From 4497026d9528d4d95084d6b55a0238f9597842bf Mon Sep 17 00:00:00 2001
From: hugova <hugova@kth.se>
Date: Tue, 25 Mar 2025 19:20:23 +0100
Subject: [PATCH] Rewrite start condition of line_down so that it start on
 exaktly the right pixel

---
 wip-hugo/routines/line/line_down.s    |  7 +++----
 wip-hugo/routines/line/line_test.s    |  4 ++--
 wip-hugo/routines/memory/pixel_draw.s | 22 +++++++++++++---------
 3 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/wip-hugo/routines/line/line_down.s b/wip-hugo/routines/line/line_down.s
index 3280e2d..40d8417 100644
--- a/wip-hugo/routines/line/line_down.s
+++ b/wip-hugo/routines/line/line_down.s
@@ -51,7 +51,7 @@
         Sub_16 >D, <D, dx, #$00
 
         jsr pixel_draw ;;only used first pixel. after this relative position is abused
-        LDY #$00
+        ;LDY #$00
         LDX X_pos
 for_x:
         ;; Paints A to address i btp_mem_pos* + Y
@@ -82,10 +82,9 @@ increment_y_pos:
         CPY #$08 ;
         BNE for_x
 move_8px_down: ; Z=1 --> C=1
-        ;; +320-8 bytes
         LDY #$00
-        Add_16 >btp_mem_pos, <btp_mem_pos, #$40, #$01
-        jmp for_x
+        Add_16 >btp_mem_pos, <btp_mem_pos, #$40, #$01; +320
+        JMP for_x
 increment_y_pos_end:
 case_2: ;; C =0 because LAG_16 so we can use !
         Add_16 >D, <D, >dy_2, <dy_2, ! ;D = D + 2*dy
diff --git a/wip-hugo/routines/line/line_test.s b/wip-hugo/routines/line/line_test.s
index 4b02ff5..1d69296 100644
--- a/wip-hugo/routines/line/line_test.s
+++ b/wip-hugo/routines/line/line_test.s
@@ -6,9 +6,9 @@
         X_pos_ = $0E
         Y_end_ = $10
         X_end_ = $11
-        LDA #$d0
+        LDA #$d2
         STA X_pos_
-        LDA #$60
+        LDA #$62
         STA Y_pos_
         LDA #$ff
         STA X_end
diff --git a/wip-hugo/routines/memory/pixel_draw.s b/wip-hugo/routines/memory/pixel_draw.s
index a6e1276..663d3bb 100755
--- a/wip-hugo/routines/memory/pixel_draw.s
+++ b/wip-hugo/routines/memory/pixel_draw.s
@@ -47,14 +47,18 @@ end__:
 	LDA #%00000111 ; A = y (mod 8)
 	AND Y_pos ;; offset to add
 
+
 	;;ading offset, same as psudocode bellow
 	;;Add_16 >btp_mem_pos, <btp_mem_pos, A, #$00
-	CLC ; Y = b_low
-	ADC >btp_mem_pos
-	STA >btp_mem_pos
-	LDA #$00
-	ADC <btp_mem_pos ; C =0
-	STA <btp_mem_pos
+	;CLC ; Y = b_low
+	;ADC >btp_mem_pos
+	;STA >btp_mem_pos
+	;LDA #$00
+	;ADC <btp_mem_pos ; C =0
+	;STA <btp_mem_pos
+
+	TAY
+	CLC
 
 	LDA #$00
 	STA $4B
@@ -87,9 +91,9 @@ end__:
 	Add_16 >btp_mem_pos, <btp_mem_pos, #<Bitmap, #>Bitmap, !
 
 	;;Let draw some stuff
-	LDX #$00
+	;LDY #$00
 	LDA byte_to_paint ;; note that both bytes are used!
-	ORA (>btp_mem_pos, X)
-	STA (>btp_mem_pos, X)
+	ORA (>btp_mem_pos), Y
+	STA (>btp_mem_pos), Y
 	RTS
 .endproc