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prog8/compiler/res/prog8lib/shared_compression.p8

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; **experimental** data compression/decompression routines, API subject to change!!
; This file contains the shared routines that work on all targets.
compression {
%option ignore_unused, merge
sub encode_rle_outfunc(uword data, uword size, uword output_function, bool is_last_block) {
; -- Compress the given data block using ByteRun1 aka PackBits RLE encoding.
; output_function = address of a routine that gets a byte arg in A,
; which is the next RLE byte to write to the compressed output buffer or file.
; is_last_block = usually true, but you can set it to false if you want to concatenate multiple
; compressed blocks (for instance if the source data is >64Kb)
; Worst case result storage size needed = (size + (size+126) / 127) + 1
; This routine is not optimized for speed but for readability and ease of use.
uword idx = 0
uword literals_start_idx = 0
ubyte literals_length = 0
asmsub call_output_function(ubyte arg @A) {
%asm {{
jmp (p8v_output_function)
}}
}
sub next_same_span() {
; returns length in cx16.r1L, and the byte value in cx16.r1H
cx16.r1H = data[idx]
cx16.r1L = 0
while data[idx]==cx16.r1H and cx16.r1L<128 and idx<size {
idx++
cx16.r1L++
}
}
sub output_literals() {
call_output_function(literals_length-1)
uword dataptr = data + literals_start_idx
ubyte i
for i in 0 to literals_length-1 {
call_output_function(@(dataptr))
dataptr++
}
literals_length = 0
}
while idx<size {
next_same_span() ; count in r1L, value in r1H
if cx16.r1L>1 {
; a replicate run
if literals_length>0
output_literals()
call_output_function((cx16.r1L^255)+2) ; 257-cx16.r1L
call_output_function(cx16.r1H)
}
else {
; add more to the literals run
if literals_length==128
output_literals()
if literals_length==0
literals_start_idx = idx-1
literals_length++
}
}
if literals_length>0
output_literals()
if is_last_block
call_output_function(128)
}
sub encode_rle(uword data, uword size, uword target, bool is_last_block) -> uword {
; -- Compress the given data block using ByteRun1 aka PackBits RLE encoding.
; Returns the size of the compressed RLE data. Worst case result storage size needed = (size + (size+126) / 127) + 1.
; is_last_block = usually true, but you can set it to false if you want to concatenate multiple
; compressed blocks (for instance if the source data is >64Kb)
; This routine is not optimized for speed but for readability and ease of use.
uword idx = 0
uword literals_start_idx = 0
ubyte literals_length = 0
uword orig_target = target
sub next_same_span() {
; returns length in cx16.r1L, and the byte value in cx16.r1H
cx16.r1H = data[idx]
cx16.r1L = 0
while data[idx]==cx16.r1H and cx16.r1L<128 and idx<size {
idx++
cx16.r1L++
}
}
sub output_literals() {
@(target) = literals_length-1
target++
uword dataptr = data + literals_start_idx
ubyte i
for i in 0 to literals_length-1 {
@(target) = @(dataptr)
target++
dataptr++
}
literals_length = 0
}
while idx<size {
next_same_span() ; count in r1L, value in r1H
if cx16.r1L>1 {
; a replicate run
if literals_length>0
output_literals()
@(target) = (cx16.r1L^255)+2 ; 257-cx16.r1L
target++
@(target) = cx16.r1H
target++
}
else {
; add more to the literals run
if literals_length==128
output_literals()
if literals_length==0
literals_start_idx = idx-1
literals_length++
}
}
if literals_length>0
output_literals()
if is_last_block {
@(target) = 128
target ++
}
return target-orig_target
}
asmsub decode_rle_srcfunc(uword source_function @AY, uword target @R0, uword maxsize @R1) clobbers(X) -> uword @AY {
; -- Decodes "ByteRun1" (aka PackBits) RLE compressed data. Control byte value 128 ends the decoding.
; Also stops decompressing when the maxsize has been reached. Returns the size of the decompressed data.
