Select Random Tile For Random Fire Abilities
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0017d708 - 0017d84c This routine select a random tile among Tiles which have their "green panel" flag at byte [0x05] Rq : the 1st loop is a bit odd, using the targetable panels 0x01 byte to host Tile ID value (not matching the panel ID) ------------------------------------------------------------------------------------------------------------------------------- 0017d708: 27bdffe0 addiu r29,r29,-0x0020 | 0017d70c: afb00010 sw r16,0x0010(r29) | 0017d710: 00008021 addu r16,r0,r0 |r16 = 0x00 green panel counter 0017d714: 00002821 addu r5,r0,r0 |r5 = 0x00 0017d718: 34090100 ori r9,r0,0x0100 |r9 = 0x100 0017d71c: 3c088019 lui r8,0x8019 |r8 = 0x80190000 0017d720: 25082dd8 addiu r8,r8,0x2dd8 |r8 = Targetable grid data pointer 0x80192dd8 0017d724: 3c068019 lui r6,0x8019 |r6 = 0x8019 0017d728: 24c6f8cc addiu r6,r6,-0x0734 |r6 = Tile data pointer 0x8018f8cc 0017d72c: 00003821 addu r7,r0,r0 |r7 = 0x00 (Targetable panel data counter) 0017d730: afbf0018 sw r31,0x0018(r29) | 0017d734: afb10014 sw r17,0x0014(r29) | 0017d738: 14a90002 bne r5,r9,0x0017d744 @ LOOP #If This iteration Tile is 0x100 Loop though all tiles 0017d73c: 00000000 nop | 0017d740: 02008821 addu r17,r16,r0 |r17 = green panel counter, low elevation tiles only 0017d744: 90c40005 lbu r4,0x0005(r6) |r4 = This iteration Tile [0x05] 0017d748: 00000000 nop | 0017d74c: 30820080 andi r2,r4,0x0080 |r2 = 0x80 if this Tile has "green panel" flag ON 0017d750: 10400006 beq r2,r0,0x0017d76c #If This Tile has green panel 0017d754: 00e81821 addu r3,r7,r8 |r3 = Targetable panel data pointer 0017d758: 24e70005 addiu r7,r7,0x0005 |r7 = Targetable panel counter + 0x05 (size of panel data) not every iteration panel and tile do not match !! It's using panels 0x01 as a stack pointer 0017d75c: 26100001 addiu r16,r16,0x0001 |r16 = green panel counter + 1 0017d760: 3082007f andi r2,r4,0x007f |r2 = r4 without "green panel" flag 0017d764: a0c20005 sb r2,0x0005(r6) |Update this Tile [0x05] without "green panel" flag 0017d768: a0650001 sb r5,0x0001(r3) |Store loop counter (TIle ID) on Panel [0x01] byte 0017d76c: 24a50001 addiu r5,r5,0x0001 |r5 = loop counter + 1 0017d770: 28a20200 slti r2,r5,0x0200 |r2 = 0x01 if counter < 0x200 0017d774: 1440fff0 bne r2,r0,0x0017d738 Λ loop while counter < 0x200 0017d778: 24c60008 addiu r6,r6,0x0008 |r6 = Tile data pointer + 0x08 0017d77c: 0c0088c3 jal 0x0002230c |-->Random_Number_Generator return r2 = random halfword (0 to 0x7fff) 0017d780: 00000000 nop | 0017d784: 00500018 mult r2,r16 |Random * green panel counter 0017d788: 00001812 mflo r3 |r3 = Random * green panel counter 0017d78c: 04610002 bgez r3,0x0017d798 #If r3 < 0x00 (random number was < 0x00) never true 0017d790: 00000000 nop | 0017d794: 24637fff addiu r3,r3,0x7fff |r3 = random positive (security ?) 