--- a/src/color_processor.asm	Wed Apr 10 10:51:07 2019 +0200
+++ b/src/color_processor.asm	Mon Jun 03 14:01:48 2019 +0200
@@ -1,8 +1,8 @@
 ;=============================================================================
 ;
-;   File File color_processor.asm									## V2.98c
+;   File File color_processor.asm             combined next generation V3.03.2
 ;
-;   Decompress and draw an image.
+;   Decompress and draw an image
 ;
 ;   Copyright (c) 2011, JD Gascuel, HeinrichsWeikamp, all right reserved.
 ;=============================================================================
@@ -10,27 +10,29 @@
 ;  2010-12-13 : [jDG] Creation.
 ;  2010-12-30 : [jDG] Revised to put temp into ACCESSRAM0
 ;
-; RATIONALS: The OSTC have a nice color screen, and a std geek attitude impose
+; RATIONALS: The OSTC has a nice color screen, and a std geek attitude impose
 ;            to show off ... ;-)
 ;
-; Inputs: TBLPTR points to the image description block.
-;         win_top, win_leftx2 the Top/Leftx2 corner here to put the image.
-; Outputs: None.
-; Trashed: TBLPTR, TABLAT, FSR2, PROD, win_width, win_height
+; Inputs   TBLPTR points to the image description block.
+;          win_top, win_leftx2 the Top/Leftx2 corner here to put the image.
+; Outputs  None
+; Trashed  TBLPTR, TABLAT, FSR2, PROD, win_width, win_height
 ;
 ; ImageBloc:
 ;       db  widthx2,  height
-;       db  nbColors, 0     ; 0 = unused yet, should remain 0 to keep packing happy
+;       db  nbColors, encoding version
 ;       dw  color0, color1, color2, color3, ...
 ;       db  packed pixels...
 ;
 ; Limitations:
-; * nbColors <= 127
-; * image width should be even
-; * image left border should be on even position, too
+; * nbColors <= 126
+; * image width is even
+; * image left border is on even column, too
 ;
-; Compressed format:
-; - 1-3 bytes pixel count, followed by 1 byte pixel color
+;
+; Compressed format in encoding version 0 and 1:
+; ----------------------------------------------
+; - 1-3 bytes pixel repetition count, followed by 1 byte pixel color
 ; - bit 7 = 1: byte holds pixel count in bits 6-0
 ; - bit 7 = 0: byte holds pixel color in bits 6-0
 ; - all pixel count bytes accumulate:
@@ -38,6 +40,16 @@
 ;   - 2 bytes pixel count: 1yyyyyyy 1xxxxxxx          -> 14 bit pixel count
 ;   - 3 bytes pixel count: 1zzzzzzz 1yyyyyyy 1xxxxxxx -> 21 bit pixel count
 ;
+; A pixel repetition count of 0 means one single pixel will be drawn,
+; a repetition count of 1 means two pixels will be drawn, and so on.
+; The image is done when all pixels as of width x high parameters have been printed.
+;
+;
+; Compressed format in encoding version 1:
+; ----------------------------------------
+; As above, but the image is done when a color index equaling 127 is encountered.
+;
+;
 ; Pixels are written column by column from left to right, with columns down first.
 ;
 ;-----------------------------------------------------------------------------
@@ -45,160 +57,166 @@
 #include	"hwos.inc"
 #include	"tft.inc"
 
-color_proc		CODE
+	extern	convert_for_display2
+
+
+color_proc	CODE
 
 ;-----------------------------------------------------------------------------
-; Note: some variables (win_width, win_height) are in BANK 0 !
 
 	global	color_image
 color_image:
-	banksel	common					; Bank 1, just to be sure...
+	tblrd*+							; read image width (in true width / 2)
+	movff	TABLAT,win_width
+	tblrd*+							; read image height
+	movff	TABLAT,win_height
+	rcall	get_colors				; read the colors
 
-	;---- Get image size -----------------------------------------------
-	tblrd*+
-	movff	TABLAT,win_width
-	tblrd*+
-	movff	TABLAT,win_height
+	tstfsz	encoding_format			; image encoded in version 0 format?
+	bra		color_image_1			; NO
 
