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Consensus.php
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133 lines (111 loc) · 3.5 KB
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<?php
namespace BitWasp\Bitcoin\Node;
use BitWasp\Bitcoin\Amount;
use BitWasp\Bitcoin\Block\BlockHeaderInterface;
use BitWasp\Bitcoin\Chain\ParamsInterface;
use BitWasp\Bitcoin\Math\Math;
use BitWasp\Bitcoin\Node\Chain\BlockIndexInterface;
class Consensus implements ConsensusInterface
{
/**
* @var Math
*/
private $math;
/**
* @var ParamsInterface
*/
private $params;
/**
* @param Math $math
* @param ParamsInterface $params
*/
public function __construct(Math $math, ParamsInterface $params)
{
$this->math = $math;
$this->params = $params;
}
/**
* @return ParamsInterface
*/
public function getParams()
{
return $this->params;
}
/**
* @param int $amount
* @return bool
*/
public function checkAmount($amount)
{
return $amount < 0 || $amount < ($this->params->maxMoney() * Amount::COIN);
}
/**
* @param int $height
* @return int|string
*/
public function getSubsidy($height)
{
$halvings = $height / $this->params->subsidyHalvingInterval();
if ($halvings >= 64) {
return 0;
}
$subsidy = 50 * Amount::COIN;
$subsidy = $subsidy >> $halvings;
return $subsidy;
}
/**
* @param BlockIndexInterface $prevIndex
* @param int $timeFirstBlock
* @return int
*/
public function calculateNextWorkRequired(BlockIndexInterface $prevIndex, $timeFirstBlock)
{
$header = $prevIndex->getHeader();
$math = $this->math;
$timespan = $this->calculateWorkTimespan($timeFirstBlock, $header);
$negative = false;
$overflow = false;
$target = $math->decodeCompact($header->getBits(), $negative, $overflow);
$limit = $this->math->decodeCompact($this->params->powBitsLimit(), $negative, $overflow);
$new = gmp_init(bcdiv(bcmul($target, $timespan), $this->params->powTargetTimespan()), 10);
if ($math->cmp($new, $limit) > 0) {
$new = $limit;
}
return gmp_strval($math->encodeCompact($new, false), 10);
}
/**
* @param ChainStateInterface $chain
* @param BlockIndexInterface $prevIndex
* @return int|string
*/
public function getWorkRequired(ChainStateInterface $chain, BlockIndexInterface $prevIndex)
{
$math = $this->math;
if ($math->cmp($math->mod($math->add($prevIndex->getHeight(), 1), $this->params->powRetargetInterval()), 0) !== 0) {
// No change in difficulty
return $prevIndex->getHeader()->getBits()->getInt();
}
// Re-target
$heightLastRetarget = $math->sub($prevIndex->getHeight(), $math->sub($this->params->powRetargetInterval(), 1));
$lastTime = $chain->fetchAncestor($heightLastRetarget)->getHeader()->getTimestamp();
return $this->calculateNextWorkRequired($prevIndex, $lastTime);
}
/**
* @param $timeFirstBlock
* @param BlockHeaderInterface $header
* @return mixed
*/
public function calculateWorkTimespan($timeFirstBlock, BlockHeaderInterface $header)
{
$timespan = $header->getTimestamp() - $timeFirstBlock;
$lowest = $this->params->powTargetTimespan() / 4;
$highest = $this->params->powTargetTimespan() * 4;
if ($timespan < $lowest) {
$timespan = $lowest;
}
if ($timespan > $highest) {
$timespan = $highest;
}
return $timespan;
}
}