From 64e1a3a723cc3eed7bd598ca8e39d37a55148860 Mon Sep 17 00:00:00 2001
From: Martin Budden <mjbudden@gmail.com>
Date: Wed, 12 Oct 2016 15:16:11 +0100
Subject: [PATCH] Improved firFilterApply efficiency

---
 src/main/common/filter.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/main/common/filter.c b/src/main/common/filter.c
index b9606795e1..dde44ca9aa 100644
--- a/src/main/common/filter.c
+++ b/src/main/common/filter.c
@@ -156,12 +156,12 @@ void firFilterUpdate(firFilter_t *filter, float input)
 float firFilterApply(const firFilter_t *filter)
 {
     float ret = 0.0f;
-    int index = filter->index;
-    for (int ii = 0; ii < filter->coeffsLength; ++ii) {
-        --index;
-        if (index < 0) {
-            index = filter->bufLength - 1;
-        }
+    int ii = 0;
+    int index;
+    for (index = filter->index - 1; index >= 0; ++ii, --index) {
+        ret += filter->coeffs[ii] * filter->buf[index];
+    }
+    for (index = filter->bufLength - 1; ii < filter->coeffsLength; ++ii, --index) {
         ret += filter->coeffs[ii] * filter->buf[index];
     }
     return ret;