add derived CPU type for AX51-CORE (used by AX208 and others) so that we can start to customize disassembly and execution

scripts/src/cpu.lua

@@ -988,12 +988,16 @@ if (CPUS["MCS51"]~=null) then
 		MAME_DIR .. "src/devices/cpu/mcs51/mcs51.cpp",
 		MAME_DIR .. "src/devices/cpu/mcs51/mcs51.h",
 		MAME_DIR .. "src/devices/cpu/mcs51/mcs51ops.hxx",
+		MAME_DIR .. "src/devices/cpu/mcs51/axc51-core.cpp",
+		MAME_DIR .. "src/devices/cpu/mcs51/axc51-core.h",
 	}
 end
 
 if (CPUS["MCS51"]~=null or _OPTIONS["with-tools"]) then
 	table.insert(disasm_files , MAME_DIR .. "src/devices/cpu/mcs51/mcs51dasm.cpp")
 	table.insert(disasm_files , MAME_DIR .. "src/devices/cpu/mcs51/mcs51dasm.h")
+	table.insert(disasm_files , MAME_DIR .. "src/devices/cpu/mcs51/axc51-core_dasm.cpp")
+	table.insert(disasm_files , MAME_DIR .. "src/devices/cpu/mcs51/axc51-core_dasm.h")
 end
 
 --------------------------------------------------

src/devices/cpu/mcs51/axc51-core.cpp

@@ -0,0 +1,28 @@
+// license:BSD-3-Clause
+// copyright-holders:David Haywood
+/*****************************************************************************
+
+	AXC51-CORE (AppoTech Inc.)
+
+	used in
+
+	AX208 SoC
+
+ *****************************************************************************/
+
+#include "emu.h"
+#include "debugger.h"
+#include "axc51-core.h"
+#include "axc51-core_dasm.h"
+
+DEFINE_DEVICE_TYPE(AX208, ax208_cpu_device, "ax208", "AppoTech AX208 (AXC51-CORE)")
+
+ax208_cpu_device::ax208_cpu_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
+	: mcs51_cpu_device(mconfig, AX208, tag, owner, clock, 0, 7)
+{
+}
+
+std::unique_ptr<util::disasm_interface> ax208_cpu_device::create_disassembler()
+{
+	return std::make_unique<axc51core_disassembler>();
+}

src/devices/cpu/mcs51/axc51-core.h

@@ -0,0 +1,32 @@
+// license:BSD-3-Clause
+// copyright-holders:David Haywood
+/*****************************************************************************
+
+	AXC51-CORE (AppoTech Inc.)
+
+	used in
+
+	AX208 SoC
+
+ *****************************************************************************/
+
+#ifndef MAME_CPU_MCS51_AXC51_CORE_H
+#define MAME_CPU_MCS51_AXC51_CORE_H
+
+#pragma once
+
+#include "mcs51.h"
+
+DECLARE_DEVICE_TYPE(AX208, ax208_cpu_device)
+
+class ax208_cpu_device : public mcs51_cpu_device
+{
+public:
+	// construction/destruction
+	ax208_cpu_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
+
+protected:
+	virtual std::unique_ptr<util::disasm_interface> create_disassembler() override;
+};
+
+#endif // MAME_CPU_MCS51_AXC51_CORE_H

src/devices/cpu/mcs51/axc51-core_dasm.cpp

@@ -0,0 +1,42 @@
+// license:BSD-3-Clause
+// copyright-holders:David Haywood
+/*****************************************************************************
+
+	AXC51-CORE (AppoTech Inc.)
+
+	used in
+
+	AX208 SoC
+
+ *****************************************************************************/
+
+#include "emu.h"
+#include "axc51-core_dasm.h"
+
+axc51core_disassembler::axc51core_disassembler() : mcs51_disassembler(default_names)
+{
+}
+
+
+offs_t axc51core_disassembler::disassemble_op(std::ostream &stream, unsigned PC, offs_t pc, const data_buffer &opcodes, const data_buffer &params, uint8_t op)
+{
+	uint32_t flags = 0;
+	uint8_t prm = 0;
+
+	switch( op )
+	{
+		// unknown, probably the 16-bit extended ocpodes, see page 14 of AX208-SP-101-EN manual, encodings not specified!
+		// note, the other AXC51-CORE based manuals don't seem to mention these, are they really AX208 specific?
+		case 0xa5:
+			prm = params.r8(PC++);
+			util::stream_format(stream, "unknown ax208 a5 $%02X", prm);
+			break;
+
+		default:
+			return mcs51_disassembler::disassemble_op(stream, PC, pc, opcodes, params, op);
+	}
+
+	return (PC - pc) | flags | SUPPORTED;
+}
+
+

src/devices/cpu/mcs51/axc51-core_dasm.h

@@ -0,0 +1,31 @@
+// license:BSD-3-Clause
+// copyright-holders:David Haywood
+/*****************************************************************************
+
+	AXC51-CORE (AppoTech Inc.)
+
+	used in
+
+	AX208 SoC
+
+ *****************************************************************************/
+
+#ifndef MAME_CPU_MCS51_AXC51_CORE_DASM_H
+#define MAME_CPU_MCS51_AXC51_CORE_DASM_H
+
+#pragma once
+
+#include "mcs51dasm.h"
+
+class axc51core_disassembler : public mcs51_disassembler
+{
+public:
+	axc51core_disassembler();
+	virtual ~axc51core_disassembler() = default;
+
+protected:
+	virtual offs_t disassemble_op(std::ostream &stream, unsigned PC, offs_t pc, const data_buffer &opcodes, const data_buffer &params, uint8_t op) override;
+};
+
+
+#endif // MAME_CPU_MCS51_AXC51_CORE_DASM_H

src/devices/cpu/mcs51/mcs51dasm.cpp

@@ -293,16 +293,14 @@ std::string mcs51_disassembler::get_bit_address( uint8_t arg ) const
 	}
 }
 