-	; Compute width * height * 2 : the number of pixels to write.
-	clrf	img_pixels+2
-	movf	win_width,W				; Compute number of pixels to draw
-	mulwf	win_height				; 0 .. 160x240
-	bcf		STATUS,C				; BEWARE: mulwf does not reset carry flag!
-	rlcf	PRODL					; x2 --> 0 .. 320x240, might be > 0xFFFF
-	rlcf	PRODH
-	movff	PRODL, img_pixels+0
-	movff	PRODH, img_pixels+1
-	rlcf	img_pixels+2			; Get the upper bit in place
-
-	clrf	WREG					; Decrement count to ease end detection
-	decf	img_pixels+0,F
-	subwfb	img_pixels+1,F
-	subwfb	img_pixels+2,F
+	; image encoding version 0 format: compute the overall number of pixels - 1 to draw
+	movf	win_width,W				; get width into WREG
+	mulwf	win_height				; multiply by hight
+	movff	PRODL,overall_pixels+0	; store product, low  byte
+	movff	PRODH,overall_pixels+1	; ...            high byte
+	clrf	overall_pixels+2		; clear upper byte
+	bcf		STATUS,C				; clear carry flag
+	rlcf	overall_pixels+0		; multiply by 2 via shift left, low   byte
+	rlcf	overall_pixels+1		; ...                           high  byte
+	rlcf	overall_pixels+2		; ...                           upper byte
+	clrf	WREG					; decrement by 1 to ease all pixel done detection
+	decf	overall_pixels+0,F		; ...
+	subwfb	overall_pixels+1,F		; ...
+	subwfb	overall_pixels+2,F		; ...
 
-	;---- Send window command --------------------------------------------
-	clrf	win_width+1				; x2 on width, for the true box size
-	rlcf	win_width+0
-	rlcf	win_width+1
-	call	TFT_box_write
-	Index_out 0x22
+color_image_1:
+	clrf	win_width+1				; clear width, high byte
+	bcf		STATUS,C				; clear carry flag
+	rlcf	win_width+0				; multiply width x 2 to get the true box width
+	rlcf	win_width+1				; ...
+	call	TFT_box_write			; set output box
+	Index_out 0x22					; frame memory data write start
 
-	;---- Read the colors ------------------------------------------------
-	rcall	get_colors
-
-	;---- Decode pixels --------------------------------------------------
 color_image_loop_xy:
-	; Get pixel count
-	clrf	img_count+0
-	clrf	img_count+1
+	; prepare to read next pixel count and color
+	clrf	pixel_count+0			; clear number of pixels
+	clrf	pixel_count+1			; ...
 
-	;---- Decode repetition count
-color_image_decode_1:
-	tblrd*+							; Get one byte
-
-	btfss	TABLAT,7				; High bit cleared ?
-	bra		color_image_decode_2	; YES: this is a color byte
+color_image_read_byte:
+	tblrd*+							; get next byte
+	btfss	TABLAT,7				; high bit cleared ?
+	bra		color_image_decode_color; YES - this is a color byte
+	;bra	color_image_decode_count; NO  - this is a pixel count byte
 
-	rlcf	TABLAT,F				; Drop high bit.
-	movlw	.7						; Move 7 bits
-color_image_decode_3:
-	rlcf	TABLAT,F				; Get bit into carry
-	rlcf	img_count+0,F			; Push into pixel count
-	rlcf	img_count+1,F
-	decfsz	WREG
-	bra		color_image_decode_3	; and loop for each 7 bits
-	bra		color_image_decode_1	; Decode next byte
+color_image_decode_count:
+	; decode pixel repetition count
+	rlcf	TABLAT,F				; drop high bit
+	movlw	.7						; move 7 bits
+color_image_decode_count_loop:
+	rlcf	TABLAT,F				; get upper bit into carry
+	rlcf	pixel_count+0,F			; push bit into pixel count (16 bit operation)
+	rlcf	pixel_count+1,F			; ...
+	decfsz	WREG					; decrement loop counter, all bits done?
+	bra		color_image_decode_count_loop	; NO  - loop
+	bra		color_image_read_byte			; YES - decode next byte
+
+color_image_decode_color:
+	; check for end-of-image tag (color index = 0x7F)  --  it is assumed that no version 0 image contains 127 colors...
+	movlw	0x7f					; encoding for end-of-image
+	cpfslt	TABLAT					; color index < end-of-image tag?
+	return							; NO - done
 
