chore: import upstream snapshot with attribution

samples/common/bfloat16.cpp

@@ -0,0 +1,60 @@
+/*
+ * SPDX-FileCopyrightText: Copyright (c) 1993-2024 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "bfloat16.h"
+#include <cstring>
+
+namespace sample
+{
+
+BFloat16::operator float() const
+{
+    static_assert(sizeof(uint32_t) == sizeof(float), "");
+    float val{0.F};
+    auto bits = static_cast<uint32_t>(mRep) << 16;
+    std::memcpy(&val, &bits, sizeof(uint32_t));
+    return val;
+}
+
+BFloat16::BFloat16(float x)
+{
+    static_assert(sizeof(uint32_t) == sizeof(float), "");
+    uint32_t bits{0};
+    std::memcpy(&bits, &x, sizeof(float));
+
+    // FP32 format: 1 sign bit, 8 bit exponent, 23 bit mantissa
+    // BF16 format: 1 sign bit, 8 bit exponent, 7 bit mantissa
+
+    // Mask for exponent
+    constexpr uint32_t exponent = 0xFFU << 23;
+
+    // Check if exponent is all 1s (NaN or infinite)
+    if ((bits & exponent) != exponent)
+    {
+        // x is finite - round to even
+        bits += 0x7FFFU + (bits >> 16 & 1);
+    }
+
+    mRep = static_cast<uint16_t>(bits >> 16);
+}
+
+BFloat16 operator+(BFloat16 x, BFloat16 y)
+{
+    return BFloat16(static_cast<float>(x) + static_cast<float>(y));
+}
+
+} // namespace sample