From 3a7c7432ca31bd9e152f36d15edd6866dffd4f82 Mon Sep 17 00:00:00 2001
From: d0k3 <tore.anon@gmail.com>
Date: Wed, 18 Apr 2018 01:24:27 +0200
Subject: [PATCH] Always read CTR carts in 1MB chunks

This fixes #346
---
 arm9/source/gamecart/gamecart.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/arm9/source/gamecart/gamecart.c b/arm9/source/gamecart/gamecart.c
index 24bc5e0..ce13912 100644
--- a/arm9/source/gamecart/gamecart.c
+++ b/arm9/source/gamecart/gamecart.c
@@ -140,9 +140,15 @@ u32 ReadCartSectors(void* buffer, u32 sector, u32 count, CartData* cdata) {
     if (!count) return 0;
     // actual cart reads
     if (cdata->cart_type & CART_CTR) {
-        Cart_Dummy();
-        Cart_Dummy();
-        CTR_CmdReadData(sector, 0x200, count, buffer8);
+        // don't read more than 1MB at once
+        const u32 max_read = 0x800;
+        u8* buff = buffer8;
+        for (u32 i = 0; i < count; i += max_read) {
+            Cart_Dummy();
+            Cart_Dummy();
+            CTR_CmdReadData(sector + i, 0x200, min(max_read, count - i), buff);
+            buff += max_read * 0x200;
+        }
         // overwrite the card2 savegame with 0xFF
         u32 card2_offset = getle32(cdata->header + 0x200);
         if ((card2_offset != 0xFFFFFFFF) &&