no overflow, we got the complete count, copy
ldd ,--x ; load 16 bit count in D (low part in B, high in A)
bra lz2gotlt ; we now have the complete count, go copy
lz2declt lsrb ; shift literals count into place
lsrb
lsrb
lz2gotlt tfr x,u
tfr d,x ; transfer 16-bit count into X
lz2cpylt lda ,-u ; copy literal byte
sta ,-y
leax -1,x ; decrement X and update Z flag
bne lz2cpylt ; loop until all literal bytes are copied
tfr u,x
lz2nolt ldb ,s ; get token again, don't pop it from the stack
lslb ; push token's X flag bit into carry
bcs lz2replg ; if token's X bit is set, rep or large offset
lslb ; push token's Y flag bit into carry
bcs lz2offs9 ; if token's Y bit is set, 9 bits offset
lslb ; push token's Z flag bit into carry
tfr cc,a ; preserve cpu flags (to preserve carry)
bsr lz2nibl ; get offset nibble in B
tfr a,cc ; restore cpu flags
rolb ; shift Z flag from carry into bit 0 of B
eorb #$e1 ; set bits 5-7 of offset, reverse bit 0
lda #$ff ; set bits 8-15 of offset
bra lz2gotof
lz2offs9 clra ; clear A (to prepare for high 8 bits of offset)
lslb ; push token's Z flag bit into carry
rola ; shift Z flag from carry into bit 0 of A
coma ; set bits 9-15 of offset, reverse bit 8
bra lz2lowof
lz2nibct fcb $00 ; nibble ready flag
lz2nibl ldb #$aa
lsr <lz2nibct,pcr ; nibble ready?
bcs lz2gotnb
inc <lz2nibct,pcr ; flag nibble as ready for next time
ldb ,-x ; load two nibbles
stb <lz2nibl+1,pcr ; store nibble for next time (low 4 bits)
lsrb ; shift 4 high bits of nibble down
lsrb
lsrb
lsrb
lz2gotnb andb #$0f ; only keep low 4 bits
lz2done rts
lz2replg lslb ; push token's Y flag bit into carry
bcs lz2rep16 ; if token's Y bit is set, rep or 16 bit offset
lslb ; push token's Z flag bit into carry
tfr cc,a ; preserve cpu flags (to preserve carry)
bsr lz2nibl ; get offset nibble in B
tfr a,cc ; restore cpu flags
rolb ; shift Z flag from carry into bit 0 of B
eorb #$e1 ; set bits 13-15 of offset, reverse bit 8
tfr b,a ; copy bits 8-15 of offset into A
suba #$02 ; substract 512 from offset
bra lz2lowof
lz2rep16 bmi lz2repof ; if token's Z flag bit is set, rep match
lda ,-x ; load high 8 bits of (negative, signed) offset
lz2lowof ldb ,-x ; load low 8 bits of offset
lz2gotof nega ; reverse sign of offset in D
negb
sbca #0
std <lz2repof+1,pcr ; store match offset
lz2repof ldd #$aaaa ; load match offset
leau d,y ; put backreference start address in U (dst+offset)
puls b ; restore token
clra ; clear A (high part of match length)
andb #$07 ; isolate MMM (embedded match length)
addb #$02 ; add MIN_MATCH_SIZE_V2
cmpb #$09 ; MIN_MATCH_SIZE_V2 + MATCH_RUN_LEN_V2?
bne lz2gotln ; no, we have the full match length, go copy
bsr lz2nibl ; get offset nibble in B
addb #$09 ; add MIN_MATCH_SIZE_V2 + MATCH_RUN_LEN_V2
cmpb #$18 ; MIN_MATCH_SIZE_V2 + MATCH_RUN_LEN_V2 + 15?
bne lz2gotln ; if not, we have the full match length, go copy
ldb ,-x ; load extra length byte
addb #$18 ; add MIN_MATCH_SIZE_V2 + MATCH_RUN_LEN_V2 + 15
bcc lz2gotln ; if no overflow, we have the full length
beq lz2done ; detect EOD code
ldd ,--x ; load 16-bit len in D (low part in B, high in A)
lz2gotln pshs x ; save source compressed data pointer
tfr d,x ; copy match length to X
lz2cpymt lda ,-u ; copy matched byte
sta ,-y
leax -1,x ; decrement X
bne lz2cpymt ; loop until all matched bytes are copied
puls x ; restore source compressed data pointer
lbra lz2token ; go decode next token