matos/core/io.h

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#pragma once
#include "stdarg.h"
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// 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 */
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}
static inline uint8_t inb(uint16_t port)
{
uint8_t ret;
asm volatile("inb %1, %0" : "=a"(ret) : "Nd"(port));
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return ret;
}