What does dword ptr mean?
the size of
Basically, it means “the size of the target operand is 32 bits”, so this will bitwise-AND the 32-bit value at the address computed by taking the contents of the ebp register and subtracting four with 0.
What is PTR in assembly language?
The dword ptr means “write a doubleword”. Yes, it stands for pointer, because you put a memory address as destination.
What does the PTR operator do?
The PTR operator may be used to override the default type of the operand. When specifying pointer overrides, the PTR keyword is optional and may be omitted. The BIT PTR type may be applied only on bits—it is not possible to change the access type from some other type to a BIT type.
What is dword in x86 assembly?
DWORD defines ‘size’ of the memory location used for move operation. In you example, you’d be moving 0000000Ah (4 bytes) into memory location ESP+18h. As 0Ah is immediate value its size cannot be determined without using DWORD , WORD , BYTE or other similar qualifier.
What is the EAX register?
EAX register, a 32-bit processor register of x86 CPUs. Environmental Audio Extensions, a number of digital signal processing presets for audio, found in Sound Blaster sound cards.
How big is a word in x86?
16 bits
In the x86 PC (Intel, AMD, etc.), although the architecture has long supported 32-bit and 64-bit registers, its native word size stems back to its 16-bit origins, and a “single” word is 16 bits. A “double” word is 32 bits. See 32-bit computer and 64-bit computer.
What is Lea Assembly?
lea — Load effective address. The lea instruction places the address specified by its first operand into the register specified by its second operand. Note, the contents of the memory location are not loaded, only the effective address is computed and placed into the register.
What is near and far procedure?
A near call refers a procedure which is in the same code segment. A Far call refers a procedure which is in different code segment It is also called Intra-segment call. It is also called Inter-segment call A Near Call replaces the old IP with new IP A FAR replaces CS & IP with new CS & IP.
What is byte ptr?
byte ptr -> it simply means that you want to fetch a byte from the address. if it said word ptr or dword ptr , you would get a word or dword from the address in source index.
What is the size of DWORD?
Windows 64-bit applications
| Name | Length |
|---|---|
| wchar_t | 2 bytes |
| WORD | 2 bytes |
| DWORD | 4 bytes |
| HANDLE | 8 bytes |
What is x86 Al?
al and ah are the 8-bit, “char” size registers. al is the low 8 bits, ah is the high 8 bits. They’re pretty similar to the old 8-bit registers of the 8008 back in 1972.
What does the EAX register do?
EAX,AX,AH,AL : Called the Accumulator register. It is used for I/O port access, arithmetic, interrupt calls, etc…
When to use DWORD _ PTR in 32 bit?
A DWORD_PTR is an unsigned long type used for pointer precision. It is used when casting a pointer to an unsigned long type to perform pointer arithmetic. DWORD_PTR is also commonly used for general 32-bit parameters that have been extended to 64 bits in 64-bit Windows.
What does the SIZE directive in dword PTR mean?
The dword ptr part is called a size directive. This page explains them, but it wasn’t possible to direct-link to the correct section. Basically, it means “the size of the target operand is 32 bits”, so this will bitwise-AND the 32-bit value at the address computed by taking the contents of the ebp register and subtracting four with 0.
What does The Dword ptrpart mean in Assembly?
The dword ptrpart is called a size directive. This pageexplains them, but it wasn’t possible to direct-link to the correct section. Basically, it means “the size of the target operand is 32 bits”, so this will bitwise-AND the 32-bit value at the address computed by taking the contents of the ebpregister and subtracting four with 0.
Can a pointer fit into a dword _ ptrbut notinto?
A pointer, however, is guaranteed to fit into a DWORD_PTRbut notinto a DWORDon 64-bit platforms. Thus, this code is correct: