The Scratch Space (Heap)

In addition to the Stack, the AVM has a Scratch Space (or heap) of \( 256 \) positions.

Like Stack values, scratch locations may hold stackValues (of either uint64 or bytes types) and are initialized as zeroed-out uint64 values.

The Scratch Space is an additional area of volatile memory used at runtime. It’s useful for storing values needed multiple times during program execution, or that stay the same for long periods. It provides a convenient place to keep such persistent or reusable data during the program execution.

⚙️ IMPLEMENTATION

Scratch Space reference implementation.

Indexing

Scratch Space locations are mapped to \( 0 \)-based integer index.

Access

The Scratch Space is accessed by the load(s) and store(s) opcodes which move data respectively:

• From the Scratch Sspace to the Stack;

• From the Stack to the Scratch Space.

Persistency

Application calls MAY inspect the final Scratch Space of earlier application call transactions in the same group using gload(s')(s), where:

• s is the integer index of a Scratch Sspace location,

• s' is the integer index of an earlier application call transaction in the group.