diff options
Diffstat (limited to 'src/mame/machine/m6502_swap_op_d5_d6.cpp')
-rw-r--r-- | src/mame/machine/m6502_swap_op_d5_d6.cpp | 62 |
1 files changed, 60 insertions, 2 deletions
diff --git a/src/mame/machine/m6502_swap_op_d5_d6.cpp b/src/mame/machine/m6502_swap_op_d5_d6.cpp index d3c661f8c2b..df832634684 100644 --- a/src/mame/machine/m6502_swap_op_d5_d6.cpp +++ b/src/mame/machine/m6502_swap_op_d5_d6.cpp @@ -4,10 +4,13 @@ m6502_swap_op_d5_d6.cpp - 6502 with instruction scrambling + 6502 / N2A03 with instruction scrambling Seen on die marked VH2009, used on polmega, silv35 - but also elsewhere + these are N2A03 derived CPUs used on VTxx systems + + VT1682 systems with this scrambling currently derive from M6502 type + but this might be incorrect ***************************************************************************/ @@ -15,6 +18,7 @@ #include "m6502_swap_op_d5_d6.h" DEFINE_DEVICE_TYPE(M6502_SWAP_OP_D5_D6, m6502_swap_op_d5_d6, "m6502_swap_op_d5_d6", "M6502 swapped D5/D6") +DEFINE_DEVICE_TYPE(N2A03_CORE_SWAP_OP_D5_D6, n2a03_core_swap_op_d5_d6, "n2a03_core_swap_op_d5_d6", "N2A03 core with swapped D5/D6") m6502_swap_op_d5_d6::m6502_swap_op_d5_d6(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) : m6502_device(mconfig, M6502_SWAP_OP_D5_D6, tag, owner, clock) @@ -64,3 +68,57 @@ u8 m6502_swap_op_d5_d6::disassembler::decrypt8(u8 value, offs_t pc, bool opcode) { return opcode ? mintf->descramble(value) : value; } + + + + + +n2a03_core_swap_op_d5_d6::n2a03_core_swap_op_d5_d6(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) : + n2a03_core_device(mconfig, N2A03_CORE_SWAP_OP_D5_D6, tag, owner, clock) +{ +} + +void n2a03_core_swap_op_d5_d6::device_start() +{ + mintf = std::make_unique<mi_decrypt>(); + init(); +} + +void n2a03_core_swap_op_d5_d6::device_reset() +{ + n2a03_core_device::device_reset(); +} + +uint8_t n2a03_core_swap_op_d5_d6::mi_decrypt::descramble(uint8_t op) +{ + return bitswap<8>(op, 7, 5, 6, 4, 3, 2, 1, 0); +} + +uint8_t n2a03_core_swap_op_d5_d6::mi_decrypt::read_sync(uint16_t adr) +{ + uint8_t res = cprogram.read_byte(adr); + + res = descramble(res); + + return res; +} + +std::unique_ptr<util::disasm_interface> n2a03_core_swap_op_d5_d6::create_disassembler() +{ + return std::make_unique<disassembler>(downcast<mi_decrypt *>(mintf.get())); +} + +n2a03_core_swap_op_d5_d6::disassembler::disassembler(mi_decrypt *mi) : mintf(mi) +{ +} + +u32 n2a03_core_swap_op_d5_d6::disassembler::interface_flags() const +{ + return SPLIT_DECRYPTION; +} + +u8 n2a03_core_swap_op_d5_d6::disassembler::decrypt8(u8 value, offs_t pc, bool opcode) const +{ + return opcode ? mintf->descramble(value) : value; +} + |