دانلود کتاب زبان اسمبلی گام به گام – برنامه نویسی با لینوکس

Assembly language is peculiar among programming languages in that there is no universal standard for case sensitivity. In the C language, all identifiers are case sensitive, and I have seen assemblers that do not recognize differences in case at all. NASM, the assembler I present in this book, is case sensitive only for programmer-defined identifiers. The instruction mnemonics and the names of registers, however, are not case sensitive. There are customs in the literature on assembly language, and one of those customs is to treat CPU instruction mnemonics and register names as uppercase in the text, and in lowercase in source code files and code snippets interspersed in the text. I’ll be following that custom here. Within discussion text, I’ll speak of MOV and registers EAX and EFLAGS. In example code, it will be mov and eax and eflags. There are two reasons for this: In text discussions, the mnemonics and registers need to stand out. It’s too easy to lose track of them amid a torrent of ordinary words. In order to read and learn from existing documents and source code outside of this one book, you need to be able to easily read assembly language whether it’s in uppercase, lowercase, or mixed case. Getting comfortablewith different ways of expressing the same thing is important. This will grate on some people in the Unix community, for whom lowercase characters are something of a fetish. I apologize in advance for the irritation, while insisting to the end that it’s still a fetish, and a fairly childish one at that.