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Merge pull request #51 from dougmasten/dev
Space optimizations for backward HD6309 depackers
This commit is contained in:
Emmanuel Marty
GitHub
commit
710257970e
@ -1,4 +1,4 @@
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; unlzsa1-6309.s - H6309 backward decompressor for raw LZSA1 - 105 bytes
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; unlzsa1-6309.s - H6309 backward decompressor for raw LZSA1 - 97 bytes
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; compress with lzsa -f1 -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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@ -25,11 +25,10 @@
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decompress_lzsa1
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leax 1,x
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bra lz1start
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bra lz1token
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lz1bigof ldd ,--x ; O set: load long 16-bit (negative, signed) offest
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lz1gotof negd ; reverse sign of offset in D
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decd ; tfm below is post-decrement, not pre-decrement
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leau d,y ; put backreference start address in U (dst+offset)
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ldd #$000f ; clear MSB match length and set mask for MMMM
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@ -45,15 +44,14 @@ lz1gotof negd ; reverse sign of offset in D
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ldd ,--x ; load 16-bit len in D (low part in B, high in A)
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bne lz1gotln ; check if we hit EOD (16-bit length = 0)
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leay 1,y ; adjust pointer to first byte of decompressed data
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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 tfr d,w ; set W with match length for TFM instruction
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leay -1,y ; tfm is post-decrement
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tfm u-,y- ; copy match bytes
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lz1start leay 1,y ; fix destination for pre-decrement again
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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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@ -83,10 +81,8 @@ lz1declt lsrb ; shift literals count into place
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lz1gotla clra ; clear A (high part of literals count)
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lz1gotlt tfr d,w ; set W with literals count for TFM instruction
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leax -1,x ; tfm is post-decrement
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leay -1,y
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tfm x-,y- ; copy literal bytes
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leax 1,x
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leay 1,y
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lz1nolt ldb ,s ; get token again, don't pop it from the stack
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bmi lz1bigof ; test O bit (small or large offset)
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@ -1,4 +1,4 @@
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; unlzsa2b-6309.s - H6309 backward decompressor for raw LZSA2 - 163 bytes
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; unlzsa2b-6309.s - H6309 backward decompressor for raw LZSA2 - 155 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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@ -25,8 +25,7 @@
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decompress_lzsa2
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clr lz2nibct ; reset nibble available flag
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leax 1,x
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leay 1,y
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leax 1,x ; adjust compressed data pointer
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bra lz2token
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lz2nibct fcb 0 ; nibble ready flag
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@ -35,7 +34,7 @@ lz2replg lslb ; push token's Y flag bit into carry
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bcs lz2rep16 ; if token's Y bit is set, rep or 16 bit offset
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sex ; push token's Z flag bit into reg A
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lbsr lz2nibl ; get offset nibble in B
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bsr lz2nibl ; get offset nibble in B
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lsla ; push token's Z flag bit into carry
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rolb ; shift Z flag from carry into bit 0 of B
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eorb #$e1 ; set bits 13-15 of offset, reverse bit 8
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@ -48,7 +47,6 @@ lz2rep16 bmi lz2repof ; if token's Z flag bit is set, rep match
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lz2lowof ldb ,-x ; load low 8 bits of offset
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lz2gotof negd ; reverse sign of offset in D
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decd ; tfm below is post-decrement, not pre-decrement
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std lz2moff+2 ; store match offset
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lz2repof ldd #$0007 ; clear MSB match length and set mask for MMM
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@ -70,9 +68,7 @@ lz2moff leau $aaaa,y ; put backreference start address in U (dst+offset)
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ldd ,--x ; load 16-bit len in D (low part in B, high in A)
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lz2gotln tfr d,w ; set W with match count for TFM instruction
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leay -1,y ; tfm is post-decrement
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tfm u-,y- ; copy match bytes
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leay 1,y ; fix destination for pre-decrement again
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lz2token ldb ,-x ; load next token into B: XYZ|LL|MMM
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tfr x,u ; save token address
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@ -92,6 +88,17 @@ lz2token ldb ,-x ; load next token into B: XYZ|LL|MMM
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ldd ,--x ; load 16 bit count in D (low part in B, high in A)
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bra lz2gotlt ; we now have the complete count, go copy
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lz2nibl com lz2nibct ; nibble ready?
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bpl lz2gotnb
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ldb ,-x ; load two nibbles
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stb lz2gotnb+1 ; store nibble for next time (low 4 bits)
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lsrb ; shift 4 high bits of nibble down
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lsrb
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lsrb
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lsrb
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rts
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lz2declt lsrb ; shift literals count into place
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lsrb
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lsrb
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@ -99,10 +106,8 @@ lz2gotla clra ; clear A (high part of literals count)
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lz2gotlt tfr d,w ; set W with literals count for TFM instruction
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leax -1,x ; tfm is post-decrement
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leay -1,y
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tfm x-,y- ; copy literal bytes
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leax 1,x
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leay 1,y
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lz2nolt ldb ,u ; get token again
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lslb ; push token's X flag bit into carry
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@ -122,15 +127,7 @@ lz2nolt ldb ,u ; get token again
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lz2offs9 deca ; set bits 9-15 of offset, reverse bit 8
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bra lz2lowof
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lz2nibl ldb #$aa
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com lz2nibct ; nibble ready?
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bpl lz2gotnb
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ldb ,-x ; load two nibbles
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stb lz2nibl+1 ; store nibble for next time (low 4 bits)
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lsrb ; shift 4 high bits of nibble down
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lsrb
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lsrb
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lsrb
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lz2gotnb andb #$0f ; only keep low 4 bits
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lz2done rts
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lz2done leay 1,y ; adjust pointer to first byte of decompressed data and then exit
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lz2gotnb ldb #$aa ; load nibble
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andb #$0f ; only keep low 4 bits
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rts
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