add pixel_calc that does the same as picel_draw without the drawing pixel part

wip-hugo/routines/circle/circle.inc

@@ -8,8 +8,8 @@
         t2    = $E1
         X_math = radius
         Y_math = $E2
-        ;; E8 - EA is used by pixel.inc
+        ;; E9 - EA is used by pixel.inc
-        byte_to_paint_qaa = byte_to_paint
+        byte_to_paint_qaa = $E8
         byte_to_paint_qcb = $E3
         byte_to_paint_qca = $E4
         byte_to_paint_qdb = $E5

wip-hugo/routines/circle/circle.s

@@ -45,7 +45,10 @@ draw_upper_px_in_circle:
         SBC radius
         STA Y_pos
 
-        JSR  pixel_draw
+        JSR  pixel_calc
+       	;; A = byte_to_paint (small_X_offset)
+	;; Y =small_y_offset
+	;; btp_mem_pos (bigg_X_offset + bigg_Y-offset)
 
         ;; initial pixel for 2 half-quarter arias
         LDA btp_mem_pos
@@ -69,7 +72,12 @@ draw_left_px_in_circle: ;similar as above
         SBC radius
         STA X_pos
 
-        JSR pixel_draw
+        JSR  pixel_calc
+       	;; A = byte_to_paint (small_X_offset)
+	;; Y =small_y_offset
+	;; btp_mem_pos (bigg_X_offset + bigg_Y-offset)
+        STA byte_to_paint_qca
+
         LDA btp_mem_pos
         STA btp_mem_pos_qca
         STA btp_mem_pos_qba
@@ -77,9 +85,6 @@ draw_left_px_in_circle: ;similar as above
         STA btp_mem_pos_qca + 1
         STA btp_mem_pos_qba + 1
 
-        LDA byte_to_paint
-        STA byte_to_paint_qca
-
         LDA temp__
         STA X_pos
 draw_lower_px_in_circle: ;similar as above
@@ -88,7 +93,12 @@ draw_lower_px_in_circle: ;similar as above
         ADC radius
         STA Y_pos
 
-        JSR pixel_draw
+        JSR  pixel_calc
+       	;; A = byte_to_paint (small_X_offset)
+	;; Y =small_y_offset
+	;; btp_mem_pos (bigg_X_offset + bigg_Y-offset)
+        STA byte_to_paint_qdb
+        STA byte_to_paint_qcb
 
         LDA btp_mem_pos
         STA btp_mem_pos_qdb
@@ -97,10 +107,6 @@ draw_lower_px_in_circle: ;similar as above
         STA btp_mem_pos_qdb + 1
         STA btp_mem_pos_qcb + 1
 
-        LDA byte_to_paint
-        STA byte_to_paint_qdb
-        STA byte_to_paint_qcb
-
         STY Y_qdb
         STY Y_qaa
 
@@ -111,7 +117,11 @@ draw_right_px_in_circle:; similar as above
         LDA X_pos
         ADC radius
         STA X_pos
-        JSR pixel_draw
+        JSR  pixel_calc
+       	;; A = byte_to_paint (small_X_offset)
+	;; Y =small_y_offset
+	;; btp_mem_pos (bigg_X_offset + bigg_Y-offset)
+	STA byte_to_paint_qaa
 
         LDA btp_mem_pos
         STA btp_mem_pos_qda
@@ -123,7 +133,6 @@ draw_right_px_in_circle:; similar as above
 
 
         LDX #$08 ; X=8 always expected inside the loop
-
         SEC
 while_x_bigger_then_y: ; C=1 here because above and branching logic
 draw_pixels:
@@ -230,13 +239,13 @@ change_x:
         DEC X_math
         STA t1    ; t1 = t2
 qaa_x:
-        ASL byte_to_paint
+        ASL byte_to_paint_qaa
         BCC qaa_x_end
 qaa_x_overflow:
         Sub_16 btp_mem_pos_qaa, btp_mem_pos_qaa + 1, #$08, #$00, ! ;-8
         Sub_16 btp_mem_pos_qda, btp_mem_pos_qda + 1, #$08, #$00, ! ;-8
         ;; Restores byte to paint
-        INC byte_to_paint
+        INC byte_to_paint_qaa
 qaa_x_end:
 
 qca_x:

wip-hugo/routines/line/line.inc

@@ -4,9 +4,10 @@
         X_end = ARGVEC + 2
         Y_end = ARGVEC + 3
         ;; private args
-        dx = $E0
+        dx            = $E0
-        dy = $E2
+        dy            = $E2
-        dy_2 = dy          ; 16-bit value (uses E1)
+        dy_2          = dy              ; 16-bit value (uses E1)
-        dx_2 = dx          ; 16-bit value (uses E3)
+        dx_2          = dx              ; 16-bit value (uses E3)
-        V = $E4             ; 16-bit value (uses E5)
+        V             = $E4             ; 16-bit value (uses E5)
-        D = $E6             ; 16-bit value (uses E7)
+        D             = $E6             ; 16-bit value (uses E7)
+        byte_to_paint = $E8

