add reconstructBigramFrequency

Change-Id: Iff20dcb9ca0d6064bb118247887fe24b812c0c61

1 files changed, 18 insertions, 0 deletions

diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java
index 2c3eee74c..273ee329d 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java
@@ -1410,4 +1410,22 @@ public class BinaryDictInputOutput {
             return false;
         }
     }
+
+    /**
+     * Calculate bigram frequency from compressed value
+     *
+     * @see #makeBigramFlags
+     *
+     * @param unigramFrequency
+     * @param bigramFrequency compressed frequency
+     * @return approximate bigram frequency
+     */
+    public static int reconstructBigramFrequency(final int unigramFrequency,
+            final int bigramFrequency) {
+        final float stepSize = (MAX_TERMINAL_FREQUENCY - unigramFrequency)
+                / (1.5f + MAX_BIGRAM_FREQUENCY);
+        final float resultFreqFloat = (float)unigramFrequency
+                + stepSize * (bigramFrequency + 1.0f);
+        return (int)resultFreqFloat;
+    }
 }