diff --git a/src/gba/input.c b/src/gba/input.c
index 65cf7a650..14372bb68 100644
--- a/src/gba/input.c
+++ b/src/gba/input.c
@@ -348,6 +348,20 @@ enum GBAKey GBAInputMapKey(const struct GBAInputMap* map, uint32_t type, int key
 	return GBA_KEY_NONE;
 }
 
+int GBAInputMapKeyBits(const struct GBAInputMap* map, uint32_t type, uint32_t bits, unsigned offset) {
+	int keys = 0;
+	for (; bits; bits >>= 1, ++offset) {
+		if (bits & 1) {
+			enum GBAKey key = GBAInputMapKey(map, type, offset);
+			if (key == GBA_KEY_NONE) {
+				continue;
+			}
+			keys |= 1 << key;
+		}
+	}
+	return keys;
+}
+
 void GBAInputBindKey(struct GBAInputMap* map, uint32_t type, int key, enum GBAKey input) {
 	struct GBAInputMapImpl* impl = _guaranteeMap(map, type);
 	GBAInputUnbindKey(map, type, input);
diff --git a/src/gba/input.h b/src/gba/input.h
index 8610b6f24..04daba364 100644
--- a/src/gba/input.h
+++ b/src/gba/input.h
@@ -30,6 +30,7 @@ void GBAInputMapInit(struct GBAInputMap*);
 void GBAInputMapDeinit(struct GBAInputMap*);
 
 enum GBAKey GBAInputMapKey(const struct GBAInputMap*, uint32_t type, int key);
+int GBAInputMapKeyBits(const struct GBAInputMap* map, uint32_t type, uint32_t bits, unsigned offset);
 void GBAInputBindKey(struct GBAInputMap*, uint32_t type, int key, enum GBAKey input);
 void GBAInputUnbindKey(struct GBAInputMap*, uint32_t type, enum GBAKey input);
 int GBAInputQueryBinding(const struct GBAInputMap*, uint32_t type, enum GBAKey input);