; Instead of a source buffer, you provide a callback function that must return the next byte to decompress in A.
; Note: the callback routine MUST NOT MODIFY the prog8 scratch variables such as P8ZP_SCRATCH_W1 etc!
%asm {{
sta _cb_mod1+1
sty _cb_mod1+2
sta _cb_mod2+1
sty _cb_mod2+2
sta _cb_mod3+1
sty _cb_mod3+2
lda cx16.r0L
ldy cx16.r0H
sta P8ZP_SCRATCH_W2 ; target ptr
sta _orig_target
sty P8ZP_SCRATCH_W2+1
sty _orig_target+1
lda cx16.r0L
clc
adc cx16.r1L
sta cx16.r1L
lda cx16.r0H
adc cx16.r1H
sta cx16.r1H ; decompression limit
_loop
; while target (W2) < limit (r1)
lda P8ZP_SCRATCH_W2
ldy P8ZP_SCRATCH_W2+1
cmp cx16.r1L
tya
sbc cx16.r1H
bcs _end
; check control byte
_cb_mod1 jsr $ffff ; modified
cmp #0
bpl _literals
cmp #128
beq _end
; replicate next byte -n+1 times
eor #255
clc
adc #2
sta P8ZP_SCRATCH_REG
_cb_mod2 jsr $ffff ; modified
ldx P8ZP_SCRATCH_REG
ldy #0
- sta (P8ZP_SCRATCH_W2),y
iny
dex
bne -
; add A to target
lda P8ZP_SCRATCH_REG
clc
adc P8ZP_SCRATCH_W2
sta P8ZP_SCRATCH_W2
bcc _loop
inc P8ZP_SCRATCH_W2+1
bcs _loop
_literals
; copy the next n+1 bytes
pha
sta P8ZP_SCRATCH_B1
ldy #0
sty P8ZP_SCRATCH_REG
_cb_mod3 jsr $ffff ; modified
ldy P8ZP_SCRATCH_REG
sta (P8ZP_SCRATCH_W2),y
inc P8ZP_SCRATCH_REG
dec P8ZP_SCRATCH_B1
bpl _cb_mod3
; add N+1 to target
pla
sec
adc P8ZP_SCRATCH_W2
sta P8ZP_SCRATCH_W2
bcc _loop
inc P8ZP_SCRATCH_W2+1
bcs _loop
.section BSS
_orig_target .word ?
.send BSS
_end
; return w2-orig_target, the size of the decompressed data
lda P8ZP_SCRATCH_W2
ldy P8ZP_SCRATCH_W2+1
sec
sbc _orig_target
tax
tya
sbc _orig_target+1
tay
txa
rts
}}
}
asmsub decode_rle(uword compressed @AY, uword target @R0, uword maxsize @R1) clobbers(X) -> uword @AY {
; -- Decodes "ByteRun1" (aka PackBits) RLE compressed data. Control byte value 128 ends the decoding.
; Also stops decompressing if the maxsize has been reached.
; Returns the size of the decompressed data.
