mirror of
https://github.com/holub/mame
synced 2025-04-22 08:22:15 +03:00
clean up (nw)
This commit is contained in:
Vas Crabb
parent
f945016811
commit
241c32eae4
@ -3,7 +3,7 @@
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/*************************************************************************
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atarixga.cpp
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Atari XGA encryption FPGA
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**************************************************************************
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@ -15,7 +15,7 @@
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? Road Riot's Revenge
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136094-0004A Primal Rage
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? T-Mek
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*************************************************************************/
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#include "emu.h"
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@ -26,9 +26,9 @@ extern const device_type ATARI_XGA = &device_creator<atari_xga_device>;
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atari_xga_device::atari_xga_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
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: device_t(mconfig, ATARI_XGA, "Atari XGA", tag, owner, clock, "xga", __FILE__),
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m_mode(FPGA_RESET),
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m_address(0),
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m_ciphertext(0)
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m_mode(FPGA_RESET),
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m_address(0),
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m_ciphertext(0)
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{
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}
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@ -42,19 +42,19 @@ atari_xga_device::atari_xga_device(const machine_config &mconfig, const char *ta
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void atari_xga_device::device_start()
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{
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m_ram = std::make_unique<UINT16[]>(RAM_WORDS);
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save_pointer(NAME(m_ram.get()), RAM_WORDS * sizeof(UINT16));
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save_item(NAME(m_address));
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save_item(NAME(m_ciphertext));
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m_ram = std::make_unique<UINT16[]>(RAM_WORDS);
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save_pointer(NAME(m_ram.get()), RAM_WORDS * sizeof(UINT16));
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save_item(NAME(m_address));
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save_item(NAME(m_ciphertext));
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}
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void atari_xga_device::device_reset()
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{
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memset(m_ram.get(), 0, RAM_WORDS * sizeof(UINT16));
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m_mode = FPGA_RESET;
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m_address = 0;
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m_ciphertext = 0;
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memset(m_ram.get(), 0, RAM_WORDS * sizeof(UINT16));
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m_mode = FPGA_RESET;
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m_address = 0;
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m_ciphertext = 0;
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}
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@ -71,22 +71,22 @@ void atari_xga_device::device_reset()
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/* key 0x10 is special, it has 15 "identical twins". */
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static const UINT8 kmap[128] =
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{
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0x6B,0x11,0x1B,0x19,0x4B,0x50,0x17,0x09,
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0x5D,0x69,0x43,0x33,0x0F,0x0C,0x28,0x3F,
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0x00,0x20,0x15,0x3C,0x57,0x38,0x00,0x07,
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0x49,0x25,0x61,0x2F,0x2B,0x4E,0x64,0x00,
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0x45,0x41,0x6D,0x52,0x31,0x66,0x22,0x59,
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0x00,0x70,0x6F,0x5B,0x46,0x6E,0x67,0x5A,
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0x26,0x30,0x2C,0x65,0x21,0x3D,0x58,0x00,
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0x5E,0x44,0x0D,0x40,0x6C,0x1C,0x51,0x0A,
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0x35,0x2A,0x13,0x4D,0x63,0x00,0x00,0x3A,
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0x00,0x48,0x54,0x24,0x60,0x1E,0x2E,0x01,
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0x56,0x03,0x37,0x00,0x04,0x00,0x05,0x06,
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0x00,0x55,0x1F,0x02,0x36,0x14,0x00,0x3B,
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0x5F,0x0E,0x1D,0x0B,0x27,0x2D,0x3E,0x00,
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0x00,0x5C,0x47,0x68,0x42,0x53,0x32,0x23,
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0x4A,0x62,0x4F,0x00,0x00,0x16,0x39,0x08,
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0x6A,0x34,0x10,0x29,0x12,0x1A,0x4C,0x18
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0x6B,0x11,0x1B,0x19,0x4B,0x50,0x17,0x09,
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0x5D,0x69,0x43,0x33,0x0F,0x0C,0x28,0x3F,
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0x00,0x20,0x15,0x3C,0x57,0x38,0x00,0x07,
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0x49,0x25,0x61,0x2F,0x2B,0x4E,0x64,0x00,
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0x45,0x41,0x6D,0x52,0x31,0x66,0x22,0x59,
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0x00,0x70,0x6F,0x5B,0x46,0x6E,0x67,0x5A,
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0x26,0x30,0x2C,0x65,0x21,0x3D,0x58,0x00,
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0x5E,0x44,0x0D,0x40,0x6C,0x1C,0x51,0x0A,
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0x35,0x2A,0x13,0x4D,0x63,0x00,0x00,0x3A,
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0x00,0x48,0x54,0x24,0x60,0x1E,0x2E,0x01,
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0x56,0x03,0x37,0x00,0x04,0x00,0x05,0x06,
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0x00,0x55,0x1F,0x02,0x36,0x14,0x00,0x3B,
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0x5F,0x0E,0x1D,0x0B,0x27,0x2D,0x3E,0x00,
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0x00,0x5C,0x47,0x68,0x42,0x53,0x32,0x23,
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0x4A,0x62,0x4F,0x00,0x00,0x16,0x39,0x08,
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0x6A,0x34,0x10,0x29,0x12,0x1A,0x4C,0x18
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};
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@ -99,106 +99,101 @@ static const UINT8 kmap[128] =
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UINT16 atari_xga_device::ctz(UINT16 x)
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{
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UINT16 n = 0;
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if (x == 0) return 16;
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if (!(x & 0x00FF)) n += 8, x >>= 8;
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if (!(x & 0x000F)) n += 4, x >>= 4;
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if (!(x & 0x0003)) n += 2, x >>= 2;
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if (!(x & 0x0001)) n += 1, x >>= 1;
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return n;
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UINT16 n = 0;
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if (x == 0) return 16;
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if (!(x & 0x00FF)) n += 8, x >>= 8;
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if (!(x & 0x000F)) n += 4, x >>= 4;
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if (!(x & 0x0003)) n += 2, x >>= 2;
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if (!(x & 0x0001)) n += 1, x >>= 1;
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return n;
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}
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size_t atari_xga_device::popcount(UINT16 x)
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{
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size_t count = 0;
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while (x != 0)
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{
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count += 1;
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x &= x - 1;
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}
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return count;
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size_t count = 0;
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while (x != 0)
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{
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count += 1;