0017d798: 00031bc3 sra r3,r3,0x0f |r3 = random from 0x00 to green panel counter = random panel 0017d79c: 00031080 sll r2,r3,0x02 |r2 = random panel * 4 0017d7a0: 00431021 addu r2,r2,r3 |r2 = random panel * 5 (panel offset) 0017d7a4: 3c018019 lui r1,0x8019 |r1 = 0x80190000 0017d7a8: 00220821 addu r1,r1,r2 |r1 = 0x80190000 + random panel offset 0017d7ac: 90242dd9 lbu r4,0x2dd9(r1) |r4 = Random panel [0x01] byte (hold loop counter value which is tile ID) 0x80192dd8 + 0x01 0017d7b0: 0071182a slt r3,r3,r17 |r3 = 0x01 if random panel is low elevation 0017d7b4: 14600003 bne r3,r0,0x0017d7c4 #If random panel is on high elevation 0017d7b8: 000410c0 sll r2,r4,0x03 |r2 = Random Tile ID * 8 0017d7bc: 24840100 addiu r4,r4,0x0100 |r4 = Random Tile ID + higher elevation offset 0017d7c0: 000410c0 sll r2,r4,0x03 |r2 = Random Higher Tile ID * 8 0017d7c4: 3c018019 lui r1,0x8019 |r1 = 0x80190000 0017d7c8: 00220821 addu r1,r1,r2 |r1 = 0x80190000 + Random tile offset 0017d7cc: 9023f8d1 lbu r3,-0x072f(r1) |r3 = Random Tile byte [0x05] value 0x8018f8cc + 0x05 0017d7d0: 00000000 nop | 0017d7d4: 34630080 ori r3,r3,0x0080 |r3 = Random Tile [0x05] + green panel flag 0017d7d8: 3c018019 lui r1,0x8019 |r1 = 0x80190000 0017d7dc: 00220821 addu r1,r1,r2 |r1 = 0x80190000 + Random tile offset 0017d7e0: a023f8d1 sb r3,-0x072f(r1) |Store random tile [0x05] byte updated with green panel flag (0x80) 0017d7e4: 34020001 ori r2,r0,0x0001 |r2 = 0x01 0017d7e8: 3c018019 lui r1,0x8019 |r1 = 0x80190000 0017d7ec: a022390f sb r2,0x390f(r1) |Store 0x01 at 0x8019390f 8019390f 0017d7f0: 04810002 bgez r4,0x0017d7fc #If random Tile ID <0x00 ??? 0017d7f4: 00802821 addu r5,r4,r0 |r5 = random tile ID 0017d7f8: 248500ff addiu r5,r4,0x00ff |r5 = random tile ID + 0x00ff 0017d7fc: 3c03800e lui r3,0x800e |r3 = 0x800e 0017d800: 90634e9c lbu r3,0x4e9c(r3) |r3 = Map Max X 0017d804: 308200ff andi r2,r4,0x00ff |r2 = low elevation Tile ID 0017d808: 0043001a div r2,r3 |low elevation ID / map Max X 0017d80c: 00001012 mflo r2 |r2 = Random Tile Y coord 0017d810: 00002010 mfhi r4 |r4 = Random Tile X coord (division reminder - Tile ID is X + Y*MaxX) 0017d814: 00051a03 sra r3,r5,0x08 |r3 = Random Tile / 0x100 = 0x01 if Random Tile is high elevation (ID >= 0x100) 0017d818: 3c018019 lui r1,0x8019 | 0017d81c: a02338cc sb r3,0x38cc(r1) |Store Random Tile elevation to Target New elevation (0x801938cc) 801938cc 0017d820: 3c018019 lui r1,0x8019 | 0017d824: a02238cb sb r2,0x38cb(r1) |Store Random Tile Y to Target New Y (0x801938cb) 801938cb 0017d828: 3c018019 lui r1,0x8019 | 0017d82c: a02438ca sb r4,0x38ca(r1) |Store Random Tile X to Target New X (0x801938ca) 801938ca 0017d830: 0c05e500 jal 0x00179400 |-->Null_some_Tile_Data_(192dd9) Nullify all targetable panels 0x01 byte 0017d834: 00000000 nop 0017d838: 8fbf0018 lw r31,0x0018(r29) 0017d83c: 8fb10014 lw r17,0x0014(r29) 0017d840: 8fb00010 lw r16,0x0010(r29) 0017d844: 27bd0020 addiu r29,r29,0x0020 0017d848: 03e00008 jr r31 0017d84c: 00000000 nop
Returns location
Battle.bin 0017ce28: Map_calculations_for_attack
