AMMCore.cpp

#include <xrpl/basics/base_uint.h>
#include <xrpl/beast/utility/Zero.h>
#include <xrpl/beast/utility/instrumentation.h>
#include <xrpl/protocol/AMMCore.h>
#include <xrpl/protocol/AccountID.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/Issue.h>
#include <xrpl/protocol/Rules.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/STAmount.h>
#include <xrpl/protocol/STObject.h>
#include <xrpl/protocol/TER.h>
#include <xrpl/protocol/UintTypes.h>
#include <xrpl/protocol/digest.h>
 
#include <algorithm>
#include <cstdint>
#include <optional>
#include <utility>
 
namespace xrpl {
 
Currency
ammLPTCurrency(Currency const& cur1, Currency const& cur2)
{
    // AMM LPToken is 0x03 plus 19 bytes of the hash
    std::int32_t constexpr AMMCurrencyCode = 0x03;
    auto const [minC, maxC] = std::minmax(cur1, cur2);
    auto const hash = sha512Half(minC, maxC);
    Currency currency;
    *currency.begin() = AMMCurrencyCode;
    std::copy(hash.begin(), hash.begin() + currency.size() - 1, currency.begin() + 1);
    return currency;
}
 
Issue
ammLPTIssue(Currency const& cur1, Currency const& cur2, AccountID const& ammAccountID)
{
    return Issue(ammLPTCurrency(cur1, cur2), ammAccountID);
}
 
NotTEC
invalidAMMAsset(Issue const& issue, std::optional<std::pair<Issue, Issue>> const& pair)
{
    if (badCurrency() == issue.currency)
        return temBAD_CURRENCY;
    if (isXRP(issue) && issue.account.isNonZero())
        return temBAD_ISSUER;
    if (pair && issue != pair->first && issue != pair->second)
        return temBAD_AMM_TOKENS;
    return tesSUCCESS;
}
 
NotTEC
invalidAMMAssetPair(Issue const& issue1, Issue const& issue2, std::optional<std::pair<Issue, Issue>> const& pair)
{
    if (issue1 == issue2)
        return temBAD_AMM_TOKENS;
    if (auto const res = invalidAMMAsset(issue1, pair))
        return res;
    if (auto const res = invalidAMMAsset(issue2, pair))
        return res;
    return tesSUCCESS;
}
 
NotTEC
invalidAMMAmount(STAmount const& amount, std::optional<std::pair<Issue, Issue>> const& pair, bool validZero)
{
    if (auto const res = invalidAMMAsset(amount.issue(), pair))
        return res;
    if (amount < beast::zero || (!validZero && amount == beast::zero))
        return temBAD_AMOUNT;
    return tesSUCCESS;
}
 
std::optional<std::uint8_t>
ammAuctionTimeSlot(std::uint64_t current, STObject const& auctionSlot)
{
    // It should be impossible for expiration to be < TOTAL_TIME_SLOT_SECS,
    // but check just to be safe
    auto const expiration = auctionSlot[sfExpiration];
    XRPL_ASSERT(expiration >= TOTAL_TIME_SLOT_SECS, "xrpl::ammAuctionTimeSlot : minimum expiration");
    if (expiration >= TOTAL_TIME_SLOT_SECS)
    {
        if (auto const start = expiration - TOTAL_TIME_SLOT_SECS; current >= start)
        {
            if (auto const diff = current - start; diff < TOTAL_TIME_SLOT_SECS)
                return diff / AUCTION_SLOT_INTERVAL_DURATION;
        }
    }
    return std::nullopt;
}
 
bool
ammEnabled(Rules const& rules)
{
    return rules.enabled(featureAMM) && rules.enabled(fixUniversalNumber);
}
 
}  // namespace xrpl