--- nono/vm/busio.h	2026/04/29 17:04:31	1.1.1.1
+++ nono/vm/busio.h	2026/04/29 17:04:35	1.1.1.2
@@ -1,6 +1,7 @@
 //
 // nono
-// Copyright (C) 2020 isaki@NetBSD.org
+// Copyright (C) 2020 nono project
+// Licensed under nono-license.txt
 //
 
 // バスとデバイスとのインタフェース。
@@ -20,15 +21,15 @@ class BusIO_B_Base: public T
 	}
 
  public:
-	virtual uint64 Read8(uint32 addr) {
+	uint64 Read8(uint32 addr) override {
 		return T::Read(Decoder(addr));
 	}
 
-	virtual uint64 Write8(uint32 addr, uint32 data) {
+	uint64 Write8(uint32 addr, uint32 data) override {
 		return T::Write(Decoder(addr), data);
 	}
 
-	virtual uint64 Peek8(uint32 addr) {
+	uint64 Peek8(uint32 addr) override {
 		return T::Peek(Decoder(addr));
 	}
 };
@@ -55,27 +56,32 @@ class BusIO_W: public T
 	}
 
  public:
-	virtual uint64 Read8(uint32 addr) {
+	uint64 Read8(uint32 addr) override {
 		if ((addr & 1) == 0) {
 			return T::Read(Decoder(addr)) >> 8;
 		} else {
 			return T::Read(Decoder(addr)) & 0xff;
 		}
 	}
-	virtual uint64 Read16(uint32 addr) {
+	uint64 Read16(uint32 addr) override {
 		return T::Read(Decoder(addr));
 	}
 
-	virtual uint64 Write8(uint32 addr, uint32 data) {
-		PANIC("not implemented\n");
-		return (int64)-1;	// XXX 未確認
+	uint64 Write8(uint32 addr, uint32 data) override {
+		uint32 offset = Decoder(addr);
+		uint32 old = T::Read(offset);
+		if ((addr & 1) == 0) {
+			return T::Write(offset, ((data << 8) & 0xff00) | (old & 0x00ff));
+		} else {
+			return T::Write(offset, (old & 0xff00) | (data & 0x00ff));
+		}
 	}
-	virtual uint64 Write16(uint32 addr, uint32 data) {
+	uint64 Write16(uint32 addr, uint32 data) override {
 		return T::Write(Decoder(addr), data);
 	}
 
 
-	virtual uint64 Peek8(uint32 addr) {
+	uint64 Peek8(uint32 addr) override {
 		if ((addr & 1) == 0) {
 			return T::Peek(Decoder(addr)) >> 8;
 		} else {
@@ -98,29 +104,29 @@ class BusIO_BE: public T
 	}
 
  public:
-	virtual uint64 Read8(uint32 addr) {
+	uint64 Read8(uint32 addr) override {
 		if ((addr & 1) == 0) {
 			return T::Read(Decoder(addr));
 		} else {
 			return (int64)-1;
 		}
 	}
-	virtual uint64 Read16(uint32 addr) {
+	uint64 Read16(uint32 addr) override {
 		return (T::Read(Decoder(addr)) << 8) | 0xff;
 	}
 
-	virtual uint64 Write8(uint32 addr, uint32 data) {
+	uint64 Write8(uint32 addr, uint32 data) override {
 		if ((addr & 1) == 0) {
 			return T::Write(Decoder(addr), data);
 		} else {
 			return (int64)-1;
 		}
 	}
-	virtual uint64 Write16(uint32 addr, uint32 data) {
+	uint64 Write16(uint32 addr, uint32 data) override {
 		return T::Write(Decoder(addr), data >> 8);
 	}
 
-	virtual uint64 Peek8(uint32 addr) {
+	uint64 Peek8(uint32 addr) override {
 		if ((addr & 1) == 0) {
 			return T::Peek(Decoder(addr));
 		} else {
@@ -139,29 +145,29 @@ class BusIO_EB: public T
 	}
 
  public:
-	virtual uint64 Read8(uint32 addr) {
+	uint64 Read8(uint32 addr) override {
 		if ((addr & 1) == 0) {
 			return (int64)-1;
 		} else {
 			return T::Read(Decoder(addr));
 		}
 	}
-	virtual uint64 Read16(uint32 addr) {
+	uint64 Read16(uint32 addr) override {
 		return T::Read(Decoder(addr)) | 0xff00;
 	}
 