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x &= x - 1;
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}
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return count;
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}
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UINT16 atari_xga_device::parity(UINT16 x)
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{
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return popcount(x) & 1;
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return popcount(x) & 1;
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}
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UINT16 atari_xga_device::lfsr1(UINT16 x)
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{
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UINT16 bit = parity(x & 0x8016);
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return (x << 1) | bit;
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const UINT16 bit = parity(x & 0x8016);
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return (x << 1) | bit;
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}
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UINT16 atari_xga_device::lfsr2(UINT16 x)
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{
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UINT16 bit = parity(x & 0x002D);
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return (x >> 1) | (bit << 15);
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UINT16 bit = parity(x & 0x002D);
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return (x >> 1) | (bit << 15);
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}
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UINT16 atari_xga_device::powers2(UINT8 k, UINT16 x)
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{
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static const UINT16 L[16] =
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{
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0x5E85,0xBD0B,0x2493,0x17A3,
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0x2F47,0x0005,0x000B,0x0017,
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0x002F,0x005E,0x00BD,0x017A,
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0x02F4,0x05E8,0x0BD0,0x17A1
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};
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static const UINT16 L[16] = {
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0x5E85,0xBD0B,0x2493,0x17A3,
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0x2F47,0x0005,0x000B,0x0017,
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0x002F,0x005E,0x00BD,0x017A,
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0x02F4,0x05E8,0x0BD0,0x17A1
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};
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UINT16 t = (x == 16) ? (L[4] ^ L[5]) : L[x];
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UINT16 t = (x == 16) ? (L[4] ^ L[5]) : L[x];
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for (size_t i = 0; i < k; ++i)
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{
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t = lfsr1(t);
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}
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return t;
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for (size_t i = 0; i < k; ++i)
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t = lfsr1(t);
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return t;
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}
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UINT16 atari_xga_device::decipher(UINT8 k, UINT16 c)
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{
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UINT16 bit, i, p = 0;
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UINT16 p = 0;
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/* Only 128 keys internally, if high bit set,
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then find the 7-bit "twin" by xor 0xA8. */
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if (k & 0x80)
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k ^= 0xA8;
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/* Only 128 keys internally, if high bit set,
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then find the 7-bit "twin" by xor 0xA8. */
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if (k & 0x80)
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k ^= 0xA8;
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k = kmap[k];
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k = kmap[k];
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if ((c & (c - 1)) == 0)
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{
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return powers2(k, ctz(c));
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}
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if ((c & (c - 1)) == 0)
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return powers2(k, ctz(c));
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for (bit = 0; bit < 5; ++bit)
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{
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if ((c >> bit) & 1)
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{
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p ^= powers2(k, bit);
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}
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}
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for (UINT16 bit = 0; bit < 5; ++bit)
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{
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if ((c >> bit) & 1)
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{
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p ^= powers2(k, bit);
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}
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}
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for (bit = 5; bit < 16; ++bit)
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{
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if ((c >> bit) & 1)
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{
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p ^= powers2(k, bit + 1);
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}
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}
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for (UINT16 bit = 5; bit < 16; ++bit)
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{
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if ((c >> bit) & 1)
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{
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p ^= powers2(k, bit + 1);
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}
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}
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UINT16 x = 0x8010;
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for (i = 0; i < k + 3; ++i)
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{
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if (x == c)
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{
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return (p == 1) ? 0 : lfsr2(p);
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}
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x = lfsr2(x);
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}
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UINT16 x = 0x8010;
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for (UINT16 i = 0; i < k + 3; ++i)
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{
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if (x == c)
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{
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return (p == 1) ? 0 : lfsr2(p);
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}
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x = lfsr2(x);
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}
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return p;
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return p;
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}
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@ -211,90 +206,86 @@ UINT16 atari_xga_device::decipher(UINT8 k, UINT16 c)
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WRITE32_MEMBER(atari_xga_device::write)
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{
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switch (m_mode)
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{
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case FPGA_RESET:
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return;
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switch (m_mode)
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{
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case FPGA_RESET:
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return;
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case FPGA_SETKEY:
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/* Write table to FPGA SRAM. */
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if (ACCESSING_BITS_16_31)
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m_ram[offset << 1] = UINT16 (data >> 16);
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if (ACCESSING_BITS_0_15)
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m_ram[(offset << 1) + 1] = UINT16(data & 0xFFFF);
