Bugfix, refactoring

pat80-io-devices/composite-pal-adapter/software/avr-assembly/character_generator.asm

@@ -9,9 +9,15 @@
 .equ LINE_COLUMNS = 46	; number of columns (characters or chunks) per line
 
 ; Draws character in register A to the screen at current coords (Y)
-; @param r16 (HIGH_ACCUM) ascii code to display
-; @modifies r0 (A), r1, r2, r3, r16 (HIGH_ACCUM), r17, Y, Z
+; @param (HIGH_ACCUM) ascii code to display
+; @modifies r0 (A), r1, r2, r3, r17, HIGH_ACCUM, Y, Z
 draw_char:
+	; Check char is valid
+	cpi HIGH_ACCUM, 0x7f
+	brlo draw_char_valid
+	ret
+
+	draw_char_valid:
 	; Glyph's first byte is at:
 	; glyph_pointer = font_starting_mem_pos + (ascii_code * number_of_bytes_per_font)
 	; But all the fonts are 1 byte large, so a glyph is 1*height bytes:
@@ -130,7 +136,7 @@ update_mem_pointer:
 	; ...+POS_COLUMN
 	add r0, POS_COLUMN
 	clr HIGH_ACCUM
-	adc r0, HIGH_ACCUM
+	adc r1, HIGH_ACCUM
 	; Set pointer to start of framebuffer
 	ldi YL, low(FRAMEBUFFER)
 	ldi YH, high(FRAMEBUFFER)
@@ -138,3 +144,17 @@ update_mem_pointer:
 	add YL, r0
 	adc YH, r1
 	ret
+
+clear_screen:
+	ldi YH, high(FRAMEBUFFER)
+	ldi YL, low(FRAMEBUFFER)
+	load_mem_loop:
+		clr HIGH_ACCUM
+		;ser HIGH_ACCUM
+		st Y+, HIGH_ACCUM
+		; if reached the last framebuffer byte, exit cycle
+		cpi YH, high(FRAMEBUFFER_END)
+		brne load_mem_loop	; if not 0, repeat h_picture_loop
+		cpi YL, low(FRAMEBUFFER_END)
+		brne load_mem_loop	; if not 0, repeat h_picture_loop
+	ret

pat80-io-devices/composite-pal-adapter/software/avr-assembly/example_data/cat.asm

@@ -6,13 +6,13 @@ draw_cat:
 	ldi ZH, high(CAT_IMAGE)
 	ldi ZL, low(CAT_IMAGE)
 	load_cat_loop:
-		lpm r17, Z+
-		st Y+, r17
+		lpm HIGH_ACCUM, Z+
+		st Y+, HIGH_ACCUM
         ; wait
-        ser r19
-        cat_wait_loop_1:
-            dec r19
-            brne cat_wait_loop_1
+        ; ser r19
+        ; cat_wait_loop_1:
+        ;     dec r19
+        ;     brne cat_wait_loop_1
 		; if reached the last framebuffer byte, exit cycle
 		cpi YH, high(FRAMEBUFFER_END)
 		brne load_cat_loop	; if not 0, repeat h_picture_loop

pat80-io-devices/composite-pal-adapter/software/avr-assembly/main.asm

@@ -25,32 +25,30 @@
 .include "m1284def.inc" ; Atmega 1280 device definition
 
 ; *** reserved registers ***
-; Cursor Position
-;     POS_COLUMN (0-46) represents the character/chunk column
-;     POS_ROWP (0-255) represent the chunk row. The caracter row is POS_ROWP/FONT_HEIGHT
-.def POS_COLUMN = r21
-.def POS_ROWP = r20
-; Internal registers
-.def A = r0	; accumulator
+; Video generator registers:
+; X(R27, R26)
 .def STATUS = r25	; signal status (see STATUS TABLE)
-;POS_COARSE = Y	; coarse position (aligned to character column)
-;DRAWING_BYTE = X	; current position in framebuffer
+.def VG_HIGH_ACCUM = r24 ; an accumulator in high registers to be used only by video_generator in interrupt
 .def LINE_COUNTER = r23
-.def VG_HIGH_ACCUM = r22 ; an accumulator in high registers to be used only by video_generator in interrupt
-.def HIGH_ACCUM = r16 ; an accumulator in high registers to be used outside of interrupts
 
-; define constant
+; Character generator registers:
+.def POS_COLUMN = r22 ; POS_COLUMN (0-46) represents the character/chunk column
+.def POS_ROWP = r21 ; POS_ROWP (0-255) represent the chunk row. The caracter row is POS_ROWP/FONT_HEIGHT
+.def HIGH_ACCUM = r20 ; an accumulator in high registers to be used outside of interrupts
+.def A = r0	; general purpose accumulator to be used outside of interrupts
+
+; Hardware pins and ports
 .equ VIDEO_PORT_OUT = PORTA		; Used all PORTA, but connected only PA0
 .equ SYNC_PIN = PC0			; Sync pin (pin 22)
 .equ DEBUG_PIN = PC1		; DEBUG: Single vertical sync pulse to trigger oscilloscope (pin 23)
-.equ DATA_PORT_IN = PINB
-.equ CLK_PIN = PD0
-.equ RS_PIN = PD1
-.equ BUSY_PIN = PD2
+.equ DATA_PORT_IN = PIND
+.equ CLK_PIN = PC2
+.equ RS_PIN = PC3
+.equ BUSY_PIN = PC4
 
-; memory
-.equ FRAMEBUFFER = 0x0100
-.equ FRAMEBUFFER_END = 0x2F00
+; Memory map
+.equ FRAMEBUFFER = 0x0F70
+.equ FRAMEBUFFER_END = 0x3C00
 .equ SCREEN_HEIGHT = 248
 
 ; start vector
@@ -77,19 +75,7 @@ main:
 
 	; **** MEMORY SETUP ****
 
-	; clear ram
-	;*** Load data into ram ***
-	Set X to 0x0100
-	ldi XH, high(FRAMEBUFFER)
-	ldi XL, low(FRAMEBUFFER)
-	load_mem_loop:
-		clr r17
-		st X+, r17
-		; if reached the last framebuffer byte, exit cycle
-		cpi XH, 0b00111110
-		brne load_mem_loop	; if not 0, repeat h_picture_loop
-		cpi XL, 0b11000000
-		brne load_mem_loop	; if not 0, repeat h_picture_loop
+	call clear_screen
 
 	
 
@@ -118,7 +104,7 @@ main:
 	; **** MAIN ROUTINE ****
 
 	; Wait for data (it never exits)
-	; jmp comm_init
+	;jmp comm_init
 
 
 	; draw example image
@@ -144,7 +130,7 @@ main:
 			inc r18
 			cpi r18, 0x5B
 			brne draw_chars
-		call draw_carriage_return
+		; call draw_carriage_return
 		jmp dctest
 
 	
@@ -160,4 +146,4 @@ main:
 .include "character_generator.asm" ; Character generator
 ;.include "communication.asm" ; Communication with Pat80
 .include "font.asm"	; Font face
-.include "example_data/cat.asm"	; Cat image
+;.include "example_data/cat.asm"	; Cat image