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astrocorp: First layers of the astoneag encryption [O. Galibert]

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This commit is contained in:
Olivier Galibert 2019-02-20 17:38:48 +01:00
parent 24da0f87e2
commit 8162f9d39b
1 changed files with 104 additions and 147 deletions
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251
src/mame/drivers/astrcorp.cpp
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@ -78,6 +78,23 @@ protected:
virtual void video_start() override;
private:
struct decryption_info {
struct {
// Address bits used for bitswap/xor selection
u8 bits[3];
struct {
// 8-8 Bitswap
u8 bits[8];
// Xor
u8 xor_mask;
} entries[8];
} rom[2];
// Global address bitswap (src -> dest, bits 12-8 only)
u8 bits[5];
};
static const decryption_info astoneag_table;
// devices
required_device<cpu_device> m_maincpu;
required_device<okim6295_device> m_oki;
@ -113,6 +130,8 @@ private:
void showhand_map(address_map &map);
void skilldrp_map(address_map &map);
void speeddrp_map(address_map &map);
void decrypt_rom(const decryption_info &table);
};
/***************************************************************************
@ -1238,155 +1257,93 @@ void astrocorp_state::init_showhanc()
#endif
}
void astrocorp_state::decrypt_rom(const decryption_info &table)
{
u32 size = memregion("maincpu")->bytes();
u16 *rom = (u16 *)memregion("maincpu")->base();
std::unique_ptr<u16[]> tmp = std::make_unique<u16[]>(size/2);
// Pass 1: decrypt high and low byte independently. They go
// trough a bitswap and an xor, choosing between 8 possibilities
// through address bits.
for(u32 i = 0; i != size; i += 2) {
u16 orig = rom[i >> 1];
u16 result = 0;
for(u32 rb = 0; rb < 2; rb ++) {
u8 val = orig >> (rb ? 0 : 8);
u32 index =
(BIT(i, table.rom[rb].bits[0]) << 2) |
(BIT(i, table.rom[rb].bits[1]) << 1) |
BIT(i, table.rom[rb].bits[2]);
val = bitswap(val,
table.rom[rb].entries[index].bits[0],
table.rom[rb].entries[index].bits[1],
table.rom[rb].entries[index].bits[2],
table.rom[rb].entries[index].bits[3],
table.rom[rb].entries[index].bits[4],
table.rom[rb].entries[index].bits[5],
table.rom[rb].entries[index].bits[6],
table.rom[rb].entries[index].bits[7]);
val = val ^ table.rom[rb].entries[index].xor_mask;
result |= val << (rb ? 0 : 8);
}
tmp[i >> 1] = result;
}
// Pass 2: copy back the decrypted data following the address
// scrambling
for(u32 i = 0; i != size; i += 2) {
u32 dest =
(i & 0xffffe0ff) |
(BIT(i, table.bits[0]) << 12) |
(BIT(i, table.bits[1]) << 11) |
(BIT(i, table.bits[2]) << 10) |
(BIT(i, table.bits[3]) << 9) |
(BIT(i, table.bits[4]) << 8);
rom[dest >> 1] = tmp[i >> 1];
}
// There's more stuff happening for addresses < 0x400...
