Cleanup for PR, return old sprite tracker

source/pool.c

@@ -1,11 +1,18 @@
 #include "pool.h"
+#include "util.h"
 
 void pool_bm_clear_idx(PoolBitmap *bm, int idx)
 {
     // Divide by 32 to get the word index
-    uint32_t i = idx >> 5;
+    uint32_t i = idx / 32;
     // Get last 5-bits, same as a modulo (% 32) operation on positive numbers
-    uint32_t b = idx & 0x1F;
+    uint32_t b = idx % 32;
+
+    // Below are the "fast" forms of the above operations, respectively.
+    // These are more efficient, but removed for readability
+    // See: https://github.com/cellos51/balatro-gba/pull/132#discussion_r2365966071
+    //uint32_t i = idx >> 5;
+    //uint32_t b = idx & 0x1F;
     bm->w[i] &= ~((uint32_t)1 << b);
 }
 
@@ -32,7 +39,7 @@ int pool_bm_get_free_idx(PoolBitmap *bm)
         }
     }
 
-    return -1;
+    return UNDEFINED;
 }