%asm {{
sta P8ZP_SCRATCH_W1 ; compressed data ptr
sty P8ZP_SCRATCH_W1+1
lda cx16.r0L
ldy cx16.r0H
sta P8ZP_SCRATCH_W2 ; target ptr
sta _orig_target
sty P8ZP_SCRATCH_W2+1
sty _orig_target+1
lda cx16.r0L
clc
adc cx16.r1L
sta cx16.r1L
lda cx16.r0H
adc cx16.r1H
sta cx16.r1H ; decompression limit
_loop ; while target (W2) < limit (r1)
lda P8ZP_SCRATCH_W2
ldy P8ZP_SCRATCH_W2+1
cmp cx16.r1L
tya
sbc cx16.r1H
bcs _end
; check control byte
ldy #0
lda (P8ZP_SCRATCH_W1),y
bpl _literals
cmp #128
beq _end
; replicate next byte -n+1 times
eor #255
clc
adc #2
pha
tax
iny
lda (P8ZP_SCRATCH_W1),y
ldy #0
- sta (P8ZP_SCRATCH_W2),y
iny
dex
bne -
; add A to target
pla
clc
adc P8ZP_SCRATCH_W2
sta P8ZP_SCRATCH_W2
bcc +
inc P8ZP_SCRATCH_W2+1
clc
+
; increase source by 2
lda P8ZP_SCRATCH_W1
adc #2
sta P8ZP_SCRATCH_W1
bcc _loop
inc P8ZP_SCRATCH_W1+1
bcs _loop
_literals
; copy the next n+1 bytes
pha
tax
inc P8ZP_SCRATCH_W1
bne +
inc P8ZP_SCRATCH_W1+1
+ ldy #0
- lda (P8ZP_SCRATCH_W1),y
sta (P8ZP_SCRATCH_W2),y
iny
dex
bpl -
; add N+1 to source
pla
tax
sec
adc P8ZP_SCRATCH_W1
sta P8ZP_SCRATCH_W1
bcc +
inc P8ZP_SCRATCH_W1+1
+ ; add N+1 to target as well
txa
sec
adc P8ZP_SCRATCH_W2
sta P8ZP_SCRATCH_W2
bcc _loop
inc P8ZP_SCRATCH_W2+1
bcs _loop
.section BSS
_orig_target .word ?
.send BSS
_end
; return w2-orig_target, the size of the decompressed data
lda P8ZP_SCRATCH_W2
ldy P8ZP_SCRATCH_W2+1
sec
sbc _orig_target
tax
tya
sbc _orig_target+1
tay
txa
rts
}}
}
asmsub decode_zx0(uword compressed @R0, uword target @R1) clobbers(A,X,Y) {
; Decompress a block of data compressed in the ZX0 format
; This can be produced using the "salvador" compressor with -classic
; It has faster decompression than LZSA and a better compression ratio as well.
; see https://github.com/emmanuel-marty/salvador for the compressor tool
; see https://github.com/einar-saukas/ZX0 for the compression format
;
; NOTE: for speed reasons this decompressor is NOT bank-aware and NOT I/O register aware;
; it only outputs to a memory buffer somewhere in the active 64 Kb address range
;
%asm {{
; ***************************************************************************
; ***************************************************************************
;
; zx0_6502.asm
;
; NMOS 6502 decompressor for data stored in Einar Saukas's ZX0 format.
;
; The code is 196 bytes long, and is self-modifying.
;
; Copyright John Brandwood 2021.
;
; Distributed under the Boost Software License, Version 1.0.
; (See accompanying file LICENSE_1_0.txt or copy at
; http://www.boost.org/LICENSE_1_0.txt)
;
; Adapted for Prog8 by Irmen de Jong
;
; ***************************************************************************
; ***************************************************************************
; ***************************************************************************
; ***************************************************************************
;
; Decompression Options & Macros
;
; ***************************************************************************
; ***************************************************************************
;
; Data usage is 8 bytes of zero-page.
;
.if cx16.r0 < $100
; r0-r15 registers are in zeropage just use those
zx0_srcptr = cx16.r0 ;$F8 ; 1 word.
zx0_dstptr = cx16.r1 ;$FA ; 1 word.
zx0_length = cx16.r2 ;$FC ; 1 word.
zx0_offset = cx16.r3 ;$FE ; 1 word.
.else
.error "in decode_zx0: r0-15 are not in zeropage and no alternatives have been set up yet" ; TODO
.endif
; ***************************************************************************
; ***************************************************************************
;
; zx0_unpack - Decompress data stored in Einar Saukas's ZX0 format.
;
; Args: zx0_srcptr = ptr to compessed data
; Args: zx0_dstptr = ptr to output buffer
; Uses: lots!
