From cd0a91b34ea061b3e109f4fb0aaef4da276d30ef Mon Sep 17 00:00:00 2001
From: hugova <hugova@kth.se>
Date: Fri, 25 Jul 2025 09:00:32 +0200
Subject: [PATCH] modify line.s to make it work if X_pos > X_end

---
 .gitignore                                   |  3 +-
 wip-hugo/routines/line/line.s                | 17 +++++++++--
 wip-hugo/routines/line/line_test_extensive.s | 32 ++++++++++++++++++++
 3 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/.gitignore b/.gitignore
index 9f406fc..537ecd2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,4 +4,5 @@
 *.lst
 *.lst
 *.note
-./build/*
+*.lbl
+build/*
diff --git a/wip-hugo/routines/line/line.s b/wip-hugo/routines/line/line.s
index 320a1a9..9768771 100644
--- a/wip-hugo/routines/line/line.s
+++ b/wip-hugo/routines/line/line.s
@@ -23,10 +23,23 @@ do_not_fix_y_end:
         SEC
         LDA X_end
         SBC X_pos
-        STA dx
-        BCC dx_no_underflow;; X_end >= X_pos
+        BCS dx_no_underflow;; X_end >= X_pos
         EOR #$ff ; Fix bit underflow
+        STA dx
+        ;; line_* expect X_pos < X_end and now its not the case.
+        ;; Lets move them around
+        LDX X_pos
+        LDY X_end
+        STX X_end
+        STY X_pos
+        LDX Y_pos
+        LDY Y_end
+        STX Y_end
+        STY Y_pos
+
+
 dx_no_underflow:
+        STA dx
         SEC
         LDA Y_pos
         SBC Y_end
diff --git a/wip-hugo/routines/line/line_test_extensive.s b/wip-hugo/routines/line/line_test_extensive.s
index 2790b51..4f79005 100644
--- a/wip-hugo/routines/line/line_test_extensive.s
+++ b/wip-hugo/routines/line/line_test_extensive.s
@@ -98,4 +98,36 @@ long_line_test_b:
         LDA Y_pos_
         CMP #$ff
         BNE @loop
+
+clear_screen__:
+        ;;Paint the bitmap black. More bitmap: https://www.c64-wiki.com/wiki/53272, https://www.c64-wiki.com/wiki/Screen_RAM#Moving_of_screen_RAM
+        Mov_16 A_start, A_start + 1, #<VIC_bank, #>VIC_bank
+        Mov_16 length, length + 1, #<$1f40,  #>$1f40
+        LDA #$00
+        jsr memset
+
+long_line_test_b_pos_end_swapped:
+        LDA #$00
+        STA X_end_
+        LDA #$00
+        STA Y_end_
+        LDA #$ff
+        STA X_pos_
+        LDA #$60
+        STA Y_pos_
+@loop:
+        LDA Y_end_
+        STA Y_end
+        LDA X_end_
+        STA X_end
+        LDA X_pos_
+        STA X_pos
+        LDA Y_pos_
+        STA Y_pos
+        jsr line
+        INC Y_end_
+        LDA Y_end_
+        CMP #$ff
+        BNE @loop
+
 .endscope