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BOOK: Professional Assembly Language
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Old May 2nd, 2007, 11:06 PM
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Default understand a piece of code in assembler

Hi, i am new in assembler code, i started to understand a program, but i am stock in the switch statement of this code:

08048b7b <phase_3>:
 8048b7b: 55 push %ebp
 8048b7c: 89 e5 mov %esp,%ebp
 8048b7e: 83 ec 24 sub $0x24,%esp
 8048b81: 8d 45 f8 lea 0xfffffff8(%ebp),%eax
 8048b84: 50 push %eax
 8048b85: 8d 45 f7 lea 0xfffffff7(%ebp),%eax
 8048b88: 50 push %eax
 8048b89: 8d 45 fc lea 0xfffffffc(%ebp),%eax
 8048b8c: 50 push %eax
 8048b8d: 68 26 97 04 08 push $0x8049726
 8048b92: ff 75 08 pushl 0x8(%ebp)
 8048b95: e8 de fc ff ff call 8048878 <sscanf@plt>
 8048b9a: 83 c4 20 add $0x20,%esp
 8048b9d: 83 f8 02 cmp $0x2,%eax
 8048ba0: 7f 05 jg 8048ba7 <phase_3+0x2c>
 8048ba2: e8 99 08 00 00 call 8049440 <explode_bomb>
 8048ba7: 83 7d fc 07 cmpl $0x7,0xfffffffc(%ebp)
 8048bab: 0f 87 bd 00 00 00 ja 8048c6e <phase_3+0xf3>
 8048bb1: 8b 45 fc mov 0xfffffffc(%ebp),%eax
 8048bb4: ff 24 85 30 97 04 08 jmp *0x8049730(,%eax,4)
 8048bbb: 81 7d f8 37 01 00 00 cmpl $0x137,0xfffffff8(%ebp)
 8048bc2: 0f 84 af 00 00 00 je 8048c77 <phase_3+0xfc>
 8048bc8: e8 73 08 00 00 call 8049440 <explode_bomb>
 8048bcd: b0 69 mov $0x69,%al
 8048bcf: e9 a5 00 00 00 jmp 8048c79 <phase_3+0xfe>
 8048bd4: 81 7d f8 7d 01 00 00 cmpl $0x17d,0xfffffff8(%ebp)
 8048bdb: 0f 84 96 00 00 00 je 8048c77 <phase_3+0xfc>
 8048be1: e8 5a 08 00 00 call 8049440 <explode_bomb>
 8048be6: b0 69 mov $0x69,%al
 8048be8: e9 8c 00 00 00 jmp 8048c79 <phase_3+0xfe>
 8048bed: 81 7d f8 20 03 00 00 cmpl $0x320,0xfffffff8(%ebp)
 8048bf4: 75 04 jne 8048bfa <phase_3+0x7f>
 8048bf6: b0 77 mov $0x77,%al
 8048bf8: eb 7f jmp 8048c79 <phase_3+0xfe>
 8048bfa: e8 41 08 00 00 call 8049440 <explode_bomb>
 8048bff: b0 77 mov $0x77,%al
 8048c01: eb 76 jmp 8048c79 <phase_3+0xfe>
 8048c03: 81 7d f8 9f 02 00 00 cmpl $0x29f,0xfffffff8(%ebp)
 8048c0a: 75 04 jne 8048c10 <phase_3+0x95>
 8048c0c: b0 75 mov $0x75,%al
 8048c0e: eb 69 jmp 8048c79 <phase_3+0xfe>
 8048c10: e8 2b 08 00 00 call 8049440 <explode_bomb>
 8048c15: b0 75 mov $0x75,%al
 8048c17: eb 60 jmp 8048c79 <phase_3+0xfe>
 8048c19: 83 7d f8 35 cmpl $0x35,0xfffffff8(%ebp)
 8048c1d: 75 04 jne 8048c23 <phase_3+0xa8>
 8048c1f: b0 61 mov $0x61,%al
 8048c21: eb 56 jmp 8048c79 <phase_3+0xfe>
 8048c23: e8 18 08 00 00 call 8049440 <explode_bomb>
 8048c28: b0 61 mov $0x61,%al
 8048c2a: eb 4d jmp 8048c79 <phase_3+0xfe>
 8048c2c: 81 7d f8 ac 03 00 00 cmpl $0x3ac,0xfffffff8(%ebp)
 8048c33: 75 04 jne 8048c39 <phase_3+0xbe>
 8048c35: b0 7a mov $0x7a,%al
 8048c37: eb 40 jmp 8048c79 <phase_3+0xfe>
 8048c39: e8 02 08 00 00 call 8049440 <explode_bomb>
 8048c3e: b0 7a mov $0x7a,%al
 8048c40: eb 37 jmp 8048c79 <phase_3+0xfe>
 8048c42: 81 7d f8 bd 03 00 00 cmpl $0x3bd,0xfffffff8(%ebp)
 8048c49: 75 04 jne 8048c4f <phase_3+0xd4>
 8048c4b: b0 70 mov $0x70,%al
 8048c4d: eb 2a jmp 8048c79 <phase_3+0xfe>
 8048c4f: e8 ec 07 00 00 call 8049440 <explode_bomb>
 8048c54: b0 70 mov $0x70,%al
 8048c56: eb 21 jmp 8048c79 <phase_3+0xfe>
 8048c58: 81 7d f8 80 03 00 00 cmpl $0x380,0xfffffff8(%ebp)
 8048c5f: 75 04 jne 8048c65 <phase_3+0xea>
 8048c61: b0 6d mov $0x6d,%al
 8048c63: eb 14 jmp 8048c79 <phase_3+0xfe>
 8048c65: e8 d6 07 00 00 call 8049440 <explode_bomb>
 8048c6a: b0 6d mov $0x6d,%al
 8048c6c: eb 0b jmp 8048c79 <phase_3+0xfe>
 8048c6e: e8 cd 07 00 00 call 8049440 <explode_bomb>
 8048c73: b0 72 mov $0x72,%al
 8048c75: eb 02 jmp 8048c79 <phase_3+0xfe>
 8048c77: b0 69 mov $0x69,%al
 8048c79: 3a 45 f7 cmp 0xfffffff7(%ebp),%al
 8048c7c: 74 05 je 8048c83 <phase_3+0x108>
 8048c7e: e8 bd 07 00 00 call 8049440 <explode_bomb>
 8048c83: c9 leave
 8048c84: c3 ret

