From 9150a79efd85450df02ba70908dbfcc3f27924b2 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Sun, 9 Jul 2017 09:59:05 -0700
Subject: [PATCH] GBA: Extend oddly-sized ROMs to full address space (fixes
 #722)

---
 CHANGES       |  1 +
 src/gba/gba.c | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/CHANGES b/CHANGES
index d10243b3a..e8e5a9c46 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,7 @@ Bugfixes:
  - GB Audio: Make audio unsigned with bias (fixes mgba.io/i/749)
 Misc:
  - GBA Timer: Use global cycles for timers
+ - GBA: Extend oddly-sized ROMs to full address space (fixes mgba.io/i/722)
 
 0.6.0: (Future)
 Features:
diff --git a/src/gba/gba.c b/src/gba/gba.c
index a6d9467ae..d5f5e2113 100644
--- a/src/gba/gba.c
+++ b/src/gba/gba.c
@@ -342,6 +342,16 @@ bool GBALoadROM(struct GBA* gba, struct VFile* vf) {
 	gba->romCrc32 = doCrc32(gba->memory.rom, gba->memory.romSize);
 	GBAHardwareInit(&gba->memory.hw, &((uint16_t*) gba->memory.rom)[GPIO_REG_DATA >> 1]);
 	GBAVFameDetect(&gba->memory.vfame, gba->memory.rom, gba->memory.romSize);
+	if (popcount32(gba->memory.romSize) != 1) {
+		// This ROM is either a bad dump or homebrew. Emulate flash cart behavior.
+#ifndef _3DS
+		void* newRom = anonymousMemoryMap(SIZE_CART0);
+		memcpy(newRom, gba->memory.rom, gba->pristineRomSize);
+		gba->memory.rom = newRom;
+#endif
+		gba->memory.romSize = SIZE_CART0;
+		gba->isPristine = false;
+	}
 	// TODO: error check
 	return true;
 }