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+#ifndef FOOLOS_X86_H
+#define FOOLOS_X86_H
+
+/**
+ * @file
+ *
+ * X86 32-bit Basics
+ * =================
+ *
+ * **All the functions are very specific to the targeted x86 architecture.**
+ *
+ * This is the header of our basic **x86** function definitions.
+ * Most of the functions are implemented in assembler in the file _asm/x86.s_,
+ * however a few short helper functions are defined in this header itself:
+ *
+ * * x86_set_page_directory()
+ * * x86_paging_enable()
+ * * x86_paging_disable()
+ *
+ *
+ * Reading and Writing Ports
+ * -------------------------
+ *
+ * The functions of the form x86_outX() and x86_inX(), where the X 
+ * indicates the value size allow reading and writing ports.
+ *
+ * * x86_outb() / x86_inb()
+ * * x86_outw() / x86_inw()
+ * * x86_outl() / x86_inl()
+ *
+ * The sizes are:
+ *
+ * * b - byte (8 bit)
+ * * w - word (16 bit)
+ * * l - double word (32 bit)
+ *
+ * Remember, that the port address is always 32 bits wide.
+ *
+ * Dependencies
+ * ------------
+ *
+ * All we need are uint32_t, uint16_t and uint8_t as provided by <stdint.h>
+ *
+ * References
+ * ----------
+ * * http://wiki.osdev.org/Interrupt_Service_Routines
+ * * https://wiki.osdev.org/CPU_Registers_x86
+ * * ...
+ *
+ */
+
+// we need uint32_t, uint16_t, uint8_t //
+#include <stdint.h>
+
+/** write byte to port */
+void     x86_outb (uint32_t port, uint8_t data);
+
+/** read byte from port */
+uint8_t  x86_inb  (uint32_t port);
+
+/** write word to port */
+void     x86_outw (uint32_t port, uint16_t data);
+
+/** read word from port */
+uint16_t x86_inw  (uint32_t port);
+
+/** write double word to port */
+void     x86_outl (uint32_t port, uint32_t data);
+
+/** read double word from port */
+uint32_t x86_inl  (uint32_t port);
+
+/** disable interrupts */
+void     x86_cli  ();
+
+/** enable interrupts */
+void     x86_sti  ();
+
+/** xchg - this can be used for semaphors and simlar */
+uint8_t  x86_xchg (uint8_t *addr, uint8_t val);
+
+/** invlpg - invalidate translation lookaside buffer */
+void     x86_invlpg(uint32_t addr);
+
+/** read value from control register specified by num */
+uint32_t x86_get_cr(uint8_t num);
+
+/** write given value to the control register specified by num */
+void     x86_set_cr(uint8_t num, uint32_t value);
+
+/** Set the address of the page directory. This is required **before** enabling paging */
+static inline void x86_set_page_directory(uint32_t pdir_addr) {x86_set_cr(3,pdir_addr);}
+
+/** Enable paging */
+static inline void x86_paging_enable()    {x86_set_cr(0,x86_get_cr(0)| 0x80000000);}
+
+/** Disable paging */
+static inline void x86_paging_disable()   {x86_set_cr(0,x86_get_cr(0)&~0x80000000);}
+
+#endif