diff --git a/media/libnblog/Entry.cpp b/media/libnblog/Entry.cpp
new file mode 100644
index 0000000..e875639
--- /dev/null
+++ b/media/libnblog/Entry.cpp
@@ -0,0 +1,262 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#define LOG_TAG "NBLog"
+//#define LOG_NDEBUG 0
+
+#include <memory>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <audio_utils/fifo.h>
+#include <media/nblog/Entry.h>
+#include <media/nblog/Events.h>
+#include <utils/Log.h>
+
+namespace android {
+namespace NBLog {
+
+int Entry::copyEntryDataAt(size_t offset) const
+{
+    // FIXME This is too slow
+    if (offset == 0) {
+        return mEvent;
+    } else if (offset == 1) {
+        return mLength;
+    } else if (offset < (size_t) (mLength + 2)) {
+        return (int) ((char *) mData)[offset - 2];
+    } else if (offset == (size_t) (mLength + 2)) {
+        return mLength;
+    } else {
+        return 0;   // FIXME is this an error?
+    }
+}
+
+EntryIterator::EntryIterator()   // Dummy initialization.
+    : mPtr(nullptr)
+{
+}
+
+EntryIterator::EntryIterator(const uint8_t *entry)
+    : mPtr(entry)
+{
+}
+
+EntryIterator::EntryIterator(const EntryIterator &other)
+    : mPtr(other.mPtr)
+{
+}
+
+const entry& EntryIterator::operator*() const
+{
+    return *(entry*) mPtr;
+}
+
+const entry* EntryIterator::operator->() const
+{
+    return (entry*) mPtr;
+}
+
+EntryIterator& EntryIterator::operator++()
+{
+    mPtr += mPtr[offsetof(entry, length)] + Entry::kOverhead;
+    return *this;
+}
+
+EntryIterator& EntryIterator::operator--()
+{
+    mPtr -= mPtr[Entry::kPreviousLengthOffset] + Entry::kOverhead;
+    return *this;
+}
+
+EntryIterator EntryIterator::next() const
+{
+    EntryIterator aux(*this);
+    return ++aux;
+}
+
+EntryIterator EntryIterator::prev() const
+{
+    EntryIterator aux(*this);
+    return --aux;
+}
+
+bool EntryIterator::operator!=(const EntryIterator &other) const
+{
+    return mPtr != other.mPtr;
+}
+
+int EntryIterator::operator-(const EntryIterator &other) const
+{
+    return mPtr - other.mPtr;
+}
+
+bool EntryIterator::hasConsistentLength() const
+{
+    return mPtr[offsetof(entry, length)] == mPtr[mPtr[offsetof(entry, length)] +
+        Entry::kOverhead + Entry::kPreviousLengthOffset];
+}
+
+void EntryIterator::copyTo(std::unique_ptr<audio_utils_fifo_writer> &dst) const
+{
+    size_t length = mPtr[offsetof(entry, length)] + Entry::kOverhead;
+    dst->write(mPtr, length);
+}
+
+void EntryIterator::copyData(uint8_t *dst) const
+{
+    memcpy((void*) dst, mPtr + offsetof(entry, data), mPtr[offsetof(entry, length)]);
+}
+
+// ---------------------------------------------------------------------------
+
+std::unique_ptr<AbstractEntry> AbstractEntry::buildEntry(const uint8_t *ptr)
+{
+    if (ptr == nullptr) {
+        return nullptr;
+    }
+    const uint8_t type = EntryIterator(ptr)->type;
+    switch (type) {
+    case EVENT_FMT_START:
+        return std::make_unique<FormatEntry>(FormatEntry(ptr));
+    case EVENT_AUDIO_STATE:
+    case EVENT_HISTOGRAM_ENTRY_TS:
+        return std::make_unique<HistogramEntry>(HistogramEntry(ptr));
+    default:
+        ALOGW("Tried to create AbstractEntry of type %d", type);
+        return nullptr;
+    }
+}
+
+EntryIterator FormatEntry::begin() const
+{
+    return EntryIterator(mEntry);
+}
+
+const char *FormatEntry::formatString() const
+{
