hls    = Hacklab LED System
panel  = Single physical LED display device that has it's own IP address.
screen = Bigger display that is formed from multiple panels.

The lib is initialized with "hlsudpcomm_t* hlsudp_open(void)""
this initializes send socket, and loads panel definitions
from a file specified in env variable PANELCONFIG.

"void hlsudp_sendtile(hlsudpcomm_t* ctx, uint8_t *pixels, int pixelsize, int frame, int xo, int yo)"
Provide pointer to context got from hlsudp_open(), 16*16 block of pixel data, pixel size in bytes
(only 6 is supported, 16 bits per channel RGB), frame number, and x,y coordinates to the
top-left corner of the tile position on screen.

After every tile has been sent, you call "void hlsudp_sendswap(hlsudpcomm_t* ctx, int frame)".
This sends broadcast packet to network which causes all panels to show new image syncronously.

It might be a good idea to send swap for previous frame just before new tiles are sent.
This allows network to transmit all packets to their destinations. If Swap packet is sent
right after tiles and packets get reordered during transmit, it might cause visible
glitches on the screen.

Use "void hlsudp_shutdown(hlsudpcomm_t* ctx)".

Basic example, 1x2 64x48 panels forming a 64x96 screen.

0,  0,  64, 96, 192.168.10.255, 9999
0,  0,  64, 48, 192.168.10.20, 9999
0, 48,  64, 48, 192.168.10.21, 9999

Fields within lines are comma separated:
x origin, y origin, width, height, IP address, UDP port (9999 by default)

First line defines the screen. It begins from top-left corner 0,0 and is
64x96 pixels in size. IP address must be the network's broadcast address.

Subsequent lines define invidual panels. first 64x48 panel is located at
screen top-left corner 0,0. The Second is under it, and thus begins from coordinates
0,48.

1. Connect all panels to a network with DHCP server
2. Wait until each panel gets an IP address. It will be shown on the panel
3. write panel addresses into the config file
4. enjoy

Simple demo uses SDL2 software rendering to do some basic effect on the LED display.
It's meant to run on Raspberry PI / raspbian, but should work on desktops too.
Requires libsdl2-dev / libsdl2-ttf-dev libs from APT.

Compile with make, and run with ./hlstest for preview.
./run.sh also uses panelconfig.txt, which should work with the real display.

This repository also includes configuration for BusyBox udhcpd server.
Run ./runudhcpd.sh in dhcp directory. This reconfigures eth0, and starts
a dhcp server. Should work for Raspberry PI atleast.