matos/core/io.h
2024-01-29 23:27:10 +01:00

33 lines
1017 B
C

#pragma once
#include "stdint.h"
// NIH http://wiki.osdev.org/Inline_Assembly/Examples#I.2FO_access
static inline void outb(uint16_t port, uint8_t val)
{
asm volatile("outb %0, %1" : : "a"(val), "Nd"(port));
/* There's an outb %al, $imm8 encoding, for compile-time constant port numbers that fit in
* 8b. (N constraint). Wider immediate constants would be truncated at assemble-time (e.g.
* "i" constraint). The outb %al, %dx encoding is the only option for all other cases.
* %1 expands to %dx because port is a uint16_t. %w1 could be used if we had the port
* number a wider C type */
}
static inline void outw(uint16_t port, int16_t val)
{
asm volatile("outw %w0, %w1" :: "a"(val), "Nd"(port));
}
static inline uint8_t inb(uint16_t port)
{
uint8_t ret;
asm volatile("inb %1, %0" : "=a"(ret) : "Nd"(port));
return ret;
}
static inline uint16_t inw(uint16_t port)
{
uint16_t ret;
asm volatile("inw %w1, %0" : "=a"(ret) : "Nd"(port));
return ret;
}