Golang common.BigMax函数代码示例

// CalcGasLimit computes the gas limit of the next block after parent.
// The result may be modified by the caller.
// This is miner strategy, not consensus protocol.
func CalcGasLimit(parent *types.Block) *big.Int {
	// contrib = (parentGasUsed * 3 / 2) / 1024
	contrib := new(big.Int).Mul(parent.GasUsed(), big.NewInt(3))
	contrib = contrib.Div(contrib, big.NewInt(2))
	contrib = contrib.Div(contrib, params.GasLimitBoundDivisor)

	// decay = parentGasLimit / 1024 -1
	decay := new(big.Int).Div(parent.GasLimit(), params.GasLimitBoundDivisor)
	decay.Sub(decay, big.NewInt(1))

	/*
		strategy: gasLimit of block-to-mine is set based on parent's
		gasUsed value.  if parentGasUsed > parentGasLimit * (2/3) then we
		increase it, otherwise lower it (or leave it unchanged if it's right
		at that usage) the amount increased/decreased depends on how far away
		from parentGasLimit * (2/3) parentGasUsed is.
	*/
	gl := new(big.Int).Sub(parent.GasLimit(), decay)
	gl = gl.Add(gl, contrib)
	gl.Set(common.BigMax(gl, params.MinGasLimit))

	// however, if we're now below the target (TargetGasLimit) we increase the
	// limit as much as we can (parentGasLimit / 1024 -1)
	if gl.Cmp(params.TargetGasLimit) < 0 {
		gl.Add(parent.GasLimit(), decay)
		gl.Set(common.BigMin(gl, params.TargetGasLimit))
	}
	return gl
}

func calcDifficultyFrontier(time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
	diff := new(big.Int)
	adjust := new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor)
	bigTime := new(big.Int)
	bigParentTime := new(big.Int)

	bigTime.SetUint64(time)
	bigParentTime.SetUint64(parentTime)

	if bigTime.Sub(bigTime, bigParentTime).Cmp(params.DurationLimit) < 0 {
		diff.Add(parentDiff, adjust)
	} else {
		diff.Sub(parentDiff, adjust)
	}
	if diff.Cmp(params.MinimumDifficulty) < 0 {
		diff.Set(params.MinimumDifficulty)
	}

	periodCount := new(big.Int).Add(parentNumber, common.Big1)
	periodCount.Div(periodCount, ExpDiffPeriod)
	if periodCount.Cmp(common.Big1) > 0 {
		// diff = diff + 2^(periodCount - 2)
		expDiff := periodCount.Sub(periodCount, common.Big2)
		expDiff.Exp(common.Big2, expDiff, nil)
		diff.Add(diff, expDiff)
		diff = common.BigMax(diff, params.MinimumDifficulty)
	}

	return diff
}

func CalcGasLimit(parent *types.Block) *big.Int {
	// ((1024-1) * parent.gasLimit + (gasUsed * 6 / 5)) / 1024
	previous := new(big.Int).Mul(big.NewInt(1024-1), parent.GasLimit())
	current := new(big.Rat).Mul(new(big.Rat).SetInt(parent.GasUsed()), big.NewRat(6, 5))
	curInt := new(big.Int).Div(current.Num(), current.Denom())

	result := new(big.Int).Add(previous, curInt)
	result.Div(result, big.NewInt(1024))
	return common.BigMax(params.GenesisGasLimit, result)
}

// CalcGasLimit computes the gas limit of the next block after parent.
// The result may be modified by the caller.
func CalcGasLimit(parent *types.Block) *big.Int {
	decay := new(big.Int).Div(parent.GasLimit(), params.GasLimitBoundDivisor)
	contrib := new(big.Int).Mul(parent.GasUsed(), big.NewInt(3))
	contrib = contrib.Div(contrib, big.NewInt(2))
	contrib = contrib.Div(contrib, params.GasLimitBoundDivisor)

	gl := new(big.Int).Sub(parent.GasLimit(), decay)
	gl = gl.Add(gl, contrib)
	gl = gl.Add(gl, big.NewInt(1))
	gl.Set(common.BigMax(gl, params.MinGasLimit))

	if gl.Cmp(params.GenesisGasLimit) < 0 {
		gl.Add(parent.GasLimit(), decay)
		gl.Set(common.BigMin(gl, params.GenesisGasLimit))
	}
	return gl
}

