diff --git a/libs/surfaceflinger/Tokenizer.cpp b/libs/surfaceflinger/Tokenizer.cpp
new file mode 100644
index 0000000..ef51d6a
--- /dev/null
+++ b/libs/surfaceflinger/Tokenizer.cpp
@@ -0,0 +1,172 @@
+/*
+ * Copyright (C) 2007 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.
+ */
+
+#include <stdio.h>
+
+#include "Tokenizer.h"
+
+// ----------------------------------------------------------------------------
+
+namespace android {
+
+ANDROID_BASIC_TYPES_TRAITS(Tokenizer::run_t)
+
+Tokenizer::Tokenizer()
+{
+}
+
+Tokenizer::Tokenizer(const Tokenizer& other)
+    : mRanges(other.mRanges)
+{
+}
+
+Tokenizer::~Tokenizer()
+{
+}
+
+uint32_t Tokenizer::acquire()
+{
+    if (!mRanges.size() || mRanges[0].first) {
+        _insertTokenAt(0,0);
+        return 0;
+    }
+    
+    // just extend the first run
+    const run_t& run = mRanges[0];
+    uint32_t token = run.first + run.length;
+    _insertTokenAt(token, 1);
+    return token;
+}
+
+bool Tokenizer::isAcquired(uint32_t token) const
+{
+    return (_indexOrderOf(token) >= 0);
+}
+
+status_t Tokenizer::reserve(uint32_t token)
+{
+    size_t o;
+    const ssize_t i = _indexOrderOf(token, &o);
+    if (i >= 0) {
+        return BAD_VALUE; // this token is already taken
+    }
+    ssize_t err = _insertTokenAt(token, o);
+    return (err<0) ? err : status_t(NO_ERROR);
+}
+
+status_t Tokenizer::release(uint32_t token)
+{
+    const ssize_t i = _indexOrderOf(token);
+    if (i >= 0) {
+        const run_t& run = mRanges[i];
+        if ((token >= run.first) && (token < run.first+run.length)) {
+            // token in this range, we need to split
+            run_t& run = mRanges.editItemAt(i);
+            if ((token == run.first) || (token == run.first+run.length-1)) {
+                if (token == run.first) {
+                    run.first += 1;
+                }
+                run.length -= 1;
+                if (run.length == 0) {
+                    // XXX: should we systematically remove a run that's empty?
+                    mRanges.removeItemsAt(i);
+                }
+            } else {
+                // split the run
+                run_t new_run;
+                new_run.first = token+1;
+                new_run.length = run.first+run.length - new_run.first;
+                run.length = token - run.first;
+                mRanges.insertAt(new_run, i+1);
+            }
+            return NO_ERROR;
+        }
+    }
+    return NAME_NOT_FOUND;
+}
+
+ssize_t Tokenizer::_indexOrderOf(uint32_t token, size_t* order) const
+{
+    // binary search
+    ssize_t err = NAME_NOT_FOUND;
+    ssize_t l = 0;
+    ssize_t h = mRanges.size()-1;
+    ssize_t mid;
+    const run_t* a = mRanges.array();
+    while (l <= h) {
+        mid = l + (h - l)/2;
+        const run_t* const curr = a + mid;
+        int c = 0;
+        if (token < curr->first)                        c = 1;
+        else if (token >= curr->first+curr->length)     c = -1;
+        if (c == 0) {
+            err = l = mid;
+            break;
+        } else if (c < 0) {
+            l = mid + 1;
+        } else {
+            h = mid - 1;
+        }
+    }
+    if (order) *order = l;
+    return err;
+}
+
+ssize_t Tokenizer::_insertTokenAt(uint32_t token, size_t index)
+{
+    const size_t c = mRanges.size();
+
+    if (index >= 1) {
+        // do we need to merge with the previous run?
+        run_t& p = mRanges.editItemAt(index-1);
+        if (p.first+p.length == token) {
+            p.length += 1;
+            if (index < c) {
+                const run_t& n = mRanges[index];
+                if (token+1 == n.first) {
+                    p.length += n.length;
+                    mRanges.removeItemsAt(index);
+                }
+            }
+            return index;
+        }
+    }
+    
+    if (index < c) {
+        // do we need to merge with the next run?
+        run_t& n = mRanges.editItemAt(index);
+        if (token+1 == n.first) {
+            n.first -= 1;
+            n.length += 1;
+            return index;
+        }
+    }
+
+    return mRanges.insertAt(run_t(token,1), index);
+}
+
+void Tokenizer::dump() const
+{
+    const run_t* ranges = mRanges.array();
+    const size_t c = mRanges.size();
+    printf("Tokenizer (%p, size = %lu)\n", this, c);
+    for (size_t i=0 ; i<c ; i++) {
+        printf("%lu: (%u, %u)\n", i, ranges[i].first, ranges[i].length);
+    }
+}
+
+}; // namespace android
+