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break;
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case FPGA_SETKEY:
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/* Write table to FPGA SRAM. */
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if (ACCESSING_BITS_16_31)
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m_ram[offset << 1] = UINT16 (data >> 16);
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if (ACCESSING_BITS_0_15)
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m_ram[(offset << 1) + 1] = UINT16(data & 0xFFFF);
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break;
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case FPGA_DECIPHER:
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/* Send Ciphertext to FPGA for decryption. */
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if (ACCESSING_BITS_16_31)
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{
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m_address = offset << 2;
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m_ciphertext = UINT16(data >> 16);
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}
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if (ACCESSING_BITS_0_15)
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{
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m_address = (offset << 2) + 2;
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m_ciphertext = UINT16(data & 0xFFFF);
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}
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break;
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}
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case FPGA_DECIPHER:
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/* Send Ciphertext to FPGA for decryption. */
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if (ACCESSING_BITS_16_31)
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{
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m_address = offset << 2;
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m_ciphertext = UINT16(data >> 16);
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}
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if (ACCESSING_BITS_0_15)
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{
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m_address = (offset << 2) + 2;
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m_ciphertext = UINT16(data & 0xFFFF);
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}
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break;
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}
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}
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READ32_MEMBER(atari_xga_device::read)
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{
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UINT32 plaintext = 0;
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switch (offset << 2)
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{
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case 0x0FC0:
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m_mode = FPGA_RESET;
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break;
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case 0x0010:
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m_mode = FPGA_SETKEY;
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break;
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case 0x0020:
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m_mode = FPGA_DECIPHER;
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break;
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}
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switch (offset << 2)
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{
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case 0x0FC0:
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m_mode = FPGA_RESET;
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break;
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case 0x0010:
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m_mode = FPGA_SETKEY;
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break;
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case 0x0020:
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m_mode = FPGA_DECIPHER;
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break;
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}
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if (m_mode == FPGA_RESET)
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return 0;
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if (m_mode == FPGA_RESET)
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{
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return 0;
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}
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UINT32 plaintext = 0;
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if (m_mode == FPGA_DECIPHER)
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{
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UINT16 address = (offset << 2) - 0x400;
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if (m_mode == FPGA_DECIPHER)
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{
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UINT16 address = (offset << 2) - 0x400;
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if (ACCESSING_BITS_0_15)
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address += 2;
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if (ACCESSING_BITS_0_15)
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address += 2;
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/* Reply with decrypted plaintext */
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if (address == m_address)
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{
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UINT16 key_offset, key_byte;
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/* Reply with decrypted plaintext */
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if (address == m_address)
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{
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UINT16 key_offset, key_byte;
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/* Algorithm to select key byte based on offset. */
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key_offset = ((((address >> 4) & 1) ^ 1) << 0)
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^ ((((address >> 2) & 1) ^ 0) << 1)
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^ ((((address >> 8) & 1) ^ 0) << 2)
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^ ((((address >> 3) & 1) ^ 1) << 3)
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^ ((((address >> 1) & 1) ^ 1) << 4)
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^ ((((address >> 6) & 1) ^ 0) << 5)
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^ ((((address >> 7) & 1) ^ 0) << 6)
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^ ((((address >> 5) & 1) ^ 1) << 7)
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^ ((((address >> 9) & 1) ^ 0) << 8)
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^ ((((address >> 10) & 1) ^ 0) << 9);
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key_byte = m_ram[key_offset];
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/* Algorithm to select key byte based on offset. */
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key_offset = ((((address >> 4) & 1) ^ 1) << 0)
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^ ((((address >> 2) & 1) ^ 0) << 1)
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^ ((((address >> 8) & 1) ^ 0) << 2)
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^ ((((address >> 3) & 1) ^ 1) << 3)
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^ ((((address >> 1) & 1) ^ 1) << 4)
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^ ((((address >> 6) & 1) ^ 0) << 5)
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^ ((((address >> 7) & 1) ^ 0) << 6)
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^ ((((address >> 5) & 1) ^ 1) << 7)
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^ ((((address >> 9) & 1) ^ 0) << 8)
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^ ((((address >> 10) & 1) ^ 0) << 9);
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key_byte = m_ram[key_offset];
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/* And now for the full magic. */
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plaintext = decipher(key_byte, m_ciphertext);
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/* And now for the full magic. */
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plaintext = decipher(key_byte, m_ciphertext);
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if (ACCESSING_BITS_16_31)
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plaintext <<= 16;
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}
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}
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if (ACCESSING_BITS_16_31)
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plaintext <<= 16;
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}
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}
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return plaintext;
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return plaintext;
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}
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