From 65bee772a1461911557b0e90c969d1d62a12751a Mon Sep 17 00:00:00 2001 From: Lokathor Date: Mon, 24 Dec 2018 12:08:11 -0700 Subject: [PATCH] zero thing cleanup --- book/src/04-non-video/01-buttons.md | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/book/src/04-non-video/01-buttons.md b/book/src/04-non-video/01-buttons.md index 6fe773a..899eb93 100644 --- a/book/src/04-non-video/01-buttons.md +++ b/book/src/04-non-video/01-buttons.md @@ -29,9 +29,11 @@ The buttons are, going up in order from the 0th bit: * R * L -Bits above that are not used. However, since the arrow left and right can never -be pressed at the same time, and the arrows up and down can never be pressed at -the same time, this register will never read as zero. +Bits above that are not used. However, since the left and right directions, as +well as the up and down directions, can never be pressed at the same time, the +`KEYINPUT` register should never read as zero. Of course, the register _might_ +read as zero if someone is using an emulator that allows for such inputs, so I +wouldn't go so far as to make it be `NonZeroU16` or anything like that. When programming, we usually are thinking of what buttons we want to have _be pressed_ instead of buttons we want to have _not be pressed_. This means that we