;
zx0_unpack:
.if cx16.r0>=$100
; set up the source and destination pointers
lda cx16.r0L
sta zx0_srcptr
lda cx16.r0H
sta zx0_srcptr+1
lda cx16.r1L
sta zx0_dstptr
lda cx16.r1H
sta zx0_dstptr+1
.endif
ldy #$FF ; Initialize default offset.
sty <zx0_offset+0
sty <zx0_offset+1
iny ; Initialize source index.
sty <zx0_length+1 ; Initialize length to 1.
ldx #$40 ; Initialize empty buffer.
zx0_next_cmd: lda #1 ; Initialize length back to 1.
sta <zx0_length + 0
txa ; Restore bit-buffer.
asl a ; Copy from literals or new offset?
bcc zx0_cp_literal
;
; Copy bytes from new offset.
;
zx0_new_offset: jsr zx0_gamma_flag ; Get offset MSB, returns CS.
tya ; Negate offset MSB and check
sbc <zx0_length + 0 ; for zero (EOF marker).
bcs zx0_got_eof
sec
ror a
sta <zx0_offset + 1 ; Save offset MSB.
lda (<zx0_srcptr),y ; Get offset LSB.
inc <zx0_srcptr + 0
beq zx0_inc_of_src
zx0_off_skip1: ror a ; Last offset bit starts gamma.
sta <zx0_offset + 0 ; Save offset LSB.
lda #-2 ; Minimum length of 2?
bcs zx0_get_lz_dst
lda #1 ; Initialize length back to 1.
sta <zx0_length + 0
txa ; Restore bit-buffer.
jsr zx0_gamma_data ; Get length, returns CS.
lda <zx0_length + 0 ; Negate lo-byte of (length+1).
eor #$FF
; bne zx0_get_lz_dst ; N.B. Optimized to do nothing!
;
; inc <zx0_length + 1 ; Increment from (length+1).
; dec <zx0_length + 1 ; Decrement because lo-byte=0.
zx0_get_lz_dst: tay ; Calc address of partial page.
eor #$FF ; Always CS from previous SBC.
adc <zx0_dstptr + 0
sta <zx0_dstptr + 0
bcs zx0_get_lz_win
dec <zx0_dstptr + 1
zx0_get_lz_win: clc ; Calc address of match.
adc <zx0_offset + 0 ; N.B. Offset is negative!
sta zx0_winptr + 0
lda <zx0_dstptr + 1
adc <zx0_offset + 1
sta zx0_winptr + 1
zx0_winptr = *+1
zx0_lz_page: lda $1234,y ; Self-modifying zx0_winptr.
sta (<zx0_dstptr),y
iny
bne zx0_lz_page
inc <zx0_dstptr + 1
lda <zx0_length + 1 ; Any full pages left to copy?
beq zx0_next_cmd
dec <zx0_length + 1 ; This is rare, so slower.
inc zx0_winptr + 1
bne zx0_lz_page ; Always true.
zx0_got_eof: rts ; Finished decompression.
;
; Copy bytes from compressed source.
;
zx0_cp_literal: jsr zx0_gamma_flag ; Get length, returns CS.
pha ; Preserve bit-buffer.
ldx <zx0_length + 0 ; Check the lo-byte of length
bne zx0_cp_byte ; without effecting CS.
zx0_cp_page: dec <zx0_length + 1 ; Decrement # of pages to copy.
zx0_cp_byte: lda (<zx0_srcptr),y ; CS throughout the execution of
sta (<zx0_dstptr),y ; of this .cp_page loop.
inc <zx0_srcptr + 0
beq zx0_inc_cp_src
zx0_cp_skip1: inc <zx0_dstptr + 0
beq zx0_inc_cp_dst
zx0_cp_skip2: dex ; Any bytes left to copy?
bne zx0_cp_byte
lda <zx0_length + 1 ; Any full pages left to copy?
bne zx0_cp_page ; Optimized for branch-unlikely.
inx ; Initialize length back to 1.
stx <zx0_length + 0
pla ; Restore bit-buffer.
asl a ; Copy from last offset or new offset?
bcs zx0_new_offset
;
; Copy bytes from last offset (rare so slower).
