Re: Buffers in Assembly (NASM)

On Jul 19, 1:18 am, ArarghMail807NOSPAM <spamt...@xxxxxxxxxx> wrote:
But how do I zero out the buffer on the stack? In C, I would just do
something like:

char buffer[64] = {0};

Which does what I show below.

What's the equivalent in assembly using NASM?

This will work for either the stack, or bss: (baring typos)
xor al,al
mov ecx,64
lea edi,buffer ; may need [] ?
rep stosb

OR:
xor eax,eax
mov ecx,16
lea edi,buffer ; may need [] ?
rep stosd

That works well. I just did this:

sub esp, 64
mov dword edi, esp ;store the location of the beginning of the buffer
in edi

xor eax, eax ; make sure al is zero for the call to stosb
mov dword ecx, 64 ; set counter to 64
rep stosb ; repeat stosb 64 times -- this could be done faster with
stosd 16?

Does stosb move up the stack by default or do I need to explicitly
specify the direction with cld?

Thanks,

Brian

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