This is code from a semestral project for computer architecture. It works on a MicroZed evaluation kit. This kit contains:

• XilinX Zynq-7000
• Dual ARM Cortex-A9
• a display, knobs, buttons, LEDs
• and more

It is running Linux operating system.

Assignment (the crossed out parts were not finished)

The semestral project will be separated to 3 individual programs. The main program will be a file browser. It will be possible to browse through the whole root file system as well as an external device. The browser will be able to perform simple operations such as copying, moving or removing files. It will be able to execute arbitrary files and support opening some file formats in specified programs.

The second part of the project will be an image viewer. The file browser will be able to open image files using this program. It will support jpeg, png and ppm formats. It will be possible to use the rotation encoders to move a cursor over the image. It will be possible to zoom to the cursor.

The last part of the project will be a text file viewer. This file viewer may open any file, but is intended mainly for plain text formats. Again, it will be possible to zoom in on the text and move through the file.

For faster debugging, a simple program that may be executed on personal computer will be made. SDL window will be used.

Evaluation ofthe completion of the assignment

The file browser unfortunately does not support operations such as moving, removing or copying files. It cannot mount external devices as planned. Only the root file system may be browsed through. However it may open files using mime types as planned. On the other hand, the text as well as image browsers support all features that were in the assignment.

Manual

File browser

Function

The program may browse through the root file system. It may execute files and open images or plain text files. A context menu may be used to open any file in the plain text viewer.

The program contains instructions accessible from the main menu.

Virtual windows

The program consists of windows that may be switched.

Default menu

It's possible to either enter the file browser or read the instructions in the main menu.

File browser

The file explorer displays what folder you are currently in and the files in it. One can navigate between folders, view context menus or launch files.

Context menu

You can run the file in the context menu or view it in the text viewer.

Dialog

A dialog box will typically be shown when an error occurs. It contains the error that occurred.

File browser entry

The file browser does not have any arguments.

Usage: ./file-browser

LED strip

The LED strip shows the vertical position in the file explorer, to show how many files still need to be gone through before the end folder.

Error conditions

Errors are reported via a dialog box.

Controls

Standard input

• h, j, k, l - move the view around the file (left, down, up, right)
• y, i, o, p - move full screen for faster navigation (left, down, up, right)
• z, x - zoom in and out of text
• n - return the view to the top of the file list
• m - view to the end of the file list
• e - exit the program
• c - file context menu
• v - confirm selection (launch file / switch folder)

Rotary encoders

• First (red) - horizontal view shift
• Second (green) - vertical view shift
• Third (blue) - zoom in or out of text
• First encoder button - end program / move back
• Second encoder button - file context menu
• Third encoder button - confirm selection (start file / switch folder)

Text file viewer

Functions

The program displays the text from a text file on the LCD display, it can be moved around with the rotary encoders. If the program does not receive the text file, it is possible that it will not display it correctly.

Running

The program cannot be run without arguments, it always needs to be run with the path to the text file. Otherwise the program will end up with the error condition shown on the RGB LEDs.

./text-viewer [path-to-file]

LED strip

The LED strip shows how much data is already loaded during the loading phase. After loading, it shows the vertical position in the file according to how much the file is shifted.

Error conditions

If the program does not start correctly, one of the RGB LEDs will light up red.

The left RGB LED indicates that no argument has been passed. The right RGB LED means that the file failed to load, does not exist or has no access rights. A specific error message appears on the standard output.

Control

Standard input

• h, j, k, l - move the view around the file (left, down, up, right)
• y, i, o, p - move full screen for faster navigation (left, down, up, right)
• z, x - zoom in and out of text
• n - return the view to the beginning of the file
• m - view to the end of the file
• e - exit the program

Rotary encoders

• First (red) - horizontal view shift
• Second (green) - vertical view shift
• Third (blue) - zoom in or out of text
• First encoder button - exit program
• Second encoder button - return the view to the beginning of the file
• Third encoder button - view to the end of the file

Image viewer

Functions

The program displays a rescaled image on the LCD that can be zoomed in using the rotary encoders or standard input. When the program starts, the image is zoomed out to fit entirely on the screen.

Starting up

The program cannot be run without arguments, it always needs to be run with the path to the image file. Otherwise the program will end with the error condition shown on the RGB LEDs.

Usage: ./image-viewer [path-to-file]

Supported formats

• jpg
• png
• ppm

Formats are differentiated by their headers, endings are not differentiated

LED strip

The LED strip shows how much data is already loaded during the loading phase. After loading, the horizontal position of the cursor in the image is displayed for easier orientation at higher magnification.

Error conditions

If the program does not start correctly, one of the RGB LEDs will light up red.

The left RGB LED indicates that no argument has been passed. The right RGB LED means that the file failed to load, it does not exist, the format is not correct or there are no access rights to it. A specific error message appears on the standard output.

Control

The program has a cursor that determines where to zoom in. The cursor appears when it is moved and a moment afterwards.

Standard input

• h, j, k, l - control the cursor or scroll across the image depending on the mode, see the m key (left, down, up, right)
• z, x - zoom in and out of the image (to where the cursor is)
• r - return to the original state (zooms out the image and sets the cursor in the middle of the image)
• m - switch between image or cursor movement modes (RGB LEDs light up green in image movement mode)
• e - exit the program

Rotary encoders

• First (red) - move the cursor horizontally or move the whole image horizontally (see button of the second encoder)
• Second (green) - move the cursor vertically or move the entire image vertically (see second encoder button)
• Third (blue) - zoom in and out
• First encoder button - exit the program
• Second encoder button - switch between image or cursor movement modes
• Third encoder button - return to the original zoom state

Compilation, installation, startup

Makefile is used for compilation.

Cross compilation for MZAPO

For cross compilation, arm-gnueabihf-gcc and dynamic libraries are needed libjpeg version 62, libpng version 16 and libmagic version 1 for MZAPO.

After compilation, the files are saved in the bin folder, to run copy them to MZAPO.

The copying can be done via ssh, you can use make, specifically TARGET_IP=[ip-addr] make copy-executable where after ip-addr the ip address of MZAPO needs to be inserted. In basic mode, it is assumed that the SSH tunnel is used and the mzapo-root-key (SSH key for mzapo) is located on the path ``/.ssh/mzapo-root-key. To change the basic settings just change the configuration in the Makefile` in the project root. The possible configurations are commented out on the lines starting `SSHOPTIONS`

You can use the serial port or ssh to boot. Alternatively, use make, to launch the file explorer: TARGET_IP=[ip-addr] make run or to launch the run-image-viewer image viewer and to launch the text file viewer run-text-viewer. The ARG environment variable is used to pass the argument

For example, you can use TARGET_IP=[ip-addr] ARG=/path/to/image make run-image-viewer or TARGET_IP=[ip-addr] ARG=/path/to/image make run-text-viewer

The program should be run with cwd in the folder where the binaries are located.

Compiling for a personal computer

For better debugging it is possible to compile the program for a personal computer where the display is simulated using the SDL window.

To compile for a PC, the environment variable COMPUTER can be used. It is then possible to use COMPUTER=1 make

After compilation, the files are in the bin folder in the root of the project. They can be run directly with the necessary parameters, see the manual.

You need to copy the files from the copy/ folder to the bin/ folder and run the program with cwd in the folder where all the binary files are located