![]() ![]() It simply defines an abbreviation for the assembler itself to use. equ is actually not a real instruction.We also have jne (jump if not equal), jl (jump if less), jnl (jump if not less), jg (jump if greater), jng (jump if not greater), jle (jump if less or equal), jnle (jump if not less or equal), jge (jump if greater or equal), jnge (jump if not greater or equal), and many more. je jumps to a label if the previous comparison was equal.$ nasm -fmacho64 triangle.asm & ld triangle.o &. Syscall invoke operating system to do the write Mov rsi, output address of string to output Mov rax, 0x02000004 system call for write Mov r9, 0 reset count of stars written on this lineĬmp r8, maxlines wait, did we already finish the last line? Inc rdx and move pointer to where next char goes Jne line not yet, keep writing on this line Inc rdx advance pointer to next cell to writeĬmp r9, r8 did we reach the number of stars for this line? Mov r9, 0 number of stars written on line so far Mov rdx, output rdx holds address of next byte to write nasm -fmacho64 triangle.asm & gcc hola.o &. This is an macOS console program that writes a little triangle of asterisks to standard bss (you'll get an error if you try to use them in To reserve space (without initializing), you can use the following pseudo instructions. There are other forms check the NASM docs. To place data in memory:ĭb 0x55,0x56,0x57 three bytes in successionĭb 'hello',13,10,'$' so are string constantsĭq 0x123456789abcdef0 eight byte constantĭt 1.234567e20 extended-precision float These examples come from Chapter 3 of the docs. In fact, we’ll not see any such instruction in this tutorial. Instructions with two memory operands are extremely rare Here are some examples from the official docs.Ġ200 still decimal - the leading 0 does not make it octalĠc8h hex - h suffix, but leading 0 is required because c8h looks like a varĠhc8 hex - for some reason NASM likes 0hĠb1100_1000 binary - 0b prefix, and by the way, underscores are allowed uses the address of the variable 'counter' as the displacement The number is called the displacement the plain register is called the base the register with the scale is called the index. The 16 integer registers are 64 bits wide and are called: (If you are familiar with the x86 architecture, you will know that this means we are skipping the FP, MMX, YMM, segment, control, debug, test, and protected mode registers.) Hopefully you have already been introduced to the x86-84 architecture, in which case, this is a quick review. ![]() In this tutorial we only care about the integer registers, the flag register, and the xmm registers. How can you remember things? Nicky Case can help you with this! Register Operands That declares bytes that will be in memory when the program runs $\mathtt\ n$ Invoke operating system routine $n$ The Intel Processor Manuals Your First Few Instructions.NASM is an awesome assembler, but assembly language is complex. text and your constant data in a section called. Generally, you put code in a section called. Most lines have an instruction followed by zero or more operands. Most programs consist of directives followed by one or more sections. In this example, the command would return when the system boot.Exercise: Identify the differences between the two programs. The example above is one way you can use the find command with the systeminfo command to find exactly what you're looking for in the system information. The command above would display information about the computer and its operating system, including networking information and installed hotfixes. Valid only when the /fo parameter is set to TABLE or CSV. Valid format values are TABLE, LIST, and CSV (comma-separated values). Specifies the format to use for the output. Specifies the password of the user account that is in the /u parameter. The default settings are those of the user who is currently logged in. Runs the command with the account permissions specified by username or domain\username. Specifies the name or IP address of a remote computer (do not use backslashes). Systeminfo syntax systeminfo ]]] /s system Systeminfo is an external command that is available in the following Microsoft operating systems as systeminfo.exe. ![]()
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