From 5a5534915596e863bd40cfc943bddcca51ef5a11 Mon Sep 17 00:00:00 2001
From: zeromus <zeromus@users.sf.net>
Date: Sat, 25 Jul 2015 23:46:58 +0000
Subject: [PATCH] support trimmed roms to non 4-aligned sizes (supposedly a
 regression from 0.9.10)

---
 desmume/src/NDSSystem.cpp            | 39 +++++++++++++++++++++++-----
 desmume/src/addons/slot1comp_rom.cpp |  2 +-
 2 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/desmume/src/NDSSystem.cpp b/desmume/src/NDSSystem.cpp
index 253e48dc6..3dc9f1047 100644
--- a/desmume/src/NDSSystem.cpp
+++ b/desmume/src/NDSSystem.cpp
@@ -545,24 +545,49 @@ void GameInfo::closeROM()
 
 u32 GameInfo::readROM(u32 pos)
 {
+	u32 num;
+	u32 data;
 	if (!romdata)
 	{
-		u32 data;
 		if (lastReadPos != pos)
 			fseek(fROM, pos + headerOffset, SEEK_SET);
-		u32 num = fread(&data, 1, 4, fROM);
+		num = fread(&data, 1, 4, fROM);
 		lastReadPos = (pos + num);
-		return LE_TO_LOCAL_32(data);
 	}
 	else
 	{
-		if(pos + 4 > romsize)
+		if(pos + 4 <= romsize)
 		{
-			printf("Panic! GameInfo reading out of buffer!\n");
-			exit(-1);
+			//fast path
+			data = LE_TO_LOCAL_32(*(u32*)(romdata + pos));
+			num = 4;
+		}
+		else
+		{
+			data = 0;
+			num = 0;
+			for(int i=0;i<4;i++)
+			{
+				if(pos >= romsize)
+					break;
+				data |= (romdata[pos]<<(i*8));
+				pos++;
+				num++;
+			}
 		}
-		return LE_TO_LOCAL_32(*(u32*)(romdata + pos));
 	}
+
+
+	//in case we didn't read enough data, pad the remainder with 0xFF
+	u32 pad = 0;
+	while(num<4)
+	{
+		pad >>= 8;
+		pad |= 0xFF000000;
+		num++;
+	}
+
+	return LE_TO_LOCAL_32(data) & ~pad | pad;
 }
 
 bool GameInfo::isDSiEnhanced()
diff --git a/desmume/src/addons/slot1comp_rom.cpp b/desmume/src/addons/slot1comp_rom.cpp
index e7139096b..aeb35c1e6 100644
--- a/desmume/src/addons/slot1comp_rom.cpp
+++ b/desmume/src/addons/slot1comp_rom.cpp
@@ -71,10 +71,10 @@ u32 Slot1Comp_Rom::read()
 			//if (address > gameInfo.header.endROMoffset)
 			//  ... the cart hardware doesnt know anything about the rom header. if it has a totally bogus endROMoffset, the cart will probably work just fine. and, the +4 is missing anyway:
 			//3. this is better: it just allows us to read 0xFF anywhere we dont have rom data. forget what the header says
+			//note: we allow the reading to proceed anyway, because the readROM method is built to allow jaggedy reads off the end of the rom to support trimmed roms
 			if(address+4 > gameInfo.romsize)
 			{
 				DEBUG_Notify.ReadBeyondEndOfCart(address,gameInfo.romsize);
-				return 0xFFFFFFFF;
 			}
 
 			//actually read from the ROM provider