دوما این که من دارم از دو کتاب استفاده می کنم یکی این مزیدی هست و دیگری که توش در مورد لینوکس توضیح هم داده این هست: assembly_language_step_by_step_programming_with_dos_and_linux_with_cd_rom
Therefore, it would make sense to become at least passingly familiar with the AT&T mnemonic set. There are some general rules that, once digested, make it much easier. Here's the list in short form:
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AT&T mnemonics and register names are invariably in lowercase. This is in keeping with the Unix convention of case sensitivity, and at complete variance with the Intel convention of uppercase for assembly language source. I've mixed uppercase and lowercase in the text and examples to get you used to seeing assembly source both ways, but you have to remember that while Intel (and hence NASM) suggests uppercase but will accept lowercase, AT&T requires lowercase.
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Register names are always preceded by the percent symbol, %. That is, what Intel would write as AX or EBX, AT&T would write as %ax and %ebx. This helps the assembler recognize register names.
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Every AT&T machine instruction mnemonic that has operands has a single-character suffix indicating how large its operands are. The suffix letters are b, w, and l, indicating byte (8 bits), word (16 bits), or long (32 bits). What Intel would write as MOV BX,AX, AT&T would write as movw %ax,%bx. (The changed order of %ax and %bx is not an error. See the next rule!)
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In the AT&T syntax, source and destination operands are placed in the opposite order from Intel syntax. That is, what Intel would write as MOV BX,AX, AT&T would write as movw %ax,%bx. In other words, in AT&T syntax, the source operand comes first, followed by the destination. This actually makes a little more sense than Intel conventions, but confusion and errors are inevitable.
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In the AT&T syntax, immediate operands are always preceded by the dollar sign, $. What Intel would write as PUSH DWORD 32, AT&T would write as pushl $32. This helps the assembler recognize immediate operands.
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AT&T documentation refers to "sections" where we would say "segments." A segment override is thus a section override in AT&T parlance. This doesn't come into play much because segments are not a big issue in 32-bit flat model programming. Still, be aware of it.
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Not all Intel instruction mnemonics have AT&T equivalents. JCXZ, JECXZ, LOOP, LOOPZ, LOOPE, LOOPNZ, and LOOPNE do not exist in the AT&T mnemonic set, and gcc never generates code that uses them. This won't be a problem for us, as we're using NASM, but you won't see these instructions in gdb displays.
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In the AT&T syntax, displacements in memory references are signed quantities placed outside parentheses containing the base, index, and scale values. I'll treat this one separately a little later, as you'll see it a lot in .s files and you should be able to understand it.
خوب اگر قرار باشه من حرف این کتاب را گوش بدم باید سینتکس AT&T را بخونم اما یک سوال پس چرا برنامه ی زیر که با سینتکس AT&T نوشته نشده را میشه با nasm کامپایل کرد؟
و یک سوال دیگه این که سینتکس بالا مربوط به چه سینتکسی هست. مطمئنا AT&T که نیست.
موضوع: فرق syntax زبان اسمبلی در لینوکس و ویندوز چیست؟ (دفعات بازدید: 6809 بار)
