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author Devin Acker <d@revenant1.net>2025-02-09 08:46:13 -0500
committer GitHub <noreply@github.com>2025-02-09 14:46:13 +0100
commit4e5dd0c5dc28d1ccc24d381c2142541ee5fe8f45 (patch)
tree7ca11e748fec01cfb0ceffe46187dc02c189bbe2
parent7eeb604776592290c8865ada6367eeaaaf291373 (diff)
scc68070: limit external memory addresses to 24 bits (fixes cdi:zombie and clones, possibly others) (#13321)
-rw-r--r--src/devices/cpu/m68000/scc68070.cpp30
-rw-r--r--src/devices/cpu/m68000/scc68070.h4
2 files changed, 34 insertions, 0 deletions
diff --git a/src/devices/cpu/m68000/scc68070.cpp b/src/devices/cpu/m68000/scc68070.cpp
index 8d612f46bfa..cca40fe092f 100644
--- a/src/devices/cpu/m68000/scc68070.cpp
+++ b/src/devices/cpu/m68000/scc68070.cpp
@@ -21,4 +21,34 @@ void scc68070_base_device::device_start()
{
m68000_musashi_device::device_start();
init_cpu_scc68070();
+
+ m_readimm16 = [this](offs_t address) -> u16 { return m_oprogram16.read_word(translate_addr(address)); };
+ m_read8 = [this](offs_t address) -> u8 { return m_program16.read_byte(translate_addr(address)); };
+ m_read16 = [this](offs_t address) -> u16 { return m_program16.read_word(translate_addr(address)); };
+ m_read32 = [this](offs_t address) -> u32 { return m_program16.read_dword(translate_addr(address)); };
+ m_write8 = [this](offs_t address, u8 data)
+ {
+ address = translate_addr(address);
+ m_program16.write_word(address & ~1, data | (data << 8), address & 1 ? 0x00ff : 0xff00);
+ };
+ m_write16 = [this](offs_t address, u16 data) { m_program16.write_word(translate_addr(address), data); };
+ m_write32 = [this](offs_t address, u32 data) { m_program16.write_dword(translate_addr(address), data); };
+}
+
+offs_t scc68070_base_device::translate_addr(offs_t address) const
+{
+ // internal addresses (0x80000000-bfffffff) are only accessible in supervisor mode;
+ // all other accesses use the external 24-bit address bus.
+ if (!(supervisor_mode() && (address >> 30) == 0x2))
+ address &= 0xffffff;
+
+ return address;
+}
+
+bool scc68070_base_device::memory_translate(int spacenum, int intention, offs_t &address, address_space *&target_space)
+{
+ target_space = &space(spacenum);
+ if (spacenum == AS_PROGRAM)
+ address = translate_addr(address);
+ return true;
}
diff --git a/src/devices/cpu/m68000/scc68070.h b/src/devices/cpu/m68000/scc68070.h
index 06ab08e20bc..1d5c361e88d 100644
--- a/src/devices/cpu/m68000/scc68070.h
+++ b/src/devices/cpu/m68000/scc68070.h
@@ -18,6 +18,10 @@ protected:
// device-level overrides
virtual void device_start() override ATTR_COLD;
+ offs_t translate_addr(offs_t address) const;
+
+ virtual bool memory_translate(int spacenum, int intention, offs_t &address, address_space *&target_space) override;
+
scc68070_base_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock,
const device_type type, address_map_constructor internal_map);
};