Module encoding 

Fuel ABI encoding primitives for O2 Exchange.

Implements the exact byte layouts from the O2 integration guide:

• u64 big-endian encoding
• Function selectors (NOT hash-based: u64(len) + utf8(name))
• Identity encoding (discriminant + 32-byte address)
• Option encoding (None = u64(0), Some = u64(1) + data)
• OrderArgs struct encoding (tightly packed enum variants)
• Session signing bytes
• Action signing bytes

Structs

CallArg

A low-level contract call used in action signing.

Enums

OrderTypeEncoding

Order type variants for encoding.

Constants

GAS_MAX

Gas value: always u64::MAX. The API overrides with its own value.

Functions

action_to_call

Convert a high-level Action to a low-level CallArg and JSON representation.

build_actions_signing_bytes

Build the signing bytes for session actions (Section 4.7 Step 2).

build_session_signing_bytes

Build the signing bytes for set_session (Section 4.6 Step 3).

build_withdraw_signing_bytes

Build the signing bytes for a withdrawal.

cancel_order_to_call

Convert a CancelOrder action to a low-level CallArg.

create_order_to_call

Convert a high-level CreateOrder action to a low-level CallArg.

encode_identity

Encode a Fuel Identity enum: u64(discriminant) + 32-byte address. discriminant: 0 = Address, 1 = ContractId

encode_option_call_data

Encode Option for call_data in action signing bytes. None -> u64(0) Some -> u64(1) + u64(len(data)) + data

encode_option_none

Encode Option::None: u64(0).

encode_option_some

Encode Option::Some(data): u64(1) + data.

encode_order_args

Encode OrderArgs struct for CreateOrder call_data. Layout: u64(price) + u64(quantity) + order_type_encoding (tightly packed)

function_selector

Encode a Fuel ABI function selector: u64_be(len(name)) + utf8(name). These are NOT hash-based like Solidity selectors.

register_referer_to_call

Convert a RegisterReferer action to a low-level CallArg.

settle_balance_to_call

Convert a SettleBalance action to a low-level CallArg. to is the destination identity (discriminant, address).

u64_be

Encode a u64 value as 8 bytes big-endian.