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- // Copyright 2014 The go-ethereum Authors
- // This file is part of the go-ethereum library.
- //
- // The go-ethereum library is free software: you can redistribute it and/or modify
- // it under the terms of the GNU Lesser General Public License as published by
- // the Free Software Foundation, either version 3 of the License, or
- // (at your option) any later version.
- //
- // The go-ethereum library is distributed in the hope that it will be useful,
- // but WITHOUT ANY WARRANTY; without even the implied warranty of
- // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- // GNU Lesser General Public License for more details.
- //
- // You should have received a copy of the GNU Lesser General Public License
- // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
- package vm
- import (
- "github.com/ethereum/go-ethereum/common"
- "github.com/ethereum/go-ethereum/common/math"
- "github.com/holiman/uint256"
- )
- // calcMemSize64 calculates the required memory size, and returns
- // the size and whether the result overflowed uint64
- func calcMemSize64(off, l *uint256.Int) (uint64, bool) {
- if !l.IsUint64() {
- return 0, true
- }
- return calcMemSize64WithUint(off, l.Uint64())
- }
- // calcMemSize64WithUint calculates the required memory size, and returns
- // the size and whether the result overflowed uint64
- // Identical to calcMemSize64, but length is a uint64
- func calcMemSize64WithUint(off *uint256.Int, length64 uint64) (uint64, bool) {
- // if length is zero, memsize is always zero, regardless of offset
- if length64 == 0 {
- return 0, false
- }
- // Check that offset doesn't overflow
- offset64, overflow := off.Uint64WithOverflow()
- if overflow {
- return 0, true
- }
- val := offset64 + length64
- // if value < either of it's parts, then it overflowed
- return val, val < offset64
- }
- // getData returns a slice from the data based on the start and size and pads
- // up to size with zero's. This function is overflow safe.
- func getData(data []byte, start uint64, size uint64) []byte {
- length := uint64(len(data))
- if start > length {
- start = length
- }
- end := start + size
- if end > length {
- end = length
- }
- return common.RightPadBytes(data[start:end], int(size))
- }
- // toWordSize returns the ceiled word size required for memory expansion.
- func toWordSize(size uint64) uint64 {
- if size > math.MaxUint64-31 {
- return math.MaxUint64/32 + 1
- }
- return (size + 31) / 32
- }
- func allZero(b []byte) bool {
- for _, byte := range b {
- if byte != 0 {
- return false
- }
- }
- return true
- }
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