See if elemental ability can be used

See if elemental ability can be used

0019b754: 90830002 lbu r3,0x0002(r4)
0019b758: 3c02801a lui r2,0x801a
0019b75c: 904201fe lbu r2,0x01fe(r2)
0019b760: 00000000 nop
0019b764: 00620018 mult r3,r2
0019b768: 90820001 lbu r2,0x0001(r4)
0019b76c: 90840000 lbu r4,0x0000(r4)
0019b770: 00021200 sll r2,r2,0x08
0019b774: 00001812 mflo r3
0019b778: 00431021 addu r2,r2,r3
0019b77c: 00441021 addu r2,r2,r4
0019b780: 000210c0 sll r2,r2,0x03
0019b784: 3c018019 lui r1,0x8019
0019b788: 00220821 addu r1,r1,r2
0019b78c: 9022f8cc lbu r2,-0x0734(r1)              
0019b790: 3c03801a lui r3,0x801a
0019b794: 8463f3c6 lh r3,-0x0c3a(r3)                     load ability ID
0019b798: 3042003f andi r2,r2,0x003f
0019b79c: 3c018006 lui r1,0x8006
0019b7a0: 00220821 addu r1,r1,r2
0019b7a4: 9022e9d0 lbu r2,-0x1630(r1)                load ability ID for terrain type
0019b7a8: 00000000 nop
0019b7ac: 00431026 xor r2,r2,r3                         r2 = 0 if they're different
0019b7b0: 03e00008 jr r31
0019b7b4: 2c420001 sltiu r2,r2,0x0001                r2 = 1 if usable