22 lines
798 B
C
22 lines
798 B
C
#pragma once
|
|
#include "types.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 uint8_t inb(uint16_t port)
|
|
{
|
|
uint8_t ret;
|
|
asm volatile ( "inb %1, %0"
|
|
: "=a"(ret)
|
|
: "Nd"(port) );
|
|
return ret;
|
|
}
|