opcodes

Manage opcode grammar files used by tiltshift decode.

Grammar files map opcode bytes to mnemonics and operand widths. They are written by hand after identifying a bytecode format and enable tiltshift decode to display named instructions rather than raw hex.

Subcommands

opcodes add

Install an opcode grammar file from a TOML path.

The file is validated and copied to ~/.config/tiltshift/opcodes/<name>.toml.

Usage

tiltshift opcodes add <NAME> <FILE>

Arguments

Argument	Description
<NAME>	Short name to install the grammar under (e.g. my-vm)
<FILE>	Path to the TOML grammar file

Example

tiltshift opcodes add my-vm /path/to/my-vm.toml

opcodes list

List all installed opcode grammars.

Shows all grammars stored at ~/.config/tiltshift/opcodes/.

Usage

tiltshift opcodes list

Grammar file format

Grammar files are TOML with the following structure:

name = "my-vm"
description = "My custom bytecode VM"  # optional

[[opcodes]]
byte = 0x00
mnemonic = "NOP"
operand_bytes = 0

[[opcodes]]
byte = 0x01
mnemonic = "PUSH"
operand_bytes = 2

[[opcodes]]
byte = 0xFF
mnemonic = "HALT"
operand_bytes = 0

Fields:

Field	Required	Description
name	yes	Human-readable grammar name
description	no	Optional longer description
[[opcodes]]	yes	One entry per known opcode
byte	yes	Opcode value (0–255)
mnemonic	yes	Instruction name (e.g. PUSH, CALL, NOP)
operand_bytes	yes	Number of bytes consumed by operands after the opcode byte

Opcodes not listed in the grammar are shown as UNKNOWN during decode and consume 1 byte.

See also

• decode — decode instructions using a grammar
• Signal Reference: BytecodeStream — how bytecode regions are detected