//.........这里部分代码省略.........

		mSize, mStart := stack.data[stack.len()-2], stack.data[stack.len()-1]

		gas.Add(gas, params.LogGas)
		gas.Add(gas, new(big.Int).Mul(big.NewInt(int64(n)), params.LogTopicGas))
		gas.Add(gas, new(big.Int).Mul(mSize, params.LogDataGas))

		newMemSize = calcMemSize(mStart, mSize)
	case EXP:
		gas.Add(gas, new(big.Int).Mul(big.NewInt(int64(len(stack.data[stack.len()-2].Bytes()))), params.ExpByteGas))
	case SSTORE:
		err := stack.require(2)
		if err != nil {
			return nil, nil, err
		}

		var g *big.Int
		y, x := stack.data[stack.len()-2], stack.data[stack.len()-1]
		val := statedb.GetState(contract.Address(), common.BigToHash(x))

		// This checks for 3 scenario's and calculates gas accordingly
		// 1. From a zero-value address to a non-zero value         (NEW VALUE)
		// 2. From a non-zero value address to a zero-value address (DELETE)
		// 3. From a non-zero to a non-zero                         (CHANGE)
		if common.EmptyHash(val) && !common.EmptyHash(common.BigToHash(y)) {
			// 0 => non 0
			g = params.SstoreSetGas
		} else if !common.EmptyHash(val) && common.EmptyHash(common.BigToHash(y)) {
			statedb.AddRefund(params.SstoreRefundGas)

			g = params.SstoreClearGas
		} else {
			// non 0 => non 0 (or 0 => 0)
			g = params.SstoreClearGas
		}
		gas.Set(g)
	case SUICIDE:
		if !statedb.IsDeleted(contract.Address()) {
			statedb.AddRefund(params.SuicideRefundGas)
		}
	case MLOAD:
		newMemSize = calcMemSize(stack.peek(), u256(32))
	case MSTORE8:
		newMemSize = calcMemSize(stack.peek(), u256(1))
	case MSTORE:
		newMemSize = calcMemSize(stack.peek(), u256(32))
	case RETURN:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-2])
	case SHA3:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-2])

		words := toWordSize(stack.data[stack.len()-2])
		gas.Add(gas, words.Mul(words, params.Sha3WordGas))
	case CALLDATACOPY:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-3])

		words := toWordSize(stack.data[stack.len()-3])
		gas.Add(gas, words.Mul(words, params.CopyGas))
	case CODECOPY:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-3])

		words := toWordSize(stack.data[stack.len()-3])
		gas.Add(gas, words.Mul(words, params.CopyGas))
	case EXTCODECOPY:
		newMemSize = calcMemSize(stack.data[stack.len()-2], stack.data[stack.len()-4])

		words := toWordSize(stack.data[stack.len()-4])
		gas.Add(gas, words.Mul(words, params.CopyGas))

	case CREATE:
		newMemSize = calcMemSize(stack.data[stack.len()-2], stack.data[stack.len()-3])
	case CALL, CALLCODE:
		gas.Add(gas, stack.data[stack.len()-1])

		if op == CALL {
			if !env.Db().Exist(common.BigToAddress(stack.data[stack.len()-2])) {
				gas.Add(gas, params.CallNewAccountGas)
			}
		}

		if len(stack.data[stack.len()-3].Bytes()) > 0 {
			gas.Add(gas, params.CallValueTransferGas)
		}

		x := calcMemSize(stack.data[stack.len()-6], stack.data[stack.len()-7])
		y := calcMemSize(stack.data[stack.len()-4], stack.data[stack.len()-5])

		newMemSize = common.BigMax(x, y)
	case DELEGATECALL:
		gas.Add(gas, stack.data[stack.len()-1])

		x := calcMemSize(stack.data[stack.len()-5], stack.data[stack.len()-6])
		y := calcMemSize(stack.data[stack.len()-3], stack.data[stack.len()-4])

		newMemSize = common.BigMax(x, y)
	}
	quadMemGas(mem, newMemSize, gas)

	return newMemSize, gas, nil
}

//.........这里部分代码省略.........

