Add support for almost all Gen III games

The only Gen III game unsupported should be Pokémon LeafGreen v1.1
(Japan); as it is undumped.

A couple of bugs have also been fixed.

The code has also been refactored a little; now payload code goes into
`payload.c`. The codebase is also ready for a planned future change to
include savedata structure definitions. This will be done when it's done
-- PRs to help would be appreciated!

1 files changed, 236 insertions, 14 deletions

@@ -1,42 +1,264 @@
 /*
  * Example Gen3-multiboot payload by slipstream/RoL 2017.
- * Supports only English Ruby, v1.0-1.2.
  *
  * This software may be modified and distributed under the terms
  * of the MIT license.  See the LICENSE file for details.
+ *
+ * main.c: setup, call payload, return gracefully back to game
  */
 #include <gba.h>
+#include "payload.h"
+
+void call_into_middle_of_titlescreen_func(u32 addr,u32 stackspace);
 
 int main(void) {
         // check the ROM code, make sure this game is supported.
-        char* ROM = 0x8000000;
+        u8* ROM = (u8*) 0x8000000;
         
-        if ((*(u32*)(&ROM[0xAC])) != 'EVXA') return 0; // Pokémon Ruby english, nothing else supported!
+        u32 gamecode = (*(u32*)(&ROM[0xAC]));
         
