C Language Development in Linux (at&t assembly language) 04

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It is also a x86 CPU, but it can be expressed in different forms of assembly languages. In Windows, we use intel-format assembly languages, while in Linux systems, at&t-format assembly languages are often used. What is at&t format assembly?CodeWhat about it? Let's write a try.

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2. . Data
4. Message:. String"Hello! \ N"
6. Length =.-Message
10. . Text
12. . Global _ start
16. _ Start:
18. Movl $ length, % edX
20. Movl $ message, % ECx
22. Movl $1, % EBX
24. Movl $4, % eax
26. Int$0x80
30. Movl $0, % EBX
32. Movl $1, % eax
34. Int$0x80

This is a simple assembly file. We can compile it in two steps. First, enter as-ststabs-O hello. O hello. s, and then enter LD-O hello. O. To verify whether the execution file is correct, enter./hello to verify.

In the as command, because we use the-gstabs option, debugging information is contained in the hello execution file. Therefore, if you want to debug in one step, you can input GDB hello for debugging.

So what is the code for the disassembly of the hello execution file? Enter objdump-s-d hello.

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2. 08048074 <_ Start>:
4. . Text
6. . Global _ start
10. _ Start:
12. Movl $ length, % edX
14. 8048074: BA 08 00 00 00 mov $0x8, % edX
16. Movl $ message, % ECx
18. 8048079: B9 9C 90 04 08 mov $ 0x804909c, % ECx
20. Movl $1, % EBX
22. 804807e: BB 01 00 00 00 mov $0x1, % EBX
24. Movl $4, % eax
26. 8048083: B8 04 00 00 00 mov $0x4, % eax
28. Int$0x80
30. 8048088: CD 80Int$0x80
34. Movl $0, % EBX
36. 804808a: BB 00 00 00 00 mov $0x0, % EBX
38. Movl $1, % eax
40. 804808f: B8 01 00 00 mov $0x1, % eax
42. Int$0x80
44. 8048094: CD 80Int$0x80
46. RET
48. 8048096: C3 RET
50.