From 08daa79e6a83eb54a550c9b70bf1c872104e8448 Mon Sep 17 00:00:00 2001
From: hugova <hugova@kth.se>
Date: Sat, 29 Mar 2025 18:09:58 +0100
Subject: [PATCH] Improve line_down from 839904 to 837970 cykles in
 line_test_time

---
 wip-hugo/macros/16aritmatic.s      | 17 +++++++++++++++--
 wip-hugo/routines/line/line_down.s | 14 +++++++++-----
 wip-hugo/source.s                  |  4 ++--
 3 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/wip-hugo/macros/16aritmatic.s b/wip-hugo/macros/16aritmatic.s
index 00b3ef5..3f65591 100755
--- a/wip-hugo/macros/16aritmatic.s
+++ b/wip-hugo/macros/16aritmatic.s
@@ -37,12 +37,13 @@
 	STA hi
 .endmacro
 
-.macro Add_16_A a_low, a_hi, b_hi, fast_unsafe
+.macro Add_16_A a_low, a_hi, b_low, b_hi, fast_unsafe
 ;; IF to run it fast
 .ifblank fast_unsafe
     CLC
 .endif
-	ADC a_low
+	LDA a_low
+	ADC b_low
 	STA a_low
 	LDA b_hi
 	ADC a_hi
@@ -64,6 +65,18 @@
         STA a_hi
 .endmacro
 
+.macro Sub_16_A a_low, a_hi, b_low, b_hi, fast_unsafe
+;; IF to run it fast
+.ifblank fast_unsafe
+        SEC
+.endif
+        SBC b_low
+        STA a_low
+        LDA a_hi
+        SBC b_hi
+        STA a_hi
+.endmacro
+
 ;; Untested
 ;; Subtraction uses the A register
 ;; a = a - b. b_low = A, b_hi = X
diff --git a/wip-hugo/routines/line/line_down.s b/wip-hugo/routines/line/line_down.s
index 7daeb10..abff7fb 100644
--- a/wip-hugo/routines/line/line_down.s
+++ b/wip-hugo/routines/line/line_down.s
@@ -61,10 +61,10 @@ selfmod:
         ;; V
         ;;Modidies SBC >V
         LDA >V
-        STA case_1 +3
+        STA case_1 +1
         ;; Modifies SBC <V
         LDA <V
-        STA case_1 +9
+        STA case_1 +7
 end_selfmod:
 
 for_x:
@@ -89,8 +89,12 @@ increment_pixel_x_end:
         ;;If D <  %00000010 00000000:  case_2
         ;;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
+case_1:
+        ;; D = D - V
+        ;; Because Lag_16:
+        ;;      C =1 so we can use !
+        ;;      A = >D
+        Sub_16_A >D, <D, #>V, #<V, !
 increment_y_pos:
         INY ; Increment Y pos inside the buffer
         CPY #$08
@@ -101,7 +105,7 @@ move_8px_down: ; Z=1 --> C=1
         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 !
+case_2:
         Add_16 >D, <D, #>dy_2, #<dy_2, ! ;D = D + 2*dy
         JMP for_x
 end:
diff --git a/wip-hugo/source.s b/wip-hugo/source.s
index b22af8d..79b7b72 100755
--- a/wip-hugo/source.s
+++ b/wip-hugo/source.s
@@ -3,8 +3,8 @@
 .include "macros/timer.s"
 
 .include "STARTUP.s"
-;.include "routines/line/line_test_time.s"
-jsr char_draw
+.include "routines/line/line_test_time.s"
+;jsr char_draw
 ;;This is used by .s files to terminate nicely without reading includes at the end!
 exit:
 jmp exit