asset compression

lib/gdeflate/Utils.h

@@ -0,0 +1,82 @@
+/*
+ * SPDX-FileCopyrightText: Copyright (c) 2020, 2021, 2022 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * SPDX-FileCopyrightText: Copyright (c) Microsoft Corportaion. 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.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#include <algorithm>
+#include <atomic>
+#include <chrono>
+#include <cstring>
+#include <limits>
+
+namespace GDeflate
+{
+    template<int N, typename T>
+    static inline T _align(T a)
+    {
+        return (a + T(N) - 1) & ~(T(N) - 1);
+    }
+
+    template<typename T>
+    static inline T _divRoundup(T a, T b)
+    {
+        return (a + b - 1) / b;
+    }
+
+    template<typename T>
+    static inline uint32_t _lzCount(T a)
+    {
+        uint32_t n = 0;
+
+        while (0 == (a & 1) && n < sizeof(T) * 8)
+        {
+            a >>= 1;
+            ++n;
+        }
+
+        return n;
+    }
+
+    template<typename T>
+    static inline T GetBits(uint32_t*& in, uint32_t& offset, uint32_t numBitsToRead)
+    {
+        constexpr uint32_t kBitsPerBucket = sizeof(*in) * 8;
+
+        T bits = 0;
+        uint32_t numBitsConsumed = 0;
+        while (numBitsConsumed < numBitsToRead)
+        {
+            const uint32_t numBits =
+                std::min(numBitsToRead - numBitsConsumed, kBitsPerBucket - (offset % kBitsPerBucket));
+
+            const T mask = std::numeric_limits<T>().max() >> (sizeof(T) * 8 - numBits);
+
+            bits |= (T(*in >> (offset % kBitsPerBucket)) & mask) << numBitsConsumed;
+
+            offset += numBits;
+            numBitsConsumed += numBits;
+
+            if (0 == offset % kBitsPerBucket)
+                in++;
+        }
+
+        return bits;
+    }
+} // namespace GDeflate