From 2cceaa71f2e006c4a47b7d5fce603c9d1a029b74 Mon Sep 17 00:00:00 2001
From: n loewen <nick@nloewen.com>
Date: Tue, 15 Aug 2023 20:53:51 +0100
Subject: [PATCH] Refactor: Rewrite fill-display: - make more use of constants
 - improve comments

---
 test-programs/fill-display.asm | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/test-programs/fill-display.asm b/test-programs/fill-display.asm
index 1d7f36a..a9b92a7 100644
--- a/test-programs/fill-display.asm
+++ b/test-programs/fill-display.asm
@@ -1,27 +1,25 @@
 ;; Fill display with $FF
 ; updated for 5x5 display
 
-=pixelIndex $24
-=pixelFill $25
+=*px  $24
+=fill $25
 
-LDA $00 ; Start of display
-STO =pixelIndex
+              ; Initialize variables...
+LDA $00       ; (Address for the first px on the display)
+STO =*px      ; Pointer to current px
+LDA $FF       ; ($FF is 'on', $00 is 'off')
+STO =fill     ; Stash value to fill with
 
-LDA $FF
-STO =pixelFill
+@paint
+ LDA (=fill)  ; (A = mem[fill] = $FF)
+ STO (=*px)   ; Paint pixel (mem[mem[*px]] = A = $FF)
 
-@copy-to-display
-  LDA ($25) ; A = mem[$25] = $FF
-  STO ($24) ; update pixel ... mem[mem[$24]] = A = $FF
-
-; increment pixel index
-LDA ($24)
+LDA (=*px)    ; Increment pixel pointer...
 ADD $01
-STO =pixelIndex
-
-LDA ($24) ; pixelIndex
-SUB $19   ; if pixelIndex - $19 == 0, we've reached the end
-FHP 2     ; Zero flag is #2
-  JMP @copy-to-display
+STO =*px
 
+LDA (=*px)    ; Test whether to loop or not...
+SUB $19       ; if *px - $19 == 0, we've reached the end
+FHP 2         ; (Zero flag is #2)
+  JMP @paint
 END
\ No newline at end of file