[Help] - Digit Sum

[nidud]

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[dedndave]

i don't know what alloca does
but it looks fine to me

Gunther
the code you posted balances the stack
it has no locals to balance out

try writing a proc that has locals - then disassemble it to examine how the stack is balanced
the way i write them, i create locals, including large buffers, and don't worry about balancing the stack

[nidud]

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[dedndave]

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mov esp,ebp
pop ebp

equiv of LEAVE

[nidud]

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[dedndave]

my mistake - it does have 2 dwords

but, what if you want to create a buffer later on
in fact, i often calculate, then push, locals as the routine progresses
it just seems much more elegant to do it that way

i'm right - you're wrong   :lol:

[nidud]

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[jj2007]

i don't know what alloca does but it looks fine to me

It's one of many C functions and methods that manipulates the stack within a procedure which forces the compiler to push the user registers before the stack frame is created. The popping of the three registers will for this reason fail.

_alloca allocates size bytes from the program stack.

How did you get alloca to work?

I tried this but both fail:

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includelib "C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\lib\libcmt.lib"
alloca PROTO C:DWORD
_alloca PROTO C:DWORD

[Gunther]

Dave,

Gunther
the code you posted balances the stack
it has no locals to balance out

a bit more concentration, please. My code has local variables, because:

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     sub        esp, 8

makes room for a REAL 8 or 2 INTEGER ... You can address it via EBP-8.

Gunther

[nidud]

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[nidud]

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[jj2007]

You may try this:

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_alloca PROTO C :DWORD

Which library? No such PROTO in \Masm32\include\*.inc ...

[nidud]

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[dedndave]

NTDLL.DLL has an export named "alloca_probe" (not prototyped in ntdll.inc, and thus not in ntdll.lib)

so, alloca could be a wrapper - or maybe a compiler internal ?

[Gunther]

Hi nidud,

a bit more concentration, please

You can address it via EBP+8.

you're right: It was a typing error. It's changed inside the original post now. I should be more concentrated, too.  :icon_redface:

Gunther