Making clearRAM safer

Fixes issue #30.
sonicretro · Feb 25, 2020 · 3143b40 · 3143b40
1 parent 8bbbb08
commit 3143b40
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/s2.macros.asm b/s2.macros.asm
@@ -52,6 +52,12 @@ bytesToWcnt function n,n>>1-1
 
 ; fills a region of 68k RAM with 0
 clearRAM macro startaddr,endaddr
+    if startaddr>endaddr
+	fatal "Starting address of clearRAM \{startaddr} is after ending address \{endaddr}."
+    elseif startaddr==endaddr
+	warning "clearRAM is clearing zero bytes. Turning this into a nop instead."
+	exitm
+    endif
     if ((startaddr)&$8000)==0
 	lea	(startaddr).l,a1
     else