From 0948e83a85e1a5eed3383b8386ecd0890056010a Mon Sep 17 00:00:00 2001
From: Rangi <remy.oukaour+rangi42@gmail.com>
Date: Tue, 2 Nov 2021 23:22:31 -0400
Subject: dec a then AddNTimes

---
 Optimizing-assembly-code.md | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Optimizing-assembly-code.md b/Optimizing-assembly-code.md
index 2ff7153..fd5b7b5 100644
--- a/Optimizing-assembly-code.md
+++ b/Optimizing-assembly-code.md
@@ -67,6 +67,7 @@ WikiTI's advice fully applies here:
   - [Enable interrupts and return](#enable-interrupts-and-return)
 - [Jump and lookup tables](#jump-and-lookup-tables)
   - [Chain comparisons](#chain-comparisons)
+  - [Off-by-one `AddNTimes`](#off-by-one-addntimes)
 
 
 ## 8-bit registers
@@ -2069,3 +2070,23 @@ JumpTable::
 	pop de
 	jp hl
 ```
+
+
+### Off-by-one `AddNTimes`
+
+Don't do this:
+
+```asm
+	ld hl, Foo
+	ld bc, BAR
+	dec a
+	call AddNTimes
+```
+
+Instead, as long as you don't need to add 255 times when a is 0, then do this:
+
+```asm
+	ld hl, Foo - BAR
+	ld bc, BAR
+	call AddNTimes
+```
-- 
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