wip-hugo/routines/line/line_down.s

@@ -62,7 +62,8 @@ selfmod:
         LDA V + 1
         STA case_1 + 7
 end_selfmod:
-        JSR pixel_draw ;;only used first pixel. after this relative position is abused
+        JSR pixel_calc ;;only used first pixel. after this relative position is abused
+        STA byte_to_paint
         ;; X = X_end - X_pos
         LDX dx
         LDY #$00

wip-hugo/routines/line/line_down_inv.s

@@ -39,7 +39,8 @@ selfmod:
         LDA V + 1
         STA case_1 + 7
 end_selfmod:
-        jsr pixel_draw
+        JSR pixel_calc ;;only used first pixel. after this relative position is abused
+        STA byte_to_paint
         LDY #$00
         LDX dy
 for_y:

wip-hugo/routines/line/line_up.s

@@ -40,7 +40,8 @@ selfmod:
         LDA V + 1
         STA case_1 + 7
 end_selfmod:
-        jsr pixel_draw
+        JSR pixel_calc ;;only used first pixel. after this relative position is abused
+        STA byte_to_paint
         Sub_16 btp_mem_pos, btp_mem_pos + 1, #$01, #$00 ;; Y has always a offset of at least 1
         LDY #$01
         LDX dx

wip-hugo/routines/line/line_up_inv.s

@@ -39,7 +39,8 @@ selfmod:
         LDA V + 1
         STA case_1 + 7
 end_selfmod:
-        jsr pixel_draw
+        JSR pixel_calc ;;only used first pixel. after this relative position is abused
+        STA byte_to_paint
         LDY #$00
         LDX dy
 for_y:

wip-hugo/routines/pixel/pixel.inc

@@ -4,6 +4,5 @@
        Y_pos = ARGVEC + 0
        X_pos = ARGVEC + 1
        ;; Private args
-       byte_to_paint = $E8
        btp_mem_pos = $E9  ; 16-bit value (uses EA), byte to paint memory position
        Bitmap = $4000

wip-hugo/routines/pixel/pixel_calc.s

@@ -0,0 +1,57 @@
+;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
+
+;;Calculates values needed to draw a pixel on screen!
+.proc pixel_calc
+        .include "pixel.inc"
+
+	;;FIND position to write byte_to_paint (btp_mem_pos)
+	;; + + + + + >  X
+	;; +
+	;; +
+	;;\/
+	;; Y
+
+	;; The screen has a wierd memory to pixel maping!
+	;; Each line of 8 pixels is one byte
+	;; 8 consecutive bytes in memory makes up a chunk and are 'under each other' on the screen
+	;; the chunks are orderd from the left to the right and then looping downwards.
+	;; Therefore we have that: btp_mem_pos = big_x_offset + smal_y_offset + big_y_offset    + bitmap_offset
+
+	;; We use a lookup-table for big_y_offset + bitmap_offset (see END.s)
+	;; (Y_pos / 8  floor)*2
+	LDA Y_pos
+	LSR A
+	LSR A
+	;; We need to remove the last digit if its still there
+	;; same as LSR ASR
+	AND #%11111110
+	TAX
+	;; big_y_offset + big_x_offset
+	CLC
+	;;A = big_x_offset
+	LDA #%11111000
+	AND X_pos
+	ADC big_y_offset, X
+	STA btp_mem_pos
+	LDA #$00
+	INX
+	ADC big_y_offset, X
+	STA btp_mem_pos + 1
+
+	;; + small_y_offset
+	LDA #%00000111 ; A = y (mod 8)
+	AND Y_pos ;; offset to add
+	TAY
+
+calc_byte_to_paint: ;; aka small_x_offset
+	LDA X_pos
+	AND #%00000111
+	TAX
+	;;this is the same as: byte_to_paint = 2^X
+	LDA binary_factor, X;; (see END.s)
+
+	;; A = byte_to_paint (small_X_offset)
+	;; Y =small_y_offset
+	;; btp_mem_pos (bigg_X_offset + bigg_Y-offset)
+	RTS
+.endproc

wip-hugo/routines/pixel/pixel_draw.s

@@ -49,7 +49,6 @@ calc_byte_to_paint: ;; aka small_x_offset
 	TAX
 	;;this is the same as: byte_to_paint = 2^X
 	LDA binary_factor, X;; (see END.s)
-	STA byte_to_paint ;; should be removed, here for other code!
 
 draw:	;;Let draw some stuff
 	ORA (btp_mem_pos), Y

wip-hugo/source.s

@@ -26,6 +26,7 @@ JMP exit
 .include "routines/circle/circle.s"
 .include "routines/triangle/triangle.s"
 .include "routines/pixel/pixel_draw.s"
+.include "routines/pixel/pixel_calc.s"
 .include "routines/text/char_draw.s"
 .include "routines/memory/memset.s"
 .include "routines/memory/memcpy.s"