54 lines
1.7 KiB
Go
54 lines
1.7 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"math/big"
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)
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// Gas costs
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const (
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GasQuickStep uint64 = 2
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GasFastestStep uint64 = 3
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GasFastStep uint64 = 5
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GasMidStep uint64 = 8
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GasSlowStep uint64 = 10
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GasExtStep uint64 = 20
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)
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// callGas returns the actual gas cost of the call.
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//
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// The cost of gas was changed during the homestead price change HF.
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// As part of EIP 150 (TangerineWhistle), the returned gas is gas - base * 63 / 64.
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func callGas(isEip150 bool, availableGas, base uint64, callCost *big.Int) (uint64, error) {
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if isEip150 {
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availableGas = availableGas - base
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gas := availableGas - availableGas/64
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// If the bit length exceeds 64 bit we know that the newly calculated "gas" for EIP150
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// is smaller than the requested amount. Therefore we return the new gas instead
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// of returning an error.
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if !callCost.IsUint64() || gas < callCost.Uint64() {
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return gas, nil
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}
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}
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if !callCost.IsUint64() {
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return 0, ErrGasUintOverflow
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}
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return callCost.Uint64(), nil
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}
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