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https://github.com/pfusik/zlib6502.git
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commit
02c09a514e
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@ -15,7 +15,7 @@ Use [xasm](https://github.com/pfusik/xasm).
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The routine uses three memory areas:
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* `inflate` - code and constants (499 bytes)
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* `inflate` - code and constants (492 bytes)
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* `inflate_data` - uninitialized data (764 bytes)
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* `inflate_zp` - variables on zero page
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42
inflate.asx
42
inflate.asx
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@ -4,7 +4,7 @@
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; Compile with xasm (http://xasm.atari.org/), for example:
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; xasm inflate.asx /l /d:inflate=$b700 /d:inflate_data=$b900 /d:inflate_zp=$f0
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; inflate is 499 bytes of code and constants
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; inflate is 492 bytes of code and constants
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; inflate_data is 764 bytes of uninitialized data
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; inflate_zp is 10 bytes on page zero
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@ -279,7 +279,7 @@ inflateDynamic_getTempCodeLengths
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; Build Huffman trees basing on code lengths (in bits)
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; stored in the *SymbolCodeLength arrays
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buildHuffmanTree
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; Clear nBitCode_totalCount, nBitCode_literalCount, nBitCode_controlCount
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; Clear nBitCode_literalCount, nBitCode_controlCount
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tya
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; lda #0
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sta:rne nBitCode_clearFrom,y+
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@ -288,21 +288,19 @@ buildHuffmanTree
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buildHuffmanTree_countCodeLengths
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ldx literalSymbolCodeLength,y
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inc nBitCode_literalCount,x
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inc nBitCode_totalCount,x
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cpy #CONTROL_SYMBOLS
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bcs buildHuffmanTree_noControlSymbol
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ldx controlSymbolCodeLength,y
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inc nBitCode_controlCount,x
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inc nBitCode_totalCount,x
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buildHuffmanTree_noControlSymbol
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iny
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bne buildHuffmanTree_countCodeLengths
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; Calculate offsets of symbols sorted by code length
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; lda #0
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ldx #-3*TREE_SIZE
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ldx #-4*TREE_SIZE
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buildHuffmanTree_calculateOffsets
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sta nBitCode_literalOffset+3*TREE_SIZE-$100,x
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add nBitCode_literalCount+3*TREE_SIZE-$100,x
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sta nBitCode_literalOffset+4*TREE_SIZE-$100,x
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add nBitCode_literalCount+4*TREE_SIZE-$100,x
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inx
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bne buildHuffmanTree_calculateOffsets
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; Put symbols in their place in the sorted array
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@ -337,26 +335,26 @@ fetchCode_nextBit
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jsr getBit
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rol @
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inx
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sub nBitCode_totalCount,x
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sub nBitCode_literalCount,x
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bcc fetchCode_literal
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; sec
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sbc nBitCode_controlCount,x
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bcs fetchCode_nextBit
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; clc
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adc nBitCode_controlCount,x
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bcs fetchCode_control
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adc nBitCode_controlOffset,x
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tax
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lda codeToControlSymbol,x
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and #$1f ; make distance symbols zero-based
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tax
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; sec
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rts
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fetchCode_literal
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; clc
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adc nBitCode_literalOffset,x
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tax
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lda codeToLiteralSymbol,x
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clc
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rts
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fetchCode_control
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; sec
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adc nBitCode_controlOffset-1,x
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tax
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lda codeToControlSymbol-1,x
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and #$1f ; make distance symbols zero-based
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tax
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sec
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rts
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; Read A minus 1 bits, but no more than 8
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getAMinus1BitsMax8
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@ -440,14 +438,12 @@ controlSymbolCodeLength
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; Huffman trees
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nBitCode_clearFrom
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nBitCode_totalCount
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org *+2*TREE_SIZE
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nBitCode_literalCount
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org *+TREE_SIZE
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org *+2*TREE_SIZE
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nBitCode_controlCount
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org *+2*TREE_SIZE
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nBitCode_literalOffset
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org *+TREE_SIZE
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org *+2*TREE_SIZE
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nBitCode_controlOffset
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org *+2*TREE_SIZE
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