-offs_t mcs51_disassembler::disassemble(std::ostream &stream, offs_t pc, const data_buffer &opcodes, const data_buffer &params)
+offs_t mcs51_disassembler::disassemble_op(std::ostream &stream, unsigned PC, offs_t pc, const data_buffer &opcodes, const data_buffer &params, uint8_t op)
 {
 	uint32_t flags = 0;
-	unsigned PC = pc;
 	std::string sym, sym2;
-	uint8_t op, data;
+	uint8_t data;
 	uint16_t addr;
 	int8_t rel;
 
-	op = opcodes.r8(PC++);
 	switch( op )
 	{
 		//NOP
@@ -1109,6 +1107,13 @@ offs_t mcs51_disassembler::disassemble(std::ostream &stream, offs_t pc, const da
 	return (PC - pc) | flags | SUPPORTED;
 }
 
+offs_t mcs51_disassembler::disassemble(std::ostream &stream, offs_t pc, const data_buffer &opcodes, const data_buffer &params)
+{
+	unsigned PC = pc;
+	uint8_t op = opcodes.r8(PC++);
+	return disassemble_op(stream, PC, pc,  opcodes, params, op);
+}
+
 i8051_disassembler::i8051_disassembler() : mcs51_disassembler(default_names)
 {
 }

src/devices/cpu/mcs51/mcs51dasm.h

@@ -63,11 +63,14 @@ public:
 	virtual u32 opcode_alignment() const override;
 	virtual offs_t disassemble(std::ostream &stream, offs_t pc, const data_buffer &opcodes, const data_buffer &params) override;
 
-private:
-	std::unordered_map<offs_t, const char *> m_names;
+protected:
+	virtual offs_t disassemble_op(std::ostream &stream, unsigned PC, offs_t pc, const data_buffer &opcodes, const data_buffer &params, uint8_t op);
 
 	std::string get_data_address( uint8_t arg ) const;
 	std::string get_bit_address( uint8_t arg ) const;
+private:
+	std::unordered_map<offs_t, const char *> m_names;
+
 };
 
 class i8051_disassembler : public mcs51_disassembler

src/mame/drivers/monon_color.cpp

@@ -7,13 +7,13 @@
    https://gbatemp.net/threads/the-monon-color-a-new-video-game-console-from-china.467788/
    https://twitter.com/Splatoon2weird/status/1072182093206052864
 
-   uses AX208 CPU (8051 @ 96Mhz with single cycle instructions + integrated video, jpeg decoder etc.)
+   uses AX208 CPU (custom 8051 @ 96Mhz with single cycle instructions, extended '16 bit' opcodes + integrated video, jpeg decoder etc.)
    https://docplayer.net/52724058-Ax208-product-specification.html
 
 ***************************************************************************/
 
 #include "emu.h"
-#include "cpu/mcs51/mcs51.h"
+#include "cpu/mcs51/axc51-core.h"
 #include "emupal.h"
 #include "screen.h"
 #include "speaker.h"
@@ -75,7 +75,7 @@ INPUT_PORTS_END
 MACHINE_CONFIG_START(monon_color_state::monon_color)
 
 	/* basic machine hardware */
-	MCFG_DEVICE_ADD("maincpu", I8051, 96000000) // AX208! (needs custom core)
+	MCFG_DEVICE_ADD("maincpu", AX208, 96000000) // (8051 / MCS51 derived) incomplete core!
 
 	/* video hardware */
 	MCFG_SCREEN_ADD("screen", RASTER)

src/tools/unidasm.cpp

@@ -87,6 +87,7 @@ using util::BIT;
 #include "cpu/mcs40/mcs40dasm.h"
 #include "cpu/mcs48/mcs48dsm.h"
 #include "cpu/mcs51/mcs51dasm.h"
+#include "cpu/mcs51/axc51-core_dasm.h"
 #include "cpu/mcs96/i8x9xd.h"
 #include "cpu/mcs96/i8xc196d.h"
 #include "cpu/melps4/melps4d.h"
@@ -315,6 +316,7 @@ static const dasm_table_entry dasm_table[] =
 	{ "arm7thumbb",      be,  0, []() -> util::disasm_interface * { arm7_unidasm.t_flag = true; return new arm7_disassembler(&arm7_unidasm); } },
 	{ "asap",            le,  0, []() -> util::disasm_interface * { return new asap_disassembler; } },
 	{ "avr8",            le,  0, []() -> util::disasm_interface * { return new avr8_disassembler; } },
+	{ "axc51core",       le,  0, []() -> util::disasm_interface * { return new axc51core_disassembler; } },
 	{ "capricorn",       le,  0, []() -> util::disasm_interface * { return new capricorn_disassembler; } },
 	{ "ccpu",            le,  0, []() -> util::disasm_interface * { return new ccpu_disassembler; } },
 	{ "cdp1801",         le,  0, []() -> util::disasm_interface * { return new cosmac_disassembler(cosmac_disassembler::TYPE_1801); } },