+/**
+ * Permute an 8x8 block according to permutation.
+ * @param block the block which will be permuted according to
+ * the given permutation vector
+ * @param permutation the permutation vector
+ * @param last the last non zero coefficient in scantable order, used to
+ * speed the permutation up
+ * @param scantable the used scantable, this is only used to speed the
+ * permutation up, the block is not (inverse) permutated
+ * to scantable order!
+ */
+static void block_permute(int16_t *block, uint8_t *permutation,
+ const uint8_t *scantable, int last)
+{
+ int i;
+ int16_t temp[64];
+
+ if (last <= 0)
+ return;
+ //FIXME it is ok but not clean and might fail for some permutations
+ // if (permutation[1] == 1)
+ // return;
+
+ for (i = 0; i <= last; i++) {
+ const int j = scantable[i];
+ temp[j] = block[j];
+ block[j] = 0;
+ }
+
+ for (i = 0; i <= last; i++) {
+ const int j = scantable[i];
+ const int perm_j = permutation[j];
+ block[perm_j] = temp[j];
+ }
+}
+