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https://github.com/emmanuel-marty/lzsa.git
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Merge pull request #63 from jbrandwood/master
Make 6502 decompress_faster_v2.asm (& v1) 3-4% faster at the cost of 1 byte extra.
This commit is contained in:
Emmanuel Marty
GitHub
commit
bed1006a6d
@ -7,7 +7,7 @@
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;
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; This code is written for the ACME assembler.
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;
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; The code is 167 bytes for the small version, and 192 bytes for the normal.
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; The code is 169 bytes for the small version, and 193 bytes for the normal.
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;
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; Copyright John Brandwood 2021.
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;
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@ -37,15 +37,16 @@ LZSA_SMALL_SIZE = 0
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; ***************************************************************************
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; ***************************************************************************
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;
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; Data usage is last 8 bytes of zero-page.
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; Data usage is last 7 bytes of zero-page.
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;
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lzsa_length = $F8 ; 1 byte.
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lzsa_cmdbuf = $F9 ; 1 byte.
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lzsa_winptr = $FA ; 1 word.
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lzsa_srcptr = $FC ; 1 word.
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lzsa_dstptr = $FE ; 1 word.
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lzsa_offset = lzsa_winptr
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LZSA_SRC_LO = $FC
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LZSA_SRC_HI = $FD
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LZSA_DST_LO = $FE
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@ -60,7 +61,6 @@ LZSA_DST_HI = $FF
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;
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; Args: lzsa_srcptr = ptr to compessed data
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; Args: lzsa_dstptr = ptr to output buffer
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; Uses: lots!
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;
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DECOMPRESS_LZSA1_FAST:
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@ -95,19 +95,14 @@ lzsa1_unpack: ldy #0 ; Initialize source index.
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lsr
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lsr
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cmp #$07 ; Extended length?
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bcc .inc_cp_len
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bcc .cp_got_len
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jsr .get_length ; CS from CMP, X=0.
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jsr .get_length ; X=0, CS from CMP, returns CC.
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stx .cp_npages + 1 ; Hi-byte of length.
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ora #0 ; Check the lo-byte of length
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beq .put_cp_len ; without effecting CC.
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.cp_got_len: tax ; Lo-byte of length.
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.inc_cp_len: inx ; Increment # of pages to copy.
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.put_cp_len: stx <lzsa_length
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tax
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.cp_page: lda (lzsa_srcptr),y ; CC throughout the execution of
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.cp_byte: lda (lzsa_srcptr),y ; CC throughout the execution of
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sta (lzsa_dstptr),y ; of this .cp_page loop.
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inc <lzsa_srcptr + 0
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bne .cp_skip1
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@ -116,28 +111,24 @@ lzsa1_unpack: ldy #0 ; Initialize source index.
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bne .cp_skip2
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inc <lzsa_dstptr + 1
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.cp_skip2: dex
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bne .cp_page
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dec <lzsa_length ; Any full pages left to copy?
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bne .cp_page
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bne .cp_byte
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.cp_npages: lda #0 ; Any full pages left to copy?
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beq .lz_offset
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dec .cp_npages + 1 ; Unlikely, so can be slow.
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bcc .cp_byte ; Always true!
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!if LZSA_SMALL_SIZE {
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;
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; Copy bytes from decompressed window.
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;
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; Shorter but slower version.
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;
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; N.B. X=0 is expected and guaranteed when we get here.
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;
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.lz_offset: !if LZSA_SMALL_SIZE {
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jsr .get_byte
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} else {
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lda (lzsa_srcptr),y
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inc <lzsa_srcptr + 0
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bne .offset_lo
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inc <lzsa_srcptr + 1
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}
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.lz_offset: jsr .get_byte ; Get offset-lo.
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.offset_lo: adc <lzsa_dstptr + 0 ; Always CC from .cp_page loop.
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sta <lzsa_winptr + 0
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@ -146,97 +137,106 @@ lzsa1_unpack: ldy #0 ; Initialize source index.
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bit <lzsa_cmdbuf
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bpl .offset_hi
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!if LZSA_SMALL_SIZE {
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jsr .get_byte
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jsr .get_byte ; Get offset-hi.
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.offset_hi: adc <lzsa_dstptr + 1 ; lzsa_winptr < lzsa_dstptr, so
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sta <lzsa_winptr + 1 ; always leaves CS.
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.lz_length: lda <lzsa_cmdbuf ; X=0 from previous loop.