-color_image_decode_2:
-	;---- Get pixel color into PROD
-	movf	TABLAT,W				; Get color index
-	addwf	WREG					; *2
-	lfsr	FSR2,buffer				; Reinitialize color table
-	movff	WREG,FSR2L				; LOW(buffer) == 0
-	movff	POSTINC2,PRODL
-	movff	POSTINC2,PRODH
+	; get pixel color into PROD
+	lfsr	FSR2,buffer				; set FSR2 pointer to base address of color table
+	rlncf	TABLAT,W				; get color index * 2 into WREG
+	movwf	FSR2L					; adjust pointer to selected color
+	movff	POSTINC2,PRODL			; read color, low  byte
+	movff	POSTINC2,PRODH			; read color, high byte
 
-	; Subtract count-1 from the number of pixel we should do.
-	movf	img_count+0,W			; Make a 24bit subtraction
-	subwf	img_pixels+0,F
-	movf	img_count+1,W
-	subwfb	img_pixels+1,F
-	movlw	0
-	subwfb	img_pixels+2,F
+	tstfsz	encoding_format			; image encoded in version 0 format?
+	bra		color_image_pixel		; NO
+	; image encoding version 0 format: subtract pixel count from the overall number of pixels to do
+	movf	pixel_count+0,W			; YES - 24 bit subtraction, low   byte
+	subwf	overall_pixels+0,F		; ...
+	movf	pixel_count+1,W			; ...                       high  byte
+	subwfb	overall_pixels+1,F		; ...
+	movlw	.0						; ...                      upper byte
+	subwfb	overall_pixels+2,F		; ...
 
-	infsnz	img_count+0				; Increment count
-	incf	img_count+1
+color_image_pixel:
+	; prepare sending of pixels to display
+	infsnz	pixel_count+0			; increment pixel repetition count by 1
+	incf	pixel_count+1			; ...
+	incf	pixel_count+1			; because decrement is done first, increment high byte once more
+	bsf		tft_rs,0				; RS_H data
+	bcf		INTCON,GIE				; disable global interrupts
+
+	btfsc	screen_type2			; display type 2 ?
+	bra		color_image_display2	; YES
+	movff	PRODH,PORTA				; NO  - move color high byte to PORTA
+	movff	PRODL,PORTH				;     - move color low  byte to PORTH
 