		var g *big.Int
		y, x := stack.data[stack.len()-2], stack.data[stack.len()-1]
		val := statedb.GetState(context.Address(), common.BigToHash(x))

		// This checks for 3 scenario's and calculates gas accordingly
		// 1. From a zero-value address to a non-zero value         (NEW VALUE)
		// 2. From a non-zero value address to a zero-value address (DELETE)
		// 3. From a nen-zero to a non-zero                         (CHANGE)
		if common.EmptyHash(val) && !common.EmptyHash(common.BigToHash(y)) {
			// 0 => non 0
			g = params.SstoreSetGas
		} else if !common.EmptyHash(val) && common.EmptyHash(common.BigToHash(y)) {
			statedb.Refund(params.SstoreRefundGas)

			g = params.SstoreClearGas
		} else {
			// non 0 => non 0 (or 0 => 0)
			g = params.SstoreClearGas
		}
		gas.Set(g)
	case SUICIDE:
		if !statedb.IsDeleted(context.Address()) {
			statedb.Refund(params.SuicideRefundGas)
		}
	case MLOAD:
		newMemSize = calcMemSize(stack.peek(), u256(32))
	case MSTORE8:
		newMemSize = calcMemSize(stack.peek(), u256(1))
	case MSTORE:
		newMemSize = calcMemSize(stack.peek(), u256(32))
	case RETURN:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-2])
	case SHA3:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-2])

		words := toWordSize(stack.data[stack.len()-2])
		gas.Add(gas, words.Mul(words, params.Sha3WordGas))
	case CALLDATACOPY:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-3])

		words := toWordSize(stack.data[stack.len()-3])
		gas.Add(gas, words.Mul(words, params.CopyGas))
	case CODECOPY:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-3])

		words := toWordSize(stack.data[stack.len()-3])
		gas.Add(gas, words.Mul(words, params.CopyGas))
	case EXTCODECOPY:
		newMemSize = calcMemSize(stack.data[stack.len()-2], stack.data[stack.len()-4])

		words := toWordSize(stack.data[stack.len()-4])
		gas.Add(gas, words.Mul(words, params.CopyGas))

	case CREATE:
		newMemSize = calcMemSize(stack.data[stack.len()-2], stack.data[stack.len()-3])
	case CALL, CALLCODE:
		gas.Add(gas, stack.data[stack.len()-1])

		if op == CALL {
			if env.State().GetStateObject(common.BigToAddress(stack.data[stack.len()-2])) == nil {
				gas.Add(gas, params.CallNewAccountGas)
			}
		}

		if len(stack.data[stack.len()-3].Bytes()) > 0 {
			gas.Add(gas, params.CallValueTransferGas)
		}

		x := calcMemSize(stack.data[stack.len()-6], stack.data[stack.len()-7])
		y := calcMemSize(stack.data[stack.len()-4], stack.data[stack.len()-5])

		newMemSize = common.BigMax(x, y)
	}

	if newMemSize.Cmp(common.Big0) > 0 {
		newMemSizeWords := toWordSize(newMemSize)
		newMemSize.Mul(newMemSizeWords, u256(32))

		if newMemSize.Cmp(u256(int64(mem.Len()))) > 0 {
			// be careful reusing variables here when changing.
			// The order has been optimised to reduce allocation
			oldSize := toWordSize(big.NewInt(int64(mem.Len())))
			pow := new(big.Int).Exp(oldSize, common.Big2, Zero)
			linCoef := oldSize.Mul(oldSize, params.MemoryGas)
			quadCoef := new(big.Int).Div(pow, params.QuadCoeffDiv)
			oldTotalFee := new(big.Int).Add(linCoef, quadCoef)

			pow.Exp(newMemSizeWords, common.Big2, Zero)
			linCoef = linCoef.Mul(newMemSizeWords, params.MemoryGas)
			quadCoef = quadCoef.Div(pow, params.QuadCoeffDiv)
			newTotalFee := linCoef.Add(linCoef, quadCoef)

