Jolly

A ByteByteJump virtual machine inspired by BytePusher.

Building and running

Install the check library, e.g. brew install check.

make test
./jolly images/echo.jolly

Demo images

The demo folder contains image files that can be executed by Jolly VM.

Features (early draft)

/!\ This is a draft of what I want, not everything is supported yet.

• 3*8-bit WordWordJump machine (3 words per address, and 8 bits per word)
• 16 MiB RAM
• Support for primitives
• Can save memory snapshot from program
• Can stop the VM from program
• Interface with operating system via primitives (e.g. read from stdin / write to stdout/stderr)

Jolly's memory

The memory of Jolly has a size of 0x1000000 bytes. It's address range is [0x000000, 0xFFFFFF].

Jolly virtual machine only has a few expectation on how its memory is organized. For Jolly, only the first 9 bytes of the memory are important.

The following table is a shortcut allowing you to not read memory.h.

Byte address	Name	Description
0x000000	PC_HIGH_ADDRESS	Address of the byte storing the most significant bits of the program counter.
0x000001	PC_MIDDLE_ADDRESS	Address of the byte storing the middle bits of the program counter.
0x000002	PC_LOW_ADDRESS	Address of the byte storing the less significant bits of the program counter.
0x000003	PRIMITIVE_IS_READY_ADDRESS	Address of the byte storing a value that triggers primitive execution.
0x000004	PRIMITIVE_CALL_ID_ADDRESS	Address of the byte storing a value that is the id of the primitive to execute.
0x000005	PRIMITIVE_RESULT_CODE_ADDRESS	Address of the byte storing a value that is the result code of the last primitive executed by the virtual machine.
0x000006	PRIMITIVE_RESULT_POINTER_HIGH_ADDRESS	Address of the byte storing the most significant bits of the result pointer.
0x000007	PRIMITIVE_RESULT_POINTER_MIDDLE_ADDRESS	Address of the byte storing the middle bits of the result pointer.
0x000008	PRIMITIVE_RESULT_POINTER_LOW_ADDRESS	Address of the byte storing the less significant bits of the result pointer.

Images provided

A set of Jolly programs are provided as binary files under the images directory.

Brainfuck interpreter

This program reads BF code from stdin and interpret it. The BF program code provided must have less than 512 characters and be terminated by q.

This is an Hello World in BF:

echo "++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.q" | ./jolly images/brainfuck.jolly

The following BF program (taken from here) computes Fibonnaci numbers and prints them.

echo '+++++++++++>+>>>>++++++++++++++++++++++++++++++++++++++++++++>++++++++++++++++++++++++++++++++<<<<<<[>[>>>>>>+>+<<<<<<<-]>>>>>>>[<<<<<<<+>>>>>>>-]<[>++++++++++[-<-[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]>[<<[>>>+<<<-]>>[-]]<<]>>>[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]>[<<+>>[-]]<<<<<<<]>>>>>[++++++++++++++++++++++++++++++++++++++++++++++++.[-]]++++++++++<[->-<]>++++++++++++++++++++++++++++++++++++++++++++++++.[-]<<<<<<<<<<<<[>>>+>+<<<<-]>>>>[<<<<+>>>>-]<-[>>.>.<<<[-]]<<[>>+>+<<<-]>>>[<<<+>>>-]<<[<+>-]>[<+>-]<<<-]q' | ./jolly images/brainfuck.jolly

Future

• Multi-threading
• FFI