BCS Primitives

Here is a list of primitives, and more descriptions below. Keep in mind all numbers are stored in little-endian byte order.

Bool

A boolean is a single byte. 0x00 represents false, 0x01 represents true. All other values are defined as invalid.

Examples:

U8

A U8 is an unsigned 8-bit integer (1 byte).

Examples:

U16

A U16 is an unsigned 16-bit integer (2 bytes).

Examples:

U32

A U32 is an unsigned 32-bit integer (4 bytes).

Examples:

U64

A U64 is an unsigned 64-bit integer (8 bytes).

Examples:

U128

A U128 is an unsigned 128-bit integer (16 bytes).

Examples:

U256

A U256 is an unsigned 256-bit integer (32 bytes).

Examples:

Address

An address is the 32-byte representation of a storage slot on Aptos. It can be used for accounts, objects, and other addressable storage.

Addresses, have special addresses 0x0 -> 0xA, and then full length addresses. Note, for legacy purposes, addresses missing 0's in front, are extended by filling the missing bytes with 0s.

Examples:

Uleb128

A uleb128 is a variable-length integer used mainly for representing sequence lengths. It is very efficient at storing small numbers, and takes up more space as the number grows. Note that the Aptos specific implementation only supports representing a u32 in the uleb128. Any value more than the max u32 is considered invalid.

Examples: