Interface AuthenticationProgramStateBCHCHIPs

The "alternate stack" is separate stack on which OP_TOALTSTACK and OP_FROMALTSTACK operate in bitcoin virtual machines.

An array of boolean values representing the current execution status of the program. This allows the state to track nested conditional branches.

The OP_IF and OP_NOTIF operations push a new boolean onto the controlStack, OP_ELSE flips the top boolean, and OP_ENDIF removes the top boolean from the controlStack.

Other instructions are only evaluated if controlStack contains no false items.

A.K.A. vfExec in the C++ implementation.

If present, the error returned by the most recent virtual machine operation.

An unsigned integer counter use to count the total number of hash digest iterations that required during this evaluation.

The full list of instructions to be evaluated by the virtual machine.

Instruction Pointer – the array index of instructions that will be read to identify the next instruction. Once ip exceeds the last index of instructions (ip === instructions.length), evaluation is complete.

The lastCodeSeparator indicates the index of the most recently executed OP_CODESEPARATOR instruction. In each of the signing serialization algorithms, the instructions are sliced at lastCodeSeparator, and the subarray is re-encoded. The resulting bytecode is called the coveredBytecode (A.K.A. scriptCode), and is part of the data hashed to create the signing serialization digest.

By default, this is -1, which indicates that the whole instructions array is included in the signing serialization.

An unsigned integer counter used by OP_UNTIL to prevent excessive use of loops.

An array of the Uint8Array values used in signature verification over the course of this program. Each raw signing serialization and data signature message should be pushed to this array in the order it was computed.

This property is not used within any AuthenticationVirtualMachine, but it is provided in the program state to assist with analysis. Because these messages must always be computed and hashed during evaluation, recording them in the state does not meaningfully affect performance.

The stack is the primary workspace of the virtual machine. Most virtual machine operations create, read, update, or delete bytecode values held on the stack.