From e321a4211c7c324993f30e1d2c24fa44e5438d03 Mon Sep 17 00:00:00 2001
From: Christopher Bonhage <me@christopherbonhage.com>
Date: Wed, 22 Jan 2025 10:36:20 -0500
Subject: [PATCH] Early return on cart_init if already initialized

Disambiguates the undefined vs null detection states.
---
 include/cart.h      |  1 +
 src/cart/cartexit.c |  9 +++++++--
 src/cart/cartinit.c | 29 ++++++++++++++++++-----------
 3 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/include/cart.h b/include/cart.h
index 4ac8c34..610b6c1 100644
--- a/include/cart.h
+++ b/include/cart.h
@@ -9,6 +9,7 @@ typedef uint32_t u32;
 #endif
 
 /* Cartridge types */
+#define CART_UNDEFINED  -2
 #define CART_NULL       -1
 #define CART_CI         0       /* 64Drive */
 #define CART_EDX        1       /* EverDrive-64 X-series */
diff --git a/src/cart/cartexit.c b/src/cart/cartexit.c
index 67e94aa..b31ef25 100644
--- a/src/cart/cartexit.c
+++ b/src/cart/cartexit.c
@@ -10,6 +10,11 @@ int cart_exit(void)
 		ed_exit,
 		sc_exit,
 	};
-	if (cart_type < 0) return -1;
-	return exit[cart_type]();
+	int result = -1;
+	if (cart_type >= 0)
+	{
+		result = exit[cart_type]();
+	}
+	cart_type = CART_UNDEFINED;
+	return result;
 }
diff --git a/src/cart/cartinit.c b/src/cart/cartinit.c
index e8a8123..7f917ba 100644
--- a/src/cart/cartinit.c
+++ b/src/cart/cartinit.c
@@ -1,7 +1,7 @@
 #include <cart.h>
 #include "cartint.h"
 
-int cart_type = CART_NULL;
+int cart_type = CART_UNDEFINED;
 
 int cart_init(void)
 {
@@ -13,8 +13,17 @@ int cart_init(void)
 		sc_init,
 	};
 	int i, result;
+	/* bail if already initialized */
+	if (cart_type != CART_UNDEFINED)
+	{
+		return -1;
+	}
 	/* bbplayer */
-	if ((IO_READ(MI_VERSION_REG) & 0xF0) == 0xB0) return -1;
+	if ((IO_READ(MI_VERSION_REG) & 0xF0) == 0xB0)
+	{
+		cart_type = CART_NULL;
+		return -1;
+	}
 	if (!__cart_dom1)
 	{
 		__cart_dom1 = 0x8030FFFF;
@@ -23,17 +32,15 @@ int cart_init(void)
 		__cart_acs_rel();
 	}
 	if (!__cart_dom2) __cart_dom2 = __cart_dom1;
-	if (cart_type < 0)
+	/* detect */
+	for (i = 0; i < CART_MAX; i++)
 	{
-		for (i = 0; i < CART_MAX; i++)
+		if ((result = init[i]()) >= 0)
 		{
-			if ((result = init[i]()) >= 0)
-			{
-				cart_type = i;
-				return result;
-			}
+			cart_type = i;
+			return result;
 		}
-		return -1;
 	}
-	return init[cart_type]();
+	cart_type = CART_NULL;
+	return -1;
 }