| name | masm-constants |
| description | Enforce constant definition and organization conventions for Miden Assembly (.masm) files. Use when editing, reviewing, or creating .masm files that define or use constants. |
MASM Constant Conventions
Placement
Constants must be defined at the top of the file, before any procedure definitions, but after imports or type aliases.
Organization
Constants Section (first)
Group non-error constants by topic. Use blank lines between sections. Common topics:
- Slot names – use
word("path::to::slot") for slot identifiers
- Memory pointer offsets – offsets into memory regions
- Local memory offsets – offsets within a procedure's local memory
- Magic numbers / values – domain-specific literals
- Event identifiers –
event("...") constants consumed by emit (e.g. const AUTH_REQUEST_EVENT = event("miden::protocol::auth::request") used as emit.AUTH_REQUEST_EVENT)
- Trace ids – plain numeric constants consumed by
trace (e.g. const PRINTLN = 0 used as trace.PRINTLN); trace takes a numeric u32 id, not an event("...") constant
Order sections by dependency or by usage frequency. Put the most widely used first.
Errors Section (after constants)
Errors (panic/assert error codes, e.g. ERR_*) go in a dedicated "errors" section, placed after the constants section. Define them with string values describing the error. (Some files in v0.15 place the errors section before the constants section; constants-first is the more common order and is preferred for new files.)
Naming
Memory Pointers
Memory pointer constants describe offsets into memory regions that are shared or global (e.g. layout of a memory region, input/output structure offsets). They are not scoped to a single procedure.
# Good: descriptive, shared usage
const ASSET_OFF = 0
const AMOUNT_OFF = 1
const NOTE_DATA_LEN = 16
# Or grouped by memory region if applicable
const INPUT_PTR_OFF = 0
const INPUT_LEN_OFF = 1
Local Memory Offsets
Local memory offsets describe offsets within a procedure's local memory. Name them with UPPERCASE descriptive names ending in _LOC (or _LOCAL):
# Good: descriptive UPPERCASE name ending in _LOC
const IS_SIGNER_FOUND_LOC = 0
const CURRENT_SIGNER_INDEX_LOC = 1
const NUM_OF_APPROVERS_LOC = 0
When several procedures in the same file define local offsets, group each procedure's locals under a section comment and, where names would otherwise collide or be ambiguous, disambiguate with an UPPERCASE context prefix derived from the procedure name. Not every constant in a group needs the prefix — use it only where it adds clarity:
# bridge_out memory locals
const BRIDGE_OUT_BURN_ASSET_LOC = 0
const DESTINATION_NETWORK_LOC = 13
const BRIDGE_OUT_IS_NATIVE_LOC = 14
# create_burn_note memory locals
const CREATE_BURN_NOTE_BURN_ASSET_LOC = 0
const ATTACHMENT_LOC = 8
Do not use a lowercase procedure-name prefix (e.g. validate_note_NOTE_IDX_LOC); that form does not appear in the protocol source. Every constant name in v0.15 source begins with an uppercase letter.
Formatting
Both const NAME = value (spaces around =) and const NAME=value (no spaces) occur in v0.15 source, and the choice varies sharply by area — miden-protocol is mostly no-space, while miden-standards and miden-agglayer are mostly spaced. Globally the two styles are roughly even. Prefer spaces around the equals sign for new or edited constants, but do not treat no-space definitions in existing files as errors. Keep a file internally consistent with its surrounding style.
Errors – string value describing the error:
const ERR_BRIDGE_NOT_MAINNET = "bridge not mainnet"
const ERR_UNAUTHORIZED = "unauthorized"
Slots – use word() with the slot path; mark them pub const when the slot is part of a component's public storage layout:
pub const THRESHOLD_CONFIG_SLOT = word("miden::standards::auth::multisig::threshold_config")
pub const AUTHORITY_SLOT = word("miden::standards::access::authority")
Offsets / numeric values – plain numbers:
const IS_SIGNER_FOUND_LOC = 0
const CURRENT_SIGNER_INDEX_LOC = 1
Visibility (pub const)
In v0.15 a constant must be declared pub const to be referenced from another module. This is not limited to storage slots: any constant imported elsewhere via use path::to::CONST (or referenced as module::CONST) must be pub, including magic numbers, memory-pointer offsets, and event identifiers. Keep purely file-local constants as plain const.
# pub because they are imported by other modules
pub const MAX_ASSETS_PER_NOTE = 64
pub const AUTH_REQUEST_EVENT = event("miden::protocol::auth::request")
# file-local only — no pub needed
const IS_SIGNER_FOUND_LOC = 0
Example Layout
# CONSTANTS
# =================================================================================================
# Storage slots
pub const AUTHORITY_SLOT = word("miden::standards::access::authority")
# Authority modes
const AUTH_CONTROLLED = 0
const OWNER_CONTROLLED = 1
const RBAC_CONTROLLED = 2
# Memory pointers
const ASSET_OFF = 0
const AMOUNT_OFF = 1
# bridge_out memory locals
const BRIDGE_OUT_BURN_ASSET_LOC = 0
const DESTINATION_NETWORK_LOC = 13
const BRIDGE_OUT_IS_NATIVE_LOC = 14
# create_burn_note memory locals
const CREATE_BURN_NOTE_BURN_ASSET_LOC = 0
const ATTACHMENT_LOC = 8
# ERRORS
# =================================================================================================
const ERR_BRIDGE_NOT_MAINNET = "bridge not mainnet"
const ERR_UNAUTHORIZED = "unauthorized"
const ERR_NOTE_NOT_FOUND = "note not found"
# PROCEDURES
# =================================================================================================
pub proc validate_note
...
end
Validation Checklist
