[FFmpeg-cvslog] af_biquad: unroll loop, remove variable copies

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Thu Feb  7 19:03:22 2013 +0100| [9f956611e33f73f6ad8d926e8a361e75aa42a491] | committer: Michael Niedermayer

af_biquad: unroll loop, remove variable copies

This makes the code about 7% faster

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9f956611e33f73f6ad8d926e8a361e75aa42a491
---

 libavfilter/af_biquads.c |   27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/libavfilter/af_biquads.c b/libavfilter/af_biquads.c
index 123d7a2..1f4d635 100644
--- a/libavfilter/af_biquads.c
+++ b/libavfilter/af_biquads.c
@@ -182,7 +182,32 @@ static void biquad_## name (const void *input, void *output, int len,         \
     double o2 = *out2;                                                        \
     int i;                                                                    \
                                                                               \
-    for (i = 0; i < len; i++) {                                               \
+    for (i = 0; i+1 < len; i++) {                                             \
+        o2 = i2 * b2 + i1 * b1 + ibuf[i] * b0 - o2 * a2 - o1 * a1;            \
+        i2 = ibuf[i];                                                         \
+        if (o2 < min) {                                                       \
+            av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
+            obuf[i] = min;                                                    \
+        } else if (o2 > max) {                                                \
+            av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
+            obuf[i] = max;                                                    \
+        } else {                                                              \
+            obuf[i] = o2;                                                     \
+        }                                                                     \
+        i++;                                                                  \
+        o1 = i1 * b2 + i2 * b1 + ibuf[i] * b0 - o1 * a2 - o2 * a1;            \
+        i1 = ibuf[i];                                                         \
+        if (o1 < min) {                                                       \
+            av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
+            obuf[i] = min;                                                    \
+        } else if (o1 > max) {                                                \
+            av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
+            obuf[i] = max;                                                    \
+        } else {                                                              \
+            obuf[i] = o1;                                                     \
+        }                                                                     \
+    }                                                                         \
+    if (i < len) {                                                            \
         double o0 = ibuf[i] * b0 + i1 * b1 + i2 * b2 - o1 * a1 - o2 * a2;     \
         i2 = i1;                                                              \
         i1 = ibuf[i];                                                         \