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fix bug where save size could be detected incorrectly, if multiple bytes in the save are identical #48

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fix bug where save size could be detected incorrectly, if multiple bytes in the save are identical #48

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2479054
Fix bug where the save size could be detected incorrectly, if multipl…
Peter0x44 May 20, 2021
ecc70c6
Properly handle 128k size saves
Peter0x44 May 20, 2021
f548395
Use safer EEPROM size check, with no risk of false positive results
Peter0x44 Jun 18, 2021
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49 changes: 36 additions & 13 deletions source/common/cardEeprom.c
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Original file line number Diff line number Diff line change
Expand Up @@ -69,7 +69,6 @@ u32 cardEepromReadID() {
return id;
}


//---------------------------------------------------------------------------------
int cardEepromGetType(void) {
//---------------------------------------------------------------------------------
Expand All @@ -79,7 +78,7 @@ int cardEepromGetType(void) {
if (( sr == 0xff && id == 0xffffff) || ( sr == 0 && id == 0 )) return -1;
if ( sr == 0xf0 && id == 0xffffff ) return 1;
if ( sr == 0x00 && id == 0xffffff ) return 2;
if ( id != 0xffffff) return 3;
if ( id != 0xffffff || ( sr == 0x02 && id == 0xffffff )) return 3;

return 0;
}
Expand All @@ -97,20 +96,38 @@ uint32 cardEepromGetSize() {
if(type == 1)
return 512;
if(type == 2) {
u32 buf1,buf2,buf3;
u32 buf1,buf2,buf3 = 0x54534554; // "TEST"
// Save the first word of the EEPROM
cardReadEeprom(0,(u8*)&buf1,4,type);
if ( !(buf1 != 0 || buf1 != 0xffffffff) ) {
buf3 = ~buf1;
cardWriteEeprom(0,(u8*)&buf3,4,type);
} else {
buf3 = buf1;
}

// Write "TEST" to it
cardWriteEeprom(0,(u8*)&buf3,4,type);

// Loop until the EEPROM mirrors and the first word shows up again
int size = 8192;
while (1) {
while (1) {
cardReadEeprom(size,(u8*)&buf2,4,type);
if ( buf2 == buf3 ) break;
// Check if it matches, if so check again with another value to ensure no false positives
if (buf2 == buf3) {
u32 buf4 = 0x74736574; // "test"
// Write "test" to the first word
cardWriteEeprom(0,(u8*)&buf4,4,type);

// Check if it still matches
cardReadEeprom(size,(u8*)&buf2,4,type);
if (buf2 == buf4) break;

// False match, write "TEST" back and keep going
cardWriteEeprom(0,(u8*)&buf3,4,type);
}
size += 8192;
};
}

// Restore the first word
cardWriteEeprom(0,(u8*)&buf1,4,type);

return size;
}

if ( buf1 != buf3 ) cardWriteEeprom(0,(u8*)&buf1,4,type);

Expand Down Expand Up @@ -153,7 +170,13 @@ uint32 cardEepromGetSize() {
if (device == 0x2211)
return 128*1024; // 1Mbit(128KByte) - MX25L1021E
}


if (id == 0xffffff) {
int sr = cardEepromCommand(SPI_EEPROM_RDSR);
if (sr == 2) { // Pokémon Mystery Dungeon - Explorers of Sky
return 128*1024; // 1Mbit (128KByte)
}
}

return 256*1024; // 2Mbit(256KByte)
}
Expand Down