any help will be appreciate, i am driving crazy with this piece of code.

 
Old January 10th, 2010, 07:45 AM
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Default

Quote:
Originally Posted by rbulus View Post
Hi, i am new in assembler code, i started to understand a program, but i am stock in the switch statement of this code:

08048b7b <phase_3>:
 8048b7b: 55 push %ebp
 8048b7c: 89 e5 mov %esp,%ebp
 8048b7e: 83 ec 24 sub $0x24,%esp
 8048b81: 8d 45 f8 lea 0xfffffff8(%ebp),%eax
 8048b84: 50 push %eax
 8048b85: 8d 45 f7 lea 0xfffffff7(%ebp),%eax
 8048b88: 50 push %eax
 8048b89: 8d 45 fc lea 0xfffffffc(%ebp),%eax
 8048b8c: 50 push %eax
 8048b8d: 68 26 97 04 08 push $0x8049726
 8048b92: ff 75 08 pushl 0x8(%ebp)
 8048b95: e8 de fc ff ff call 8048878 <sscanf@plt>
 8048b9a: 83 c4 20 add $0x20,%esp
 8048b9d: 83 f8 02 cmp $0x2,%eax
 8048ba0: 7f 05 jg 8048ba7 <phase_3+0x2c>
 8048ba2: e8 99 08 00 00 call 8049440 <explode_bomb>
 8048ba7: 83 7d fc 07 cmpl $0x7,0xfffffffc(%ebp)
 8048bab: 0f 87 bd 00 00 00 ja 8048c6e <phase_3+0xf3>
 8048bb1: 8b 45 fc mov 0xfffffffc(%ebp),%eax
 8048bb4: ff 24 85 30 97 04 08 jmp *0x8049730(,%eax,4)
 8048bbb: 81 7d f8 37 01 00 00 cmpl $0x137,0xfffffff8(%ebp)
 8048bc2: 0f 84 af 00 00 00 je 8048c77 <phase_3+0xfc>
 8048bc8: e8 73 08 00 00 call 8049440 <explode_bomb>
 8048bcd: b0 69 mov $0x69,%al
 8048bcf: e9 a5 00 00 00 jmp 8048c79 <phase_3+0xfe>
 8048bd4: 81 7d f8 7d 01 00 00 cmpl $0x17d,0xfffffff8(%ebp)
 8048bdb: 0f 84 96 00 00 00 je 8048c77 <phase_3+0xfc>
 8048be1: e8 5a 08 00 00 call 8049440 <explode_bomb>
 8048be6: b0 69 mov $0x69,%al
 8048be8: e9 8c 00 00 00 jmp 8048c79 <phase_3+0xfe>
 8048bed: 81 7d f8 20 03 00 00 cmpl $0x320,0xfffffff8(%ebp)
 8048bf4: 75 04 jne 8048bfa <phase_3+0x7f>
 8048bf6: b0 77 mov $0x77,%al
 8048bf8: eb 7f jmp 8048c79 <phase_3+0xfe>
 8048bfa: e8 41 08 00 00 call 8049440 <explode_bomb>
 8048bff: b0 77 mov $0x77,%al
 8048c01: eb 76 jmp 8048c79 <phase_3+0xfe>
 8048c03: 81 7d f8 9f 02 00 00 cmpl $0x29f,0xfffffff8(%ebp)
