in the name of zero

i’ve only been slacking, eating and watching anime since summer started. this afternoon, i found the time to begin work on assemblifying a bash script i saw some days ago. the bash script has been modified already but it’s former function was simply a “for loop” wget to fetch a 0-22 page html version of a book - 1984. while i really didn’t achieve a boost in speed nor a significant cut in file size over the bash counterpart, the activity presented me a scenario where i had to do string and buffer manipulations in asm. also, i cheated, since i used extern printf print the strings. the program’s current size is 8.0 kilobytes which is double the size of the bash script. though i can pass the fault to gcc, linking of additional sections to produce the final elf object.

nothing much from this one really. again, some things are better off scripted. check her site out for even shorter suggestions. anyway, the program is complete now. here goes.

; miss godiane's wget sript assemblified
	
extern printf
	
        global main
section .text
main
        push ebp
        mov ebp, esp
        and esp, -0x10
	
        mov ecx, (url2 - url1)  ; construct website domain
        mov esi, url1
        mov edi, buf
        cld
rep     movsb
	
        xor ecx, ecx            ; initialize
	
_loop
        push edi                ; save offset address
        push ecx                ; save counter value
	
        mov eax, ecx            ; accumulator holds it now
        mov cl, 0xa             ; divisor value
        div cl
	
        test al, al             ; two digit number?
        jz _ones
	
        add al, 0x30            ; deal with tens place
        mov byte [edi], al
        inc edi
_ones
        add ah, 0x30            ; deal with ones place
        mov byte [edi], ah
	
        inc edi                 ; append html extension
        mov ecx, (eurl - url2)
        mov esi, url2
rep     movsb
	
        push st
        call printf
        pop edx                 ; clear the stack
	
        mov byte [wget+13], 0x0
        lea dword ebx, [wget]
        mov dword [wget+14], ebx
        lea dword ebx, [buf]
        mov dword [wget+18], ebx
        xor edx, edx
        mov dword [wget+22], edx
	
        mov eax, 0xb            ; sys_execve
        mov ebx, wget
        lea ecx, [wget+14]
        xor edx, edx
        int 0x80
	
        pop ecx                 ; restor counter value
        pop edi                 ; restore offset address
	
        inc ecx                 ; next html page please.
        cmp ecx, 22             ; are we there yet?
        jle _loop               ; 'til 22.html only
	
_exit
        xor eax, eax            ; graceful exit
        leave
        ret
	
section .data
        wget    db '/usr/bin/wget stefanieNULL'
        st      db 'Getting part %d of 22 of 1984',0xa,0x0
        url1    db 'http://www.george-orwell.org/1984/'
        url2    db '.html',0x0
        eurl
	
section .bss
        buf     resb 500