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Merge pull request #47 from dougmasten/dom
Various optimizations to the 6809 LZSA depackers
This commit is contained in:
Emmanuel Marty
GitHub
commit
a9b5a7511c
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@ -1,4 +1,4 @@
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; unlzsa1.s - 6809 decompression routine for raw LZSA1 - 117 bytes
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; unlzsa1.s - 6809 decompression routine for raw LZSA1 - 111 bytes
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; compress with lzsa -r <original_file> <compressed_file>
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;
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; in: x = start of compressed data
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@ -23,7 +23,45 @@
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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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decompress_lzsa1
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decompress_lzsa1 equ lz1token
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lz1bigof ldb ,x+ ; O set: load long 16 bit (negative, signed) offset
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lda ,x+ ; (little endian)
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lz1gotof leau d,y ; put backreference start address in U (dst+offset)
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puls b ; restore token
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clra ; clear A (high part of match length)
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andb #$0F ; isolate MMMM (embedded match length)
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addb #$03 ; add MIN_MATCH_SIZE
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cmpb #$12 ; MATCH_RUN_LEN?
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bne lz1gotln ; no, we have the full match length, go copy
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addb ,x+ ; add extra match length byte + MIN_MATCH_SIZE + MATCH_RUN_LEN
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bcc lz1gotln ; if no overflow, we have the full length
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bne lz1midln
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ldb ,x+ ; load 16-bit len in D (low part in B, high in A)
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lda ,x+ ; (little endian)
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bne lz1gotln ; check if we hit EOD (16-bit length = 0)
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tstb
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bne lz1gotln ; go copy matched bytes if not
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rts ; done, bail
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lz1midln tfr b,a ; copy high part of len into A
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ldb ,x+ ; grab low 8 bits of len in B
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lz1gotln pshs x ; save source compressed data pointer
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tfr d,x ; copy match length to X
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lz1cpymt lda ,u+ ; copy matched byte
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sta ,y+
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leax -1,x ; decrement X
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bne lz1cpymt ; loop until all matched bytes are copied
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puls x ; restore source compressed data pointer
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lz1token ldb ,x+ ; load next token into B: O|LLL|MMMM
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pshs b ; save it
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@ -50,59 +88,18 @@ lz1declt lsrb ; shift literals count into place
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lsrb
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lsrb
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lsrb
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lz1gotlt tfr x,u
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tfr d,x ; transfer 16-bit count into X
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lz1cpylt lda ,u+ ; copy literal byte
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sta ,y+
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sta ,y+
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leax -1,x ; decrement X and update Z flag
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bne lz1cpylt ; loop until all literal bytes are copied
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tfr u,x
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lz1nolt ldb ,s ; get token again, don't pop it from the stack
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tstb ; test O bit (small or large offset)
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bmi lz1bigof
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bmi lz1bigof ; test O bit (small or large offset)
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ldb ,x+ ; O clear: load 8 bit (negative, signed) offset
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lda #$ff ; set high 8 bits
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bra lz1gotof
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lz1bigof ldb ,x+ ; O set: load long 16 bit (negative, signed) offset
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lda ,x+ ; (little endian)
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lz1gotof leau d,y ; put backreference start address in U (dst+offset)
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puls b ; restore token
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clra ; clear A (high part of match length)
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andb #$0F ; isolate MMMM (embedded match length)
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addb #$03 ; add MIN_MATCH_SIZE
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cmpb #$12 ; MATCH_RUN_LEN?
