====== E Task Project -- System Calls ======
You have to present the E2 and E3 tasks personally. E0 and E1 are evaluated automatically by the Upload System.

<fc #FF0000>''WARNING: This information might be out of date. This version is up-to-date for the summer term 2016.''</fc>

===== Task E0: Fibonacci number computation (x86) =====

Your task is to create a program in assembly language (x86) for computing [[https://en.wikipedia.org/wiki/Fibonacci_number|Fibonacci number]] without using any other libraries. For reading a value from stdin and printing the result use "int 0x80" system call. Details are in the PDF provided.

[[http://labe.felk.cvut.cz/~stepan/33OSD/files/e0/cfibo.c|cfibo.c -- Reference implementation in C language]]

[[http://labe.felk.cvut.cz/~stepan/33OSD/files/e0/cfibo_errchk.c|cfibo_errchk.c -- Reference implementation in C language with error checking]]

[[http://labe.felk.cvut.cz/~stepan/33OSD/files/e0/Makefile|Makefile for E0 task]]

Please upload only ''.s'' file with assembly code.


[[http://labe.felk.cvut.cz/~stepan/33OSD/files/e0-asm-syscalls.pdf|E0_Syscalls (PDF)]]

===== Task E1: System Calls from Userspace (x86) =====

[[http://labe.felk.cvut.cz/~stepan/33OSD/files/syscalls.pdf|Support information and specification (PDF)]]


[[http://labe.felk.cvut.cz/~stepan/33OSD/files/e1-syscalls-inline-asm.pdf|Inline assembly info (PDF)]]

[[https://github.com/0xAX/linux-insides/blob/master/Theory/asm.md|Inline assembly at linux-insides]]

Create a program that: 
  * opens a (text) file named ''file.txt'' (in the current directory)
  * reads the first 100 characters from the file (or the whole file if it is shorter)
  * prints the first line read to the ''stdout'' (a line is terminated by the ''EOL'' character)
  * executes a program ''/bin/date'' (using a syscall ''execve()'')

Implement the program using system calls //only//. Do not use standard C libraries -- Use gcc parameters ''-nostdlib -nostdinc'' for compilation.

Implement the task in one ''.c'' file. You can eventually create a few other included files ''.h''. Upload the solution file (single ''.c'' in a ''ZIP'' archive) using the [[http://cw.felk.cvut.cz/upload|Upload System]]. 

<note tip>If you copied the code from PDF slides and have not been able to compile it, you probably need to correct the quotes around the ''memory'' keyword.</note>

===== Task E2: Nova OS, user/kernel context switch, execution of ELF executable  =====
[[http://labe.felk.cvut.cz/~stepan/33OSD/files/osd-e2-kernel.pdf|Support materials and E2 task specs (PDF)]]

[[http://labe.felk.cvut.cz/~stepan/33OSD/files/osd-e2.tar.gz|OS kernel source (tar.gz)]]

[[http://www.ibiblio.org/gferg/ldp/GCC-Inline-Assembly-HOWTO.html|GCC inline assembler howto (online)]]

Upload only changed files to the [[http://cw.felk.cvut.cz/upload|Upload System]], i.e. only ''ec.cc''.

<note tip>
  * If you cannot compile the code, you probably need the ''g++'' compiler (package) installed. 
  * If the hypervisor does not execute, you probably need the ''qemu'' emulator (package) installed.
</note>

<note tip>If you have lost your mouse cursor, it has been grabbed by the ''QEMU'' console. Press ''Ctrl+Alt'' to release it.</note>
===== Task E3: User processes, system calls from kernel side =====

[[http://labe.felk.cvut.cz/~stepan/33OSD/files/osd-e3-kern-syscall.pdf|E3 specification (PDF)]]