rename rng.c to random.c and rom4.c to overworld.c

src/random.c

@@ -0,0 +1,32 @@
+#include "global.h"
+#include "random.h"
+
+// The number 1103515245 comes from the example implementation of rand and srand
+// in the ISO C standard.
+
+EWRAM_DATA static u8 sUnknown = 0;
+EWRAM_DATA static u32 sRandCount = 0;
+
+u16 Random(void)
+{
+    gRngValue = 1103515245 * gRngValue + 24691;
+    sRandCount++;
+    return gRngValue >> 16;
+}
+
+void SeedRng(u16 seed)
+{
+    gRngValue = seed;
+    sUnknown = 0;
+}
+
+void SeedRng2(u16 seed)
+{
+    gRng2Value = seed;
+}
+
+u16 Random2(void)
+{
+    gRng2Value = 1103515245 * gRng2Value + 24691;
+    return gRng2Value >> 16;
+}