From 36a5ca52124e0729239f09e0fad38a3a52b4419f Mon Sep 17 00:00:00 2001
From: d_m <d_m@plastic-idolatry.com>
Date: Sun, 29 Oct 2023 00:27:19 -0400
Subject: [PATCH] Improve comments a bit.

---
 icn_to_bmp.tal | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/icn_to_bmp.tal b/icn_to_bmp.tal
index efc4afb..646a0f4 100644
--- a/icn_to_bmp.tal
+++ b/icn_to_bmp.tal
@@ -137,16 +137,19 @@
     STH2r  STA JMP2r            ( ; addr+2<-r )
 
 @write-header ( -> )
+    ( NOTE: you'll see some swaps just before stores )
+    ( this is because the BMP header uses a little-endian byte order )
     .adj-tile-w LDZ2 .tile-h LDZ2 MUL2 ( aw*h )
     #30 SFT2 #0020 ADD2                ( 32+aw*h*8 )
-    SWP ;bmp-header/total-size STA2
-    .tile-h LDZ2 #30 SFT2 SWP ;bmp-header/pixel-h STA2    ( )
-    .tile-w LDZ2 #30 SFT2 SWP ;bmp-header/pixel-w STA2    ( )
+    SWP ;bmp-header/total-size STA2    ( ; write total-size )
+    .tile-h LDZ2 #30 SFT2 SWP ;bmp-header/pixel-h STA2 ( ; write height )
+    .tile-w LDZ2 #30 SFT2 SWP ;bmp-header/pixel-w STA2 ( ; write width )
 
     ( these colors are specified in RGB order )
-    #ff #ff #ff ;bmp-header/color0 write-color
-    #00 #00 #00 ;bmp-header/color1 write-color
+    #ff #ff #ff ;bmp-header/color0 write-color ( ; write color 0 )
+    #00 #00 #00 ;bmp-header/color1 write-color ( ; write color 1 )
 
+    ( actually write out the BMP header now )
     .out-file LDZ2 .File2/name DEO2
     #0020 .File2/len DEO2
     ;bmp-header .File2/w DEO2
@@ -179,5 +182,5 @@
     &color1 00 00 00        ( 29: color 1, blue/green/red MOD )
                             ( 32: start of pixel data MOD )
 
-@bmp-buf $7f8
-@icn-dat $c000 ( 48k )
+@bmp-buf $7f8  (  2040 bytes: buffer for one BMP row )
+@icn-dat $c000 ( 49152 bytes: buffer for the entire ICN file )