Move av1_indices_from_tree() to common code space.

Move the av1_indices_from_tree() function from av1/encoder/treewriter.c
 to aom_dsp/prob.c so that it can be used by both the encoder and
 the decoder.

Change-Id: Ie43c599f425c3503b1ff93f0c77b5033a05b1bb4

aom_dsp/prob.c

diff --git a/aom_dsp/prob.c b/aom_dsp/prob.c
index 233ff4f..d65ace8 100644
--- a/aom_dsp/prob.c
+++ b/aom_dsp/prob.c
@@ -205,4 +205,20 @@
   }
   return nsymbs;
 }
+
+/* This code assumes that tree contains as unique leaf nodes the integer values
+    0 to len - 1 and produces the forward and inverse mapping tables in ind[]
+    and inv[] respectively. */
+void av1_indices_from_tree(int *ind, int *inv, int len,
+                           const aom_tree_index *tree) {
+  int i;
+  int index;
+  for (i = index = 0; i < TREE_SIZE(len); i++) {
+    const aom_tree_index j = tree[i];
+    if (j <= 0) {
+      inv[index] = -j;
+      ind[-j] = index++;
+    }
+  }
+}
 #endif

aom_dsp/prob.h

diff --git a/aom_dsp/prob.h b/aom_dsp/prob.h
index 9731d01..12e0afe 100644
--- a/aom_dsp/prob.h
+++ b/aom_dsp/prob.h
@@ -124,6 +124,9 @@
       }                                                \
     }                                                  \
   } while (0)
+
+void av1_indices_from_tree(int *ind, int *inv, int len,
+                           const aom_tree_index *tree);
 #endif
 
 DECLARE_ALIGNED(16, extern const uint8_t, aom_norm[256]);

av1/encoder/treewriter.c

diff --git a/av1/encoder/treewriter.c b/av1/encoder/treewriter.c
index 742ffca..50be724 100644
--- a/av1/encoder/treewriter.c
+++ b/av1/encoder/treewriter.c
@@ -32,22 +32,6 @@
   tree2tok(tokens, tree, 0, 0, 0);
 }
 
-/* This code assumes that tree contains as unique leaf nodes the integer values
-    0 to len - 1 and produces the forward and inverse mapping tables in ind[]
-    and inv[] respectively. */
-void av1_indices_from_tree(int *ind, int *inv, int len,
-                           const aom_tree_index *tree) {
-  int i;
-  int index;
-  for (i = index = 0; i < TREE_SIZE(len); i++) {
-    const aom_tree_index j = tree[i];
-    if (j <= 0) {
-      inv[index] = -j;
-      ind[-j] = index++;
-    }
-  }
-}
-
 static unsigned int convert_distribution(unsigned int i, aom_tree tree,
                                          unsigned int branch_ct[][2],
                                          const unsigned int num_events[]) {

av1/encoder/treewriter.h

diff --git a/av1/encoder/treewriter.h b/av1/encoder/treewriter.h
index e16b43f..9a4cb86 100644
--- a/av1/encoder/treewriter.h
+++ b/av1/encoder/treewriter.h
@@ -28,8 +28,6 @@
 };
 
 void av1_tokens_from_tree(struct av1_token *, const aom_tree_index *);
-void av1_indices_from_tree(int *ind, int *inv, int len,
-                           const aom_tree_index *tree);
 
 static INLINE void av1_write_token(aom_writer *w, const aom_tree_index *tree,
                                    const aom_prob *probs,