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// license:BSD-3-Clause
// copyright-holders:Morten Shearman Kirkegaard, Samuel Neves, Peter Wilhelmsen
/*************************************************************************
atarixga.h
Atari XGA encryption FPGA
*************************************************************************/
#ifndef __MACHINE_ATARIXGA__
#define __MACHINE_ATARIXGA__
extern const device_type ATARI_XGA;
class atari_xga_device : public device_t
{
public:
// construction/destruction
atari_xga_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock);
DECLARE_WRITE32_MEMBER(write);
DECLARE_READ32_MEMBER(read);
protected:
virtual void device_start() override;
virtual void device_reset() override;
private:
static const size_t RAM_WORDS = 2048;
enum fpga_mode
{
FPGA_RESET,
FPGA_SETKEY,
FPGA_DECIPHER
};
UINT16 powers2(UINT8 k, UINT16 x);
UINT16 lfsr2(UINT16 x);
UINT16 lfsr1(UINT16 x);
UINT16 parity(UINT16 x);
size_t popcount(UINT16 x);
UINT16 ctz(UINT16 x);
UINT16 decipher(UINT8 k, UINT16 c);
fpga_mode m_mode;
UINT16 m_address; // last written address
UINT16 m_ciphertext; // last written ciphertext
std::unique_ptr<UINT16[]> m_ram; // CY7C185-45PC, only 16-Kbit used
};
#endif
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