TON Assembly

This repository contains an assembler and disassembler implementation for TVM bitcode.

This implementation provides a complete cycle
Text -> Internal representation -> Cells -> BoC -> Cells -> Internal representation -> Text, this means that the same
text assembly can be obtained from a text assembly, going through all the compilation and decompilation steps.

The assembler correctly handles cases where the code does not fit into a single cell and automatically
creates a separate reference for the remaining code.
Current implementation optimizes cases where the reference can be folded into more efficient instructions
(e.g. IF into IFREF), thereby optimizing gas consumption.

During compilation, the assembler collects additional mappings that can be used to convert the TVM log into a full trace
that will refer to specific instructions in the decompiled version of the contract.

This mapping looks like this:

``
cell-hash + offset -> instruction
`

This implementation is able to generate a coverage report for the contract by BoC and logs
from Sandbox.
The proof of concept can be found in the ./src/coverage folder.

instructionNameForOpcode() function can be used to get the name of the instruction for a given opcode, which is useful
for runtime debugging with TVM since TVM itself provides only integer opcodes.

CLI Tools

This package includes two command-line utilities for working with TON Assembly:

$3

Compile TVM Assembly files to BOC format:

`bash


Install globally

npm install -g ton-assembly

Use the assembler

tasm contract.tasm -o contract.boc

Or via yarn scripts

yarn assembler contract.tasm -o contract.boc
`

$3

Disassemble BOC files back to TVM Assembly:

`bash


Use the disassembler

tdisasm contract.boc -o contract.tasm

Or via yarn scripts

yarn disassembler contract.boc -o contract.tasm
`

Both tools support multiple output formats (binary, hex, base64) and provide verbose output options.

#### Example Usage

`bash


Compile assembly to BOC

tasm contract.tasm -o contract.boc --verbose

Disassemble BOC back to assembly

tdisasm contract.boc -o decompiled.tasm --verbose

Full round-trip test

tasm decompiled.tasm -o recompiled.boc

contract.boc and recompiled.boc should be identical!

Work with different formats

tasm contract.tasm -f hex > contract.hex
tdisasm contract.hex -f hex -o contract.tasm

Assemble from string directly

tasm -s "PUSHINT_4 1" -f hex

Disassemble from hex/base64 strings directly

tdisasm -s "b5ee9c72410102010027000114ff008e83f4a413ed43d901002fa64ce73b5134348034c7f487f4fffd0115501b05485b1460ec17065c" -f hex -o contract.tasm
tdisasm -s "te6cckEBAgEAJwABFP8AjoP0pBPtQ9kBAC+mTOc7UTQ0gDTH9If0//0BFVAbBUhbFGDsFwZc" -f base64
``

See CLI documentation for detailed usage instructions.

Library Usage

In addition to the CLI tools, this package can be used as a library for programmatic compilation, decompilation, and log
tracing.

For detailed information, see the API Documentation.

Validity

The assembler was tested on 106k contracts from the blockchain
where it successfully decompiled and compiled all contracts into equivalent Cells.

License

This project is licensed under the MIT License — see the LICENSE file for details.

MIT © TON Studio.