feat: add WASM host functions

.github/CODEOWNERS

@@ -1,8 +1,2 @@
 # Allow anyone to review any change by default.
 *
-
-# Require the rpc-reviewers team to review changes to the rpc code.
-include/xrpl/protocol/ @xrplf/rpc-reviewers
-src/libxrpl/protocol/ @xrplf/rpc-reviewers
-src/xrpld/rpc/ @xrplf/rpc-reviewers
-src/xrpld/app/misc/ @xrplf/rpc-reviewers

include/xrpl/basics/Number.h

@@ -341,6 +341,10 @@ abs(Number x) noexcept
 Number
 power(Number const& f, unsigned n);
 
+// logarithm with base 10
+Number
+lg(Number const& value);
+
 // Returns f^(1/d)
 // Uses Newton–Raphson iterations until the result stops changing
 // to find the root of the polynomial g(x) = x^d - f

include/xrpl/protocol/IOUAmount.h

@@ -39,6 +39,13 @@ class IOUAmount : private boost::totally_ordered<IOUAmount>,
     normalize();
 
 public:
+    /* The range for the mantissa when normalized */
+    static std::int64_t constexpr minMantissa = 1000000000000000ull;
+    static std::int64_t constexpr maxMantissa = 9999999999999999ull;
+    /* The range for the exponent when normalized */
+    static int constexpr minExponent = -96;
+    static int constexpr maxExponent = 80;
+
     IOUAmount() = default;
     explicit IOUAmount(Number const& other);
     IOUAmount(beast::Zero);

include/xrpl/protocol/Protocol.h

@@ -116,6 +116,13 @@ std::uint8_t constexpr vaultMaximumIOUScale = 18;
  * another vault; counted from 0 */
 std::uint8_t constexpr maxAssetCheckDepth = 5;
 
+/** The maximum length of a Data field in Escrow object that can be updated by
+ * Wasm code */
+std::size_t constexpr maxWasmDataLength = 4 * 1024;
+
+/** The maximum length of a parameters passed from Wasm code*/
+std::size_t constexpr maxWasmParamLength = 1024;
+
 /** A ledger index. */
 using LedgerIndex = std::uint32_t;
 

include/xrpl/protocol/TER.h

@@ -122,6 +122,8 @@ enum TEMcodes : TERUnderlyingType {
     temARRAY_TOO_LARGE,
     temBAD_TRANSFER_FEE,
     temINVALID_INNER_BATCH,
+
+    temBAD_WASM,
 };
 
 //------------------------------------------------------------------------------

src/libxrpl/basics/Number.cpp

@@ -604,6 +604,48 @@ power(Number const& f, unsigned n)
     return r;
 }
 
+// Continued fraction approximation of ln(x)
+static Number
+ln(Number const& x, unsigned iterations = 50)
+{
+    if (x <= 0)
+        throw std::runtime_error("Not positive value");
+
+    Number const z = (x - 1) / (x + 1);
+    Number const zz = z * z;
+    Number denom = Number(1, -10);
+
+    // Construct the fraction from the bottom up
+    for (int i = iterations; i > 0; --i)
+    {
+        Number k(2 * i - 1);
+        denom = k - (i * i * zz / denom);
+    }
+
+    auto const r = 2 * z / denom;
+    return r;
+}
+
+Number
+lg(Number const& x)
+{
+    static Number const ln10 = ln(Number(10));
+
+    if (x <= Number(10))
+    {
+        auto const r = ln(x) / ln10;
+        return r;
+    }
+
+    // ln(x) = ln(normX * 10^norm) = ln(normX) + norm * ln(10)
+    int diffExp = 15 + x.exponent();
+    Number const normalX = x / Number(1, diffExp);  // (1 <= normalX < 10)
+    auto const lnX = ln(normalX) + diffExp * ln10;
+
+    auto const r = lnX / ln10;
+    return r;
+}
+
 // Returns f^(1/d)
 // Uses Newton–Raphson iterations until the result stops changing
 // to find the non-negative root of the polynomial g(x) = x^d - f

src/libxrpl/protocol/IOUAmount.cpp

@@ -39,13 +39,6 @@ setSTNumberSwitchover(bool v)
     *getStaticSTNumberSwitchover() = v;
 }
 
-/* The range for the mantissa when normalized */
-static std::int64_t constexpr minMantissa = 1000000000000000ull;
-static std::int64_t constexpr maxMantissa = 9999999999999999ull;
-/* The range for the exponent when normalized */
-static int constexpr minExponent = -96;
-static int constexpr maxExponent = 80;
-
 IOUAmount
 IOUAmount::minPositiveAmount()
 {
@@ -293,7 +286,8 @@ mulRatio(
         {
             if (!result)
             {
-                return IOUAmount(-minMantissa, minExponent);
+                return IOUAmount(
+                    -IOUAmount::minMantissa, IOUAmount::minExponent);
             }
             // This subtraction cannot underflow because `result` is not zero
             return IOUAmount(result.mantissa() - 1, result.exponent());

src/libxrpl/protocol/TER.cpp

@@ -200,6 +200,7 @@ transResults()
         MAKE_ERROR(temARRAY_TOO_LARGE,           "Malformed: Array is too large."),
         MAKE_ERROR(temBAD_TRANSFER_FEE,          "Malformed: Transfer fee is outside valid range."),
         MAKE_ERROR(temINVALID_INNER_BATCH,       "Malformed: Invalid inner batch transaction."),
+        MAKE_ERROR(temBAD_WASM,                  "Malformed: Provided WASM code is invalid."),
 
         MAKE_ERROR(terRETRY,                  "Retry transaction."),
         MAKE_ERROR(terFUNDS_SPENT,            "DEPRECATED."),