Add more instructions. Fix JR bug. Start implementation of IO R/W

gb/io.go

@@ -0,0 +1,46 @@
+package gb
+
+import (
+	"fmt"
+	"os"
+)
+
+var SerialData [2]byte
+
+func IORead(address uint16) byte {
+	if address == 0xFF01 {
+		return SerialData[0]
+	}
+
+	if address == 0xFF02 {
+		return SerialData[1]
+	}
+
+	if (address >= 0xFF04) && (address <= 0xFF07) {
+		fmt.Printf("Reading from IO: invalid address %X. Timer not yet implemented!", address)
+		os.Exit(1)
+	}
+
+	fmt.Printf("Reading from IO: invalid address %X", address)
+	os.Exit(1)
+
+	return 0
+}
+
+func IOWrite(address uint16, value byte) {
+	if address == 0xFF01 {
+		SerialData[0] = value
+	}
+
+	if address == 0xFF02 {
+		SerialData[1] = value
+	}
+
+	if (address >= 0xFF04) && (address <= 0xFF07) {
+		fmt.Printf("Writing to IO: invalid address %X. Timer not yet implemented!", address)
+		os.Exit(1)
+	}
+
+	fmt.Printf("Writing to IO: invalid address %X", address)
+	os.Exit(1)
+}