Flapjack

This is a toy shell developed to learn about operating systems and the C programming language
Flapjack is the name given to the shell while the language it runs is called Varelse
Think of it as the commands are Varelse while the environment Varelse is run in is called Flapjack

References

• https://cloudaffle.com/series/customizing-the-prompt/moving-the-cursor/ for ansi codes for moving the cursor
• https://viewsourcecode.org/snaptoken/kilo/ for entering raw mode and handling user input in raw mode

Commands

You do not know Varelse
The language itself is designed to look alien

1 2 ;

Move contents of register 2 into 1

1 "Data" :

Load the value "Data" into register 1

-

Display contents of child process background creation, stdio and registers

"Name" <

Declare a label called "Name"

1 >

Jump to label referenced by register 1

1 2 >

Jump to label referenced by register 1 if register 2 is not empty

1 @

Change to directory referenced by register 1

1 2 ... #

Call program referenced by register 1 with args specified in the following registers given
Return value is put into register 0

1 2 ... _

Perform dir command with arguments specified in registers given

)

Perform clear command

1 ... \

Perform echo command with arguments specified in registers given

1 (

Set stdin to what's in register 1

(

Set stdin back to its default

1 ]

Set stdout to what's in register 1

]

Set stdout back to its default

}

Toggle stdout write / append mode

1 [

Set stderr to what's in register 1

[

Set stderr back to its default

{

Toggle stderr write / append mode

~

Toggle background creation for child processes

?

Display the current environment

1 2 +

Set environment variable specified in register 1 to the contents of register 2

1 2 /

Put the contents of the environment variable specified in register 1 into register 2

=

Exit the terminal

1 2 ... ^

Push registers onto stack

1 2 ... .

Pop values of stack into registers