GHDL + GTKWave setup

1# Install ghdl tool using this command:
  sudo dpkg --install ghdl_0.33-1jessie1_amd64.deb
  
  First you need to find it and download it from here (there are other versions as well): 
  https://sourceforge.net/projects/ghdl-updates/files/Builds/ghdl-0.33/debian/

  Ubuntu 16.04 Fix: https://github.com/ghdl/ghdl/issues/166#issuecomment-482078983
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  Had to manually download and Install dependencies:
        sudo dpkg -i gnat-4.8-base_4.8.2-8ubuntu3_amd64.deb
        sudo dpkg -i libgnat-4.8_4.8.2-8ubuntu3_amd64.deb

  First download them from here: 
        https://packages.ubuntu.com/trusty/amd64/gnat-4.8-base/download
        https://packages.ubuntu.com/trusty/i386/libgnat-4.8/download
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  For more details: 
  https://sourceforge.net/p/ghdl-updates/wiki/Debian%20Instructions/
  
  Everything else you need for ghdl: https://media.readthedocs.org/pdf/ghdl/latest/ghdl.pdf

2# Install gtkwave tool, used to examine waves generated by ghdl simulator. 
    I tested only on Ubuntu 14.04
  sudo apt-get update
  sudo apt-get install gtkwave
  
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Now we have all tools set for Vivado-free simulation experience.

I gathered these commands to further improve my experience using these tools.
Save this file as sim.sh:
  https://gist.github.com/milannedic/354e558e81edb2d6b63d5217de04f921

# My specific situation required this kind of organization, feel free to modify sim.sh 
# to fit your needs due to project hierarchies:
  psds-vezbe
    psds_v1
      1_1
      1_2
      ...
      n_m
    psds_v2
      1_1
      1_2
      ...
      n_m
    ...
    
# I placed libraries and packages .vhd files in psds-vezbe so they can be used throughout the
# whole practicing process and included when needed in all my design files.
# So thats why its called this way:
    ./sim.sh psds_v2 2_1 top_level_tb 1000ns wave.gtkw

--1. top_level_tb is a name of testbench .vhd file placed in psds-vezbe/psds_v2/2_1
--2. 1000ns is desired simulation time you want to observe in your waves.
--3. wave.gtk wave is a file you need to manualy generate from gtkwave tool and save it in psds-vezbe/psds_v2/2_1
--    so you dont have to append all your signals to the waves each time you run it.

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Basic workaround:
Source: http://www.dossmatik.de/ghdl/GHDL_uart_sim.pdf

ghdl -i *.vhd
ghdl -m -fexplicit --ieee=synopsys top_level_tb
ghdl -r  top_level_tb --stop-time=500us --wave=wave.ghw
gtkwave wave.ghw

-- These lines will include all .vhd files into work library and link everything
-- .vhd files must be named as entities they contain.
-- Execute these commands positioned in psds-vezbe/psds_v2/2_1

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# clean.sh
-----------------------------------------------------------------------------
# Save these lines as clean.sh, place it in psds-vezbe
# I call it before pushing my project files to Gitlab and this is basically 
# make clean command in this "wheel reinvention" scenario
# It will remove all object files and other unnecessary files these tools generate during operation.
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echo -e "\n\n\t\t -- Removing all .o files"
find . -name '*.o' -delete	# clean all .o files

echo -e "\t\t -- Removing all .cf files"
find . -name '*.cf' -delete	# clean all .cf files

echo -e "\t\t -- Removing all .ghw files\n\n"
find . -name '*.ghw' -delete	# clean all .ghw files

execs=$(find ./ -type f | xargs file | grep "ELF.*executable" | awk -F: '{print $1}' | xargs echo)

exec_print="\t\t -- Deleting all executables: $execs"

echo -e "$exec_print \n\n"

# delete executables
find ./ -type f | xargs file | grep "ELF.*executable" | awk -F: '{print $1}' | xargs rm

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It is important to perform this:
sudo chmod +x sim.sh
sudo chmod +x clean.sh

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# Might be a good resource as well:
https://www.fpgarelated.com/showarticle/20.php