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+/*
+ * Copyright (c) 2017 Richard Braun.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ *
+ * I/O ports access.
+ *
+ * The x86 architecture is special in that, in addition to the physical memory
+ * address space, it also has an I/O port space. Most modern processors use
+ * the physical memory address space to access memory-mapped device memory and
+ * registers, and that's also the case on x86, but the I/O port space is also
+ * used for this purpose, at least for some legacy devices.
+ */
+
+#ifndef _IO_H
+#define _IO_H
+
+#include <stdint.h>
+
+/*
+ * Read a byte from an I/O port.
+ */
+uint8_t io_read(uint16_t port);
+
+/*
+ * Write a byte to an I/O port.
+ */
+void io_write(uint16_t port, uint8_t byte);
+
+#endif /* _IO_H */