}
const astrocorp_state::decryption_info astrocorp_state::astoneag_table = {
{
{
{ 11, 10, 9 },
{
{ { 7, 5, 4, 6, 0, 3, 2, 1 }, 0x00 },
{ { 1, 4, 6, 0, 2, 5, 3, 7 }, 0xd0 },
{ { 1, 7, 4, 3, 6, 5, 0, 2 }, 0x88 },
{ { 6, 5, 2, 3, 7, 1, 0, 4 }, 0xd1 },
{ { 6, 1, 7, 2, 4, 0, 3, 5 }, 0x64 },
{ { 1, 7, 2, 6, 5, 4, 3, 0 }, 0x83 },
{ { 6, 7, 4, 2, 5, 0, 1, 3 }, 0x81 },
{ { 7, 5, 1, 0, 2, 4, 6, 3 }, 0xea },
}
},
{
{ 12, 10, 8 },
{
{ { 6, 5, 4, 3, 2, 1, 0, 7 }, 0x90 },
{ { 2, 4, 0, 7, 5, 6, 3, 1 }, 0x32 },
{ { 7, 1, 0, 6, 5, 2, 3, 4 }, 0xa9 },
{ { 2, 0, 3, 5, 1, 4, 6, 7 }, 0xa2 },
{ { 3, 0, 6, 5, 2, 1, 4, 7 }, 0x02 },
{ { 0, 1, 6, 4, 5, 2, 7, 3 }, 0x30 },
{ { 3, 5, 2, 7, 6, 1, 4, 0 }, 0x0a },
{ { 0, 6, 4, 2, 7, 3, 1, 5 }, 0x81 },
}
},
},
{ 12, 9, 11, 8, 10 }
};
void astrocorp_state::init_astoneag()
{
#if 0
uint16_t *rom = (uint16_t*)memregion("maincpu")->base();
uint16_t x;
int i;
for (i = 0x25100/2; i < 0x25200/2; i++)
{
x = 0x0000;
if ( (i & 0x0001) ) x |= 0x0200;
if ( (i & 0x0004) && !(i & 0x0001) ) x |= 0x0080;
if ( (i & 0x0040) || (i & 0x0001) ) x |= 0x0040;
if ( (i & 0x0010) && !(i & 0x0001) ) x |= 0x0020;
if ( !(i & 0x0020) || (i & 0x0001) ) x |= 0x0010;
if ( (i & 0x0002) || (i & 0x0001) ) x |= 0x0008;
if ( (i & 0x0008) && !(i & 0x0001) ) x |= 0x0004;
if ( !(i & 0x0040) && !(i & 0x0001) ) x |= 0x0002;
if ( (i & 0x0040) && !(i & 0x0001) ) x |= 0x0001;
rom[i] ^= x;
}
/*
for (i = 0x25300/2; i < 0x25400/2; i++)
{
x = 0x1300;
rom[i] ^= x;
}
*/
for (i = 0x25400/2; i < 0x25500/2; i++)
{
x = 0x4200;
if ( (i & 0x0001) ) x |= 0x0400;
if ( (i & 0x0020) && !(i & 0x0001) ) x |= 0x0080;
if ( !(i & 0x0010) || (i & 0x0001) ) x |= 0x0040;
if ( (i & 0x0040) && !(i & 0x0001) ) x |= 0x0020;
if ( !(i & 0x0004) || (i & 0x0001) ) x |= 0x0010;
if ( !(i & 0x0040) && !(i & 0x0001) ) x |= 0x0004;
if ( (i & 0x0008) && !(i & 0x0001) ) x |= 0x0002;
if ( (i & 0x0002) || (i & 0x0001) ) x |= 0x0001;
rom[i] ^= x;
}
for (i = 0x25500/2; i < 0x25600/2; i++)
{
x = 0x4200;
if ( (i & 0x0001) ) x |= 0x0400;
if ( (i & 0x0010) && !(i & 0x0001) ) x |= 0x0080;
if ( (i & 0x0040) && !(i & 0x0001) ) x |= 0x0040;
if ( !(i & 0x0002) && !(i & 0x0001) ) x |= 0x0020;
if ( !(i & 0x0040) && !(i & 0x0001) ) x |= 0x0010;
if ( (i & 0x0008) && !(i & 0x0001) ) x |= 0x0008;
if ( (i & 0x0020) && !(i & 0x0001) ) x |= 0x0004;
if ( (i & 0x0004) && !(i & 0x0001) ) x |= 0x0002;
if ( (i & 0x0001) ) x |= 0x0001;
rom[i] ^= x;