         void(*loadsave)(char a1);
+        void(*mainloop)();
+        pSaveBlock1 gSaveBlock1;
+        pSaveBlock2 gSaveBlock2;
+        pSaveBlock3 gSaveBlock3;
+        u32 titlemid = 0;
         // get the address of the save loading function.
-        switch (ROM[0xBC]) { // version number
-                case 0:
-                        loadsave = 0x8125EC9;
+        switch (gamecode) {
+                // --- R/S ---
+                case 'DVXA': // Ruby German
+                case 'DPXA': // Sapphire German
+                        // TODO: detect debug ROM?
+                        gSaveBlock1 = (pSaveBlock1) 0x2025734;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024EA4;
+                        gSaveBlock3 = (pSaveBlock3) 0x20300A0;
+                        loadsave = (void(*)(char)) 0x8126249; // same for v1.0 + v1.1
+                        mainloop = (void(*)()) 0x80003D9;
+                        break;
+                case 'FVXA': // Ruby French
+                case 'FPXA': // Sapphire French
+                        gSaveBlock1 = (pSaveBlock1) 0x2025734;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024EA4;
+                        gSaveBlock3 = (pSaveBlock3) 0x20300A0;
+                        loadsave = (void(*)(char)) 0x8126351; // same for v1.0 + v1.1
+                        mainloop = (void(*)()) 0x80003D9;
+                        break;
+                case 'IVXA': // Ruby Italian
+                case 'IPXA': // Sapphire Italian
+                        gSaveBlock1 = (pSaveBlock1) 0x2025734;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024EA4;
+                        gSaveBlock3 = (pSaveBlock3) 0x20300A0;
+                        loadsave = (void(*)(char)) 0x8126249; // same for v1.0 + v1.1
+                        mainloop = (void(*)()) 0x80003D9;
+                        break;
+                case 'SVXA': // Ruby Spanish
+                case 'SPXA': // Sapphire Spanish
+                        gSaveBlock1 = (pSaveBlock1) 0x2025734;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024EA4;
+                        gSaveBlock3 = (pSaveBlock3) 0x20300A0;
+                        loadsave = (void(*)(char)) 0x8126349; // same for v1.0 + v1.1
+                        mainloop = (void(*)()) 0x80003D9;
+                        break;
+                case 'EVXA': // Ruby English
+                case 'EPXA': // Sapphire English
+                        gSaveBlock1 = (pSaveBlock1) 0x2025734;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024EA4;
+                        gSaveBlock3 = (pSaveBlock3) 0x20300A0;
+                        mainloop = (void(*)()) 0x80002A5;
+                        switch (ROM[0xBC]) { // version number
+                                case 0:
+                                        loadsave = (void(*)(char)) 0x8125EC9;
+                                        break;
+                                case 1:
+                                case 2:
+                                        loadsave = (void(*)(char)) 0x8125EE9;
+                                        break;
+                                default:
+                                        return 0; // unsupported version
+                        }
+                        break;
+                case 'JVXA': // Ruby Japanese
+                case 'JPXA': // Sapphire Japanese
+                        gSaveBlock1 = (pSaveBlock1) 0x2025494;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024C04;
+                        gSaveBlock3 = (pSaveBlock3) 0x202FDBC;
+                        loadsave = (void(*)(char)) 0x8120d05; // same for v1.0 + v1.1
+                        mainloop = (void(*)()) 0x80002A9;
+                        break;
+                /// --- FR/LG ---
+                // In FR/LG, the function that initialises the save-block pointers to default does not set up saveblock3.
+                // Which will need to be set up before loading the save if we want boxed Pokémon to not disappear.
+                // Oh, and loadsave() offset is different between FR and LG...
+                case 'DRPB': // FireRed German
+                case 'DGPB': // LeafGreen German
+                        gSaveBlock1 = (pSaveBlock1) 0x202552C;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024588;
+                        gSaveBlock3 = (pSaveBlock3) 0x2029314;
+                        *(pSaveBlock3*)(0x3004f60) = gSaveBlock3;
+                        loadsave = (void(*)(char)) ( (gamecode << 8) == 'RPB\x00' ? 0x80da721 : 0x80da6f5 );
+                        mainloop = (void(*)()) 0x8000425;
+                        titlemid = 0x80791df;
+                        break;
+                case 'FRPB': // FireRed French
+                case 'FGPB': // LeafGreen French
+                        gSaveBlock1 = (pSaveBlock1) 0x202552C;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024588;
+                        gSaveBlock3 = (pSaveBlock3) 0x2029314;
+                        *(pSaveBlock3*)(0x3004f60) = gSaveBlock3;
+                        loadsave = (void(*)(char)) ( (gamecode << 8) == 'RPB\x00' ? 0x80da7e1 : 0x80da7b5 );
+                        mainloop = (void(*)()) 0x8000417;
+                        titlemid = 0x807929f;
+                        break;
+                case 'IRPB': // FireRed Italian
+                case 'IGPB': // LeafGreen Italian
+                        gSaveBlock1 = (pSaveBlock1) 0x202552C;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024588;
+                        gSaveBlock3 = (pSaveBlock3) 0x2029314;
+                        *(pSaveBlock3*)(0x3004f60) = gSaveBlock3;
+                        loadsave = (void(*)(char)) ( (gamecode << 8) == 'RPB\x00' ? 0x80da721 : 0x80da6f5 );
+                        mainloop = (void(*)()) 0x8000425;
+                        titlemid = 0x80791cb;
                         break;
-                case 1:
-                case 2:
-                        loadsave = 0x8125EE9;
+                case 'SRPB': // FireRed Spanish
+                case 'SGPB': // LeafGreen Spanish
+                        gSaveBlock1 = (pSaveBlock1) 0x202552C;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024588;
+                        gSaveBlock3 = (pSaveBlock3) 0x2029314;
+                        *(pSaveBlock3*)(0x3004f60) = gSaveBlock3;
+                        loadsave = (void(*)(char)) ( (gamecode << 8) == 'RPB\x00' ? 0x80da809 : 0x80da7dd );
+                        mainloop = (void(*)()) 0x8000417;
+                        titlemid = 0x80792b3;
+                        break;
+                case 'ERPB': // FireRed English
+                case 'EGPB': // LeafGreen English
+                        gSaveBlock1 = (pSaveBlock1) 0x202552C;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024588;
+                        gSaveBlock3 = (pSaveBlock3) 0x2029314;
+                        *(pSaveBlock3*)(0x3005010) = gSaveBlock3;
+                        switch (ROM[0xBC]) { // version number
+                                case 0:
+                                        loadsave = (void(*)(char)) ( (gamecode << 8) == 'RPB\x00' ? 0x80da4fd : 0x80da4d1 );
+                                        mainloop = (void(*)()) 0x800041b;
+                                        titlemid = 0x807927b;
+                                        break;
+                                case 1:
+                                        loadsave = (void(*)(char)) ( (gamecode << 8) == 'RPB\x00' ? 0x80da511 : 0x80da4e5 );
