section .data
hello db ' ) Hello, world!',10 ; Our dear string
helloLen equ $ - hello ; Length of our dear string
section .bss
loopctr resd 1
looplimit resd 1
stringbuf resb 16 ; XXX - String for ASCII version of number (lib_print_number)
stringlen resb 1 ; XXX - Length of string (lib_print_number)
section .text
global _start
_start:
mov dword [loopctr],0
mov dword [looplimit],1000
pop ebx ; argc (argument count)
pop ebx ; argv[0] (argument 0, the program name)
pop ebx ; The first real arg, a filename
mov eax,8 ; The syscall number for creat() (we already have the filename in ebx)
mov ecx,00644Q ; Read/write permissions in octal (rw_rw_rw_)
int 80h ; Call the kernel ; Now we have a file descriptor in eax
test eax,eax ; Lets make sure the file descriptor is valid
js skipWrite ; If the file descriptor has the sign flag ; (which means it's less than 0) there was an oops, ; so skip the writing. Otherwise call the filewrite "procedure"
call fileWrite
skipWrite:
mov ebx,eax ; If there was an error, save the errno in ebx
mov eax,1 ; Put the exit syscall number in eax
int 80h ; Bail out
; proc fileWrite - write a string to a file
fileWrite:
mov ebx,eax ; sys_creat returned file descriptor into eax, now move into ebx
mov eax,4 ; sys_write ; ebx is already set up
mov ecx,hello ; We are putting the ADDRESS of hello in ecx
mov edx,helloLen ; This is the VALUE of helloLen because it's a constant (defined with equ)
jmp myloop
myloop:
call lib_print_number ; XXX - First write the contents of loopctr to the file
push eax
int 80h ; this is where my string is written so the print number needs to be called first
pop eax
inc dword [loopctr]
push edx
mov edx,[loopctr]
cmp dword edx,[looplimit]
pop edx
je end
jmp myloop
; endp fileWrite
end:
mov eax,6 ; sys_close (ebx already contains file descriptor)
int 80h
ret
lib_print_number: ; XXX from here to end of file -- all new
pusha
push ebx ; Save the file descriptor for now
mov eax, 0 ; Start converting number to ASCII
mov word ax, [loopctr]
mov edi, stringbuf
mov ebx, 10 ; Base of the decimal system
mov ecx, 0 ; Number of digits generated
.next_divide:
mov edx, 0 ; EAX extended to (EDX,EAX)
div ebx ; Divide by the number-base
push edx ; Save remainder on the stack
inc ecx ; And count this remainder
cmp eax, 0 ; Was the quotient zero?
jne .next_divide ; No, do another division
mov byte [stringlen], cl ; Save length of string
.next_digit:
pop eax ; Else pop recent remainder
add al, '0' ; And convert to a numeral
stosb ; Store to memory-buffer
loop .next_digit ; Again for other remainders
mov al, 10 ; Store carriage return char
stosb
; Now write the string to the screen
mov eax, 4 ; sys_write kernel call
pop ebx ; Get file descriptor back
mov ecx, stringbuf
mov edx, 0
mov byte dl, [stringlen]
int 0x80 ; Call kernel
popa
ret