From 9694d8d55b67ecc174769d50f033102be42c9952 Mon Sep 17 00:00:00 2001
From: hugova <hugova@kth.se>
Date: Wed, 5 Mar 2025 22:42:00 +0100
Subject: [PATCH] Redused paint_pixel to 1 call in draw line

---
 wip-hugo/routines/line/line.inc         |  3 ++
 wip-hugo/routines/line/line_down.s      | 46 +++++++++++++++++++++----
 wip-hugo/routines/line/line_test_time.s |  4 +--
 wip-hugo/routines/memory/pixel_draw.s   |  3 +-
 4 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/wip-hugo/routines/line/line.inc b/wip-hugo/routines/line/line.inc
index 8f5777b..b7d9fcd 100644
--- a/wip-hugo/routines/line/line.inc
+++ b/wip-hugo/routines/line/line.inc
@@ -9,3 +9,6 @@
     dx_2 = dy_2
     V = $0809
     D = $0a0b
+    ;;These are also used in pixel_draw. Look there to find out more
+    byte_to_paint = $FE ;Byte with one 1 that corasponds to a pixel.
+    btp_mem_pos =$494A; byte to paint memory position ;Position of byte on screen
diff --git a/wip-hugo/routines/line/line_down.s b/wip-hugo/routines/line/line_down.s
index 06a32f6..edccd11 100644
--- a/wip-hugo/routines/line/line_down.s
+++ b/wip-hugo/routines/line/line_down.s
@@ -32,7 +32,6 @@
 
     ;dy_2 = dy*2
     mult_16 >dy_2, <dy_2, !
-
     ;; D = 2*dy - dx
     ;; In loop we have that D = D -V
     ;; So D needs to be at least >=V.
@@ -49,10 +48,33 @@
     Add_16 >D, <D, #$ff, #$01, !
     Sub_16 >D, <D, dx, #$00
 
+start_paint:
+    LDY #$00
+    jsr pixel_draw ;;only used first pixel. after this relative position is abused
+    ;byte_to_paint = $FE ;Byte with one 1 that corasponds to a pixel.
+    ;btp_mem_pos =$494A; byte to paint memory position ;Position of byte on screen
+    jmp increment_x_pos_end
+
 for_x:
-    jsr pixel_draw
-    ;;Increment X until X_pos = X_end and Y_pos = Y_end
-    INC X_pos
+    ;; Lets increment btp_mem_pos with +8
+    ;; Read more in pixel_draw to understand this!
+increment_x_pos:
+    INC X_pos;; legacy
+    CLC
+    LDA byte_to_paint
+    ROR byte_to_paint
+    LDX #$00
+    ORA (>btp_mem_pos, X)
+    STA (>btp_mem_pos, X)
+    BCS move_8px_left
+    jmp increment_x_pos_end
+move_8px_left:
+;; add +8 to btp_mem_pos. Find more of why in pixel_draw
+Add_16 >btp_mem_pos, <btp_mem_pos, #$08, #$00
+;; reset byte_to_paint
+LDA #%10000000
+STA byte_to_paint
+increment_x_pos_end:
     LDX X_pos
     CPX X_end
     BEQ end
@@ -60,11 +82,21 @@ for_x:
     ;;else case 1.
     Lag_16 >D, <D, #$00, #$02, case_2
 case_1:; C =1 so we can use !
+    Sub_16 >D, <D, >V, <V ; D = D - V
+    increment_y_pos:
     INC Y_pos
-    Sub_16 >D, <D, >V, <V, !; D = D - V
-    JMP for_x
+    Add_16 >btp_mem_pos, <btp_mem_pos, #$01, #$00
+    INY
+    CPY #$08 ;
+    BEQ move_8px_down
+    jmp for_x
+move_8px_down:
+    ;; +320-8 bytes
+    LDY #$00
+    Add_16 >btp_mem_pos, <btp_mem_pos,#$38 , #$01
+    jmp for_x
 case_2: ;; C =0 because LAG_16 so we can use !
-    Add_16 >D, <D, >dy_2, <dy_2, !;D = D + 2*dy
+    Add_16 >D, <D, >dy_2, <dy_2 ;D = D + 2*dy
     JMP for_x
 end:
     RTS
diff --git a/wip-hugo/routines/line/line_test_time.s b/wip-hugo/routines/line/line_test_time.s
index d050fcc..7806575 100644
--- a/wip-hugo/routines/line/line_test_time.s
+++ b/wip-hugo/routines/line/line_test_time.s
@@ -7,7 +7,7 @@
     X_pos_ = $0E
     Y_end_ = $10
     X_end_ = $11
-    LDA #$a0
+    LDA #$00
     STA X_pos_
     LDA #$30
     STA Y_pos_
@@ -28,7 +28,7 @@ time_start
     jsr line
     INC Y_end
     LDA Y_end
-    CMP #$40
+    CMP #$50
     BEQ end__
     jmp @loop
 end__:
diff --git a/wip-hugo/routines/memory/pixel_draw.s b/wip-hugo/routines/memory/pixel_draw.s
index 2c49d47..21261bc 100755
--- a/wip-hugo/routines/memory/pixel_draw.s
+++ b/wip-hugo/routines/memory/pixel_draw.s
@@ -13,7 +13,6 @@
 	TAX
 
 	;;Store pixel in byte_to_paint
-	TAX
 	LDA #%10000000
 	INX
 @shift_btp:
@@ -87,7 +86,7 @@ end__:
 
 	;;Let draw some stuff
 	LDX #$00
-	LDA byte_to_paint
+	LDA byte_to_paint ;; note that both bytes are used!
 	ORA (>btp_mem_pos, X)
 	STA (>btp_mem_pos, X)
 	RTS