1 files changed, 130 insertions, 0 deletions
diff --git a/media/libstagefright/SkipCutBuffer.cpp b/media/libstagefright/SkipCutBuffer.cpp
new file mode 100755
index 0000000..6d331b0
--- /dev/null
+++ b/media/libstagefright/SkipCutBuffer.cpp
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+/*
+ * Copyright (C) 2012 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_NDEBUG 0
+#define LOG_TAG "SkipCutBuffer"
+#include <utils/Log.h>
+
+#include <media/stagefright/foundation/ADebug.h>
+#include <media/stagefright/MediaBuffer.h>
+#include <media/stagefright/SkipCutBuffer.h>
+
+namespace android {
+
+SkipCutBuffer::SkipCutBuffer(int32_t skip, int32_t cut, int32_t output_size) {
+    mFrontPadding = skip;
+    mBackPadding = cut;
+    mWriteHead = 0;
+    mReadHead = 0;
+    mCapacity = cut + output_size;
+    mCutBuffer = new char[mCapacity];
+    ALOGV("skipcutbuffer %d %d %d", skip, cut, mCapacity);
+}
+
+SkipCutBuffer::~SkipCutBuffer() {
+    delete[] mCutBuffer;
+}
+
+void SkipCutBuffer::submit(MediaBuffer *buffer) {
+    int32_t offset = buffer->range_offset();
+    int32_t buflen = buffer->range_length();
+
+    // drop the initial data from the buffer if needed
+    if (mFrontPadding > 0) {
+        // still data left to drop
+        int32_t to_drop = (buflen < mFrontPadding) ? buflen : mFrontPadding;
+        offset += to_drop;
+        buflen -= to_drop;
+        buffer->set_range(offset, buflen);
+        mFrontPadding -= to_drop;
+    }
+
+
+    // append data to cutbuffer
+    char *src = ((char*) buffer->data()) + offset;
+    write(src, buflen);
+
+
+    // the mediabuffer is now empty. Fill it from cutbuffer, always leaving
+    // at least mBackPadding bytes in the cutbuffer
+    char *dst = (char*) buffer->data();
+    size_t copied = read(dst, buffer->size());
+    buffer->set_range(0, copied);
+}
+
+void SkipCutBuffer::clear() {
+    mWriteHead = mReadHead = 0;
+}
+
+void SkipCutBuffer::write(const char *src, size_t num) {
+    int32_t sizeused = (mWriteHead - mReadHead);
+    if (sizeused < 0) sizeused += mCapacity;
+
+    // everything must fit
+    CHECK_GE((mCapacity - size_t(sizeused)), num);
+
+    size_t copyfirst = (mCapacity - mWriteHead);
+    if (copyfirst > num) copyfirst = num;
+    if (copyfirst) {
+        memcpy(mCutBuffer + mWriteHead, src, copyfirst);
+        num -= copyfirst;
+        src += copyfirst;
+        mWriteHead += copyfirst;
+        CHECK_LE(mWriteHead, mCapacity);
+        if (mWriteHead == mCapacity) mWriteHead = 0;
+        if (num) {
+            memcpy(mCutBuffer, src, num);
+            mWriteHead += num;
+        }
+    }
+}
+
+size_t SkipCutBuffer::read(char *dst, size_t num) {
+    int32_t available = (mWriteHead - mReadHead);
+    if (available < 0) available += mCapacity;
+
+    available -= mBackPadding;
+    if (available <=0) {
+        return 0;
+    }
+    if (available < num) {
+        num = available;
+    }
+
+    size_t copyfirst = (mCapacity - mReadHead);
+    if (copyfirst > num) copyfirst = num;
+    if (copyfirst) {
+        memcpy(dst, mCutBuffer + mReadHead, copyfirst);
+        num -= copyfirst;
+        dst += copyfirst;
+        mReadHead += copyfirst;
+        CHECK_LE(mReadHead, mCapacity);
+        if (mReadHead == mCapacity) mReadHead = 0;
+        if (num) {
+            memcpy(dst, mCutBuffer, num);
+            mReadHead += num;
+        }
+    }
+    return available;
+}
+
+size_t SkipCutBuffer::size() {
+    int32_t available = (mWriteHead - mReadHead);
+    if (available < 0) available += mCapacity;
+    return available;
+}
+
+}  // namespace android