decimal to unicode

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Overflowz

Joined: 03 Sep 2010
Posts: 1046

Overflowz 21 Oct 2012, 22:21

Hi. I'm having trouble about swapping for example AL register. I'm getting random value in eax, for example 123h and I want to convert it to unicode string. I'm trying to do it by division, but as I guess, I must store all results by reverse order.. Any other ways to do that? I tried this example for 2 bytes and works fine, but if I'll get more than 2 byte result, it will just stuck. Help Sad

Code:

;decimal to unicode.
        xor ebx,ebx
@@:
        mov ecx,10 ;base 10 system.
        xor edx,edx
        div ecx
        ;is it done yet?
        test eax,eax
        jz @f
        add edx,'0' ;make it ascii.
        xchg dh,dl ;now unicode.
        mov bx, dx
        shl ebx,16 ;bitshift for plasing another values.
        jmp @b
@@:
        ret

21 Oct 2012, 22:21

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 21 Oct 2012, 23:18

Since the architecture is little-endian storing DX without any swapping should already provide the wide character you need, so search the forum for an IntToStr implementation and modify it to store DX instead of DL.

21 Oct 2012, 23:18

Overflowz

Joined: 03 Sep 2010
Posts: 1046

Overflowz 21 Oct 2012, 23:33

You don't get me. I have e.g 123h decimal. When I'm converting to unicode, it must be written with big-endian.
if I get remainders first time 1, second time 2, and last time 3, it must be written as 3, 2 and 1.

21 Oct 2012, 23:33

AsmGuru62

Joined: 28 Jan 2004
Posts: 1561
Location: Toronto, Canada

AsmGuru62 22 Oct 2012, 04:05

This is possible solution:

Code:

;
; EAX = value to convert into string
; EDI = address of the UNICODE string buffer
;
UInt32_to_UNICODE:
    pusha
    xor    ebx, ebx    ; EBX = 0 to count digits in result

    push    10        ; ECX = 10
    pop    ecx

.divide_by_10:
    xor    edx, edx
    div    ecx

    add    dl, '0'        ; Store next digit into stack
    push    edx
    inc    ebx

    test    eax, eax    ; Is there more digits?
    jnz    .divide_by_10    ; Yes. Go back for more.
    ;
    ; At this point stack has EBX digits stored.
    ; These must be put into buffer at EDI.
    ;
    mov    ecx, ebx

.save_result:
    pop    eax
    stosw
    loop    .save_result
    ;
    ; Terminate string with null
    ;
    mov    [edi], cx
    popa
    ret

22 Oct 2012, 04:05

Overflowz

Joined: 03 Sep 2010
Posts: 1046

Overflowz 22 Oct 2012, 09:57

AsmGuru62
.......... HOW I FORGOT ABOUT STACK! I feel like a dumbass right now. Thank you, AsmGuru62!

22 Oct 2012, 09:57

AsmGuru62

Joined: 28 Jan 2004
Posts: 1561
Location: Toronto, Canada

AsmGuru62 22 Oct 2012, 14:27

This code assumes that Direction Flag is cleared, because for Win32 it is always cleared in User code.
If you're coding for your own OS, then probably, you should add CLD at the beginning of that procedure.

22 Oct 2012, 14:27

baldr

Joined: 19 Mar 2008
Posts: 1651

baldr 21 Nov 2012, 16:52

AsmGuru62 wrote:

If you're coding for your own OS, then probably, you should add CLD at the beginning of that procedure.

And save/restore it if calling/API conventions don't specify its state clearly. ;-)

21 Nov 2012, 16:52

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