X86 assembly syntax: at & T and Intel

Assembly language source code mainly adopts two kinds of Syntax ：AT&T Grammar and Intel grammar .

They all belong to the second generation language , But the syntax of both is in variables 、 Constant 、 Register access 、 Segment and instruction size overrides 、 There are great differences in indirect address recording and offset .

AT&T Assembly syntax % As the front buffer of all register names , With $ As a literal constant （ Also called immediate operands ） Slow forward .

It sorts the operands like this ： The source operand is on the left , The destination operand is on the right .
Use AT&T grammar ,EAX Register plus 4 Today is ：add $0×4 , %eax.

GNU Assembler （Gas） And many others GNU Tools （ Such as gcc and gdb） All use AT&T grammar .
Intel Syntax and AT&T The grammar is different , It does not require registers and text preambles .

Its operands are sorted in the same way as AT&T The syntax operands are just the opposite ： The source operand is on the right , The destination operand is on the left .

Use Intel grammar , The instruction of the above addition is ：add eax 0×4 .

Use Intel Syntax assemblers include Microsoft assembler （MASM）、Borland Of Turbo Assembler （TASM） and Netwide Assembler （NASM）