ethereum.istanbul.vm.instructions.storage
Ethereum Virtual Machine (EVM) Storage Instructions ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. contents:: Table of Contents :backlinks: none :local:
Introduction
Implementations of the EVM storage related instructions.
sload
Loads to the stack, the value corresponding to a certain key from the storage of the current account.
Parameters
evm : The current EVM frame.
def sload(evm: Evm) -> None:
30 | """ |
---|---|
31 | Loads to the stack, the value corresponding to a certain key from the |
32 | storage of the current account. |
33 |
|
34 | Parameters |
35 | ---------- |
36 | evm : |
37 | The current EVM frame. |
38 |
|
39 | """ |
40 | # STACK |
41 | key = pop(evm.stack).to_be_bytes32() |
42 | |
43 | # GAS |
44 | charge_gas(evm, GAS_SLOAD) |
45 | |
46 | # OPERATION |
47 | value = get_storage(evm.env.state, evm.message.current_target, key) |
48 | |
49 | push(evm.stack, value) |
50 | |
51 | # PROGRAM COUNTER |
52 | evm.pc += 1 |
sstore
Stores a value at a certain key in the current context's storage.
Parameters
evm : The current EVM frame.
def sstore(evm: Evm) -> None:
56 | """ |
---|---|
57 | Stores a value at a certain key in the current context's storage. |
58 |
|
59 | Parameters |
60 | ---------- |
61 | evm : |
62 | The current EVM frame. |
63 |
|
64 | """ |
65 | # STACK |
66 | key = pop(evm.stack).to_be_bytes32() |
67 | new_value = pop(evm.stack) |
68 | if evm.gas_left <= GAS_CALL_STIPEND: |
69 | raise OutOfGasError |
70 | |
71 | original_value = get_storage_original( |
72 | evm.env.state, evm.message.current_target, key |
73 | ) |
74 | current_value = get_storage(evm.env.state, evm.message.current_target, key) |
75 | |
76 | if original_value == current_value and current_value != new_value: |
77 | if original_value == 0: |
78 | gas_cost = GAS_STORAGE_SET |
79 | else: |
80 | gas_cost = GAS_STORAGE_UPDATE |
81 | else: |
82 | gas_cost = GAS_SLOAD |
83 | |
84 | # Refund Counter Calculation |
85 | if current_value != new_value: |
86 | if original_value != 0 and current_value != 0 and new_value == 0: |
87 | # Storage is cleared for the first time in the transaction |
88 | evm.refund_counter += int(GAS_STORAGE_CLEAR_REFUND) |
89 |
|
90 | if original_value != 0 and current_value == 0: |
91 | # Gas refund issued earlier to be reversed |
92 | evm.refund_counter -= int(GAS_STORAGE_CLEAR_REFUND) |
93 |
|
94 | if original_value == new_value: |
95 | # Storage slot being restored to its original value |
96 | if original_value == 0: |
97 | # Slot was originally empty and was SET earlier |
98 | evm.refund_counter += int(GAS_STORAGE_SET - GAS_SLOAD) |
99 | else: |
100 | # Slot was originally non-empty and was UPDATED earlier |
101 | evm.refund_counter += int(GAS_STORAGE_UPDATE - GAS_SLOAD) |
102 | |
103 | charge_gas(evm, gas_cost) |
104 | if evm.message.is_static: |
105 | raise WriteInStaticContext |
106 | set_storage(evm.env.state, evm.message.current_target, key, new_value) |
107 | |
108 | # PROGRAM COUNTER |
109 | evm.pc += 1 |