From a9c6830605ed6aacb6f49fcdc00df2d7bb6bea02 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Fri, 27 Sep 2002 15:38:54 +0000
Subject: [PATCH] minor optimization of h263_encode_motion()
Originally committed as revision 976 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavcodec/h263.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/libavcodec/h263.c b/libavcodec/h263.c
index 6a59906a089..b8bfc85e125 100644
--- a/libavcodec/h263.c
+++ b/libavcodec/h263.c
@@ -1079,7 +1079,7 @@ INT16 *h263_pred_motion(MpegEncContext * s, int block,
static void h263_encode_motion(MpegEncContext * s, int val, int f_code)
{
- int range, l, m, bit_size, sign, code, bits;
+ int range, l, bit_size, sign, code, bits;
if (val == 0) {
/* zero vector */
@@ -1090,12 +1090,20 @@ static void h263_encode_motion(MpegEncContext * s, int val, int f_code)
range = 1 << bit_size;
/* modulo encoding */
l = range * 32;
- m = 2 * l;
+#if 1
+ val+= l;
+ val&= 2*l-1;
+ val-= l;
+ sign = val>>31;
+ val= (val^sign)-sign;
+ sign&=1;
+#else
if (val < -l) {
- val += m;
+ val += 2*l;
} else if (val >= l) {
- val -= m;
+ val -= 2*l;
}
+
assert(val>=-l && val<l);
if (val >= 0) {
@@ -1104,6 +1112,7 @@ static void h263_encode_motion(MpegEncContext * s, int val, int f_code)
val = -val;
sign = 1;
}
+#endif
val--;
code = (val >> bit_size) + 1;
bits = val & (range - 1);
--
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