;
zx0_old_offset: jsr zx0_gamma_flag ; Get length, returns CS.
tya ; Negate the lo-byte of length.
sbc <zx0_length + 0
sec ; Ensure CS before zx0_get_lz_dst!
bne zx0_get_lz_dst
dec <zx0_length + 1 ; Decrement because lo-byte=0.
bcs zx0_get_lz_dst ; Always true!
;
; Optimized handling of pointers crossing page-boundaries.
;
zx0_inc_of_src: inc <zx0_srcptr + 1
bne zx0_off_skip1 ; Always true.
zx0_inc_cp_src: inc <zx0_srcptr + 1
bcs zx0_cp_skip1 ; Always true.
zx0_inc_cp_dst: inc <zx0_dstptr + 1
bcs zx0_cp_skip2 ; Always true.
zx0_inc_ga_src: inc <zx0_srcptr + 1
bne zx0_gamma_skip ; Always true.
;
; Get 16-bit interlaced Elias gamma value.
;
zx0_gamma_data: asl a ; Get next bit.
rol <zx0_length + 0
zx0_gamma_flag: asl a
bcc zx0_gamma_data ; Loop until finished or empty.
bne zx0_gamma_done ; Bit-buffer empty?
zx0_gamma_load: lda (<zx0_srcptr),y ; Reload the empty bit-buffer
inc <zx0_srcptr + 0 ; from the compressed source.
beq zx0_inc_ga_src
zx0_gamma_skip: rol a
bcs zx0_gamma_done ; Finished?
zx0_gamma_word: asl a ; Get next bit.
rol <zx0_length + 0
rol <zx0_length + 1
asl a
bcc zx0_gamma_word ; Loop until finished or empty.
beq zx0_gamma_load ; Bit-buffer empty?
zx0_gamma_done: tax ; Preserve bit-buffer.
rts
}}
}
asmsub decode_tscrunch(uword compressed @R0, uword target @R1) clobbers(A,X,Y) {
; Decompress a block of data compressed by TSCRUNCH
; see https://github.com/tonysavon/TSCrunch
; It has extremely fast decompression (approaching RLE speeds),
; better compression as RLE, but slightly worse compression ration than LZSA
;
; NOTE: for speed reasons this decompressor is NOT bank-aware and NOT I/O register aware;
; it only outputs to a memory buffer somewhere in the active 64 Kb address range
%asm {{
;NMOS 6502 decompressor for data stored in TSCrunch format.
;
;Copyright Antonio Savona 2022.
; Distributed under the Apache software License v2.0 https://www.apache.org/licenses/LICENSE-2.0
;
; Adapted for Prog8 and 6502 CMOS by Irmen de Jong.
.if cx16.r0 < $100
; r0-r15 registers are in zeropage just use those
tsget = cx16.r0 ; 2 bytes
tsput = cx16.r1 ; 2 bytes
tstemp = cx16.r2
lzput = cx16.r3 ; 2 bytes
.else
.error "in decode_tscrunch: r0-15 are not in zeropage and no alternatives have been set up yet" ; TODO
.endif
.if cx16.r0>=$100
; set up the source and destination pointers
lda cx16.r0L
sta tsget
lda cx16.r0H
sta tsget+1
lda cx16.r1L
sta tsput
lda cx16.r1H
sta tsput+1
.endif
ldy #0
lda (tsget),y
sta optRun + 1
inc tsget
bne entry2
inc tsget + 1
entry2:
; ILLEGAL lax (tsget),y
lda (tsget),y
tax
bmi rleorlz
cmp #$20
bcs lz2
; literal
tay
ts_delit_loop:
lda (tsget),y
dey
sta (tsput),y
bne ts_delit_loop
txa
inx
updatezp_noclc:
adc tsput
sta tsput
bcs updateput_hi
putnoof:
txa
update_getonly:
adc tsget
sta tsget
bcc entry2
inc tsget+1
bcs entry2
updateput_hi:
inc tsput+1
clc
bcc putnoof
rleorlz:
