加入s16 的step forward 函数

Signed-off-by: huhui <huhui@sharkgulf.com>

Applications/math/fast_math.h

@@ -83,6 +83,23 @@ static __INLINE void step_towards(float *value, float goal, float step) {
     }
 }
 
+static __INLINE void step_towards_s16(s16 *value, s16 goal, s16 step) {
+    if (*value < goal) {
+        if ((*value + step) < goal) {
+            *value += step;
+        } else {
+            *value = goal;
+        }
+    } else if (*value > goal) {
+        if ((*value - step) > goal) {
+            *value -= step;
+        } else {
+            *value = goal;
+        }
+    }
+}
+
+
 /**
  * Fast atan2
  *