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skylncr.cpp: very minor start at descrambling superb2k

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This commit is contained in:
Ivan Vangelista 2021-06-08 18:06:24 +02:00
parent f06d9e8c71
commit 07a1542a7c
1 changed files with 24 additions and 1 deletions
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25
src/mame/drivers/skylncr.cpp
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@ -166,6 +166,7 @@ public:
void init_miaction();
void init_olymp();
void init_sonikfig();
void init_superb2k();
READ_LINE_MEMBER(mbutrfly_prot_r);
@ -2257,6 +2258,28 @@ void skylncr_state::init_olymp() // very weird, needs to be checked / finished,
m_decrypted_opcodes[x] = ROM[x] ^ 0x18;
}
void skylncr_state::init_superb2k() // TODO: very preliminary, just enough to read some strings
{
uint8_t *const rom = memregion("maincpu")->base();
std::vector<uint8_t> buffer(0x10000);
memcpy(&buffer[0], rom, 0x10000);
// descramble addresses. At a first glance, swaps seem to change if address line bits 13 or 14 are set (possibly 15 too, but not verified yet)
// the scrambled address line bits appear to be 1, 3, 6, 9 and 12
// it's possible XORs and are data lines swaps are involved, too, at least for opcodes
for (int i = 0x00000; i < 0x10000; i++)
{
switch (i & 0x6000)
{
case 0x0000: rom[i] = buffer[bitswap<24>(i, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)]; break; // TODO: everything
case 0x2000: rom[i] = buffer[bitswap<24>(i, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 1, 11, 10, 9, 8, 7, 3, 5, 4, 12, 2, 6, 0)]; break; // TODO: 0x200 blocks are good (see 0x3e00-0x3fff), rest to be determined
case 0x4000: rom[i] = buffer[bitswap<24>(i, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 1, 11, 10, 3, 8, 7, 6, 5, 4, 9, 2, 12, 0)]; break; // TODO: 0x40 blocks are good, there's still at least a wrong swap (see 0x5200-0x52ff)
case 0x6000: rom[i] = buffer[bitswap<24>(i, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 3, 11, 10, 1, 8, 7, 9, 5, 4, 12, 2, 6, 0)]; break; // TODO: 0x20 blocks are good (see 0x7fa0-0x7fbf)
}
}
}
} // Anonymous namespace
@ -2280,4 +2303,4 @@ GAME( 2000?,olymp, 0, olymp, skylncr, skylncr_state, init_olymp,
GAME( 2000, sonikfig, 0, skylncr, sonikfig, skylncr_state, init_sonikfig, ROT0, "Z Games", "Sonik Fighter (version 02, encrypted)", MACHINE_WRONG_COLORS | MACHINE_NOT_WORKING | MACHINE_SUPPORTS_SAVE )
GAME( 199?, rolla, 0, skylncr, skylncr, skylncr_state, empty_init, ROT0, "Random Games", "unknown 'Rolla' slot machine", MACHINE_IS_SKELETON ) // internal CPU ROM not dumped
GAME( 2000?,score5, 0, skylncr, score5, skylncr_state, init_sonikfig, ROT0, "Z Games", "Score 5", MACHINE_WRONG_COLORS | MACHINE_NOT_WORKING | MACHINE_SUPPORTS_SAVE ) // game runs but screen is completely black due to palette mishandling
GAME( 2000?,superb2k, 0, skylncr, skylncr, skylncr_state, empty_init, ROT0, "Random Games", "Super Butterfly 2000", MACHINE_IS_SKELETON ) // encrypted / different CPU type ?
GAME( 2000?,superb2k, 0, skylncr, skylncr, skylncr_state, init_superb2k, ROT0, "Random Games", "Super Butterfly 2000", MACHINE_IS_SKELETON ) // encrypted / different CPU type ?