Stack Alignment D
D-7
Example D-2 Aligned ebp-based Stack Frames
void _stdcall foo (int k)
{
int j;
foo:
push ebx
mov ebx, esp
sub esp, 0x00000008
and esp, 0xfffffff0
add esp, 0x00000008 // esp is (8 mod 16)
after add
jmp common
foo.aligned:
push ebx // esp is (8 mod 16)
after push
mov ebx, esp
common:
push ebp // this slot will be
used for
// duplicate return pt
push ebp // esp is (0 mod 16)
after push
// (rtn,ebx,ebp,ebp)
mov ebp, [ebx + 4] // fetch return pointer
and store
mov [esp + 4], ebp // relative to ebp
// (rtn,ebx,rtn,ebp)
mov ebp, esp // ebp is (0 mod 16)
sub esp, 28 // esp is (4 mod 16)
//see Note A
push edx // esp is (0 mod 16)
after push
continued
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