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82 lines
2.3 KiB
Go
82 lines
2.3 KiB
Go
// Copyright 2014 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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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/common/math"
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)
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// calculates the memory size required for a step
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func calcMemSize(off, l *big.Int) *big.Int {
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if l.Sign() == 0 {
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return common.Big0
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}
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return new(big.Int).Add(off, l)
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}
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// getData returns a slice from the data based on the start and size and pads
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// up to size with zero's. This function is overflow safe.
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func getData(data []byte, start uint64, size uint64) []byte {
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length := uint64(len(data))
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if start > length {
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start = length
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}
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end := start + size
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if end > length {
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end = length
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}
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return common.RightPadBytes(data[start:end], int(size))
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}
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// getDataBig returns a slice from the data based on the start and size and pads
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// up to size with zero's. This function is overflow safe.
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func getDataBig(data []byte, start *big.Int, size *big.Int) []byte {
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dlen := big.NewInt(int64(len(data)))
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s := math.BigMin(start, dlen)
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e := math.BigMin(new(big.Int).Add(s, size), dlen)
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return common.RightPadBytes(data[s.Uint64():e.Uint64()], int(size.Uint64()))
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}
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// bigUint64 returns the integer casted to a uint64 and returns whether it
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// overflowed in the process.
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func bigUint64(v *big.Int) (uint64, bool) {
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return v.Uint64(), v.BitLen() > 64
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}
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// toWordSize returns the ceiled word size required for memory expansion.
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func toWordSize(size uint64) uint64 {
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if size > math.MaxUint64-31 {
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return math.MaxUint64/32 + 1
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}
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return (size + 31) / 32
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}
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func allZero(b []byte) bool {
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for _, byte := range b {
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if byte != 0 {
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return false
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}
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}
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return true
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}
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