credits: update to use compressed hgr image

split_screen/Makefile

@@ -10,7 +10,7 @@ split.dsk:	BISHOP BISHOP.BAS RAINBOW.BAS RAINBOW KATC.BIN CREDITS
 	$(DOS33) -y split.dsk SAVE A BISHOP.BAS
 	$(DOS33) -y split.dsk SAVE A RAINBOW.BAS
 	$(DOS33) -y split.dsk BSAVE -a 0x0c00 RAINBOW
-	$(DOS33) -y split.dsk BSAVE -a 0x1000 CREDITS
+	$(DOS33) -y split.dsk BSAVE -a 0x4000 CREDITS
 #	$(DOS33) -y split.dsk BSAVE -a 0x2000 LENNA.BIN
 	$(DOS33) -y split.dsk BSAVE -a 0x2000 KATC.BIN
 
@@ -32,13 +32,17 @@ RAINBOW:	rainbow.o
 RAINBOW.BAS:	rainbow.bas
 	$(TOKENIZE) < rainbow.bas > RAINBOW.BAS
 
-credits.o:	credits.s tfv_sprites.inc mockingboard.s
+credits.o:	credits.s tfv_sprites.inc mockingboard.s \
+		lz4_decode.s \
+		KATC.BIN.lz4
 	ca65 -o credits.o credits.s -l credits.lst
 
 CREDITS:	credits.o
-	ld65 -o CREDITS credits.o -C ../linker_scripts/apple2_1000.inc
+	ld65 -o CREDITS credits.o -C ../linker_scripts/apple2_4000.inc
 
 
+KATC.BIN.lz4:	KATC.BIN
+	lz4 -f -16 KATC.BIN
 
 KATC.BIN:	kat.bmp
 	../bmp2dhr/b2d kat.bmp hgr dither

split_screen/credits.s

@@ -62,6 +62,26 @@
 no_init_mb:
 
 
+	;==========================
+	; Load the background image
+
+	lda	#<katahdin
+	sta	LZ4_SRC
+	lda	#>katahdin
+	sta	LZ4_SRC+1
+
+	lda	#<(katahdin_end-8)		; skip checksum at end
+	sta	LZ4_END
+	lda	#>(katahdin_end-8)		; skip checksum at end
+	sta	LZ4_END+1
+
+	lda	#<$2000			; Destination is HGR page0
+	sta	LZ4_DST
+	lda	#>$2000
+	sta	LZ4_DST+1
+
+	jsr	lz4_decode
+
 	;==========================
 	; setup text screen
 
@@ -954,10 +974,14 @@ line6:.asciiz	"             .                         "
 .include "../asm_routines/gr_offsets.s"
 .include "tfv_sprites.inc"
 
-.align	$1000
+.include "lz4_decode.s"
 
-graphics:
+;.align	$1000
-.incbin	"KATC.BIN"
 
+katahdin:
+.incbin	"KATC.BIN.lz4",11		; skip the header
+katahdin_end:
+
+.align $100
 music:
 .incbin "music.tfv"

