github.com/digdeepmining/go-atheios@v1.5.13-0.20180902133602-d5687a2e6f43/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"
    21  	"math/big"
    22  
    23  	"github.com/atheioschain/go-atheios/common"
    24  	"github.com/atheioschain/go-atheios/params"
    25  )
    26  
    27  // Type is the VM type accepted by **NewVm**
    28  type Type byte
    29  
    30  const (
    31  	StdVmTy Type = iota // Default standard VM
    32  	JitVmTy             // LLVM JIT VM
    33  	MaxVmTy
    34  )
    35  
    36  var (
    37  	Pow256 = common.BigPow(2, 256) // Pow256 is 2**256
    38  
    39  	U256 = common.U256 // Shortcut to common.U256
    40  	S256 = common.S256 // Shortcut to common.S256
    41  
    42  	Zero = common.Big0 // Shortcut to common.Big0
    43  	One  = common.Big1 // Shortcut to common.Big1
    44  
    45  	max = big.NewInt(math.MaxInt64) // Maximum 64 bit integer
    46  )
    47  
    48  // calculates the memory size required for a step
    49  func calcMemSize(off, l *big.Int) *big.Int {
    50  	if l.Cmp(common.Big0) == 0 {
    51  		return common.Big0
    52  	}
    53  
    54  	return new(big.Int).Add(off, l)
    55  }
    56  
    57  // calculates the quadratic gas
    58  func quadMemGas(mem *Memory, newMemSize, gas *big.Int) {
    59  	if newMemSize.Cmp(common.Big0) > 0 {
    60  		newMemSizeWords := toWordSize(newMemSize)
    61  		newMemSize.Mul(newMemSizeWords, u256(32))
    62  
    63  		if newMemSize.Cmp(u256(int64(mem.Len()))) > 0 {
    64  			// be careful reusing variables here when changing.
    65  			// The order has been optimised to reduce allocation
    66  			oldSize := toWordSize(big.NewInt(int64(mem.Len())))
    67  			pow := new(big.Int).Exp(oldSize, common.Big2, Zero)
    68  			linCoef := oldSize.Mul(oldSize, params.MemoryGas)
    69  			quadCoef := new(big.Int).Div(pow, params.QuadCoeffDiv)
    70  			oldTotalFee := new(big.Int).Add(linCoef, quadCoef)
    71  
    72  			pow.Exp(newMemSizeWords, common.Big2, Zero)
    73  			linCoef = linCoef.Mul(newMemSizeWords, params.MemoryGas)
    74  			quadCoef = quadCoef.Div(pow, params.QuadCoeffDiv)
    75  			newTotalFee := linCoef.Add(linCoef, quadCoef)
    76  
    77  			fee := newTotalFee.Sub(newTotalFee, oldTotalFee)
    78  			gas.Add(gas, fee)
    79  		}
    80  	}
    81  }
    82  
    83  // Simple helper
    84  func u256(n int64) *big.Int {
    85  	return big.NewInt(n)
    86  }
    87  
    88  // Mainly used for print variables and passing to Print*
    89  func toValue(val *big.Int) interface{} {
    90  	// Let's assume a string on right padded zero's
    91  	b := val.Bytes()
    92  	if b[0] != 0 && b[len(b)-1] == 0x0 && b[len(b)-2] == 0x0 {
    93  		return string(b)
    94  	}
    95  
    96  	return val
    97  }
    98  
    99  // getData returns a slice from the data based on the start and size and pads
   100  // up to size with zero's. This function is overflow safe.
   101  func getData(data []byte, start, size *big.Int) []byte {
   102  	dlen := big.NewInt(int64(len(data)))
   103  
   104  	s := common.BigMin(start, dlen)
   105  	e := common.BigMin(new(big.Int).Add(s, size), dlen)
   106  	return common.RightPadBytes(data[s.Uint64():e.Uint64()], int(size.Uint64()))
   107  }
   108  
   109  // useGas attempts to subtract the amount of gas and returns whether it was
   110  // successful
   111  func useGas(gas, amount *big.Int) bool {
   112  	if gas.Cmp(amount) < 0 {
   113  		return false
   114  	}
   115  
   116  	// Sub the amount of gas from the remaining
   117  	gas.Sub(gas, amount)
   118  	return true
   119  }