1 files changed, 24 insertions, 0 deletions

diff --git a/src/core/file_sys/fssystem/fssystem_utility.cpp b/src/core/file_sys/fssystem/fssystem_utility.cpp
new file mode 100644
index 000000000..4dddfd75a
--- /dev/null
+++ b/src/core/file_sys/fssystem/fssystem_utility.cpp
@@ -0,0 +1,24 @@
+#include "core/file_sys/fssystem/fssystem_utility.h"
+
+namespace FileSys {
+
+void AddCounter(void* counter_, size_t counter_size, u64 value) {
+    u8* counter = static_cast<u8*>(counter_);
+    u64 remaining = value;
+    u8 carry = 0;
+
+    for (size_t i = 0; i < counter_size; i++) {
+        auto sum = counter[counter_size - 1 - i] + (remaining & 0xFF) + carry;
+        carry = static_cast<u8>(sum >> (sizeof(u8) * 8));
+        auto sum8 = static_cast<u8>(sum & 0xFF);
+
+        counter[counter_size - 1 - i] = sum8;
+
+        remaining >>= (sizeof(u8) * 8);
+        if (carry == 0 && remaining == 0) {
+            break;
+        }
+    }
+}
+
+} // namespace FileSys