; ILLEGAL: alr #$7f
and #$7f
lsr a
bcc ts_delz
; RLE
beq optRun
plain:
ldx #2
iny
sta tstemp ; number of bytes to de-rle
lda (tsget),y ; fetch rle byte
ldy tstemp
runStart:
sta (tsput),y
ts_derle_loop:
dey
sta (tsput),y
bne ts_derle_loop
; update zero page with a = runlen, x = 2 , y = 0
lda tstemp
bcs updatezp_noclc
done:
rts
; LZ2
lz2:
beq done
ora #$80
adc tsput
sta lzput
lda tsput + 1
sbc #$00
sta lzput + 1
; y already zero
lda (lzput),y
sta (tsput),y
iny
lda (lzput),y
sta (tsput),y
tya
dey
adc tsput
sta tsput
bcs lz2_put_hi
skp:
inc tsget
bne entry2
inc tsget + 1
bne entry2
lz2_put_hi:
inc tsput + 1
bcs skp
; LZ
ts_delz:
lsr a
sta lzto + 1
iny
lda tsput
bcc long
sbc (tsget),y
sta lzput
lda tsput+1
sbc #$00
ldx #2
; lz MUST decrunch forward
lz_put:
sta lzput+1
ldy #0
lda (lzput),y
sta (tsput),y
iny
lda (lzput),y
sta (tsput),y
ts_delz_loop:
iny
lda (lzput),y
sta (tsput),y
lzto: cpy #0
bne ts_delz_loop
tya
; update zero page with a = runlen, x = 2, y = 0
ldy #0
; clc not needed as we have len - 1 in A (from the encoder) and C = 1
jmp updatezp_noclc
optRun:
ldy #255
sty tstemp
ldx #1
; A is zero
bne runStart
long:
; carry is clear and compensated for from the encoder
adc (tsget),y
sta lzput
iny
; ILLEGAL: lax (tsget),y
lda (tsget),y
tax
ora #$80
adc tsput + 1
cpx #$80
rol lzto + 1
ldx #3
bne lz_put
; !notreached!
}}
}
asmsub decode_tscrunch_inplace(uword compressed @R0) clobbers(A,X,Y) {
; Decompress a block of data compressed by TSCRUNCH *in place*
; This can save an extra memory buffer if you are reading crunched data from a file into a buffer.
; see https://github.com/tonysavon/TSCrunch
; It has extremely fast decompression (approaching RLE speeds),
; better compression as RLE, but slightly worse compression ration than LZSA
;
; NOTE: to allow in-place decompression you need to use -i switch when crunching.
; also, both the input data file and compressed data file are PRG files with a load header!
; NOTE: for speed reasons this decompressor is NOT bank-aware and NOT I/O register aware;
; it only outputs to a memory buffer somewhere in the active 64 Kb address range
%asm {{
; NMOS 6502 decompressor for data stored in TSCrunch format.
;
; Copyright Antonio Savona 2022.
; Distributed under the Apache software License v2.0 https://www.apache.org/licenses/LICENSE-2.0
;
; Adapted for Prog8 and 6502 CMOS by Irmen de Jong.
.if cx16.r0 < $100
; r0-r15 registers are in zeropage just use those
tsget = cx16.r0 ; 2 bytes
tsput = cx16.r1 ; 2 bytes
tstemp = cx16.r2
lzput = cx16.r3 ; 2 bytes
.else
.error "in decode_tscrunch: r0-15 are not in zeropage and no alternatives have been set up yet" ; TODO
.endif
.if cx16.r0>=$100
; set up the source and destination pointer
lda cx16.r0L
sta tsget
lda cx16.r0H
sta tsget+1
.endif
ldy #$ff
- iny
lda (tsget),y
sta tsput , y ; last iteration trashes lzput, with no effect.