			fee := newTotalFee.Sub(newTotalFee, oldTotalFee)
			gas.Add(gas, fee)
		}
	}

	return newMemSize, gas, nil
}

//.........这里部分代码省略.........
	case EXP:
		gas.Add(gas, new(big.Int).Mul(big.NewInt(int64(len(stack.data[stack.len()-2].Bytes()))), params.ExpByteGas))
	case SSTORE:
		err := stack.require(2)
		if err != nil {
			return nil, nil, err
		}

		var g *big.Int
		y, x := stack.data[stack.len()-2], stack.data[stack.len()-1]
		val := statedb.GetState(context.Address(), common.BigToHash(x))
		if len(val) == 0 && len(y.Bytes()) > 0 {
			// 0 => non 0
			g = params.SstoreSetGas
		} else if len(val) > 0 && len(y.Bytes()) == 0 {
			statedb.Refund(self.env.Origin(), params.SstoreRefundGas)

			g = params.SstoreClearGas
		} else {
			// non 0 => non 0 (or 0 => 0)
			g = params.SstoreClearGas
		}
		gas.Set(g)
	case SUICIDE:
		if !statedb.IsDeleted(context.Address()) {
			statedb.Refund(self.env.Origin(), params.SuicideRefundGas)
		}
	case MLOAD:
		newMemSize = calcMemSize(stack.peek(), u256(32))
	case MSTORE8:
		newMemSize = calcMemSize(stack.peek(), u256(1))
	case MSTORE:
		newMemSize = calcMemSize(stack.peek(), u256(32))
	case RETURN:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-2])
	case SHA3:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-2])

		words := toWordSize(stack.data[stack.len()-2])
		gas.Add(gas, words.Mul(words, params.Sha3WordGas))
	case CALLDATACOPY:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-3])

		words := toWordSize(stack.data[stack.len()-3])
		gas.Add(gas, words.Mul(words, params.CopyGas))
	case CODECOPY:
		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-3])

		words := toWordSize(stack.data[stack.len()-3])
		gas.Add(gas, words.Mul(words, params.CopyGas))
	case EXTCODECOPY:
		newMemSize = calcMemSize(stack.data[stack.len()-2], stack.data[stack.len()-4])

		words := toWordSize(stack.data[stack.len()-4])
		gas.Add(gas, words.Mul(words, params.CopyGas))

	case CREATE:
		newMemSize = calcMemSize(stack.data[stack.len()-2], stack.data[stack.len()-3])
	case CALL, CALLCODE:
		gas.Add(gas, stack.data[stack.len()-1])

		if op == CALL {
			if self.env.State().GetStateObject(common.BigToAddress(stack.data[stack.len()-2])) == nil {
				gas.Add(gas, params.CallNewAccountGas)
			}
		}

		if len(stack.data[stack.len()-3].Bytes()) > 0 {
			gas.Add(gas, params.CallValueTransferGas)
		}

		x := calcMemSize(stack.data[stack.len()-6], stack.data[stack.len()-7])
		y := calcMemSize(stack.data[stack.len()-4], stack.data[stack.len()-5])

		newMemSize = common.BigMax(x, y)
	}

	if newMemSize.Cmp(common.Big0) > 0 {
		newMemSizeWords := toWordSize(newMemSize)
		newMemSize.Mul(newMemSizeWords, u256(32))

		if newMemSize.Cmp(u256(int64(mem.Len()))) > 0 {
			oldSize := toWordSize(big.NewInt(int64(mem.Len())))
			pow := new(big.Int).Exp(oldSize, common.Big2, Zero)
			linCoef := new(big.Int).Mul(oldSize, params.MemoryGas)
			quadCoef := new(big.Int).Div(pow, params.QuadCoeffDiv)
			oldTotalFee := new(big.Int).Add(linCoef, quadCoef)

			pow.Exp(newMemSizeWords, common.Big2, Zero)
			linCoef = new(big.Int).Mul(newMemSizeWords, params.MemoryGas)
			quadCoef = new(big.Int).Div(pow, params.QuadCoeffDiv)
			newTotalFee := new(big.Int).Add(linCoef, quadCoef)

			fee := new(big.Int).Sub(newTotalFee, oldTotalFee)
			gas.Add(gas, fee)
		}
	}

	return newMemSize, gas, nil
}