a minimal working demo on bare metal

2 files changed, 77 insertions, 6 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
diff --git a/src/arch/x86_64/asm/startup.s b/src/arch/x86_64/asm/startup.s
index 4c696e1..7b5bbff 100644
--- a/src/arch/x86_64/asm/startup.s
+++ b/src/arch/x86_64/asm/startup.s
@@ -17,7 +17,7 @@
 ;   Constants
 ;
 
-; stack for the main function
+; stack for the main function (renamed to _entry())
 STACKSIZE: equ 65536
 
 ; video memory base address
@@ -59,8 +59,8 @@ pagetable_end:  equ 0x200000
 [GLOBAL _ZdlPvm]
 
 ; functions from the C parts of the system
-[EXTERN main]
-[EXTERN guardian]
+[EXTERN _entry]
+;[EXTERN guardian]
 
 ; addresses provided by the compiler
 [EXTERN ___BSS_START__]
@@ -204,7 +204,7 @@ fill_tables3_done:
 ;   system start, part 2 (in 64-bit Long Mode)
 ;
 ;   This code clears the BSS segment and initializes IDT and PICs. Then the
-;   constructors of global C++ objects are called, and finally main() is run.
+;   constructors of global C++ objects are called, and finally _entry() is run.
 ;
 
 longmode_start:
@@ -234,7 +234,7 @@ clear_bss:
 	;mov cr4, rax
 
 	call   _init   ; call constructors of global objects
-	call   main    ; call the OS kernel's C / C++ part
+	call   _entry  ; call the OS kernel's C / C++ part
 	call   _fini   ; call destructors
 	cli            ; Usually we should not get here.
 	hlt
@@ -279,7 +279,7 @@ wrapper_body:
 
 	; pass interrupt number as the first parameter
 	mov    rdi, rax
-	call   guardian
+;	call   guardian
 
 	; restore volatile registers
 	pop    r11