CSC231 ledOn.asm

;;; -------------------------------------------------------------------
;;; ledON.asm
;;; D. Thiebaut
;;; This program turns the LED On on the Arduino stamp.
;;; The program simply writes an \r -terminated string to /dev/ttyUSB0
;;; that simply puts a 1 on Digital Pin 13.  The string is "w d 13 1\r"
;;;
;;;
;;; nasm -f elf ledON.asm
;;; nasm -f elf asm_io.asm
;;; gcc -m32 -o ledON driver.c asm_io.o ledON.o
;;; (use -m32 on 64-bit machines)
;;;
;;; Without the asm_io.* and driver.c wrappers, then link with
;;; ld -melf_i386 ledON.o -o ledON
;;; (use -melf_i386 on 64-bit machines)
;;;
;;; To Execute:
;;;
;;; ./ledON
;;;
;;; -------------------------------------------------------------------

%include "asm_io.inc"

%assign EXIT            1
%assign OPEN            5
%assign CLOSE           6
%assign READ            3
%assign CREATE          8
%assign WRITE           4
%assign STDOUT          1
%assign O_CREAT         64
%assign O_RDONLY        0
%assign O_WRONLY        1
%assign O_APPEND        1024
%assign O_RDWR          2
%assign S_IRUSR         00400q
%assign S_IWUSR         00200q
%assign S_IXUSR         00100q


;;;          ____        _
;;;         |  _ \  __ _| |_ __ _
;;;         | | | |/ _` | __/ _` |
;;;         | |_| | (_| | || (_| |
;;;         |____/ \__,_|\__\__,_|
;;;


          section        .data
errorMsg  db     "Error accessing file!",0x0a, 0
errorMsg1 db     "Error opening file!",0x0a, 0
usb       db     "/dev/ttyUSB0",0
handle    dd     0
noRead    dd     0
msg       db     "w d 13 1", 0x0d
msgLen    equ    $-msg

          section .bss
%assign   MAXBUF  100
buffer    resb    MAXBUF

;;;           ____          _
;;;          / ___|___   __| | ___
;;;         | |   / _ \ / _` |/ _ \
;;;         | |__| (_) | (_| |  __/
;;;          \____\___/ \__,_|\___|
;;;


        section .text

global  asm_main
asm_main:

;;; open file, write string, close file...

        mov     ebx, usb
        call    openFile
        mov     dword[handle], eax
        mov     ebx, [handle]
        mov     ecx, msg
        mov     edx, msgLen
        call    writeFile
        mov     ebx, dword[handle]
        call    closeFile
        
;;; we're done!
        ret

;;; if there's a problem, we exit right away
exit:
        mov     eax,EXIT
        mov     ebx,0
        int     0x80             ; final system call


;;; --------------------------------------------------------
;;; openFile
;;; put address of ASCIIZ file name in ebx
;;; handle returned in eax
;;; --------------------------------------------------------
openFile:
        mov     eax, OPEN
        mov     ecx,O_WRONLY | O_APPEND ; mode for opening file
        mov     edx,S_IRUSR | S_IWUSR
        int     0x80
        test    eax,eax         ; test for errors
        jns     doneOpenFile
        mov     eax, errorMsg1
        call    print_string
        jmp     exit
doneOpenFile:
        ret                     ; handle in eax

;;; --------------------------------------------------------
;;; closeFile: the handle must be in ebx on entry.
;;;               Closes the file
;;; --------------------------------------------------------
closeFile:
        mov     eax,CLOSE
        int     0x80
        ret

;;; --------------------------------------------------------
;;; readFile: on entry:
;;;                  handle in ebx
;;;                  buffer address in ecx
;;;                  max buffer length in edx
;;; on exit: number of chars read in eax
;;; --------------------------------------------------------
readFile:
        mov     eax,READ
        int     0x80
        test    eax,eax
        jns     doneReadFile
        mov     eax, errorMsg
        call    print_string
        jmp     exit
doneReadFile:
        ret


;;; --------------------------------------------------------
;;; writeFile:
;;; on entry:
;;;         handle is in ebx
;;;         buffer address is in ecx,
;;;         number of chars is in edx.
;;; --------------------------------------------------------
writeFile:
        mov     eax,WRITE
        int     0x80
        test    eax,eax
        jns     doneWriteFile
        mov     eax, errorMsg
        call    print_string
        jmp     exit
doneWriteFile:
        ret