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bne lz1gotln ; no, we have the full match length, go copy
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ldb ,x+ ; grab extra match length byte
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addb #$12 ; add MIN_MATCH_SIZE + MATCH_RUN_LEN
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bcc lz1gotln ; if no overflow, we have the full length
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bne lz1midln
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ldb ,x+ ; load 16-bit len in D (low part in B, high in A)
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lda ,x+ ; (little endian)
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bne lz1gotln ; check if we hit EOD (16-bit length = 0)
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tstb
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bne lz1gotln ; go copy matched bytes if not
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rts ; done, bail
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lz1midln tfr b,a ; copy high part of len into A
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ldb ,x+ ; grab low 8 bits of len in B
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lz1gotln pshs x ; save source compressed data pointer
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tfr d,x ; copy match length to X
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lz1cpymt lda ,u+ ; copy matched byte
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sta ,y+
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leax -1,x ; decrement X
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bne lz1cpymt ; loop until all matched bytes are copied
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puls x ; restore source compressed data pointer
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bra lz1token ; go decode next token
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@ -1,4 +1,4 @@
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; unlzsa1b.s - 6809 backward decompression routine for raw LZSA1 - 116 bytes
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; unlzsa1b.s - 6809 backward decompression routine for raw LZSA1 - 112 bytes
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; compress with lzsa -r -b <original_file> <compressed_file>
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;
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; in: x = last byte of compressed data
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@ -62,9 +62,7 @@ lz1cpylt lda ,-u ; copy literal byte
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tfr u,x
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lz1nolt ldb ,s ; get token again, don't pop it from the stack
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tstb ; test O bit (small or large offset)
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bmi lz1bigof
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bmi lz1bigof ; test O bit (small or large offset)
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ldb ,-x ; O clear: load 8 bit (negative, signed) offset
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lda #$ff ; set high 8 bits
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@ -84,8 +82,7 @@ lz1gotof nega ; reverse sign of offset in D
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cmpb #$12 ; MATCH_RUN_LEN?
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bne lz1gotln ; no, we have the full match length, go copy
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ldb ,-x ; grab extra match length byte
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addb #$12 ; add MIN_MATCH_SIZE + MATCH_RUN_LEN
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addb ,-x ; add extra match length byte + MIN_MATCH_SIZE + MATCH_RUN_LEN
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bcc lz1gotln ; if no overflow, we have the full length
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bne lz1midln
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@ -1,4 +1,4 @@
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; unlzsa2.s - 6809 decompression routine for raw LZSA2 - 187 bytes
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; unlzsa2.s - 6809 decompression routine for raw LZSA2 - 183 bytes
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; compress with lzsa -f2 -r <original_file> <compressed_file>
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;
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; in: x = start of compressed data
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@ -40,8 +40,7 @@ lz2token ldb ,x+ ; load next token into B: XYZ|LL|MMM
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cmpb #$12 ; LITERALS_RUN_LEN_V2 + 15 ?
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bne lz2gotlt ; if not, we have the full literals count, go copy
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ldb ,x+ ; load extra literals count byte
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addb #$12 ; add LITERALS_RUN_LEN + 15
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addb ,x+ ; add extra literals count byte + LITERALS_RUN_LEN + 15
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bcc lz2gotlt ; if no overflow, we got the complete count, copy
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ldb ,x+ ; load low 8 bits of little-endian literals count
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@ -1,4 +1,4 @@
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; unlzsa2.s - 6809 backward decompression routine for raw LZSA2 - 189 bytes
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; unlzsa2b.s - 6809 backward decompression routine for raw LZSA2 - 187 bytes
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; compress with lzsa -f2 -r -b <original_file> <compressed_file>
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;
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; in: x = last byte of compressed data
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@ -42,8 +42,7 @@ lz2token ldb ,-x ; load next token into B: XYZ|LL|MMM
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cmpb #$12 ; LITERALS_RUN_LEN_V2 + 15 ?
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bne lz2gotlt ; if not, we have the full literals count, go copy
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ldb ,-x ; load extra literals count byte
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addb #$12 ; add LITERALS_RUN_LEN + 15
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addb ,-x ; add extra literals count byte + LITERALS_RUN_LEN + 15
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bcc lz2gotlt ; if no overflow, we got the complete count, copy
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ldd ,--x ; load 16 bit count in D (low part in B, high in A)
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