github.com/vantum/vantum@v0.0.0-20180815184342-fe37d5f7a990/core/vm/common.go (about)

     1  // Copyright 2014 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package vm
    18  
    19  import (
    20  	"math/big"
    21  
    22  	"github.com/vantum/vantum/common"
    23  	"github.com/vantum/vantum/common/math"
    24  )
    25  
    26  // calculates the memory size required for a step
    27  func calcMemSize(off, l *big.Int) *big.Int {
    28  	if l.Sign() == 0 {
    29  		return common.Big0
    30  	}
    31  
    32  	return new(big.Int).Add(off, l)
    33  }
    34  
    35  // getData returns a slice from the data based on the start and size and pads
    36  // up to size with zero's. This function is overflow safe.
    37  func getData(data []byte, start uint64, size uint64) []byte {
    38  	length := uint64(len(data))
    39  	if start > length {
    40  		start = length
    41  	}
    42  	end := start + size
    43  	if end > length {
    44  		end = length
    45  	}
    46  	return common.RightPadBytes(data[start:end], int(size))
    47  }
    48  
    49  // getDataBig returns a slice from the data based on the start and size and pads
    50  // up to size with zero's. This function is overflow safe.
    51  func getDataBig(data []byte, start *big.Int, size *big.Int) []byte {
    52  	dlen := big.NewInt(int64(len(data)))
    53  
    54  	s := math.BigMin(start, dlen)
    55  	e := math.BigMin(new(big.Int).Add(s, size), dlen)
    56  	return common.RightPadBytes(data[s.Uint64():e.Uint64()], int(size.Uint64()))
    57  }
    58  
    59  // bigUint64 returns the integer casted to a uint64 and returns whether it
    60  // overflowed in the process.
    61  func bigUint64(v *big.Int) (uint64, bool) {
    62  	return v.Uint64(), v.BitLen() > 64
    63  }
    64  
    65  // toWordSize returns the ceiled word size required for memory expansion.
    66  func toWordSize(size uint64) uint64 {
    67  	if size > math.MaxUint64-31 {
    68  		return math.MaxUint64/32 + 1
    69  	}
    70  
    71  	return (size + 31) / 32
    72  }
    73  
    74  func allZero(b []byte) bool {
    75  	for _, byte := range b {
    76  		if byte != 0 {
    77  			return false
    78  		}
    79  	}
    80  	return true
    81  }