+    return (const char*) mEntry + offsetof(entry, data);
+}
+
+size_t FormatEntry::formatStringLength() const
+{
+    return mEntry[offsetof(entry, length)];
+}
+
+EntryIterator FormatEntry::args() const
+{
+    auto it = begin();
+    ++it; // skip start fmt
+    ++it; // skip timestamp
+    ++it; // skip hash
+    // Skip author if present
+    if (it->type == EVENT_FMT_AUTHOR) {
+        ++it;
+    }
+    return it;
+}
+
+int64_t FormatEntry::timestamp() const
+{
+    auto it = begin();
+    ++it; // skip start fmt
+    return it.payload<int64_t>();
+}
+
+log_hash_t FormatEntry::hash() const
+{
+    auto it = begin();
+    ++it; // skip start fmt
+    ++it; // skip timestamp
+    // unaligned 64-bit read not supported
+    log_hash_t hash;
+    memcpy(&hash, it->data, sizeof(hash));
+    return hash;
+}
+
+int FormatEntry::author() const
+{
+    auto it = begin();
+    ++it; // skip start fmt
+    ++it; // skip timestamp
+    ++it; // skip hash
+    // if there is an author entry, return it, return -1 otherwise
+    return it->type == EVENT_FMT_AUTHOR ? it.payload<int>() : -1;
+}
+
+EntryIterator FormatEntry::copyWithAuthor(
+        std::unique_ptr<audio_utils_fifo_writer> &dst, int author) const
+{
+    auto it = begin();
+    it.copyTo(dst);     // copy fmt start entry
+    (++it).copyTo(dst); // copy timestamp
+    (++it).copyTo(dst); // copy hash
+    // insert author entry
+    size_t authorEntrySize = Entry::kOverhead + sizeof(author);
+    uint8_t authorEntry[authorEntrySize];
+    authorEntry[offsetof(entry, type)] = EVENT_FMT_AUTHOR;
+    authorEntry[offsetof(entry, length)] =
+        authorEntry[authorEntrySize + Entry::kPreviousLengthOffset] =
+        sizeof(author);
+    *(int*) (&authorEntry[offsetof(entry, data)]) = author;
+    dst->write(authorEntry, authorEntrySize);
+    // copy rest of entries
+    while ((++it)->type != EVENT_FMT_END) {
+        it.copyTo(dst);
+    }
+    it.copyTo(dst);
+    ++it;
+    return it;
+}
+
+int64_t HistogramEntry::timestamp() const
+{
+    return EntryIterator(mEntry).payload<HistTsEntry>().ts;
+}
+
+log_hash_t HistogramEntry::hash() const
+{
+    return EntryIterator(mEntry).payload<HistTsEntry>().hash;
+}
+
+int HistogramEntry::author() const
+{
+    EntryIterator it(mEntry);
+    return it->length == sizeof(HistTsEntryWithAuthor)
+            ? it.payload<HistTsEntryWithAuthor>().author : -1;
+}
+
+EntryIterator HistogramEntry::copyWithAuthor(
+        std::unique_ptr<audio_utils_fifo_writer> &dst, int author) const
+{
+    // Current histogram entry has {type, length, struct HistTsEntry, length}.
+    // We now want {type, length, struct HistTsEntryWithAuthor, length}
+    uint8_t buffer[Entry::kOverhead + sizeof(HistTsEntryWithAuthor)];
+    // Copy content until the point we want to add the author
+    memcpy(buffer, mEntry, sizeof(entry) + sizeof(HistTsEntry));
+    // Copy the author
+    *(int*) (buffer + sizeof(entry) + sizeof(HistTsEntry)) = author;
+    // Update lengths
+    buffer[offsetof(entry, length)] = sizeof(HistTsEntryWithAuthor);
+    buffer[offsetof(entry, data) + sizeof(HistTsEntryWithAuthor) + offsetof(ending, length)]
+        = sizeof(HistTsEntryWithAuthor);
+    // Write new buffer into FIFO
+    dst->write(buffer, sizeof(buffer));
+    return EntryIterator(mEntry).next();
+}
+
+}   // namespace NBLog
+}   // namespace android