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and #$0F
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adc #$03 - 1 ; CS from previous ADC.
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cmp #$12 ; Extended length?
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bcc .lz_got_len
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jsr .get_length ; CS from CMP, X=0, returns CC.
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stx .lz_npages + 1 ; Hi-byte of length.
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.lz_got_len: tax ; Lo-byte of length.
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.lz_byte: lda (lzsa_winptr),y ; CC throughout the execution of
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sta (lzsa_dstptr),y ; of this .lz_page loop.
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inc <lzsa_winptr + 0
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bne .lz_skip1
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inc <lzsa_winptr + 1
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.lz_skip1: inc <lzsa_dstptr + 0
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bne .lz_skip2
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inc <lzsa_dstptr + 1
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.lz_skip2: dex
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bne .lz_byte
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.lz_npages: lda #0 ; Any full pages left to copy?
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beq .cp_length
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dec .lz_npages + 1 ; Unlikely, so can be slow.
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bcc .lz_byte ; Always true!
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} else {
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;
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; Copy bytes from decompressed window.
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;
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; Longer but faster.
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;
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; N.B. X=0 is expected and guaranteed when we get here.
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;
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.lz_offset: lda (lzsa_srcptr),y ; Get offset-lo.
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inc <lzsa_srcptr + 0
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bne .offset_lo
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inc <lzsa_srcptr + 1
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.offset_lo: sta <lzsa_offset + 0
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lda #$FF ; Get offset-hi.
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bit <lzsa_cmdbuf
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bpl .offset_hi
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lda (lzsa_srcptr),y
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inc <lzsa_srcptr + 0
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bne .offset_hi
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inc <lzsa_srcptr + 1
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}
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.offset_hi: adc <lzsa_dstptr + 1 ; lzsa_winptr < lzsa_dstptr, so
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sta <lzsa_winptr + 1 ; always leaves CS.
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!if LZSA_SMALL_SIZE {
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.offset_hi: sta <lzsa_offset + 1
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.lz_length: lda <lzsa_cmdbuf ; X=0 from previous loop.
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and #$0F
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adc #$03 - 1 ; CS from previous ADC.
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cmp #$12 ; Extended length?
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bcc .inc_lz_len
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jsr .get_length ; CS from CMP, X=0, returns CC.
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ora #0 ; Check the lo-byte of length
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beq .put_lz_len ; without effecting CC.
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.inc_lz_len: inx ; Increment # of pages to copy.
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.put_lz_len: stx <lzsa_length
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tax
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.lz_page: lda (lzsa_winptr),y ; CC throughout the execution of
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sta (lzsa_dstptr),y ; of this .lz_page loop.
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inc <lzsa_winptr + 0
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bne .skip3
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inc <lzsa_winptr + 1
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.skip3: inc <lzsa_dstptr + 0
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bne .skip4
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inc <lzsa_dstptr + 1
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.skip4: dex
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bne .lz_page
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dec <lzsa_length ; Any full pages left to copy?
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bne .lz_page
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jmp .cp_length ; Loop around to the beginning.
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} else {
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.lz_length: lda <lzsa_cmdbuf ; X=0 from previous loop.
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and #$0F
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adc #$03 - 1 ; CS from previous ADC.
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adc #$03 ; Always CC from .cp_page loop.
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cmp #$12 ; Extended length?
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bcc .got_lz_len
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jsr .get_length ; CS from CMP, X=0, returns CC.
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jsr .get_length ; X=0, CS from CMP, returns CC.
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.got_lz_len: tay ; Check the lo-byte of length.
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beq .lz_page
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.got_lz_len: inx ; Hi-byte of length+256.
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inx ; Increment # of pages to copy.
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eor #$FF ; Negate the lo-byte of length
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tay ; and check for zero.
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iny
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eor #$FF
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.get_lz_win: adc <lzsa_winptr + 0 ; Calc address of partial page.
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sta <lzsa_winptr + 0 ; Always CC from previous CMP.
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bcs .get_lz_dst
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dec <lzsa_winptr + 1
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.get_lz_dst: tya ; Calc address of partial page.
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clc
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adc <lzsa_dstptr + 0
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sta <lzsa_dstptr + 0
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bcs .get_lz_idx
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.get_lz_dst: adc <lzsa_dstptr + 0 ; Calc address of partial page.
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sta <lzsa_dstptr + 0 ; Always CC from .cp_page loop.
