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clarify chipId checks and fake booting

This commit is contained in:
zeromus 2013-08-31 18:51:09 +00:00
parent dd56e6c231
commit 4baad291dc
2 changed files with 12 additions and 18 deletions
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20
desmume/src/NDSSystem.cpp
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@ -2647,7 +2647,7 @@ void NDS_Reset()
_MMU_write08<ARMCPU_ARM9>(0x027FFC80 + fw_index, temp_buffer[fw_index]); _MMU_write08<ARMCPU_ARM9>(0x027FFC80 + fw_index, temp_buffer[fw_index]);
} }
//firmware copies the whole header to Main RAM 0x27FFE00 on startup. (http://nocash.emubase.de/gbatek.htm#dscartridgeheader) //something copies the whole header to Main RAM 0x27FFE00 on startup. (http://nocash.emubase.de/gbatek.htm#dscartridgeheader)
//once upon a time this copied 0x90 more. this was thought to be wrong, and changed. //once upon a time this copied 0x90 more. this was thought to be wrong, and changed.
if(nds.Is_DSI()) if(nds.Is_DSI())
{ {
@ -2669,20 +2669,18 @@ void NDS_Reset()
MMU.ARM9_REG[0x300] = 1; MMU.ARM9_REG[0x300] = 1;
MMU.ARM7_REG[0x300] = 1; MMU.ARM7_REG[0x300] = 1;
//firmware makes system think it's booted from card -- EXTREMELY IMPORTANT!!! Thanks to cReDiAr //firmware makes system think it's booted from card -- EXTREMELY IMPORTANT!!! This is actually checked by some things. (which things?) Thanks to cReDiAr
_MMU_write08<ARMCPU_ARM9>(0x02FFFC40,0x1); _MMU_write08<ARMCPU_ARM7>(0x02FFFC40,0x1); //<zero> removed redundant write to ARM9, this is going to shared main memory. But one has to wonder why r3478 was made which corrected a typo resulting in only ARMCPU_ARM7 getting used.
_MMU_write08<ARMCPU_ARM7>(0x02FFFC40,0x1);
//the chipId is read several times
//for some reason, each of those reads get stored here.
_MMU_write32<ARMCPU_ARM7>(0x027FF800, gameInfo.chipID); //1st chipId
_MMU_write32<ARMCPU_ARM7>(0x027FF804, gameInfo.chipID); //2nd (secure) chipId
_MMU_write32<ARMCPU_ARM7>(0x027FFC00, gameInfo.chipID); //3rd (secure) chipId
//
_MMU_write32<ARMCPU_ARM7>(0x027FF800, gameInfo.chipID); // Chip ID
_MMU_write32<ARMCPU_ARM7>(0x027FF804, gameInfo.chipID); // Secure Chip ID
_MMU_write32<ARMCPU_ARM7>(0x027FFC00, gameInfo.chipID); // 2nd Secure Chip ID
// Write the header checksum to memory // Write the header checksum to memory
_MMU_write16<ARMCPU_ARM9>(0x027FF808, gameInfo.header.headerCRC16); _MMU_write16<ARMCPU_ARM9>(0x027FF808, gameInfo.header.headerCRC16);
// Write the header checksum to memory (the firmware needs it to see the cart)
//_MMU_write16<ARMCPU_ARM9>(0x027FF808, T1ReadWord(MMU.CART_ROM, 0x15E));
// Save touchscreen calibration info in a structure // Save touchscreen calibration info in a structure
// so we can easily access it at any time // so we can easily access it at any time
// TODO - this isn't good. need revising. // TODO - this isn't good. need revising.

10
desmume/src/addons/slot1comp_protocol.cpp
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@ -209,13 +209,9 @@ u32 Slot1Comp_Protocol::read_GCDATAIN(u8 PROCNUM)
case eSlot1Operation_90_ChipID: case eSlot1Operation_90_ChipID:
case eSlot1Operation_B8_ChipID: case eSlot1Operation_B8_ChipID:
// Note: the BIOS stores the chip ID in main memory
// Most games continuously compare the chip ID with //Most games continuously compare the current chipId with the value in
// the value in memory, probably to know if the card //stored in memory at boot-up, probably to know if the card was removed.
// was removed.
// As DeSmuME normally boots directly from the game, the chip
// ID in main mem is zero and this value needs to be
// zero too.
//staff of kings verifies this (it also uses the arm7 IRQ 20 to detect card ejects) //staff of kings verifies this (it also uses the arm7 IRQ 20 to detect card ejects)
return chipId; return chipId;