1.1 --- a/clojure/com/aurellem/gb/mem_util.clj	Sun Apr 08 08:43:52 2012 -0500
     1.2 +++ b/clojure/com/aurellem/gb/mem_util.clj	Sun Apr 08 01:28:39 2012 -0500
     1.3 @@ -190,3 +190,43 @@
     1.4  
     1.5  (defn restore-rom! [] (write-rom! original-rom))
     1.6  
     1.7 +
     1.8 +(defn endian-flip
     1.9 +  "Flip the bytes of the two-byte number."
    1.10 +  [n]
    1.11 +  (assert (< n 0xFFFF))
    1.12 +  (+ (* 0x100 (rem n 0x100))
    1.13 +        (int (/ n 0x100))))
    1.14 +
    1.15 +
    1.16 +(defn offset->ptr
    1.17 +  "Convert an offset into a little-endian pointer."
    1.18 +  [n]
    1.19 +  (->
    1.20 +   n
    1.21 +   (rem 0x10000) ;; take last four bytes
    1.22 +   (rem 0x4000)   ;; get relative offset from the start of the bank
    1.23 +   (+ 0x4000)
    1.24 +   endian-flip))
    1.25 +
    1.26 +(defn offset->bank
    1.27 +  "Get the bank of the offset."
    1.28 +  [n]
    1.29 +  (int (/ n 0x4000)))
    1.30 +
    1.31 +(defn ptr->offset
    1.32 +  "Convert a two-byte little-endian pointer into an offset."
    1.33 +  [bank ptr]
    1.34 +  (->
    1.35 +   ptr
    1.36 +   endian-flip
    1.37 +   (- 0x4000)
    1.38 +   (+ (* 0x4000 bank))
    1.39 +   ))
    1.40 +
    1.41 +(defn same-bank-offset
    1.42 +  "Convert a ptr into an absolute offset by using the bank of the reference."
    1.43 +  [reference ptr]
    1.44 +  (ptr->offset
    1.45 +   (offset->bank reference)
    1.46 +   ptr))
    1.47 \ No newline at end of file