Initialize 'zp_pause_toggle' before NMI enablement

Otherwise we might randomly get weird scenarios like the title screen
not showing up properly.

Fixes: bc99212539f6 ("Toggle a "Paused" message on top of the screen")

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>

2 files changed, 15 insertions, 2 deletions

diff --git a/src/driver.s b/src/driver.s
index 1449de5..1ac5718 100644
--- a/src/driver.s
+++ b/src/driver.s
@@ -49,6 +49,15 @@
     ;; this, but we have plenty of RAM left.
     zp_pause_toggle = $39
 
+    ;; Initialization routine that is to be called before enabling NMIs back for
+    ;; the first time.
+    .proc init_before_nmi
+        lda #0
+        sta Driver::zp_pause_toggle
+
+        rts
+    .endproc
+
     ;; Switch from the title screen to the main screen. Note that this function
     ;; is to be called with the PPU disabled. If that's not the case, then it
     ;; will set the proper values to disable it on the next `nmi` call and set
@@ -157,7 +166,6 @@
         lda #0
         sta zp_pause_timer
         sta Driver::zp_moved_out
-        sta Driver::zp_pause_toggle
 
         ;; Initialize variables for sprite cycling.
         sta zp_next_bullet_cycle
diff --git a/src/jetpac.s b/src/jetpac.s
index 5c1c099..52ec1f7 100644
--- a/src/jetpac.s
+++ b/src/jetpac.s
@@ -121,7 +121,8 @@
     sta PPU::zp_control
 
     ;; Initialize other global variables which the rest of the game assume to
-    ;; have zero as their initial values.
+    ;; have zero as their initial values. Note that it's important to have these
+    ;; variables defined before
     sta Globals::zp_flags
     sta Joypad::zp_buttons1
     sta Joypad::zp_buttons2
@@ -146,6 +147,10 @@
     ;; Initialize some variables from the "Game Over" side of the game.
     jsr Over::init
 
+    ;; Initialize variables from the game's driver that need to be set before
+    ;; NMIs start ticking.
+    jsr Driver::init_before_nmi
+
     ;; Initialize some PAL-specific constants.
     .ifdef PAL
         lda #0