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diff --git a/src/mame/sun/sun1_mmu.h b/src/mame/sun/sun1_mmu.h
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+++ b/src/mame/sun/sun1_mmu.h
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+// license:BSD-3-Clause
+// copyright-holders:Patrick Mackinlay
+
+#ifndef MAME_SUN_SUN1_MMU_H
+#define MAME_SUN_SUN1_MMU_H
+
+#pragma once
+
+#include "cpu/m68000/m68000.h"
+
+class sun1mmu_device
+ : public device_t
+ , public m68000_device::mmu
+{
+public:
+ template <unsigned N, typename T> void set_space(T &&tag, int spacenum) { m_space[N].set_tag(std::forward<T>(tag), spacenum); }
+
+ enum error_type : unsigned
+ {
+ MMU_DEFER = 0, // invalid multibus access
+ MMU_ERROR = 1, // bus error (system space, segment protection, nonexistent page)
+ };
+ auto error() { return m_error.bind(); }
+
+ sun1mmu_device(machine_config const &mconfig, char const *tag, device_t *owner, u32 clock = 0);
+
+ // register access
+ void context_w(u16 data);
+ u16 segment_r(offs_t offset);
+ void segment_w(offs_t offset, u16 data, u16 mem_mask);
+ u16 page_r(offs_t offset);
+ void page_w(offs_t offset, u16 data, u16 mem_mask);
+
+protected:
+ // device_t implementation
+ virtual void device_start() override ATTR_COLD;
+ virtual void device_reset() override ATTR_COLD;
+
+ // m68000_device::mmu implementation
+ virtual u16 read_program(offs_t addr, u16 mem_mask) override;
+ virtual void write_program(offs_t addr, u16 data, u16 mem_mask) override;
+ virtual u16 read_data(offs_t addr, u16 mem_mask) override;
+ virtual void write_data(offs_t addr, u16 data, u16 mem_mask) override;
+ virtual u16 read_cpu(offs_t addr, u16 mem_mask) override;
+ virtual void set_super(bool super) override;
+
+ std::optional<std::pair<unsigned, offs_t>> translate(offs_t const address, unsigned const mode);
+ template <bool Execute> u16 mmu_read(offs_t logical, u16 mem_mask);
+ void mmu_write(offs_t logical, u16 data, u16 mem_mask);
+
+private:
+ required_address_space m_space[4];
+ devcb_write_line m_error;
+
+ memory_access<24, 1, 0, ENDIANNESS_BIG>::specific m_cpu_mem;
+ memory_access<24, 1, 0, ENDIANNESS_BIG>::specific m_cpu_spc;
+
+ // only 20 of the possible 24 memory address lines are connected
+ memory_access<20, 1, 0, ENDIANNESS_LITTLE>::specific m_bus_mem;
+ memory_access<16, 1, 0, ENDIANNESS_LITTLE>::specific m_bus_pio;
+
+ u16 m_context;
+ u16 m_segment[16][64];
+ u16 m_page[1024];
+
+ bool m_stall;
+ bool m_super;
+};
+
+DECLARE_DEVICE_TYPE(SUN1MMU, sun1mmu_device)
+
+#endif // MAME_SUN_SUN1_MMU_H