Snippet:Plot - Revision history

E5frog: /* Coordinate-Adjusted Version */

2020-08-16T11:26:48Z

‎Coordinate-Adjusted Version

2020-08-16T11:18:06Z

‎Original Version

2020-08-16T11:14:07Z

‎Original Version

2020-05-31T15:43:58Z

2020-05-31T15:43:06Z

‎Coordinate-Adjusted Version

2014-05-22T16:49:44Z

‎Coordinate-Adjusted Version

2014-03-01T15:06:17Z

‎Coordinate-Adjusted Version

2014-03-01T12:52:40Z

‎Coordinate-Adjusted Version

2014-03-01T12:21:14Z

‎Coordinate-Adjusted Version

2014-03-01T12:15:59Z

‎Coordinate-Adjusted Version

@@ Line 14: / Line 14: @@
 ; plot out a single point on the screen
 ; uses three registers as "arguments"
-; r1 = color $00 = green, $40 = %01000000 = red, $80 = %10000000 = blue, $C0 = %11000000 = background
+; r1 = color
-; r2 = x (to screen) (0-101)
+; r2 = x (to screen) (0-127)
-; r3 = y (to screen) (0-57)
+; r3 = y (to screen) (0-63)
 plot:

@@ Line 109: / Line 109: @@
 For the columns it's [255,192] from top to bottom which equals [0,63]. Routine is not a subroutine as that adds at least 8.5 cycles.<br>
 If using one top level subroutine it's another 8.5 cycle... A JMP is only 5.5 cycles and a branch is only 3 or 3.5 cycle. <br>
-You can use '''DS r'''to increase coordinate and there's no need to repeat the color setting if it's a repeated one color plot.<br>
+You can use '''DS r''' (that uses 1c5) to increase coordinates. Ports are latched, no need to repeat the color setting if it's a repeated one color plot.<br>
 It's a handy routine to use when changing the palette.

@@ Line 65: / Line 65: @@
 ; r2 = x (to screen) (4-105)
 ; r3 = y (to screen) (4-61)
 plot:
@@ Line 95: / Line 104: @@
 	pop							; return from the subroutine
 </pre>

@@ Line 43: / Line 43: @@
 	; delay until it's fully updated
-	lis	6					; Value here is 4 in Videocart 21, Bowling
+	lis	6
 .plotDelay:
 	ai	$ff
@@ Line 88: / Line 88: @@
 	; delay until it's fully updated
-	lis	6
+	lis	6					; Value here is 4 in Videocart 21, Bowling
 .plotDelay:
 	ai	$ff

@@ Line 3: / Line 3: @@
 == Coordinate-Adjusted Version ==
-The following is the annotated source, with adjustments for the coordinates:
+The following is the annotated source, with adjustments for the coordinates.
@@ Line 35: / Line 36: @@
 	; transfer data to the screen memory by toggling ARM
-	li	$60					; %01100000, block controller input, set ARM to 1
+	lis	6
-	outs	0
+	sl	4
-	li	$50					; %01010000, block controller input, ARM = 0, bit 5 (which is N/C) is set to 1...
+	outs	0					; %01100000, no controller inputs, set b5 ARM to 1
-	outs	0
+	sl	1
 	; delay until it's fully updated

@@ Line 49: / Line 49: @@
 </pre>
-The adjustment of x and y is to allow the coordinates 0, 0 to access the ''upper-left pixel'' of the screen. VRAM in the Channel F actually expands four pixels above and to the left of that pixel. If you need a quicker plotting function, you can sacrifice this convenience and use the original version.
+The adjustment of x and y is to allow the coordinates 0, 0 to access the ''upper-left pixel'' of the screen (at least in MESS, for real it may be better or worse). VRAM in the Channel F actually expands four pixels above and to the left of that pixel. If you need a quicker plotting function, you can sacrifice this convenience and use the original version.
 == Original Version ==

@@ Line 20: / Line 20: @@
 	; set the color using r1
 	lr	A, 1
-	outs	1
+	outs	1					; Color is set by bit 6 and 7 only
 	; set the column using r2
@@ Line 30: / Line 30: @@
 	; set the row using r3
 	lis	4
-	as	3					; fix the y coordinate
+	as	3					; adjust the y coordinate
 	com
-	outs	5					; place inverted coordinate for y on port 5
+	outs	5					; place inverted coordinate for y on port 5 (bit 6, 7 not used, those are for sound)
 	; transfer data to the screen memory by toggling ARM