Term Screen

Usage

# clone repo
git clone https://github.com/MwauratheAlex/term_screen.git
cd term_screen

# Build the binary
go build -o term main.go
# Run
# input.bin generated by 'make_stream.py'
# you can use any other binary stream as long as it conforms to specifications
./term < input.bin
# input.txt is assumed to be a file containing commands

Examples

Basic testing binary

./term < examples/input.bin

Christmas

./term < examples/xmas.bin

Santa

./term < examples/santa.bin

Animated Santa

• I added a delay command

[0x08, 0x00]

• The above byte sequence will delay for 1 millisecond
• Of course we could have specified the time in the command itself, but that's for later.
• Here is an animated example.

./term < examples/animated_santa.bin

• The animation can definately be better.
• Feel free to fork and improve if you are interested.

The binary generating scripts were mainly done with chatgpt. Have fun.

Specifications

Imagine a stream of bytes supplied to a program to render them is a screen inside a terminal.

Below is the defination of the binary format used for communication between a computer and the screen:

+--------------+----------------+-------------+-------------+-----+---------------+
| Command Byte | Length of Byte | Data Byte 0 | Data Byte 1 | ... | Data Byte n-1 |
+--------------+----------------+-------------+-------------+-----+---------------+

The data format is an array of bytes, containing sections of above form, in succession. Each section begins with a command byte, specifying type of operation to be performed on the screen, followed by a length byte, and then a sequence of of data bytes, which function as arguements to the command as specified below:

• 0x1 - Screen setup: Defines the dimensions and color setting of the screen. The screen must be setup before any command is sent. Commands are ignored if the screen hasn't been setup.

Data format: Byte 0: Screen Width (in characters) Byte 1: Screen Height (in characters) Byte 2: Color Mode (0x00 for monochrome, 0x01 for 16 colors, 0x02 for 256 colors)

• 0x2 – Draw character: Places a character at a given coordinate of the screen. Data format: Byte 0: x coordinate Byte 1: y coordinate Byte 2: Color index Byte 3: Character to display (ASCII)

• 0x3 – Draw line: Draws a line from one coordinate of the screen to another. Data format: Byte 0: x1 (starting coordinate) Byte 1: y1 (starting coordinate) Byte 2: x2 (ending coordinate) Byte 3: y2 (ending coordinate) Byte 4: Color index Byte 5: Character to use (ASCII)

• 0x4 – Render text: Renders a string starting from a specific position. Data format: Byte 0: x coordinate Byte 1: y coordinate Byte 2: Color index Byte 3-n: Text data (ASCII characters)

• 0x5 – Cursor movement: Moves cursor to a specific location without drawing on the screen. Data format: Byte 0: x coordinate Byte 1: y coordinate

• 0x6 – Draw at cursor: Draws a character at the cursor location. Data format: Byte 0: Character to draw (ASCII) Byte 1: Color index

• 0x7 – Clear screen: Data format: No additional data.

• 0xFF – End of file: Marks the end of binary stream. Data format: No additional data.

The program should draw the screen from within a terminal window, but the question of whether to do so inside the terminal from which it is launched or to launch a separate terminal window is left to the implementer.