22 lines
799 B
C
22 lines
799 B
C
#pragma once
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#include "stdarg.h"
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// NIH http://wiki.osdev.org/Inline_Assembly/Examples#I.2FO_access
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static inline void outb(uint16_t port, uint8_t val)
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{
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asm volatile ( "outb %0, %1" : : "a"(val), "Nd"(port) );
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/* There's an outb %al, $imm8 encoding, for compile-time constant port numbers that fit in 8b. (N constraint).
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* Wider immediate constants would be truncated at assemble-time (e.g. "i" constraint).
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* The outb %al, %dx encoding is the only option for all other cases.
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* %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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}
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static inline uint8_t inb(uint16_t port)
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{
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uint8_t ret;
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asm volatile ( "inb %1, %0"
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: "=a"(ret)
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: "Nd"(port) );
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return ret;
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}
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