push ebp
mov ebp, esp
sub esp, 18Creating a stackframe with size of local variables not divisible by 4 [asm]
Author
I'm writing some code in assembly and somehow I managed to write a standard function header which creates 18 bytes of space on the stack
In 32-bit stack mode (which Win32 uses), push and pop don't take any size operands, they automatically push or pop 4 bytes at a time. On 16-bit OS's such as DOS, they push/pop 2 at a time. There is some flag on the CPU to set this (from kernel mode).
Since push/pops work in this way, its a fatal error to have esp not divisible by the push/pop frame size.
I don't know exactly why the PC just freezes though.
Since push/pops work in this way, its a fatal error to have esp not divisible by the push/pop frame size.
I don't know exactly why the PC just freezes though.
Author
Enlightment [smile]
Probably this part of documentation confused me:
My theory for the freezing up, is bad return address when ret'ing window procedure...
And also: thanks for the reply [smile]
Oxyd
Probably this part of documentation confused me:
PUSH imm8 ; 6A ib [186] PUSH imm16 ; o16 68 iw [186] PUSH imm32 ; o32 68 id [386]My theory for the freezing up, is bad return address when ret'ing window procedure...
And also: thanks for the reply [smile]
Oxyd
No probs.
I'm a bit unsure what happens when you push a byte register onto the stack, presumably it zero extends or something like that.
This is also the reason that PC's need to boot up in real-mode (16-bit), I think you can only set the stack word size in this mode.
I'm a bit unsure what happens when you push a byte register onto the stack, presumably it zero extends or something like that.
This is also the reason that PC's need to boot up in real-mode (16-bit), I think you can only set the stack word size in this mode.
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