# Operating-System-Simulator
### OS simulator created for CS480 (Operating Systems) course (Spring 2022)
Config file and metadata file upload code and helper functions (`Sim01`) were written by Dr. Michael Leverington, and each character has been typed/debugged by me, myself, and I.
`Sim02` consists of the basic structure of the actual **simulator.c** file, involving the creation and management of Process Control Blocks. Operations default to *non-preemptive* **F**irst **C**ome **F**irst **S**erve (`FCFS-N`).
`Sim03` implements the `SJF-N` (**S**hortest **J**ob **F**irst) scheduler as well as memory management display and operations.
`Sim04` introduces preemptive scheduling, allowing for interrupts. The scheduling algorithms added are `FCFS-P`, `SRTF-P`, and `RR-P`.
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### Instructions to run simulation:
##
### Runtime flags
There are three flags the simulator is capable of taking in to run the simulation:
`-rs` *run simulator* -> runs the simulator by using data from the config and metadata files given
`-dc` *display config* -> shows all configuration information of the given config file
`-dm` *display metadata* -> outputs the op code stream that the simulator is meant to interpret
### Command structure
After compiling using the command `make -f Sim0X_mf` where **X** is the number of the simulator, the program can be run by typing:
`./Sim0X -rs -dc -dm config.cnf` where config.cnf is the given configuration file
The flags are not required, but are necessary for the program to execute in any meaningful way.
### Required files
For the simulation to run, a configuration file must be provided. Without one, the program will display a message including the required command structure. Two files in total are required:
#### Configuration File
Here is an example of a properly formatted configuration file. If the format is incorrect, or if the arguments given are not allowed/specified, the program will not run and will spit out an error.
>Start Simulator Configuration File:
>Version/Phase: 1.05
>File Path: metadatafile.mdf
>CPU Scheduling Code: SJF-N
>Quantum Time (cycles): 3
>Memory Available (KB): 11100
>Processor Cycle Time (msec): 10
>I/O Cycle Time (msec): 20
>Log To: Both
>Log File Path: logfile.lgf
>End Simulator Configuration File.
The details for specific number ranges allowed can be found in the boolean function **valueInRange** in the **configops.c** file. The order of configuration specifications does not matter, as long as the Start and End lines are ... at the start and end.
#### Metadata File
The metadata file (that must be specified in the configuration file) includes the actual operations that the program will simulate.
There is one `sys start` op code in the beginning and one `sys end` op code at the end of the file.
Each `app start` is interpreted as a separate process, and is bounded by an `app end`.
The number of `app start` & `app end` commands must be equal, or the program will not run.
>Start Program Meta-Data Code:
>
sys start
>
app start, 0
>
dev in, keyboard, 50
>
cpu process, 7
>
dev out, video signal, 42
>
cpu process, 5
>
dev out, hard drive, 21
>
dev in, usb, 14
>
dev in, keyboard, 50
>
cpu process, 9
>
dev out, hard drive, 30
>
cpu process, 5
>
app end
>
app start, 0
>
dev in, video signal, 42
>
dev out, hard drive, 18
>
dev in, hard drive, 15
>
dev in, hard drive, 27
>
cpu process, 9
>
dev out, hard drive, 21
>
cpu process, 7
>
cpu process, 5
>
app end
>
app start, 0
>
dev in, usb, 12
>
dev out, video signal, 70
>
dev in, video signal, 35
>
cpu process, 5
>
dev out, monitor, 100
>
dev in, video signal, 63
>
cpu process, 5
>
dev out, video signal, 70
>
cpu process, 8
>
dev in, serial, 36
>
dev out, video signal, 63
>
dev out, sound signal, 30
>
app end
>
app start, 0
>
dev in, hard drive, 21
>
cpu process, 5
>
dev out, monitor, 60
>
cpu process, 8
>
dev in, video signal, 56
>
dev in, hard drive, 21
>
dev in, hard drive, 15
>
dev in, video signal, 49
>
dev out, hard drive, 30
>
app end
>
sys end
>
End Program Meta-Data Code.
If the simulator is given the metadata file above, four Process Control Blocks (PCBs) will be created corresponding to the four `app start` op codes given. The simulator will then use the given scheduling code to display and run the corresponding operations accordingly.
##
Here is an example of the simulator running with the Shortest Job First Non-preemptive scheduling algorithm:
