[FFmpeg-cvslog] avcodec/xbmdec: convert() minor speed increase

[Jose Da Silva]

ffmpeg | branch: master | Jose Da Silva <digital at joescat.com> | Sun Jan 31 19:51:04 2021 -0800| [8c3d31fbeee157d6f529402c86371c857026fcff] | committer: Paul B Mahol

avcodec/xbmdec: convert() minor speed increase

If we test for {0..9} first, we have tested for 10/16th of all possible
characters first and avoid testing the remaining 6/16th of all possible
characters, which can be either 6/16th lowercase or 6/16th uppercase.

Signed-off-by: Joe Da Silva <digital at joescat.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=8c3d31fbeee157d6f529402c86371c857026fcff
---

 libavcodec/xbmdec.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/libavcodec/xbmdec.c b/libavcodec/xbmdec.c
index b783d5abe5..52615dc7ab 100644
--- a/libavcodec/xbmdec.c
+++ b/libavcodec/xbmdec.c
@@ -28,12 +28,12 @@
 
 static int convert(uint8_t x)
 {
-    if (x >= 'a')
-        x -= 87;
-    else if (x >= 'A')
-        x -= 55;
-    else
+    if (x <= '9')
         x -= '0';
+    else if (x >= 'a')
+        x -= ('a' - 10);
+    else
+        x -= ('A' - 10);
     return x;
 }