Get Tile Data Pointer
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# ROUTINE: GET TILE DATA POINTER
# Parameters:
# r4 = X Coordinate
# r5 = Y Coordinate
# r6 = Higher Elevation bit
# Returns:
# r2 = Pointer to Tile Data for specified coordinates
00183fb4: 3c07800e lui r7,0x800e
00183fb8: 90e74e9c lbu r7,0x4e9c(r7) # Map Max X Coordinate
00183fbc: 3c03800e lui r3,0x800e
00183fc0: 90634ea0 lbu r3,0x4ea0(r3) # Map Max Y Coordinate
00183fc4: 04800009 bltz r4,0x00183fec # if ((X Coordinate < 0)
00183fc8: 0087102a slt r2,r4,r7
00183fcc: 10400007 beq r2,r0,0x00183fec # or (X Coordinate >= Map Max X Coordinate)
00183fd0: 00000000 nop
00183fd4: 04a00005 bltz r5,0x00183fec # or (Y Coordinate < 0)
00183fd8: 00a3102a slt r2,r5,r3
00183fdc: 10400003 beq r2,r0,0x00183fec # or (Y Coordiante >= Map Max Y Coordinate)
00183fe0: 2cc20002 sltiu r2,r6,0x0002
00183fe4: 14400003 bne r2,r0,0x00183ff4 # or (Higher Elevation bit >= 2)
00183fe8: 00a70018 mult r5,r7
# ) {
00183fec: 08061005 j 0x00184014 Return 0 (null)
00183ff0: 00001021 addu r2,r0,r0
# }
00183ff4: 00061200 sll r2,r6,0x08 # [Higher Elevation bit] * 256
00183ff8: 00001812 mflo r3 # (Y Coordinate * Map Max X Coordinate)
00183ffc: 00431021 addu r2,r2,r3 # [Higher Elevation bit] * 256 + (Y Coordinate * Map Max X Coordinate)
00184000: 00441021 addu r2,r2,r4 # [Higher Elevation bit] * 256 + (Y Coordinate * Map Max X Coordinate) + X Coordinate
00184004: 000210c0 sll r2,r2,0x03 # Offset for tile at coordinates: ([Higher Elevation bit] * 256 + (Y Coordinate * Map Max X Coordinate) + X Coordinate) * 8
00184008: 3c038019 lui r3,0x8019
0018400c: 2463f8cc addiu r3,r3,-0x0734 # Tile data base pointer (0x8018f8cc)
00184010: 00431021 addu r2,r2,r3 # Pointer to Tile data for this tile
00184014: 03e00008 jr r31 # Return Tile data pointer
00184018: 00000000 nop
