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--- sd:code_gremlins [2026/03/13 08:19] – appledog
+++ sd:code_gremlins [2026/04/01 04:17] (current) – appledog
@@ Line 70: / Line 70: @@
 Weakness: His true name. You must call him by his true name: The carry gremlin. Call him by his name and, his true form revealed, he will disappear in a puff of smoke.
+=== Zero gremlins
+This is really a goblin, but it is wearing a mask. Remove the mask and you see.. a goblin! Hes gobblin your CPU time. But wait.. he's wearing another mask! Remove the mask and what do you find?
+    NOP
+Great scott! We're being invaded by NOPs!
+To get rid of this Goblin, remember which ops set cpu flags. Before you flagrantly issue a CMP against zero, ask yourself; is it already set?
+Here is the magic scroll to find and eradicate these gremlins; but beware, they are wearing masks, you must thoroughly investigate each case.
+    [^;]CMP [A-Za-z]+,\s*[#$]?0\b
+or maybe
+    ^\s+(LD|ADD|SUB|AND|OR|XOR|SHR|SHL|INC|DEC|MOV)\w*.*\n\s+CMP\s+[A-Za-z]+,\s*[#$]?0\b\n\s+JZ
+Surefire cases look like this:
+    LDA [$C000]
+    CMP A, #0
+    JZ @label
+Here, the CMP is always redundant as LD sets Z. Other common ops that set Z; ST, AND, DIV, MOV, INC, DEC...
+=== Zero gremlins II: The Revenge
+The Zero gremlin never really went away, he just changed masks.
+    ^\s+(LD|ST)\w+.*\n\s+(INC|DEC)\s+
+    ^\s+(INC|DEC)\s+.*\n\s+(LD|ST)\w+
+The above will unmask these goblins right away!
 == History