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sierra19XX 2021-03-12 21:45:06 +11:00
parent dae3af89d1
commit d3ffefbe2d
2 changed files with 95 additions and 0 deletions
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8
libraries/chain/include/graphene/chain/protocol/asset.hpp
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@ -150,6 +150,14 @@ namespace graphene { namespace chain {
bool operator != ( const price& a, const price& b );
asset operator * ( const asset& a, const price& b );
price operator * ( const price& p, const ratio_type& r );
price operator / ( const price& p, const ratio_type& r );
inline price& operator *= ( price& p, const ratio_type& r )
{ return p = p * r; }
inline price& operator /= ( price& p, const ratio_type& r )
{ return p = p / r; }
/**
* @class price_feed
* @brief defines market parameters for margin positions

87
libraries/chain/protocol/asset.cpp
View file

@ -111,6 +111,93 @@ namespace graphene { namespace chain {
return price{base,quote};
} FC_CAPTURE_AND_RETHROW( (base)(quote) ) }
price operator * ( const price& p, const ratio_type& r )
{ try {
p.validate();
FC_ASSERT( r.numerator() > 0 && r.denominator() > 0 );
if( r.numerator() == r.denominator() ) return p;
boost::rational<int128_t> p128( p.base.amount.value, p.quote.amount.value );
boost::rational<int128_t> r128( r.numerator(), r.denominator() );
auto cp = p128 * r128;
auto ocp = cp;
bool shrinked = false;
bool using_max = false;
static const int128_t max( GRAPHENE_MAX_SHARE_SUPPLY );
while( cp.numerator() > max || cp.denominator() > max )
{
if( cp.numerator() == 1 )
{
cp = boost::rational<int128_t>( 1, max );
using_max = true;
break;
}
else if( cp.denominator() == 1 )
{
cp = boost::rational<int128_t>( max, 1 );
using_max = true;
break;
}
else
{
cp = boost::rational<int128_t>( cp.numerator() >> 1, cp.denominator() >> 1 );
shrinked = true;
}
}
if( shrinked ) // maybe not accurate enough due to rounding, do additional checks here
{
int128_t num = ocp.numerator();
int128_t den = ocp.denominator();
if( num > den )
{
num /= den;
if( num > max )
num = max;
den = 1;
}
else
{
den /= num;
if( den > max )
den = max;
num = 1;
}
boost::rational<int128_t> ncp( num, den );
if( num == max || den == max ) // it's on the edge, we know it's accurate enough
cp = ncp;
else
{
// from the accurate ocp, now we have ncp and cp. use the one which is closer to ocp.
// TODO improve performance
auto diff1 = abs( ncp - ocp );
auto diff2 = abs( cp - ocp );
if( diff1 < diff2 ) cp = ncp;
}
}
price np = asset( static_cast<int64_t>(cp.numerator()), p.base.asset_id )
/ asset( static_cast<int64_t>(cp.denominator()), p.quote.asset_id );
if( shrinked || using_max )
{
if( ( r.numerator() > r.denominator() && np < p )
|| ( r.numerator() < r.denominator() && np > p ) )
// even with an accurate result, if p is out of valid range, return it
np = p;
}
np.validate();
return np;
} FC_CAPTURE_AND_RETHROW( (p)(r.numerator())(r.denominator()) ) }
price operator / ( const price& p, const ratio_type& r )
{ try {
return p * ratio_type( r.denominator(), r.numerator() );
} FC_CAPTURE_AND_RETHROW( (p)(r.numerator())(r.denominator()) ) }
price price::max( asset_id_type base, asset_id_type quote ) { return asset( share_type(GRAPHENE_MAX_SHARE_SUPPLY), base ) / asset( share_type(1), quote); }
price price::min( asset_id_type base, asset_id_type quote ) { return asset( 1, base ) / asset( GRAPHENE_MAX_SHARE_SUPPLY, quote); }