github.com/ontio/ontology@v1.14.4/vm/evm/common.go (about)

     1  // Copyright (C) 2021 The Ontology Authors
     2  // Copyright 2014 The go-ethereum Authors
     3  // This file is part of the go-ethereum library.
     4  //
     5  // The go-ethereum library is free software: you can redistribute it and/or modify
     6  // it under the terms of the GNU Lesser General Public License as published by
     7  // the Free Software Foundation, either version 3 of the License, or
     8  // (at your option) any later version.
     9  //
    10  // The go-ethereum library is distributed in the hope that it will be useful,
    11  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    12  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    13  // GNU Lesser General Public License for more details.
    14  //
    15  // You should have received a copy of the GNU Lesser General Public License
    16  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    17  
    18  package evm
    19  
    20  import (
    21  	"math"
    22  
    23  	"github.com/ethereum/go-ethereum/common"
    24  	"github.com/holiman/uint256"
    25  )
    26  
    27  // calcMemSize64 calculates the required memory size, and returns
    28  // the size and whether the result overflowed uint64
    29  func calcMemSize64(off, l *uint256.Int) (uint64, bool) {
    30  	if !l.IsUint64() {
    31  		return 0, true
    32  	}
    33  	return calcMemSize64WithUint(off, l.Uint64())
    34  }
    35  
    36  // calcMemSize64WithUint calculates the required memory size, and returns
    37  // the size and whether the result overflowed uint64
    38  // Identical to calcMemSize64, but length is a uint64
    39  func calcMemSize64WithUint(off *uint256.Int, length64 uint64) (uint64, bool) {
    40  	// if length is zero, memsize is always zero, regardless of offset
    41  	if length64 == 0 {
    42  		return 0, false
    43  	}
    44  	// Check that offset doesn't overflow
    45  	offset64, overflow := off.Uint64WithOverflow()
    46  	if overflow {
    47  		return 0, true
    48  	}
    49  	val := offset64 + length64
    50  	// if value < either of it's parts, then it overflowed
    51  	return val, val < offset64
    52  }
    53  
    54  // getData returns a slice from the data based on the start and size and pads
    55  // up to size with zero's. This function is overflow safe.
    56  func getData(data []byte, start uint64, size uint64) []byte {
    57  	length := uint64(len(data))
    58  	if start > length {
    59  		start = length
    60  	}
    61  	end := start + size
    62  	if end > length {
    63  		end = length
    64  	}
    65  	return common.RightPadBytes(data[start:end], int(size))
    66  }
    67  
    68  // toWordSize returns the ceiled word size required for memory expansion.
    69  func toWordSize(size uint64) uint64 {
    70  	if size > math.MaxUint64-31 {
    71  		return math.MaxUint64/32 + 1
    72  	}
    73  
    74  	return (size + 31) / 32
    75  }
    76  
    77  func allZero(b []byte) bool {
    78  	for _, byte := range b {
    79  		if byte != 0 {
    80  			return false
    81  		}
    82  	}
    83  	return true
    84  }