port_io.h

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/**
 * @file port_io.h
 * @brief c wrappers for asm port operations
 */
#ifndef _HAL_PORT_IO_H
#define _HAL_PORT_IO_H
 
#include "stdint.h"
 
/**
 * @brief read byte from low level port
 * @param port port to read from
 * @return value in port
 */
static inline uint8_t inb(uint16_t port) {
        uint8_t result;
        __asm__ volatile(
                        "inb %1, %0"
                        : "=a" (result)
                        : "Nd" (port));
        return result;
}
 
/**
 * @brief write byte to low level port
 * @param port port to write to
 * @param val value to write to port
 */
static inline void outb(uint16_t port, uint8_t val) {
        __asm__ volatile(
                        "outb %0, %1"
                        :
                        : "a" (val), "Nd" (port));
}
 
/**
 * @brief read word from low level port
 * @param port port to read from
 * @return value in port
 */
static inline uint16_t inw(uint16_t port) {
        uint16_t result;
        __asm__ volatile(
                        "inw %1, %0"
                        : "=a" (result)
                        : "Nd" (port));
        return result;
}
 
/**
 * @brief write word to low level port
 * @param port port to write to
 * @param val value to write to port
 */
static inline void outw(uint16_t port, uint16_t val) {
        __asm__ volatile(
                        "outw %0, %1"
                        :
                        : "a" (val), "Nd" (port));
}
 
/**
 * @brief read double word from low level port
 * @param port port to read from
 * @return value in port
 */
static inline uint32_t inl(uint16_t port) {
        uint32_t result;
        __asm__ volatile(
                        "inl %1, %0"
                        : "=a" (result)
                        : "Nd" (port));
        return result;
}
 
/**
 * @brief write double word to low level port
 * @param port port to write to
 * @param val value to write to port
 */
static inline void outl(uint16_t port, uint32_t val) {
        __asm__ volatile(
                        "outl %0, %1"
                        :
                        : "a" (val), "Nd" (port));
}
 
/**
 * @brief perform a short wait (1-4 microseconds)
 *
 * This function outputs to a random unused port (0x80 is almost always unused after booting)
 * Since output takes some time, this function can work as a small wait
 */
static inline void io_wait(void) {
    outb(0x80, 0);
}
 
#endif