From b21e3d2588749568c777a84435905bef110f3479 Mon Sep 17 00:00:00 2001
From: Miquel Sabaté Solà <mikisabate@gmail.com>
Date: Thu, 20 Mar 2025 18:01:34 +0100
Subject: Clear VBlank on reset on all examples
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This was an oversight from the very first example that has propagated
into the other ones.

Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com>
---
 basics/chr-ram.s | 1 +
 basics/flicker.s | 1 +
 basics/input.s   | 1 +
 basics/persist.s | 1 +
 basics/sprite.s  | 5 ++++-
 basics/unrom.s   | 1 +
 6 files changed, 9 insertions(+), 1 deletion(-)

(limited to 'basics')

diff --git a/basics/chr-ram.s b/basics/chr-ram.s
index bb2186e..48b2a74 100644
--- a/basics/chr-ram.s
+++ b/basics/chr-ram.s
@@ -75,6 +75,7 @@ chr:
     stx $2001
     stx $4010
 
+    bit $2002
 @vblankwait1:
     bit $2002
     bpl @vblankwait1
diff --git a/basics/flicker.s b/basics/flicker.s
index 5677968..2cca1dd 100644
--- a/basics/flicker.s
+++ b/basics/flicker.s
@@ -184,6 +184,7 @@
     stx $2001                   ; PPUMASK
     stx $4010                   ; APU DMC
 
+    bit $2002                   ; PPUSTATUS
 @vblankwait1:
     bit $2002                   ; PPUSTATUS
     bpl @vblankwait1
diff --git a/basics/input.s b/basics/input.s
index df49a66..c51a500 100644
--- a/basics/input.s
+++ b/basics/input.s
@@ -56,6 +56,7 @@
     stx $2001
     stx $4010
 
+    bit $2002
 @vblankwait1:
     bit $2002
     bpl @vblankwait1
diff --git a/basics/persist.s b/basics/persist.s
index e7dfb07..49d3c81 100644
--- a/basics/persist.s
+++ b/basics/persist.s
@@ -80,6 +80,7 @@
 reset_mmc1:
     inc reset_mmc1
 
+    bit $2002
 @vblankwait1:
     bit $2002
     bpl @vblankwait1
diff --git a/basics/sprite.s b/basics/sprite.s
index b9e183b..27beb91 100644
--- a/basics/sprite.s
+++ b/basics/sprite.s
@@ -174,7 +174,10 @@
     ;; will see how we can take advantage of this when we use the PPU properly
     ;; down the road.
 
-    ;; First of the two waits.
+    ;; First of the two waits. The `bit` outside of the loop is not a typo, but
+    ;; since the VBlank flag is in an unknown state after reset, we clear it now
+    ;; so the next loop does not exit immediately by mistake.
+    bit $2002                   ; PPUSTATUS
 @vblankwait1:
     bit $2002                   ; PPUSTATUS
     bpl @vblankwait1
diff --git a/basics/unrom.s b/basics/unrom.s
index eb49b17..60b52d6 100644
--- a/basics/unrom.s
+++ b/basics/unrom.s
@@ -139,6 +139,7 @@ bankswitch_nosave:
     stx $2001
     stx $4010
 
+    bit $2002
 @vblankwait1:
     bit $2002
     bpl @vblankwait1
-- 
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