Tracing V2 prototype [NOT FOR REVIEW]

base/trace_event/v2/proto_utils.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_TRACE_EVENT_V2_PROTO_UTILS_H_
+#define BASE_TRACE_EVENT_V2_PROTO_UTILS_H_
+
+#include <inttypes.h>
+
+#include "base/base_export.h"
+#include "base/macros.h"
+
+namespace base {
+namespace trace_event {
+namespace v2 {
+
+class BASE_EXPORT ProtoUtils {
+public:
+  static const uint32_t kFieldTypeVarInt = 0;
+  static const uint32_t kFieldTypeFixed64 = 1;
+  static const uint32_t kFieldTypeLengthLimited = 2;
+  static const uint32_t kFieldTypeFixed32 = 5;
+
+  static inline uint32_t GetVarIntFieldHeader(uint32_t field_id) {
+    return (field_id << 3) | kFieldTypeVarInt;
+  }
+
+  static inline uint32_t GetFixed64FieldHeader(uint32_t field_id) {
+    return (field_id << 3) | kFieldTypeFixed64;
+  }
+
+  static inline uint32_t GetLengthLimitedFieldHeader(uint32_t field_id) {
+    return (field_id << 3) | kFieldTypeLengthLimited;
+  }
+
+  static inline uint32_t GetFixed32FieldHeader(uint32_t field_id) {
+    return (field_id << 3) | kFieldTypeFixed32;
+  }
+
+  static inline size_t EncodeVarIntUnsigned(uint64_t value, uint8_t *buf) {
+    uint8_t *cur = buf;
+    value &= 0x7FFFFFFF;
+    do {
+      char w = (char)(value & 0x7F);
+      value >>= 7;
+      if (value)
+        w |= 0x80;
+      *cur = w;
+      ++cur;
+    } while (value);
+    return cur - buf;
+  }
+
+  static inline void
+  EncodeRedundantVarIntUnsigned(uint64_t value, size_t length, uint8_t *buf) {
+    for (size_t i = 0; i < length; ++i) {
+      const uint8_t msb = (i < length - 1) ? 0x80 : 0;
+      buf[i] = static_cast<uint8_t>((value & 0x7F) | msb);
+      value >>= 7;
+    }
+  }
+
+  DISALLOW_COPY_AND_ASSIGN(ProtoUtils);
+};
+
+} // namespace v2
+} // namespace trace_event
+} // namespace base
+
+#endif // BASE_TRACE_EVENT_V2_PROTO_UTILS_H_