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> Main > whats the opcode difference? |
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b1528932 09 Jul 2010, 14:21
in long mode 40+ is REX prefix, only way to encode inc/dec is by modrm opcode.
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09 Jul 2010, 14:21 |
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sinsi 09 Jul 2010, 15:01
In long mode lots of opcodes referring to the high 8-bit registers are prefix bytes to use r8-r15.
>in long mode 40+ is REX prefix yes, from what I see it is 40..4F This is why you see in the 64-bit mode column the letters N.E. bad crash |
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09 Jul 2010, 15:01 |
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revolution 09 Jul 2010, 15:59
Teehee wrote: [see image] In 64-bit code fasm has no choice and "chooses" the two-byte variant. |
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09 Jul 2010, 15:59 |
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Teehee 10 Jul 2010, 00:05
hmm.. so is there many ways to do the same?
Manual says FE /0 is to r/m8, but when i look to inc al it shows me: Code: FEC0 inc al what that C mean? from where it comes? Last edited by Teehee on 10 Jul 2010, 00:11; edited 1 time in total |
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10 Jul 2010, 00:05 |
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revolution 10 Jul 2010, 00:11
Teehee wrote: what that C mean? from where it comes? |
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10 Jul 2010, 00:11 |
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Teehee 10 Jul 2010, 00:15
oh.. i didn't see yet.. that must happen when you don't use linear reading
sorry to annoy you, uncle revolution.  _________________ Sorry if bad english. |
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10 Jul 2010, 00:15 |
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