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open_agb_firm
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Fixed ROM mirrors for 1 MiB ROMs. Thanks to @endrift for discovering this.

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profi200 2023-09-20 00:15:31 +02:00
parent 855f6b131a
commit dc5ac1749f
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GPG Key ID: FD2BAB7782919B0A
1 changed files with 27 additions and 23 deletions
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50
source/arm11/open_agb_firm.c
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@ -95,36 +95,40 @@ static KHandle g_frameReadyEvent = 0;
static u32 fixRomPadding(u32 romFileSize)
static u32 fixRomPadding(const u32 romFileSize)
{
// Pad unused ROM area with 0xFFs (trimmed ROMs).
// Smallest retail ROM chip is 8 Mbit (1 MiB).
u32 romSize = nextPow2(romFileSize);
if(romSize < 0x100000u) romSize = 0x100000u;
memset((void*)(LGY_ROM_LOC + romFileSize), 0xFFFFFFFFu, romSize - romFileSize);
if(romSize > 0x100000u) // >1 MiB.
{
// Fake "open bus" padding.
u32 padding = (LGY_ROM_LOC + romSize) / 2;
padding = __pkhbt(padding, padding + 1, 16); // Copy lower half + 1 to upper half.
for(uintptr_t i = LGY_ROM_LOC + romSize; i < LGY_ROM_LOC + LGY_MAX_ROM_SIZE; i += 4)
{
*(u32*)i = padding;
padding = __uadd16(padding, 0x00020002u); // Unsigned parallel halfword-wise addition.
}
}
else
{
if(romSize < 0x100000) romSize = 0x100000;
const uintptr_t romLoc = LGY_ROM_LOC;
memset((void*)(romLoc + romFileSize), 0xFFFFFFFF, romSize - romFileSize);
// ROM mirroring (Classic NES Series/possibly others with 8 Mbit ROM).
// Mirror ROM across the entire 32 MiB area.
for(uintptr_t i = LGY_ROM_LOC + romSize; i < LGY_ROM_LOC + LGY_MAX_ROM_SIZE; i += romSize)
u32 mirroredSize = romSize;
if(romSize == 0x100000) // 1 MiB.
{
// ROM mirroring for Classic NES Series/others with 8 Mbit ROM.
// The ROM is mirrored exactly 4 times.
// Thanks to endrift for discovering this.
mirroredSize = 0x400000; // 4 MiB.
uintptr_t mirrorLoc = romLoc + romSize;
do
{
//memcpy((void*)i, (void*)(i - romSize), romSize); // 0x23A15DD
memcpy((void*)i, (void*)LGY_ROM_LOC, romSize); // 0x237109B
}
memcpy((void*)mirrorLoc, (void*)romLoc, romSize);
mirrorLoc += romSize;
} while(mirrorLoc < romLoc + mirroredSize);
}
// Fake "open bus" padding.
u32 padding = (romLoc + mirroredSize) / 2;
padding = __pkhbt(padding, padding + 1, 16); // Copy lower half + 1 to upper half.
for(uintptr_t i = romLoc + mirroredSize; i < romLoc + LGY_MAX_ROM_SIZE; i += 4)
{
*(u32*)i = padding;
padding = __uadd16(padding, 0x20002); // Unsigned parallel halfword-wise addition.
}
// We don't return the mirrored size because the db hashes are over unmirrored dumps.
return romSize;
}
@ -142,7 +146,7 @@ static Result loadGbaRom(const char *const path, u32 *const romSizeOut)
}
u32 read;
res = fRead(f, (u8*)LGY_ROM_LOC, fileSize, &read);
res = fRead(f, (void*)LGY_ROM_LOC, fileSize, &read);
fClose(f);
if(read == fileSize) *romSizeOut = fixRomPadding(fileSize);