-	virtual uint64 Write8(uint32 addr, uint32 data) {
+	uint64 Write8(uint32 addr, uint32 data) override {
 		if ((addr & 1) == 0) {
 			return (int64)-1;
 		} else {
 			return T::Write(Decoder(addr), data);
 		}
 	}
-	virtual uint64 Write16(uint32 addr, uint32 data) {
+	uint64 Write16(uint32 addr, uint32 data) override {
 		return T::Write(Decoder(addr), data & 0xff);
 	}
 
-	virtual uint64 Peek8(uint32 addr) {
+	uint64 Peek8(uint32 addr) override {
 		if ((addr & 1) == 0) {
 			return (int64)-1;
 		} else {
@@ -170,6 +176,47 @@ class BusIO_EB: public T
 	}
 };
 
+// バイトデバイスを奇数アドレスに配置し、偶数アドレスは非接続。
+template <class T>
+class BusIO_FB: public T
+{
+ private:
+	inline uint32 Decoder(uint32 addr) {
+		return (addr >> 1) & (T::NPORT - 1);
+	}
+
+ public:
+	uint64 Read8(uint32 addr) override {
+		if ((addr & 1) == 0) {
+			return 0xff;
+		} else {
+			return T::Read(Decoder(addr));
+		}
+	}
+	uint64 Read16(uint32 addr) override {
+		return T::Read(Decoder(addr)) | 0xff00;
+	}
+
+	uint64 Write8(uint32 addr, uint32 data) override {
+		if ((addr & 1) == 0) {
+			return 0;
+		} else {
+			return T::Write(Decoder(addr), data);
+		}
+	}
+	uint64 Write16(uint32 addr, uint32 data) override {
+		return T::Write(Decoder(addr), data & 0xff);
+	}
+
+	uint64 Peek8(uint32 addr) override {
+		if ((addr & 1) == 0) {
+			return 0xff;
+		} else {
+			return T::Peek(Decoder(addr));
+		}
+	}
+};
+
 // バイトデバイスをロングワードの先頭に配置し、他は非接続。
 template <class T>
 class BusIO_BFFF: public T
@@ -180,43 +227,43 @@ class BusIO_BFFF: public T
 	}
 
  public:
-	virtual uint64 Read8(uint32 addr) {
+	uint64 Read8(uint32 addr) override {
 		if ((addr & 3) == 0) {
 			return T::Read(Decoder(addr));
 		} else {
 			return 0xff;
 		}
 	}
-	virtual uint64 Read16(uint32 addr) {
+	uint64 Read16(uint32 addr) override {
 		if ((addr & 2) == 0) {
 			return (T::Read(Decoder(addr)) << 8) | 0xff;
 		} else {
 			return 0xffff;
 		}
 	}
-	virtual uint64 Read32(uint32 addr) {
+	uint64 Read32(uint32 addr) override {
 		return (T::Read(Decoder(addr)) << 24) | 0x00ffffff;
 	}
 
-	virtual uint64 Write8(uint32 addr, uint32 data) {
+	uint64 Write8(uint32 addr, uint32 data) override {
 		if ((addr & 3) == 0) {
 			return T::Write(Decoder(addr), data);
 		} else {
 			return 0;
 		}
 	}
-	virtual uint64 Write16(uint32 addr, uint32 data) {
+	uint64 Write16(uint32 addr, uint32 data) override {
 		if ((addr & 2) == 0) {
 			return T::Write(Decoder(addr), data >> 8);
 		} else {
 			return 0;
 		}
 	}
-	virtual uint64 Write32(uint32 addr, uint32 data) {
+	uint64 Write32(uint32 addr, uint32 data) override {
 		return T::Write(Decoder(addr), data >> 24);
 	}
 
