GR support

Author: MoneroOcean

xmrig/base/tools/cryptonote/umul128.h

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+/*
+  * This program is free software: you can redistribute it and/or modify
+  * it under the terms of the GNU General Public License as published by
+  * the Free Software Foundation, either version 3 of the License, or
+  * any later version.
+  *
+  * This program is distributed in the hope that it will be useful,
+  * but WITHOUT ANY WARRANTY; without even the implied warranty of
+  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+  * GNU General Public License for more details.
+  *
+  * You should have received a copy of the GNU General Public License
+  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+  *
+  * Additional permission under GNU GPL version 3 section 7
+  *
+  * If you modify this Program, or any covered work, by linking or combining
+  * it with OpenSSL (or a modified version of that library), containing parts
+  * covered by the terms of OpenSSL License and SSLeay License, the licensors
+  * of this Program grant you additional permission to convey the resulting work.
+  *
+  */
+
+#pragma once
+
+
+#include <cstdint>
+
+#ifdef XMRIG_64_BIT
+#   ifdef _MSC_VER
+#       include <intrin.h>
+#       pragma intrinsic(_umul128)
+#       define __umul128 _umul128
+#   elif defined __GNUC__
+        static inline uint64_t _umul128(uint64_t a, uint64_t b, uint64_t* hi)
+        {
+            unsigned __int128 r = (unsigned __int128) a * (unsigned __int128) b;
+            *hi = r >> 64;
+            return (uint64_t) r;
+        }
+#       define __umul128 _umul128
+#   endif
+#else
+static inline uint64_t __umul128(uint64_t multiplier, uint64_t multiplicand, uint64_t *product_hi) {
+    // multiplier   = ab = a * 2^32 + b
+    // multiplicand = cd = c * 2^32 + d
+    // ab * cd = a * c * 2^64 + (a * d + b * c) * 2^32 + b * d
+    uint64_t a = multiplier >> 32;
+    uint64_t b = multiplier & 0xFFFFFFFF;
+    uint64_t c = multiplicand >> 32;
+    uint64_t d = multiplicand & 0xFFFFFFFF;
+
+    //uint64_t ac = a * c;
+    uint64_t ad = a * d;
+    //uint64_t bc = b * c;
+    uint64_t bd = b * d;
+
+    uint64_t adbc = ad + (b * c);
+    uint64_t adbc_carry = adbc < ad ? 1 : 0;
+
+    // multiplier * multiplicand = product_hi * 2^64 + product_lo
+    uint64_t product_lo = bd + (adbc << 32);
+    uint64_t product_lo_carry = product_lo < bd ? 1 : 0;
+    *product_hi = (a * c) + (adbc >> 32) + (adbc_carry << 32) + product_lo_carry;
+
+    return product_lo;
+}
+#endif