make char_draw faster using lookup-table

wip-hugo/routines/pixel/pixel_draw.s

@@ -57,8 +57,6 @@ calc_byte_to_paint:
 	AND Y_pos ;; offset to add
 	TAY
 
-	;Add_16 btp_mem_pos, btp_mem_pos + 1, #<Bitmap, #>Bitmap, !
-
 	;;Let draw some stuff
 	LDA byte_to_paint ;; note that both bytes are used!
 	ORA (btp_mem_pos), Y

wip-hugo/routines/text/char.inc

@@ -3,16 +3,8 @@
        Y_pos   = ARGVEC + 1
        code    = ARGVEC + 2
 
-       ;; 16-bit value, we reuse bytes from X_pos
-       X_pos_offset_hi = $ED
-       X_pos_offset_lo = X_pos
-       ;; 16-bit value, we reuse bytes from Y_pos
-       Y_pos_offset_hi = $EC
-       Y_pos_offset_lo = Y_pos
-
        ;; private variables
        screen_position = $EE ; 16-bit value (uses EF)
-       temp_value = $EC      ; 16-bit value (uses ED)
 
        ;; What you will see bellow is .. interesting. I want to reuse
        ;; code and I need it for a 16-bit pointer. Because 6502 pointers expect the bytes to be besides each other

wip-hugo/routines/text/char_draw.s

@@ -7,21 +7,11 @@
 .proc char_draw; user-procedure :clobbers (A Y) :clobbers-arguments 4
         .include "char.inc"
 
-        ;#### TEMP INIT DATA ####
-        LDA #$10
-        STA code
-        LDA #04
-        STA X_pos
-        LDA #02
-        STA Y_pos
-
 ;;Do arithimatic to know where to read and write bytes.
-initial:
+calculate_petski_position:
         ;We first need to clear some memory
         LDA #$00
         STA petski_position + 1
-        STA Y_pos_offset_hi
-        STA X_pos_offset_hi
 
         ;;We need the relative offset for bytes to read and write.
         ;; This is code *8 because 8byte is one character
@@ -32,34 +22,35 @@ initial:
         ;; Add starting position
         Add_16 petski_position, petski_position + 1, #<Character_generator_ROM , #>Character_generator_ROM, !
 
-        ;;Calculate screen_position to use
+calculate_screen_position:
-        Mov_16 screen_position, screen_position + 1, #<VIC_bank, #>VIC_bank
+        ;; Therefore we have that: btp_mem_pos = big_x_offset + smal_y_offset + big_y_offset    + bitmap_offset
 
-        ;; Add the X_pos has a offset multiplier of *8 because 1 chunk = 8 addresses
+	;; We use a lookup-table for big_y_offset + bitmap_offset (see END.s)
-        ;; *8
-        Mult_16 X_pos_offset_lo, X_pos_offset_hi
-        Mult_16 X_pos_offset_lo, X_pos_offset_hi
-        Mult_16 X_pos_offset_lo, X_pos_offset_hi
-        ;; Add
-        Add_16 screen_position, screen_position + 1, X_pos, #$00, !
-
-        ;; And Y_pos has a offset multiplier of "screen length" = 320 = (2*2 +1)*2^6
-        ;;Y_pos*2*2 +1 |Lets reuse X_pos for storage
         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
+	LDA big_y_offset, X
+	STA screen_position
+	INX
+	LDA big_y_offset, X
+	STA screen_position + 1
+
+	;; Y = big_x_offset
+	LDA #%11111000
+	AND X_pos
 	STA X_pos
-        Mult_16 Y_pos_offset_lo,  Y_pos_offset_hi
+	;; Y += smal_y_offset
-        Mult_16 Y_pos_offset_lo,  Y_pos_offset_hi
+	LDA #%00000111 ; A = y (mod 8)
-        Add_16  Y_pos_offset_lo,  Y_pos_offset_hi, X_pos, #$00, !
+	AND Y_pos ;; offset to add
-        ;; *2^6
+	CLC
-        Mult_16 Y_pos_offset_lo,  Y_pos_offset_hi
+	ADC X_pos
-        Mult_16 Y_pos_offset_lo,  Y_pos_offset_hi
+	Add_16 screen_position, screen_position + 1, A, #$00
-        Mult_16 Y_pos_offset_lo,  Y_pos_offset_hi
+
-        Mult_16 Y_pos_offset_lo,  Y_pos_offset_hi
+move_data:
-        Mult_16 Y_pos_offset_lo,  Y_pos_offset_hi
-        Mult_16 Y_pos_offset_lo,  Y_pos_offset_hi
-        ;; Add
-        Add_16 screen_position, screen_position + 1, Y_pos_offset_lo,  Y_pos_offset_hi, !
-        initial_end:
 
         ;; One character is 8 byte, move these bytes to screen
         LDY #$07

wip-hugo/routines/text/char_draw_test.s

@@ -2,9 +2,8 @@
         .include "char.inc"
         LDA #$10
         STA code
-        LDA #04
+        LDA #$20
         STA X_pos
-        LDA #02
         STA Y_pos
         JSR char_draw
 .endscope