-	virtual uint64 Peek8(uint32 addr) {
+	uint64 Peek8(uint32 addr) override {
 		if ((addr & 3) == 0) {
 			return T::Peek(Decoder(addr));
 		} else {
@@ -234,26 +281,26 @@ class BusIO_WW: public T
 		return (addr >> 2) & (T::NPORT - 1);
 	}
  public:
-	virtual uint64 Read8(uint32 addr) {
+	uint64 Read8(uint32 addr) override {
 		if ((addr & 1) == 0) {
 			return T::Read(Decoder(addr)) >> 8;
 		} else {
 			return T::Read(Decoder(addr)) & 0xff;
 		}
 	}
-	virtual uint64 Read16(uint32 addr) {
+	uint64 Read16(uint32 addr) override {
 		return T::Read(Decoder(addr));
 	}
 
-	virtual uint64 Write8(uint32 addr, uint32 data) {
+	uint64 Write8(uint32 addr, uint32 data) override {
 		PANIC("not implemented\n");
 		return (int64)-1;	// XXX 未確認
 	}
-	virtual uint64 Write16(uint32 addr, uint32 data) {
+	uint64 Write16(uint32 addr, uint32 data) override {
 		return T::Write(Decoder(addr), data);
 	}
 
-	virtual uint64 Peek8(uint32 addr) {
+	uint64 Peek8(uint32 addr) override {
 		if ((addr & 1) == 0) {
 			return T::Peek(Decoder(addr)) >> 8;
 		} else {
@@ -271,7 +318,7 @@ class BusIO_WF: public T
 		return (addr >> 2) & (T::NPORT - 1);
 	}
  public:
-	virtual uint64 Read8(uint32 addr) {
+	uint64 Read8(uint32 addr) override {
 		switch (addr & 3) {
 		 case 0:
 			return T::Read(Decoder(addr)) >> 8;
@@ -283,7 +330,7 @@ class BusIO_WF: public T
 		}
 		__unreachable();
 	}
-	virtual uint64 Read16(uint32 addr) {
+	uint64 Read16(uint32 addr) override {
 		if ((addr & 2) == 0) {
 			return T::Read(Decoder(addr));
 		} else {
@@ -291,18 +338,18 @@ class BusIO_WF: public T
 		}
 	}
 
-	virtual uint64 Write8(uint32 addr, uint32 data) {
+	uint64 Write8(uint32 addr, uint32 data) override {
 		PANIC("not implemented\n");
 		return 0;	// XXX 未確認
 	}
-	virtual uint64 Write16(uint32 addr, uint32 data) {
+	uint64 Write16(uint32 addr, uint32 data) override {
 		if ((addr & 2) == 0) {
 			return T::Write(Decoder(addr), data);
 		} else {
 			return 0;
 		}
 	}
-	virtual uint64 Peek8(uint32 addr) {
+	uint64 Peek8(uint32 addr) override {
 		switch (addr & 3) {
 		 case 0:
 			return T::Peek(Decoder(addr)) >> 8;
@@ -331,7 +378,7 @@ class BusIO_X68kSPC : public T
 	}
 
  public:
-	virtual uint64 Read8(uint32 addr) {
+	uint64 Read8(uint32 addr) override {
 		if ((addr & 1) == 0) {
 			return (uint64)-1;
 		} else {
@@ -345,7 +392,7 @@ class BusIO_X68kSPC : public T
 			}
 		}
 	}
-	virtual uint64 Read16(uint32 addr) {
+	uint64 Read16(uint32 addr) override {
 		addr = Decoder(addr);
 		if (addr < 0x10) {
 			// 前半16ポートは SASI 跡地
@@ -355,7 +402,7 @@ class BusIO_X68kSPC : public T
 		}
 	}
 
-	virtual uint64 Write8(uint32 addr, uint32 data) {
+	uint64 Write8(uint32 addr, uint32 data) override {
 		if ((addr & 1) == 0) {
 			return (uint64)-1;
 		} else {
@@ -370,7 +417,7 @@ class BusIO_X68kSPC : public T
 			}
 		}
 	}
-	virtual uint64 Write16(uint32 addr, uint32 data) {
+	uint64 Write16(uint32 addr, uint32 data) override {
 		addr = Decoder(addr);
 		if (addr < 0x10) {
 			// 前半16ポートは SASI 跡地。
@@ -382,7 +429,7 @@ class BusIO_X68kSPC : public T
 		}
 	}
 
-	virtual uint64 Peek8(uint32 addr) {
+	uint64 Peek8(uint32 addr) override {
 		if ((addr & 1) == 0) {
 			return (uint64)-1;
 		} else {