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add: Add two values, returning a new value. Base instruction 0xD6 add.ovf: Add signed integer values with overflow check. Base instruction 0xD7 add.ovf.un: Add unsigned integer values with overflow check. Base instruction 0x5F and: Bitwise AND of two integral values, returns an integral value. Base instruction 0xFE 0x00 arglist
In computer programming, assembly language (alternatively assembler language [1] or symbolic machine code), [2] [3] [4] often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. [5]
Code that adds two numbers in x86 assembly language, where eax and edx specify two different general-purpose registers: add eax , edx Code in an intermediate language (IL), where 0 is eax and 1 is edx:
11111110 is the two's complement form of signed integer −2. If 11111111 represents unsigned integer binary number 255 (ADD al,255), then the interpretation of the result would be 254, which is not correct, because the most significant bit of the result went into the Carry_Flag, which therefore cannot be ignored.
x86 assembly language has two primary syntax branches: Intel syntax and AT&T syntax. [6] Intel syntax is dominant in the DOS and Windows environments, while AT&T syntax is dominant in Unix-like systems, as Unix was originally developed at AT&T Bell Labs. [7] Below is a summary of the main differences between Intel syntax and AT&T syntax:
Translation of assembly language into machine language. A much more human-friendly rendition of machine language, named assembly language, uses mnemonic codes to refer to machine code instructions, rather than using the instructions' numeric values directly, and uses symbolic names to refer to storage locations and sometimes registers. [3]
An example, suppose we add 127 and 127 using 8-bit registers. 127+127 is 254, but using 8-bit arithmetic the result would be 1111 1110 binary, which is the two's complement encoding of −2, a negative number. A negative sum of positive operands (or vice versa) is an overflow.
INT is an assembly language instruction for x86 processors that generates a software interrupt. It takes the interrupt number formatted as a byte value. [1] When written in assembly language, the instruction is written like this: INT X. where X is the software interrupt that should be generated (0-255).