+                                        mainloop = (void(*)()) 0x8000429;
+                                        titlemid = 0x807928f;
+                                        break;
+                                default:
+                                        return 0; // unsupported version
+                        }
+                        break;
+                case 'JRPB': // FireRed Japanese
+                case 'JGPB': // LeafGreen Japanese
+                        gSaveBlock1 = (pSaveBlock1) 0x202548C;
+                        gSaveBlock2 = (pSaveBlock2) 0x20244E8;
+                        gSaveBlock3 = (pSaveBlock3) 0x202924C;
+                        *(pSaveBlock3*)(0x3005050) = gSaveBlock3;
+                        switch (ROM[0xBC]) { // version number
+                                case 0:
+                                        loadsave = (void(*)(char)) ( (gamecode << 8) == 'RPB\x00' ? 0x80db4e5 : 0x80db4b9 );
+                                        mainloop = (void(*)()) 0x800041b;
+                                        titlemid = ( (gamecode << 8) == 'RPB\x00' ? 0x8078a0d : 0x8078a0f );
+                                        break;
+                                case 1:
+                                        if ((gamecode << 8) == 'GPB\x00') {
+                                                // LeafGreen v1.1 Japanese is undumped.
+                                                // Therefore, it is unsupported.
+                                                // I will make guesses at the offsets in the comments, but I will not actually implement them until LeafGreen v1.1 is dumped.
+                                                return 0;
+                                        }
+                                        loadsave = (void(*)(char)) 0x80db529; // potential LG1.1 address: 0x80db4fd
+                                        mainloop = (void(*)()) 0x8000417;
+                                        titlemid = 0x8078987; // potential LG1.1 address: 0x8078989
+                                        break;
+                                default:
+                                        return 0; // unsupported version
+                        }
+                        break;
+                /// --- Emerald ---
+                // In Emerald, the saveblock pointer that isn't set up is saveblock1 (in FR/LG it was saveblock3).
+                // The initial save loading code after the copyright screen is also updated, now it sets up ASLR/crypto here before loading the save.
+                case 'DEPB': // Emerald German
+                        gSaveBlock1 = (pSaveBlock1) 0x2025A00;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024A54;
+                        gSaveBlock3 = (pSaveBlock3) 0x2029808;
+                        *(pSaveBlock1*)(0x3005d8c) = gSaveBlock1;
+                        loadsave = (void(*)(char)) 0x8153075;
+                        mainloop = (void(*)()) 0x800042b;
+                        titlemid = 0x816fdb5;
+                        break;
+                case 'FEPB': // Emerald French
+                        gSaveBlock1 = (pSaveBlock1) 0x2025A00;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024A54;
+                        gSaveBlock3 = (pSaveBlock3) 0x2029808;
+                        *(pSaveBlock1*)(0x3005d8c) = gSaveBlock1;
+                        loadsave = (void(*)(char)) 0x815319d;
+                        mainloop = (void(*)()) 0x800042b;
+                        titlemid = 0x816fedd;
+                        break;
+                case 'IEPB': // Emerald Italian
+                        gSaveBlock1 = (pSaveBlock1) 0x2025A00;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024A54;
+                        gSaveBlock3 = (pSaveBlock3) 0x2029808;
+                        *(pSaveBlock1*)(0x3005d8c) = gSaveBlock1;
+                        loadsave = (void(*)(char)) 0x8153065;
+                        mainloop = (void(*)()) 0x800042b;
+                        titlemid = 0x816fda5;
+                        break;
+                case 'SEPB': // Emerald Spanish
+                        gSaveBlock1 = (pSaveBlock1) 0x2025A00;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024A54;
+                        gSaveBlock3 = (pSaveBlock3) 0x2029808;
+                        *(pSaveBlock1*)(0x3005d8c) = gSaveBlock1;
+                        loadsave = (void(*)(char)) 0x8153175;
+                        mainloop = (void(*)()) 0x800042b;
+                        titlemid = 0x816feb5;
+                        break;
+                case 'EEPB': // Emerald English
+                        gSaveBlock1 = (pSaveBlock1) 0x2025A00;
+                        gSaveBlock2 = (pSaveBlock2) 0x2024A54;
+                        gSaveBlock3 = (pSaveBlock3) 0x2029808;
+                        *(pSaveBlock1*)(0x3005d8c) = gSaveBlock1;
+                        loadsave = (void(*)(char)) 0x81534d1;
+                        mainloop = (void(*)()) 0x800042b;
+                        titlemid = 0x817014d;
+                        break;
+                case 'JEPB': // Emerald Japanese
+                        gSaveBlock1 = (pSaveBlock1) 0x20256A4;
+                        gSaveBlock2 = (pSaveBlock2) 0x20246F8;
+                        gSaveBlock3 = (pSaveBlock3) 0x20294AC;
+                        *(pSaveBlock1*)(0x3005aec) = gSaveBlock1;
+                        loadsave = (void(*)(char)) 0x815340d;
+                        mainloop = (void(*)()) 0x800042b;
+                        titlemid = 0x816ff45;
                         break;
                 default:
-                        return 0; //bail out
+                        return 0; // this game isn't supported
         }
         loadsave(0);
         // now the save is loaded, we can do what we want with the loaded blocks.
-        // here as a small PoC, changing first letter of player name to 'z'.
-        u8* gSaveBlock2 = 0x2024EA4;
-        gSaveBlock2[0] = 0xee; // 'z'
+        // time to call the payload.
+        payload(gSaveBlock1,gSaveBlock2,gSaveBlock3);
+        // In FR/LG/Emerald, just returning to the game is unwise.
+        // The game reloads the savefile.
+        // In FR/LG, this is done at the title screen after setting ASLR/saveblock-crypto up. (probably because at initial save-load, SaveBlock3 ptr isn't set up lol)
+        // So, better bypass the title screen and get the game to return directly to the Continue/New Game screen.
+        // In Emerald, the save reload happens after the Continue option was chosen, so we have no choice but to bypass everything and get the game to go straight to the overworld.
+        // Easiest way to do this is to call into the middle of the function we want, using an ASM wrapper to set up the stack.
+        // Here goes...
+        if (titlemid) {
+                // Function reserves an extra 4 bytes of stack space in FireRed, and none in Emerald.
+                call_into_middle_of_titlescreen_func(titlemid,((gamecode << 8) == 'EPB\x00' ? 0 : 4));
+        }
         // Now we've done what we want, time to return to the game.
         // Can't just return, the game will reload the save.
         // So let's just call the main-loop directly ;)
-        void(*mainloop)() = 0x80002A5;
         // turn the sound back on before we head back to the game
         *(vu16 *)(REG_BASE + 0x84) = 0x8f;
+        // re-enable interrupts
+        REG_IME = 1;
         mainloop();
         // Anything past here will not be executed.
         return 0;