-        ; Loop sending pixel color
-        incf    img_count+1             ; Because we decrement first, should add one here !
-        bsf     tft_rs,0    ; RS_H				; Data
-	bcf	INTCON,GIE
-	
-color_image_loop_pixel:	
-	btfsc	screen_type2		; Display 2?
-	bra	color_image_display2		; Yes
-	
-    	movff	PRODH,PORTA	; Move high byte to PORTA
-        movff	PRODL,PORTH	; Move low byte to PORTH
-        bcf		tft_nwr
-        bsf		tft_nwr
-	decfsz  img_count+0
-        bra     color_image_loop_pixel
-        decfsz  img_count+1
-        bra     color_image_loop_pixel
-	bra	color_image_loop_pixel2
-	
+color_image_pixel1_loop:
+	bcf		tft_nwr					; toggle write signal
+	bsf		tft_nwr					; ...
+	decfsz	pixel_count+0			; decrement pixel counter, low  byte
+	bra		color_image_pixel1_loop	; loop if not zero
+	decfsz	pixel_count+1			; decrement pixel counter, high byte
+	bra		color_image_pixel1_loop	; loop if not zero
+	bra		color_image_pixel_com	; all pixels transmitted
+
 color_image_display2:
-    extern  convert_for_display2
-	call	convert_for_display2	; Convert 16Bit RGB b'RRRRRGGG GGGBBBBB' into 24Bit RGB b'RRRRRR00 GGGGGG00 BBBBBB00'
-color_image_display2_loop:	
-    	movff   win_color5,PORTH		; Move high byte to PORTH (DISPLAY is bigendian)
-        bcf		tft_nwr
-        bsf		tft_nwr
-        movff   win_color4,PORTH		; Move low byte to PORTH
-        bcf		tft_nwr
-        bsf		tft_nwr
-        movff   win_color3,PORTH        ; Move low(est) byte to PORTH
-        bcf		tft_nwr
-        bsf		tft_nwr
-	decfsz  img_count+0
-        bra     color_image_display2_loop
-        decfsz  img_count+1
-        bra     color_image_display2_loop
+	call	convert_for_display2	; convert 16 bit RGB b'RRRRRGGG GGGBBBBB'
+									; into    24 bit RGB b'RRRRRR00 GGGGGG00 BBBBBB00'
+color_image_pixel2_loop:
+	movff	win_color5,PORTH		; move upper byte to PORTH (DISPLAY is big endian)
+	bcf		tft_nwr					; toggle write signal
+	bsf		tft_nwr					; ...
+	movff	win_color4,PORTH		; move high  byte to PORTH
+	bcf		tft_nwr					; toggle write signal
+	bsf		tft_nwr					; ...
+	movff	win_color3,PORTH		; move low   byte to PORTH
+	bcf		tft_nwr					; toggle write signal
+	bsf		tft_nwr					; ...
+	decfsz	pixel_count+0			; decrement pixel counter, low  byte
+	bra		color_image_pixel2_loop	; loop if not zero
+	decfsz	pixel_count+1			; decrement pixel counter, high byte
+	bra		color_image_pixel2_loop	; loop if not zero
 
-color_image_loop_pixel2:
-        bsf	INTCON,GIE
-        ; And count (on a 24bit counter)
-        clrf    WREG                    ; Make a 24bit decrement.
-        decf    img_pixels+0
-        subwfb  img_pixels+1,F
-        subwfb  img_pixels+2,F
+color_image_pixel_com:
+	bsf		INTCON,GIE				; re-enable global interrupts
+
+	tstfsz	encoding_format			; image encoded in version 0 format?
+	bra		color_image_loop_xy		; NO - loop to process next byte from image data
 
-        bnn     color_image_loop_xy     ; Not finished ? loop...
-
-        ;---- Closeup --------------------------------------------------------        
-;        Index_out 0x00
-        return
+	; image encoding version 0 format: step counter
+	clrf	WREG					; make a 24 bit decrement
+	decf	overall_pixels+0		; ...
+	subwfb	overall_pixels+1,F		; ...
+	subwfb	overall_pixels+2,F		; ...
+	bnn		color_image_loop_xy		; all pixels done? NO  - loop
+	return							;                  YES - done
 
 
 	global	get_colors
 get_colors:
 	tblrd*+							; read number of image colors
 	movff	TABLAT,lo				; store in lo
-	tblrd*+							; skip one spare byte (future flags ?)
 	movf	lo,W
+	tblrd*+							; read image encoding format
+	movff	TABLAT,encoding_format	; store encoding format
 	lfsr	FSR2,buffer				; set up buffer as storage for the colors
 get_colors_loop:
-	tblrd*+
-	btfss	use_custom_colors		; shall custom colors be used?
-	movff	TABLAT,POSTINC2			; NO
-	tblrd*+
-	btfss	use_custom_colors		; shall custom colors be used?
-	movff	TABLAT,POSTINC2			; NO
-	decfsz	WREG
-	bra		get_colors_loop
-
-	bcf		use_custom_colors		; clear custom colors request
-	return
+	tblrd*+							; read color from stored image, low  byte
+	btfss	use_custom_colors		; shall use custom colors?
+	movff	TABLAT,POSTINC2			; NO - copy color read to buffer
+	tblrd*+							; read color from stored image, high byte
+	btfss	use_custom_colors		; shall use custom colors?
+	movff	TABLAT,POSTINC2			; NO - copy color read to buffer
+	decfsz	WREG					; decrement loop counter, done?
+	bra		get_colors_loop			; NO  - loop
+	bcf		use_custom_colors		; YES - clear custom colors request
+	return							;     - done
 
 	END