a minimal working demo on bare metal

1 files changed, 71 insertions, 0 deletions

diff --git a/src/arch/x86_64/asm/io_port.s b/src/arch/x86_64/asm/io_port.s
index e69de29..9ddc4e6 100644
--- a/src/arch/x86_64/asm/io_port.s
+++ b/src/arch/x86_64/asm/io_port.s
@@ -0,0 +1,71 @@
+;***************************************************************************
+;* 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