ethereum training
Ethereum Virtual Machine
Ethereum POC5 (well, almost...)
Ethereum Yellowpaper
- Stack based architecture (256bit word size)
- Transaction-based state machine
- Low level bytecode language “EVM code”
- Pay fee per step (no infinite loops)
- Code is immutable
Transaction-based state machine
Ethereum Accounts
- accounts are identified by 20 byte-address i.e.
0xd32fd7ecf43d1c2c0c553f1f515a8b5973456ec2 - have ether balance
- either externally owned (user accounts)
- private key known to owner
- or contract with:
- contract code
- storage (empty by default)
- no private key
Denominations
| 1 | Wei |
| 10^12 | Szabo |
| 10^15 | Finney |
| 10^18 | Ether |
Messages / Transactions
- transactions have value: amount in ether
- recipient: address (externally owner or contract), or none to create contract
- data arguments
- cost of execution gas/gasprice
- contracts can return a value (functions)
Fees
- gas used to pay for execution of contracts
gaslimit- maximum amount of gas to paygasprice- fee to pay to miner per step
- when contract runs out-of-gas (OOG): state changes reverted (except for balance & fees)
Fee schedule
| 1 | Default amount of gas to pay for execution cycle. |
| 0 | STOP or SUICIDE
|
| 20 | SHA3, SLOAD, BALANCE, CALL
|
| 100 | SSTORE (sometimes double or waived)
|
| 1 | Every additional word when expanding memory |
| 5 | Every byte of data or code for a transaction |
| 500 | Every transaction |
Code execution
- init/code block: init executed upon creation, returns body with code to be persisted
- Stack - each item 256 bit, LIFO, push/pop
- Memory - word based indexing, unlimited byte array (limited by fees), reset at end of computation
- Storage - persisted key/value store
Operations
Arithmetic Operations
ADD | Addition operation |
MUL | Multiplication operation |
SUB | Subtraction operation |
DIV | Integer division operation |
SDIV | Signed integer division operation |
MOD | Modulo remainder operation |
SMOD | Signed modulo remainder operation |
EXP | Expontential operation |
NEG | Negation operation |
Relation Operations
LT | Less-than comparison |
GT | Greater-than comparison |
EQ | Equality comparison |
NOT | Simple not operator |
Bitwise Logic Operations
AND | Bitwise AND operation |
OR | Bitwise OR operation |
XOR | Bitwise XOR operation |
BYTE | Retrieve single byte from word |
Crypto Operations
SHA3 | Compute SHA3-256 hash |
Environmental Information
ADDRESS | Get address of currently executing account |
BALANCE | Get balance of currently executing account |
ORIGIN | Get execution origination address |
CALLER | Get caller address |
CALLVALUE | Get deposited value by the instruction/transaction responsible for this execution |
CALLDATALOAD | Get input data of current environment |
CALLDATASIZE | Get size of input data in current environment |
GASPRICE | Get price of gas in current environment |
Block Information
PREVHASH | Get hash of most recent complete block |
COINBASE | Get the block’s coinbase address |
TIMESTAMP | Get the block’s timestamp |
NUMBER | Get the block’s number |
DIFFICULTY | Get the block’s difficulty |
GASLIMIT | Get the block’s gas limit |
Stack, Memory and Storage Operations
PUSH1..32 | Place n-byte item on stack |
POP | Remote item from stack |
DUP | Duplicate stack item |
SWAP | Exchange stack items |
MLOAD | Load word from memory |
MSTORE | Save word to memory |
MSTORE8 | Save byte to memory |
SLOAD | Load word from storage |
SSTORE | Save word to storage |
Flow Operations
STOP | Halts execution |
JUMP | Alter the program counter |
JUMPI | Conditionally alter the program counter |
PC | Get the program counter |
MSIZE | Get the size of the active memory |
GAS | Get the amount of available gas |
System Operations
CREATE | Create a new contract |
CALL | Message-call into contract |
RETURN | Halt execution returning output data |
SUICIDE | Halt execution and obliterate account |
What's next?
⇒ Learn Serpent
Questions / Feedback?