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bcs .get_lz_win
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dec <lzsa_dstptr + 1
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.get_lz_idx: tya ; Negate the lo-byte of length.
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eor #$FF
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tay
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iny
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.get_lz_win: clc ; Calc address of match.
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adc <lzsa_offset + 0 ; N.B. Offset is negative!
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sta <lzsa_winptr + 0
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lda <lzsa_dstptr + 1
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adc <lzsa_offset + 1
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sta <lzsa_winptr + 1
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.lz_page: lda (lzsa_winptr),y
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.lz_byte: lda (lzsa_winptr),y
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sta (lzsa_dstptr),y
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iny
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bne .lz_page
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inc <lzsa_winptr + 1
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bne .lz_byte
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inc <lzsa_dstptr + 1
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dex ; Any full pages left to copy?
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bne .lz_page
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bne .lz_more
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jmp .cp_length ; Loop around to the beginning.
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.lz_more: inc <lzsa_winptr + 1 ; Unlikely, so can be slow.
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bne .lz_byte ; Always true!
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}
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;
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@ -252,30 +252,32 @@ lzsa1_unpack: ldy #0 ; Initialize source index.
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inc <lzsa_srcptr + 1
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.skip_inc: bcc .got_length ; No overflow means done.
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cmp #$01 ; Overflow to 256 or 257?
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bcc .extra_word
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clc ; MUST return CC!
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tax ; Overflow to 256 or 257?
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beq .extra_word
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.extra_byte: clc ; MUST return CC!
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inx
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bne .get_byte ; Always NZ from previous INX.
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.extra_byte: jsr .get_byte ; So rare, this can be slow!
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pha
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.check_length: pla ; Length-lo.
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bne .got_length ; Check for zero.
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dex ; Do one less page loop if so.
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.got_length: rts
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.extra_word: jsr .get_byte ; So rare, this can be slow!
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pha
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jsr .get_byte ; So rare, this can be slow!
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tax
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beq .finished ; Length-hi == 0 at EOF.
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pla ; Length-lo.
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rts
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.get_byte: lda (lzsa_srcptr),y ; Subroutine version for when
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inc <lzsa_srcptr + 0 ; inlining isn't advantageous.
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beq .next_page
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.got_length: rts
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.next_page: inc <lzsa_srcptr + 1 ; Inc & test for bank overflow.
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rts
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bne .check_length ; Length-hi == 0 at EOF.
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.finished: pla ; Length-lo.
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pla ; Decompression completed, pop
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pla ; return address.
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rts
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.get_byte: lda (lzsa_srcptr),y ; Subroutine version for when
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inc <lzsa_srcptr + 0 ; inlining isn't advantageous.
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beq .next_page
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rts
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.next_page: inc <lzsa_srcptr + 1 ; Inc & test for bank overflow.
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rts
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@ -7,7 +7,7 @@
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;
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; This code is written for the ACME assembler.
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;
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; The code is 240 bytes for the small version, and 255 bytes for the normal.
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; The code is 241 bytes for the small version, and 256 bytes for the normal.
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;
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; Copyright John Brandwood 2021.
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;
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@ -66,7 +66,6 @@ LZSA_DST_HI = $FF
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;
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; Args: lzsa_srcptr = ptr to compessed data
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; Args: lzsa_dstptr = ptr to output buffer
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; Uses: lots!
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;
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DECOMPRESS_LZSA2_FAST:
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@ -101,34 +100,28 @@ lzsa2_unpack: ldx #$00 ; Hi-byte of length or offset.
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lsr
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lsr
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cmp #$03 ; Extended length?
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bcc .inc_cp_len
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bcc .cp_got_len
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inx
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jsr .get_length ; X=1 for literals, returns CC.
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jsr .get_length ; X=0 for literals, returns CC.
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stx .cp_npages + 1 ; Hi-byte of length.
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ora #0 ; Check the lo-byte of length
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beq .put_cp_len ; without effecting CC.
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.cp_got_len: tax ; Lo-byte of length.
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.inc_cp_len: inx ; Increment # of pages to copy.
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.put_cp_len: stx <lzsa_length
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tax
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.cp_page: lda (lzsa_srcptr),y ; CC throughout the execution of
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.cp_byte: lda (lzsa_srcptr),y ; CC throughout the execution of
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sta (lzsa_dstptr),y ; of this .cp_page loop.