}
/*
for (i = 0x25700/2; i < 0x25800/2; i++)
{
x = 0x6800;
if ( !(i & 0x0001) ) x |= 0x8000;
if ( !(i & 0x0040) || ((i & 0x0001) || !(i & 0x0001)) ) x |= 0x0100;
rom[i] ^= x;
}
*/
for (i = 0x25800/2; i < 0x25900/2; i++)
{
x = 0x8300;
if ( (i & 0x0040) || (i & 0x0001) ) x |= 0x2000;
if ( (i & 0x0002) || (i & 0x0001) ) x |= 0x0080;
if ( !(i & 0x0040) && !(i & 0x0001) ) x |= 0x0040;
if ( (i & 0x0020) && !(i & 0x0001) ) x |= 0x0020;
if ( !(i & 0x0004) || (i & 0x0001) ) x |= 0x0010;
if ( !(i & 0x0040) && !(i & 0x0001) ) x |= 0x0008;
if ( (i & 0x0010) && !(i & 0x0001) ) x |= 0x0004;
if ( (i & 0x0008) && !(i & 0x0001) ) x |= 0x0002;
if ( !(i & 0x0040) && !(i & 0x0001) ) x |= 0x0001;
rom[i] ^= x;
}
// for (i = 0x25900/2; i < 0x25a00/2; i++)
for (i = 0x25c00/2; i < 0x25d00/2; i++)
{
// changed from 25400
// x = 0x4200;
x = 0x4000;
// if ( (i & 0x0001) ) x |= 0x0400;
if ( (i & 0x0020) && !(i & 0x0001) ) x |= 0x0080;
if ( !(i & 0x0010) || (i & 0x0001) ) x |= 0x0040;
if ( (i & 0x0040) && !(i & 0x0001) ) x |= 0x0020;
if ( !(i & 0x0004) || (i & 0x0001) ) x |= 0x0010;
if ( !(i & 0x0040) && !(i & 0x0001) ) x |= 0x0004;
if ( (i & 0x0008) && !(i & 0x0001) ) x |= 0x0002;
if ( (i & 0x0002) || (i & 0x0001) ) x |= 0x0001;
rom[i] ^= x;
}
/*
for (i = 0x25d00/2; i < 0x25e00/2; i++)
{
x = 0x4000;
if ( !(i & 0x0040) ) x |= 0x0800;
if ( !(i & 0x0040) && !(i & 0x0001) ) x |= 0x0100; // almost!!
if ( ((i & 0x0040)&&((i & 0x0020)||(i & 0x0010))) || !(i & 0x0001) ) x |= 0x0200; // almost!!
if ( (!(i & 0x0040) || !(i & 0x0008)) && !(i & 0x0001) ) x |= 0x0008;
if ( (i & 0x0040) || !(i & 0x0020) || (i & 0x0001) ) x |= 0x0001; // almost!!
rom[i] ^= x;
}
*/
/*
for (i = 0x25e00/2; i < 0x25f00/2; i++)
{
x = 0xa600;
if ( (i & 0x0040) && (i & 0x0001) ) x |= 0x4000;
if ( (i & 0x0040) && (i & 0x0001) ) x |= 0x0800;
if ( !(i & 0x0001) ) x |= 0x0100;
if ( ( (i & 0x0040) && (i & 0x0008) && !(i & 0x0001)) ||
( !(i & 0x0040) && ((i & 0x0004) ^ (i & 0x0002)) && !(i & 0x0001) ) ) x |= 0x0002; // almost!!
if ( !(i & 0x0040) || !(i & 0x0002) || (i & 0x0001) ) x |= 0x0001;
rom[i] ^= x;
}
*/
for (i = 0x26f00/2; i < 0x27000/2; i++)
{
x = 0xb94c;
rom[i] ^= x;
}
for (i = 0x27000/2; i < 0x27100/2; i++)
{
x = 0x5f10;
rom[i] ^= x;
}
#endif
decrypt_rom(astoneag_table);
}
GAME( 2000, showhand, 0, showhand, showhand, astrocorp_state, init_showhand, ROT0, "Astro Corp.", "Show Hand (Italy)", MACHINE_SUPPORTS_SAVE )