sysiosystem::exchange_state Struct Reference

#include <exchange_state.hpp>

Collaboration diagram for sysiosystem::exchange_state:

Classes
struct	connector

Public Member Functions
uint64_t	primary_key () const
asset	convert_to_exchange (connector &reserve, const asset &payment)
asset	convert_from_exchange (connector &reserve, const asset &tokens)
asset	convert (const asset &from, const symbol &to)
asset	direct_convert (const asset &from, const symbol &to)

Static Public Member Functions
static int64_t	get_bancor_output (int64_t inp_reserve, int64_t out_reserve, int64_t inp)
static int64_t	get_bancor_input (int64_t out_reserve, int64_t inp_reserve, int64_t out)

Public Attributes
asset	supply
connector	base
connector	quote

Detailed Description

Uses Bancor math to create a 50/50 relay between two asset types.

The state of the bancor exchange is entirely contained within this struct. There are no external side effects associated with using this API.

Definition at line 17 of file exchange_state.hpp.

Member Function Documentation

convert()

asset sysiosystem::exchange_state::convert	(	const asset &	from,
		const symbol &	to )

Definition at line 39 of file exchange_state.cpp.

   {
      const auto& sell_symbol  = from.symbol;
      const auto& base_symbol  = base.balance.symbol;
      const auto& quote_symbol = quote.balance.symbol;
      check( sell_symbol != to, "cannot convert to the same symbol" );
 
      asset out( 0, to );
      if ( sell_symbol == base_symbol && to == quote_symbol ) {
         const asset tmp = convert_to_exchange( base, from );
         out = convert_from_exchange( quote, tmp );
      } else if ( sell_symbol == quote_symbol && to == base_symbol ) {
         const asset tmp = convert_to_exchange( quote, from );
         out = convert_from_exchange( base, tmp );
      } else {
         check( false, "invalid conversion" );
      }
      return out;
   }

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convert_from_exchange()

asset sysiosystem::exchange_state::convert_from_exchange	(	connector &	reserve,
		const asset &	tokens )

Definition at line 25 of file exchange_state.cpp.

   {
      const double R0 = reserve.balance.amount;
      const double S0 = supply.amount;
      const double dS = -tokens.amount; // dS < 0, tokens are subtracted from supply
      const double Fi = double(1) / reserve.weight;
 
      double dR = R0 * ( std::pow(1. + dS / S0, Fi) - 1. ); // dR < 0 since dS < 0
      if ( dR > 0 ) dR = 0; // rounding errors
      reserve.balance.amount -= int64_t(-dR);
      supply                 -= tokens;
      return asset( int64_t(-dR), reserve.balance.symbol );
   }

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convert_to_exchange()

asset sysiosystem::exchange_state::convert_to_exchange	(	connector &	reserve,
		const asset &	payment )

Definition at line 11 of file exchange_state.cpp.

   {
      const double S0 = supply.amount;
      const double R0 = reserve.balance.amount;
      const double dR = payment.amount;
      const double F  = reserve.weight;
 
      double dS = S0 * ( std::pow(1. + dR / R0, F) - 1. );
      if ( dS < 0 ) dS = 0; // rounding errors
      reserve.balance += payment;
      supply.amount   += int64_t(dS);
      return asset( int64_t(dS), supply.symbol );
   }

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direct_convert()

asset sysiosystem::exchange_state::direct_convert	(	const asset &	from,
		const symbol &	to )

Definition at line 59 of file exchange_state.cpp.

   {
      const auto& sell_symbol  = from.symbol;
      const auto& base_symbol  = base.balance.symbol;
      const auto& quote_symbol = quote.balance.symbol;
      check( sell_symbol != to, "cannot convert to the same symbol" );
 
      asset out( 0, to );
      if ( sell_symbol == base_symbol && to == quote_symbol ) {
         out.amount = get_bancor_output( base.balance.amount, quote.balance.amount, from.amount );
         base.balance  += from;
         quote.balance -= out;
      } else if ( sell_symbol == quote_symbol && to == base_symbol ) {
         out.amount = get_bancor_output( quote.balance.amount, base.balance.amount, from.amount );
         quote.balance += from;
         base.balance  -= out;
      } else {
         check( false, "invalid conversion" );
      }
      return out;
   }

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get_bancor_input()

int64_t sysiosystem::exchange_state::get_bancor_input ( int64_t out_reserve, int64_t inp_reserve, int64_t out )

static

Definition at line 96 of file exchange_state.cpp.

   {
      const double ob = out_reserve;
      const double ib = inp_reserve;
 
      int64_t inp = (ib * out) / (ob - out);
 
      if ( inp < 0 ) inp = 0;
 
      return inp;
   }

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get_bancor_output()

int64_t sysiosystem::exchange_state::get_bancor_output ( int64_t inp_reserve, int64_t out_reserve, int64_t inp )

static

Definition at line 81 of file exchange_state.cpp.

   {
      const double ib = inp_reserve;
      const double ob = out_reserve;
      const double in = inp;
 
      int64_t out = int64_t( (in * ob) / (ib + in) );
 
      if ( out < 0 ) out = 0;
 
      return out;
   }

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primary_key()

uint64_t sysiosystem::exchange_state::primary_key ( ) const

inline

Definition at line 30 of file exchange_state.hpp.

{ return supply.symbol.raw(); }

Member Data Documentation

base

connector sysiosystem::exchange_state::base

Definition at line 27 of file exchange_state.hpp.

quote

connector sysiosystem::exchange_state::quote

Definition at line 28 of file exchange_state.hpp.

supply

asset sysiosystem::exchange_state::supply

Definition at line 18 of file exchange_state.hpp.

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The documentation for this struct was generated from the following files:

• /Users/svetlasyrimis/Desktop/wire-network/WN-org/wire-system-contracts/contracts/sysio.system/include/sysio.system/exchange_state.hpp
• /Users/svetlasyrimis/Desktop/wire-network/WN-org/wire-system-contracts/contracts/sysio.system/src/exchange_state.cpp