II-17: Initialize wCurKeys and wNewKeys (#76)

Co-authored-by: Eldred Habert <[email protected]>

Author: kav

src/part2/input.md

@@ -29,6 +29,13 @@ First, let's set aside some room for the two variables that `UpdateKeys` will us
 Each variable must reside in RAM, and not ROM, because ROM is "Read-Only" (so you can't modify it).
 Additionally, each variable only needs to be one byte large, so we use `db` ("Define Byte") to reserve one byte of RAM for each.
 
+Before we read these variables we will also want to initialize them.
+We can do that below our initialization  of `wFrameCounter`.
+
+```rgbasm,linenos,start={{#line_no_of "" ../../unbricked/input/main.asm:initialize-vars}}
+{{#include ../../unbricked/input/main.asm:initialize-vars}}
+```
+
 We're going to use the `and` opcode, which we can use to set the zero flag (`z`) to the value of the bit.
 We can use this along with the `PADF` constants in hardware.inc to read a particular key.
 

unbricked/bricks/main.asm

@@ -90,8 +90,11 @@ ClearOam:
 	ld a, %11100100
 	ld [rOBP0], a
 
+	; Initialize global variables
 	ld a, 0
 	ld [wFrameCounter], a
+	ld [wCurKeys], a
+	ld [wNewKeys], a
 
 Main:
 	ld a, [rLY]

unbricked/collision/main.asm

@@ -90,8 +90,11 @@ ClearOam:
 	ld a, %11100100
 	ld [rOBP0], a
 
+	; Initialize global variables
 	ld a, 0
 	ld [wFrameCounter], a
+	ld [wCurKeys], a
+	ld [wNewKeys], a
 
 ; ANCHOR: momentum
 Main:

unbricked/functions/main.asm

@@ -68,6 +68,7 @@ ClearOam:
 	ld a, %11100100
 	ld [rOBP0], a
 
+	; Initialize global variables
 	ld a, 0
 	ld [wFrameCounter], a
 

unbricked/input/main.asm

@@ -68,8 +68,13 @@ ClearOam:
 	ld a, %11100100
 	ld [rOBP0], a
 
+	; ANCHOR: initialize-vars
+	; Initialize global variables
 	ld a, 0
 	ld [wFrameCounter], a
+	ld [wCurKeys], a
+	ld [wNewKeys], a
+	; ANCHOR_END: initialize-vars
 
 ; ANCHOR: main
 Main:

unbricked/objects/main.asm

@@ -94,6 +94,7 @@ ClearOam:
 ; ANCHOR_END: enable-oam
 
 ; ANCHOR: main-loop
+	; Initialize global variables
 	ld a, 0
 	ld [wFrameCounter], a