It carries a Linux Kernel there at its core. This is a penetration testing and security-focused OS.
#What is parrot os code
return directive is used to ensure the value held in the register named result is placed into the correct register for it to be seen as a return value by the code calling the sub. Then, once _fact returns, the value returned by _fact is placed into the register given the name result. Other calling related registers are then set up, followed by _fact being invoked.
First, the value in register $I0 is moved into the appropriate register for it to be received as an integer parameter by the _fact function. This single line of PIR actually represents quite a few lines of PASM. Much of what follows has been seen in previous examples, apart from the line reading: param int n, specifies that this subroutine takes one integer parameter and that we'd like to refer to the register it was passed in by the name n for the rest of the sub. This is significant as the label is then visible to other subroutines. A point that was glossed over earlier is why the names of subroutines, all start with an underscore! This is done simply as a way of showing that the label is global rather than scoped to a particular subroutine.
# registers of the same type on one line. This example introduces some more instructions and PIR syntax. This can be int (for I registers), float (for N registers), string (for S registers), pmc (for P registers) or the name of a PMC type. The '.local' directive indicates that the named register is only needed inside the current compilation unit (that is, between. These are later mapped to real numbered registers. To make PIR even more readable, named registers can be used. It is also possible to use an = notation instead of writing the set instruction. However, by replacing S1 with $S1 we can delegate the choice of which register to use to Parrot. Here we have stated exactly which register to use. We can modify hello.pir to first store the string Hello world!\n in a register and then use that register with the print instruction. The third line contains the 'end' instruction, which causes the interpreter to terminate. The assembler takes care of deciding which variant of the instruction to use for us. In this case, we are calling the variant of the instruction that accepts a constant string. The second line contains the print instruction. In this above example, '.sub _main' states that the instructions that follow make up a subroutine named '_main', until a '.end' is encountered. Here is the list of programming examples to make you aware of the various aspects of Parrot Programming.Ĭreate a file called hello.pir that contains the following code:Īs expected, this will display the text 'Hello world!' on the console, followed by a new line (due to the \n). Parrot programing is similar to assembly language programing and you get a chance to work at lower level.