AND

Table of Contents

1. AND (and)
   1. Basic function
   2. Instruction format
   3. Behavioral characteristics
   4. Example
   5. Common uses

AND (and)

Basic function

AND performs a bitwise logical AND operation:

1
x1 = x1 & x2

Instruction format

1
and x1, x2

x1 can be a register or memory
x2 is a register or an immediate value
but memory-to-memory is not allowed

Behavioral characteristics

• Commonly used for bit clearing
• ZF is set if the result is all zeros
• OF and CF are cleared
• It does not produce a carry concept, because it is a logical operation

Example

1
and eax, 0xFF
2
; 保留低 8 位
3

4
and rax, rbx
5
and [rbp-0x8], 0x1

Common uses

• Masking operations —> IP&24 subnet mask
• Bit condition checking
• Alignment calculations (such as aligning an address to 4, 8, or 16 bytes)

For example, aligning to 16 bytes:

1
and rsp, -0x10