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inc <lzsa_srcptr + 0
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bne .cp_skip1
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inc <lzsa_srcptr + 1
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.cp_skip1: inc <lzsa_dstptr + 0
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bne .cp_skip2
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inc <lzsa_dstptr + 1
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.cp_skip2: dex
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bne .cp_page
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dec <lzsa_length ; Any full pages left to copy?
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bne .cp_page
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bne .cp_byte
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.cp_npages: lda #0 ; Any full pages left to copy?
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beq .lz_offset
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dec .cp_npages + 1 ; Unlikely, so can be slow.
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bcc .cp_byte ; Always true!
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;
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; Copy bytes from decompressed window.
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@ -193,7 +186,7 @@ lzsa2_unpack: ldx #$00 ; Hi-byte of length or offset.
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.set_offset: stx <lzsa_offset + 1 ; Save new offset.
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sta <lzsa_offset + 0
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.lz_length: ldx #$00 ; Hi-byte of length.
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.lz_length: ldx #1 ; Hi-byte of length+256.
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lda <lzsa_cmdbuf
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and #$07
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@ -202,49 +195,48 @@ lzsa2_unpack: ldx #$00 ; Hi-byte of length or offset.
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cmp #$09 ; Extended length?
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bcc .got_lz_len
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jsr .get_length ; X=0 for match, returns CC.
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jsr .get_length ; X=1 for match, returns CC.
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inx ; Hi-byte of length+256.
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.got_lz_len: eor #$FF ; Negate the lo-byte of length
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tay ; and check for zero.
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iny
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beq .get_lz_win
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eor #$FF
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inx ; Increment # of pages to copy.
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.get_lz_dst: adc <lzsa_dstptr + 0 ; Calc address of partial page.
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sta <lzsa_dstptr + 0 ; Always CC from previous CMP.
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bcs .get_lz_win
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dec <lzsa_dstptr + 1
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.get_lz_win: clc ; Calc address of match.
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lda <lzsa_dstptr + 0 ; N.B. Offset is negative!
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adc <lzsa_offset + 0
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adc <lzsa_offset + 0 ; N.B. Offset is negative!
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sta <lzsa_winptr + 0
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lda <lzsa_dstptr + 1
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adc <lzsa_offset + 1
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sta <lzsa_winptr + 1
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.lz_page: lda (lzsa_winptr),y
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.lz_byte: lda (lzsa_winptr),y
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sta (lzsa_dstptr),y
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iny
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bne .lz_page
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inc <lzsa_winptr + 1
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bne .lz_byte
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inc <lzsa_dstptr + 1
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dex ; Any full pages left to copy?
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bne .lz_page
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bne .lz_more
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jmp .cp_length ; Loop around to the beginning.
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.lz_more: inc <lzsa_winptr + 1 ; Unlikely, so can be slow.
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bne .lz_byte ; Always true!
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;
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; Lookup tables to differentiate literal and match lengths.
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;
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.nibl_len_tbl: !byte 9 ; 2+7 (for match).
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!byte 3 ; 0+3 (for literal).
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.nibl_len_tbl: !byte 3 ; 0+3 (for literal).
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!byte 9 ; 2+7 (for match).
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.byte_len_tbl: !byte 24 - 1 ; 2+7+15 - CS (for match).
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!byte 18 - 1 ; 0+3+15 - CS (for literal).
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.byte_len_tbl: !byte 18 - 1 ; 0+3+15 - CS (for literal).
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!byte 24 - 1 ; 2+7+15 - CS (for match).
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;
|
||||
; Get 16-bit length in X:A register pair, return with CC.
|
||||
@ -263,13 +255,15 @@ lzsa2_unpack: ldx #$00 ; Hi-byte of length or offset.
|
||||
bcc .got_length
|
||||
beq .finished
|
||||
|
||||
.word_length: jsr .get_byte ; So rare, this can be slow!
|
||||
.word_length: clc ; MUST return CC!
|
||||
jsr .get_byte ; So rare, this can be slow!
|
||||
pha
|
||||
jsr .get_byte ; So rare, this can be slow!
|
||||
tax
|
||||
pla
|
||||
clc ; MUST return CC!
|
||||
rts
|
||||
bne .got_word ; Check for zero lo-byte.
|
||||
dex ; Do one less page loop if so.
|
||||
.got_word: rts
|
||||
|
||||
.get_byte: lda (lzsa_srcptr),y ; Subroutine version for when
|
||||
inc <lzsa_srcptr + 0 ; inlining isn't advantageous.
|
||||
|
||||
Loading…
Reference in New Issue
Block a user