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;***************************************************************************
;* Operating-System Construction *
;*---------------------------------------------------------------------------*
;* *
;* I O _ P O R T *
;* *
;*---------------------------------------------------------------------------*
;* The functions defined here encapsulate the machine instructions 'in' and *
;* 'out' for class IO_Port. *
;*****************************************************************************
; EXPORTED FUNCTIONS
[GLOBAL _outb]
[GLOBAL _outw]
[GLOBAL _inb]
[GLOBAL _inw]
; FUNCTION IMPLEMENTATIONS
[SECTION .text]
; OUTB: Byte-wise output via an I/O port.
;
; C prototype: void outb (int port, int value);
_outb:
push rbp
mov rbp, rsp
mov rdx, rdi
mov rax, rsi
out dx, al
pop rbp
ret
; OUTW: Word-wise output via an I/O port.
;
; C prototype: void outw (int port, int value);
_outw:
push rbp
mov rbp, rsp
mov rdx, rdi
mov rax, rsi
out dx, ax
pop rbp
ret
; INB: Byte-wise input via an I/O port.
;
; C prototype: unsigned char inb (int port);
_inb:
push rbp
mov rbp, rsp
mov rdx, rdi
in al, dx
pop rbp
ret
; INW: Word-wise input via an I/O port.
;
; C prototype: unsigned short inw (int port);
_inw:
push rbp
mov rbp, rsp
mov rdx, rdi
in ax, dx
pop rbp
ret
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