(store word) transfers from a register to the memory. Lw (load word) transfers from the memory to a register, while sw Sequence, with bit 31 being the Most Significant Bit and bit 0 being Value, while la $a0, str loads the string of str to theĪ word is (as much as we are talking about MIPS) a 32 bits With li $v0, 4 the $v0 register has now 4 as la (loadĪddress) is also a pseudo-instruction that loads an address to a Later) that instantly loads a register with a value. Li (load immediate) is a pseudo-instruction (we'll talk about that If a system call hasĪrguments, those are put at the $a0-$a2 registers.
To use a system call, a call code is needed to be put to System calls are a set of services provided from the operating system. Li $v0, 10 # system call for terminating the executionīefore illustrating the results through MARS, a little more explanation about these commands is needed: Sw $t2, 0($t0) #storing the sum of register $t2 as a word at the first place of $t0 Lw $s1, 0($t0) #loading our number as a word to another register, $s1Īddi $t2, $s1, 8 #adding our number ($s1) with 8 and leaving the sum to register $t2 La $t0, number #loading our number from data section to the $t0 register La $a0, str #loading our string from data section to the $a0 register Li $v0, 4 #system call for printing strings Well, we can change what we had a bit for just that. What about, dunno, adding a number or something? asm filetypeīut the code above prints just a character, what about the good ol' "Hello World"? Syscall #Call to the System to terminate the execution Li $v0, 10 #11=system code for terminating, $v0=register that gets the system code for terminating (optional, but desirable) Syscall #Call to the System to execute our instructions and print the character at the a0 register La $a0, 'a' #'a'=our example character, $a0=register that accepts the character for printing Li $v0, 11 #11=system code for printing a character, $v0=register that gets the system code for printing as value Now, let's see the example code from above and explain each line. Ii) the machine code for each instruction at the "code" column,Īnd the data segment where we can have a look at a representation of the memory of a processor with little-endian order.Īfter assembling, we can execute our code either all at once (F5) or step by step (F7), as well as rewinding the execution several steps backwards to the back (F8). I) each line of assembly code gets cleared of "pseudoinstructions" (we'll talk about those in a sec) at the "basic" column and To three segments: the editor at the upper left where all of the code is being written, the compiler/output right beneath the editor and the list of registers that represent the "CPU" for our program.Īfter assembling (by simply pressing F3) the environment changes, with two new segments getting the position of the editor: the text segment where
MARS MIPS simulator is an assembly language editor, assembler, simulator & debugger for the MIPS processor, developed by Pete Sanderson and Kenneth Vollmar at Missouri State University ( src).Īs for installing the 4.5 version, you might need the suitable Java SDK for your system from hereīefore assembling, the environment of this simulator can be simplisticly split