split_screen/lz4_decode.s

@@ -0,0 +1,213 @@
+; LZ4 data decompressor for Apple II
+
+; Code by Peter Ferrie (qkumba) (peter.ferrie@gmail.com)
+; "LZ4 unpacker in 143 bytes (6502 version) (2013)"
+;    http://pferrie.host22.com/misc/appleii.htm
+; This is that code, but with comments and labels added for clarity.
+; I also found a bug when decoding with runs of multiples of 256
+;   which has since been fixed upstream.
+
+; For LZ4 reference see
+; https://github.com/lz4/lz4/wiki/lz4_Frame_format.md
+
+; LZ4 summary:
+;
+; HEADER:
+;       Should: check for magic number 04 22 4d 18
+;	FLG: 64 in our case (01=version, block.index=1, block.checksum=0
+;		size=0, checksum=1, reserved
+;	MAX Blocksize: 40 (64kB)
+;	HEADER CHECKSUM: a7
+;	BLOCK HEADER: 4 bytes (le)  length If highest bit set, uncompressed!
+;			data (see below), followed by checksum?
+; BLOCKS:
+;	Token byte.  High 4-bits literal length, low 4-bits copy length
+;	+ If literal length==15, then following byte gets added to length
+;	  If that byte was 255, then keep adding bytes until not 255
+;       + The literal bytes follow.  There may be zero of them
+;	+ Next is block copy info.  little-endian 2-byte offset to
+;	  be subtracted from current read position indicating source
+;	+ The low 4-bits of the token are the copy length, which needs
+;         4 added to it.  As with the literal length, if it is 15 then
+;	  you read a byte and add (and if that byte is 255, keep adding)
+
+; At end you have 4 byte end-of-block marker (all zeros?) then
+;                 4 bytes of checksum (if marked in flags)
+;                 our code does that, so be sure to set end -8
+
+
+;LZ4_SRC	EQU $00
+;LZ4_DST	EQU $02
+;LZ4_END	EQU $04
+;COUNT		EQU $06
+;DELTA		EQU $08
+
+;UNPACK_BUFFER	EQU $5E00	; offset of first unpacked byte
+
+
+	;======================
+	; LZ4 decode
+	;======================
+	; input buffer in LZ4_SRC
+        ; output buffer hardcoded still
+	; size in ENDH:ENDL
+
+lz4_decode:
+;	lda	LZ4_SRC	 		; packed data offset
+;	clc
+;	adc	LZ4_END
+;	sta	LZ4_END
+;	lda	LZ4_SRC+1
+;	adc	LZ4_END+1
+;	sta	LZ4_END+1
+
+;	lda	#>UNPACK_BUFFER		; original unpacked data offset
+;	sta	LZ4_DST+1
+;	lda	#<UNPACK_BUFFER
+;	sta	LZ4_DST
+
+unpmain:
+	ldy	#0			; used to index, always zero
+
+parsetoken:
+	jsr	getsrc			; get next token
+	pha				; save for later (need bottom 4 bits)
+
+	lsr				; number of literals in top 4 bits
+	lsr				; so shift into place
+	lsr
+	lsr
+	beq	copymatches		; if zero, then no literals
+					; jump ahead and copy
+
+	jsr	buildcount		; add up all the literal sizes
+					; result is in ram[count+1]-1:A
+	tax				; now in ram[count+1]-1:X
+	jsr	docopy			; copy the literals
+
+	lda	LZ4_SRC			; 16-bit compare
+	cmp	LZ4_END			; to see if we have reached the end
+	lda	LZ4_SRC+1
+	sbc	LZ4_END+1
+	bcs	done
+
+copymatches:
+	jsr	getsrc			; get 16-bit delta value
+	sta	DELTA
+	jsr	getsrc
+	sta	DELTA+1
+
+	pla				; restore token
+	and	#$0f			; get bottom 4 bits
+					; match count.  0 means 4
+					; 15 means 19+, must be calculated
+
+	jsr	buildcount		; add up count bits, in ram[count+1]-:A
+
+	clc
+	adc	#4			; adjust count by 4 (minmatch)
+
+	tax				; now in ramp[count+1]-1:X
+
+	beq	copy_no_adjust		; BUGFIX, don't increment if
+					;	exactly a multiple of 0x100
+	bcc	copy_no_adjust
+
+	inc	COUNT+1			; increment if we overflowed
+copy_no_adjust:
+
+	lda	LZ4_SRC+1			; save src on stack
+	pha
+	lda	LZ4_SRC
+	pha
+
+	sec				; subtract delta
+	lda	LZ4_DST			; from destination, make new src
+	sbc	DELTA
+	sta	LZ4_SRC
+	lda	LZ4_DST+1
+	sbc	DELTA+1
+	sta	LZ4_SRC+1
+
+	jsr	docopy			; do the copy
+
+	pla				; restore the src
+	sta	LZ4_SRC
+	pla
+	sta	LZ4_SRC+1
+
+	jmp	parsetoken		; back to parsing tokens
+
+done:
+	pla
+	rts
+
+	;=========
+	; getsrc
+	;=========
+	; gets byte from src into A, increments pointer
+getsrc:
+	lda	(LZ4_SRC), Y		; get a byte from src
+	inc	LZ4_SRC			; increment pointer
+	bne	done_getsrc		; update 16-bit pointer
+	inc	LZ4_SRC+1			; on 8-bit overflow
+done_getsrc:
+	rts
+
+	;============
+	; buildcount
+	;============
+buildcount:
+	ldx	#1			; high count starts at 1
+	stx	COUNT+1			; (loops at zero?)
+	cmp	#$0f			; if LITERAL_COUNT < 15, we are done
+	bne	done_buildcount
+buildcount_loop:
+	sta	COUNT			; save LITERAL_COUNT (15)
+	jsr	getsrc			; get the next byte
+	tax				; put in X
+	clc
+	adc	COUNT			; add new byte to old value
+	bcc	bc_8bit_oflow		; if overflow, increment high byte
+	inc	COUNT+1
+bc_8bit_oflow:
+	inx				; check if read value was 255
+	beq	buildcount_loop		; if it was, keep looping and adding
+done_buildcount:
+	rts
+
+	;============
+	; getput
+	;============
+	; gets a byte, then puts the byte
+getput:
+	jsr	getsrc
+	; fallthrough to putdst
+
+	;=============
+	; putdst
+	;=============
+	; store A into destination
+putdst:
+	sta 	(LZ4_DST), Y		; store A into destination
+	inc	LZ4_DST			; increment 16-bit pointer
+	bne	putdst_end		; if overflow, increment top byte
+	inc	LZ4_DST+1
+putdst_end:
+	rts
+
+	;=============================
+	; docopy
+	;=============================
+	; copies ram[count+1]-1:X bytes
+	; from src to dst
+docopy:
+
+docopy_loop:
+	jsr	getput			; get/put byte
+	dex				; decrement count
+	bne	docopy_loop		; if not zero, loop
+	dec	COUNT+1			; if zero, decrement high byte
+	bne	docopy_loop		; if not zero, loop
+
+	rts