// calculateGasAndSize calculates the required given the opcode and stack items calculates the new memorysize for
// the operation. This does not reduce gas or resizes the memory.
func calculateGasAndSize(env Environment, context *Context, caller ContextRef, op OpCode, statedb *state.StateDB, mem *Memory, stack *stack) (*big.Int, *big.Int, error) {
var (
gas = new(big.Int)
newMemSize *big.Int = new(big.Int)
)
err := baseCheck(op, stack, gas)
if err != nil {
return nil, nil, err
}
// stack Check, memory resize & gas phase
switch op {
case SWAP1, SWAP2, SWAP3, SWAP4, SWAP5, SWAP6, SWAP7, SWAP8, SWAP9, SWAP10, SWAP11, SWAP12, SWAP13, SWAP14, SWAP15, SWAP16:
n := int(op - SWAP1 + 2)
err := stack.require(n)
if err != nil {
return nil, nil, err
}
gas.Set(GasFastestStep)
case DUP1, DUP2, DUP3, DUP4, DUP5, DUP6, DUP7, DUP8, DUP9, DUP10, DUP11, DUP12, DUP13, DUP14, DUP15, DUP16:
n := int(op - DUP1 + 1)
err := stack.require(n)
if err != nil {
return nil, nil, err
}
gas.Set(GasFastestStep)
case LOG0, LOG1, LOG2, LOG3, LOG4:
n := int(op - LOG0)
err := stack.require(n + 2)
if err != nil {
return nil, nil, err
}
mSize, mStart := stack.data[stack.len()-2], stack.data[stack.len()-1]
gas.Add(gas, params.LogGas)
gas.Add(gas, new(big.Int).Mul(big.NewInt(int64(n)), params.LogTopicGas))
gas.Add(gas, new(big.Int).Mul(mSize, params.LogDataGas))
newMemSize = calcMemSize(mStart, mSize)
case EXP:
gas.Add(gas, new(big.Int).Mul(big.NewInt(int64(len(stack.data[stack.len()-2].Bytes()))), params.ExpByteGas))
case SSTORE:
err := stack.require(2)
if err != nil {
return nil, nil, err
}
var g *big.Int
y, x := stack.data[stack.len()-2], stack.data[stack.len()-1]
val := statedb.GetState(context.Address(), common.BigToHash(x))
// This checks for 3 scenario's and calculates gas accordingly
// 1. From a zero-value address to a non-zero value (NEW VALUE)
// 2. From a non-zero value address to a zero-value address (DELETE)
// 3. From a nen-zero to a non-zero (CHANGE)
if common.EmptyHash(val) && !common.EmptyHash(common.BigToHash(y)) {
// 0 => non 0
g = params.SstoreSetGas
} else if !common.EmptyHash(val) && common.EmptyHash(common.BigToHash(y)) {
statedb.Refund(params.SstoreRefundGas)
g = params.SstoreClearGas
} else {
// non 0 => non 0 (or 0 => 0)
g = params.SstoreClearGas
}
gas.Set(g)
case SUICIDE:
if !statedb.IsDeleted(context.Address()) {
statedb.Refund(params.SuicideRefundGas)
}
case MLOAD:
newMemSize = calcMemSize(stack.peek(), u256(32))
case MSTORE8:
newMemSize = calcMemSize(stack.peek(), u256(1))
case MSTORE:
newMemSize = calcMemSize(stack.peek(), u256(32))
case RETURN:
newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-2])
case SHA3:
newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-2])
words := toWordSize(stack.data[stack.len()-2])
gas.Add(gas, words.Mul(words, params.Sha3WordGas))
case CALLDATACOPY:
newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-3])
words := toWordSize(stack.data[stack.len()-3])
gas.Add(gas, words.Mul(words, params.CopyGas))
case CODECOPY:
newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-3])
words := toWordSize(stack.data[stack.len()-3])
gas.Add(gas, words.Mul(words, params.CopyGas))
case EXTCODECOPY:
newMemSize = calcMemSize(stack.data[stack.len()-2], stack.data[stack.len()-4])
words := toWordSize(stack.data[stack.len()-4])
gas.Add(gas, words.Mul(words, params.CopyGas))
case CREATE:
newMemSize = calcMemSize(stack.data[stack.len()-2], stack.data[stack.len()-3])
case CALL, CALLCODE:
gas.Add(gas, stack.data[stack.len()-1])
if op == CALL {
if env.State().GetStateObject(common.BigToAddress(stack.data[stack.len()-2])) == nil {
gas.Add(gas, params.CallNewAccountGas)
}
}
if len(stack.data[stack.len()-3].Bytes()) > 0 {
gas.Add(gas, params.CallValueTransferGas)
}
x := calcMemSize(stack.data[stack.len()-6], stack.data[stack.len()-7])
y := calcMemSize(stack.data[stack.len()-4], stack.data[stack.len()-5])
newMemSize = common.BigMax(x, y)
}
if newMemSize.Cmp(common.Big0) > 0 {
newMemSizeWords := toWordSize(newMemSize)
newMemSize.Mul(newMemSizeWords, u256(32))
if newMemSize.Cmp(u256(int64(mem.Len()))) > 0 {
oldSize := toWordSize(big.NewInt(int64(mem.Len())))
pow := new(big.Int).Exp(oldSize, common.Big2, Zero)
linCoef := new(big.Int).Mul(oldSize, params.MemoryGas)
quadCoef := new(big.Int).Div(pow, params.QuadCoeffDiv)
oldTotalFee := new(big.Int).Add(linCoef, quadCoef)
pow.Exp(newMemSizeWords, common.Big2, Zero)
linCoef = new(big.Int).Mul(newMemSizeWords, params.MemoryGas)
quadCoef = new(big.Int).Div(pow, params.QuadCoeffDiv)
newTotalFee := new(big.Int).Add(linCoef, quadCoef)
fee := new(big.Int).Sub(newTotalFee, oldTotalFee)
gas.Add(gas, fee)
}
}
return newMemSize, gas, nil
}