[FFmpeg-cvslog] lavfi/af_sofalizer: remove exp2 and replace clz by ff_clz

[Ganesh Ajjanagadde]

ffmpeg | branch: master | Ganesh Ajjanagadde <gajjanagadde at gmail.com> | Tue Dec 29 13:16:08 2015 -0800| [9dba3f8f09834b68f4671de37ee67a95c09c4378] | committer: Ganesh Ajjanagadde

lavfi/af_sofalizer: remove exp2 and replace clz by ff_clz

ff_clz is faster, and uses an intrinsic (at the moment on GCC). exp2 is
a wasteful function for a simple integer exponentiation.

Untested.

Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9dba3f8f09834b68f4671de37ee67a95c09c4378
---

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

diff --git a/libavfilter/af_sofalizer.c b/libavfilter/af_sofalizer.c
index 6a24cbc..0f1231f 100644
--- a/libavfilter/af_sofalizer.c
+++ b/libavfilter/af_sofalizer.c
@@ -30,6 +30,7 @@
 
 #include "libavcodec/avfft.h"
 #include "libavutil/float_dsp.h"
+#include "libavutil/intmath.h"
 #include "libavutil/opt.h"
 #include "avfilter.h"
 #include "internal.h"
@@ -952,18 +953,6 @@ static av_cold int init(AVFilterContext *ctx)
     return 0;
 }
 
-static inline unsigned clz(unsigned x)
-{
-    unsigned i = sizeof(x) * 8;
-
-    while (x) {
-        x >>= 1;
-        i--;
-    }
-
-    return i;
-}
-
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
@@ -996,8 +985,8 @@ static int config_input(AVFilterLink *inlink)
     }
     /* buffer length is longest IR plus max. delay -> next power of 2
        (32 - count leading zeros gives required exponent)  */
-    s->buffer_length = exp2(32 - clz((uint32_t)n_max));
-    s->n_fft         = exp2(32 - clz((uint32_t)(n_max + inlink->sample_rate)));
+    s->buffer_length = 1 << (32 - ff_clz(n_max));
+    s->n_fft         = 1 << (32 - ff_clz(n_max + inlink->sample_rate));
 
     if (s->type == FREQUENCY_DOMAIN) {
         av_fft_end(s->fft[0]);