1 files changed, 50 insertions, 0 deletions
diff --git a/externals/oboe/src/flowgraph/resampler/IntegerRatio.cpp b/externals/oboe/src/flowgraph/resampler/IntegerRatio.cpp
new file mode 100644
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+++ b/externals/oboe/src/flowgraph/resampler/IntegerRatio.cpp
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+/*
+ * Copyright 2019 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 "IntegerRatio.h"
+
+using namespace RESAMPLER_OUTER_NAMESPACE::resampler;
+
+// Enough primes to cover the common sample rates.
+static const int kPrimes[] = {
+        2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41,
+        43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97,
+        101, 103, 107, 109, 113, 127, 131, 137, 139, 149,
+        151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199};
+
+void IntegerRatio::reduce() {
+    for (int prime : kPrimes) {
+        if (mNumerator < prime || mDenominator < prime) {
+            break;
+        }
+
+        // Find biggest prime factor for numerator.
+        while (true) {
+            int top = mNumerator / prime;
+            int bottom = mDenominator / prime;
+            if ((top >= 1)
+                && (bottom >= 1)
+                && (top * prime == mNumerator) // divided evenly?
+                && (bottom * prime == mDenominator)) {
+                mNumerator = top;
+                mDenominator = bottom;
+            } else {
+                break;
+            }
+        }
+
+    }
+}