cpy #3
bne -
pha
lda lzput
sta optRun + 1
tya
ldy #0
beq update_getonly
entry2:
; ILLEGAL lax (tsget),y
lda (tsget),y
tax
bmi rleorlz
cmp #$20
bcs lz2
; literal
inc tsget
beq updatelit_hi
return_from_updatelit:
ts_delit_loop:
lda (tsget),y
sta (tsput),y
iny
dex
bne ts_delit_loop
tya
tax
; carry is clear
ldy #0
updatezp_noclc:
adc tsput
sta tsput
bcs updateput_hi
putnoof:
txa
update_getonly:
adc tsget
sta tsget
bcc entry2
inc tsget+1
bcs entry2
updatelit_hi:
inc tsget+1
bcc return_from_updatelit
updateput_hi:
inc tsput+1
clc
bcc putnoof
rleorlz:
; ILLEGAL: alr #$7f
and #$7f
lsr a
bcc ts_delz
; RLE
beq optRun
plain:
ldx #2
iny
sta tstemp ; number of bytes to de-rle
lda (tsget),y ; fetch rle byte
ldy tstemp
runStart:
sta (tsput),y
ts_derle_loop:
dey
sta (tsput),y
bne ts_derle_loop
; update zero page with a = runlen, x = 2 , y = 0
lda tstemp
bcs updatezp_noclc
done:
pla
sta (tsput),y
rts
; LZ2
lz2:
beq done
ora #$80
adc tsput
sta lzput
lda tsput + 1
sbc #$00
sta lzput + 1
; y already zero
lda (lzput),y
sta (tsput),y
iny
lda (lzput),y
sta (tsput),y
tya
dey
adc tsput
sta tsput
bcs lz2_put_hi
skp:
inc tsget
bne entry2
inc tsget + 1
bne entry2
lz2_put_hi:
inc tsput + 1
bcs skp
; LZ
ts_delz:
lsr a
sta lzto + 1
iny
lda tsput
bcc long
sbc (tsget),y
sta lzput
lda tsput+1
sbc #$00
ldx #2
; lz MUST decrunch forward
lz_put:
sta lzput+1
ldy #0
lda (lzput),y
sta (tsput),y
iny
lda (lzput),y
sta (tsput),y
ts_delz_loop:
iny
lda (lzput),y
sta (tsput),y
lzto: cpy #0
bne ts_delz_loop
tya
; update zero page with a = runlen, x = 2, y = 0
ldy #0
; clc not needed as we have len - 1 in A (from the encoder) and C = 1
jmp updatezp_noclc
optRun:
ldy #255
sty tstemp
ldx #1
; A is zero
bne runStart
long:
; carry is clear and compensated for from the encoder
adc (tsget),y
sta lzput
iny
; ILLEGAL lax (tsget),y
lda (tsget),y
tax
ora #$80
adc tsput + 1
cpx #$80
rol lzto + 1
ldx #3
bne lz_put
; !notreached!
}}
}
/***
; prog8 source code for the RLE routines above:
sub decode_rle_prog8(uword @zp compressed, uword @zp target, uword maxsize) -> uword {
cx16.r0 = target ; original target
cx16.r1 = target+maxsize ; decompression limit
while target<cx16.r1 {
cx16.r2L = @(compressed)
if_neg {
if cx16.r2L==128
break
; replicate the next byte -n+1 times
compressed++
cx16.r3L = @(compressed)
repeat 2+(cx16.r2L^255) {
@(target) = cx16.r3L
target++
}
compressed++
} else {
; copy the next n+1 bytes
compressed++
repeat cx16.r2L+1 {
@(target) = @(compressed)
compressed++
target++
}
}
}
return target-cx16.r0
}
sub decode_rle_callback_prog8(uword producer_callback, uword @zp target, uword maxsize) -> uword {
cx16.r0 = target ; original target
cx16.r1 = target+maxsize ; decompression limit
while target<cx16.r1 {
cx16.r2L = lsb(call(producer_callback))
if_neg {
if cx16.r2L==128
break
; replicate the next byte -n+1 times
cx16.r3L = lsb(call(producer_callback))
repeat 2+(cx16.r2L^255) {
@(target) = cx16.r3L
target++
}
} else {
; copy the next n+1 bytes
repeat cx16.r2L+1 {
@(target) = lsb(call(producer_callback))
target++
}
}
}
return target-cx16.r0
}
***/
}
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