A examples/lib/upcase.xyw

@@ -0,0 +1,22 @@ 
+;.include "lib/macros.xyw"
+
+; Convert a string to uppercase 
+; a16 -[xw]-
+.label upcase
+  ; store index
+  POPxw
+  .label upcase.loop
+    LDBxw $00 EQU upcase.end JCNw
+    ; check if a lowercase letter
+    LDBxw $60 GTH
+    LDBxw $7B LTH
+    AND upcase.change JCNw
+    ; continue
+    INCxw upcase.loop JMPw
+    .label upcase.change
+      ; convert to uppercase  
+      LDBxw $20 SUB STBxw
+      ; continue 
+      INCxw upcase.loop JMPw
+    .label upcase.end
+      RTS