 8048c0a: 75 04 jne 8048c10 <phase_3+0x95>
 8048c0c: b0 75 mov $0x75,%al
 8048c0e: eb 69 jmp 8048c79 <phase_3+0xfe>
 8048c10: e8 2b 08 00 00 call 8049440 <explode_bomb>
 8048c15: b0 75 mov $0x75,%al
 8048c17: eb 60 jmp 8048c79 <phase_3+0xfe>
 8048c19: 83 7d f8 35 cmpl $0x35,0xfffffff8(%ebp)
 8048c1d: 75 04 jne 8048c23 <phase_3+0xa8>
 8048c1f: b0 61 mov $0x61,%al
 8048c21: eb 56 jmp 8048c79 <phase_3+0xfe>
 8048c23: e8 18 08 00 00 call 8049440 <explode_bomb>
 8048c28: b0 61 mov $0x61,%al
 8048c2a: eb 4d jmp 8048c79 <phase_3+0xfe>
 8048c2c: 81 7d f8 ac 03 00 00 cmpl $0x3ac,0xfffffff8(%ebp)
 8048c33: 75 04 jne 8048c39 <phase_3+0xbe>
 8048c35: b0 7a mov $0x7a,%al
 8048c37: eb 40 jmp 8048c79 <phase_3+0xfe>
 8048c39: e8 02 08 00 00 call 8049440 <explode_bomb>
 8048c3e: b0 7a mov $0x7a,%al
 8048c40: eb 37 jmp 8048c79 <phase_3+0xfe>
 8048c42: 81 7d f8 bd 03 00 00 cmpl $0x3bd,0xfffffff8(%ebp)
 8048c49: 75 04 jne 8048c4f <phase_3+0xd4>
 8048c4b: b0 70 mov $0x70,%al
 8048c4d: eb 2a jmp 8048c79 <phase_3+0xfe>
 8048c4f: e8 ec 07 00 00 call 8049440 <explode_bomb>
 8048c54: b0 70 mov $0x70,%al
 8048c56: eb 21 jmp 8048c79 <phase_3+0xfe>
 8048c58: 81 7d f8 80 03 00 00 cmpl $0x380,0xfffffff8(%ebp)
 8048c5f: 75 04 jne 8048c65 <phase_3+0xea>
 8048c61: b0 6d mov $0x6d,%al
 8048c63: eb 14 jmp 8048c79 <phase_3+0xfe>
 8048c65: e8 d6 07 00 00 call 8049440 <explode_bomb>
 8048c6a: b0 6d mov $0x6d,%al
 8048c6c: eb 0b jmp 8048c79 <phase_3+0xfe>
 8048c6e: e8 cd 07 00 00 call 8049440 <explode_bomb>
 8048c73: b0 72 mov $0x72,%al
 8048c75: eb 02 jmp 8048c79 <phase_3+0xfe>
 8048c77: b0 69 mov $0x69,%al
 8048c79: 3a 45 f7 cmp 0xfffffff7(%ebp),%al
 8048c7c: 74 05 je 8048c83 <phase_3+0x108>
 8048c7e: e8 bd 07 00 00 call 8049440 <explode_bomb>
 8048c83: c9 leave
 8048c84: c3 ret

any help will be appreciate, i am driving crazy with this piece of code.
You are calling scanf to determine input on whether to explode the bomb. I would be careful - it might go boom.




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