[FFmpeg-cvslog] avcodec/apedec: Factor constant sign out of loop in long_filter_high_3800()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sun Apr 23 23:54:50 2023 +0200| [b2a3279dbe1f1c6a2b9c36a6137281c828b5d0e4] | committer: Michael Niedermayer

avcodec/apedec: Factor constant sign out of loop in long_filter_high_3800()

930 -> 850 cycles

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b2a3279dbe1f1c6a2b9c36a6137281c828b5d0e4
---

 libavcodec/apedec.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c
index 40cd78a991..772636afde 100644
--- a/libavcodec/apedec.c
+++ b/libavcodec/apedec.c
@@ -955,9 +955,20 @@ static void long_filter_high_3800(int32_t *buffer, int order, int shift, int len
     for (i = order; i < length; i++) {
         dotprod = 0;
         sign = APESIGN(buffer[i]);
-        for (j = 0; j < order; j++) {
-            dotprod += delayp[j] * (unsigned)coeffs[j];
-            coeffs[j] += ((delayp[j] >> 31) | 1) * sign;
+        if (sign == 1) {
+            for (j = 0; j < order; j++) {
+                dotprod += delayp[j] * (unsigned)coeffs[j];
+                coeffs[j] += (delayp[j] >> 31) | 1;
+            }
+        } else if (sign == -1) {
+            for (j = 0; j < order; j++) {
+                dotprod += delayp[j] * (unsigned)coeffs[j];
+                coeffs[j] -= (delayp[j] >> 31) | 1;
+            }
+        } else {
+            for (j = 0; j < order; j++) {
+                dotprod += delayp[j] * (unsigned)coeffs[j];
+            }
         }
         buffer[i] -= (unsigned)(dotprod >> shift);
         delayp ++;