For maintenance operations or for testing, gas can be Unaccounted. Otherwise, the computation is Limited by the remaining gas in the context.

check_limit_is_valid ctxt limit checks that the given gas limit is well-formed, i.e., it does not exceed the hard gas limit per operation as defined in ctxt and it is positive.

set_limit ctxt limit returns a context with a given limit level of gas allocated for an operation.

set_unlimited allows unlimited gas consumption.

remaining_operation_gas ctxt returns the current gas level in the context ctxt for the current operation. If gas is Unaccounted, an arbitrary value will be returned.

reset_block_gas ctxt returns a context where the remaining gas in the block is reset to the constant hard_gas_limit_per_block, i.e., as if no operations have been included in the block.

/!\ Do not call this function unless you want to validate operations on their own (like in the mempool).

level ctxt is the current gas level in ctxt for the current operation.

update_remaining_operation_gas ctxt remaining sets the current gas level for operations to remaining.

consumed since until is the operation gas level difference between context since and context until. This function returns Arith.zero if any of the two contexts allows for an unlimited gas consumption. This function also returns Arith.zero if since has less gas than until.

block_level ctxt returns the block gas level in context ctxt.

Costs are computed using a saturating arithmetic. See Saturation_repr.

consume ctxt cost subtracts cost to the current operation gas level in ctxt. This operation may fail with Operation_quota_exceeded if the operation gas level would go below zero.

consume_limit_in_block ctxt limit consumes limit in the current block gas level of the context. This operation may fail with error Block_quota_exceeded if not enough gas remains in the block. This operation may also fail with Gas_limit_too_high if limit is greater than the allowed limit for operation gas level.

The cost of free operation is 0.

atomic_step_cost x corresponds to x milliunit of gas.

step_cost x corresponds to x units of gas.

Cost of allocating qwords of storage. alloc_cost n estimates the cost of allocating n qwords of storage.

Cost of allocating bytes in the storage. alloc_bytes_cost b estimates the cost of allocating b bytes of storage.

Cost of allocating bytes in the storage.

alloc_mbytes_cost b estimates the cost of allocating b bytes of storage and the cost of an header to describe these bytes.

Cost of reading the storage. read_bytes_cost n estimates the cost of reading n bytes of storage.

Cost of writing to storage. write_bytes_const n estimates the cost of writing n bytes to the storage.

Multiply a cost by a factor. Both arguments are saturated arithmetic values, so no negative numbers are involved.

Add two costs together.

cost_of_repr is an internal operation needed to inject costs for Storage_costs into Gas.cost.