[FFmpeg-devel] [PATCH] avutil: Rename RSHIFT macro to ROUNDED_RSHIFT

[FeRD (Frank Dana)]

The RSHIFT macro in libavutil/common.h does not actually perform
a bitwise right-shift, but rather a rounded version of the same
operation, as is noted by a comment above the macro. The rounded
divsion macro on the very next line is named ROUNDED_DIV, which
seems far more clear.

This patch renames RSHIFT to ROUNDED_RSHIFT, then updates all
uses of the macro to use the new name. (These are all located
in three codec files under libavcodec/.)

Signed-off-by: FeRD (Frank Dana) <ferdnyc at gmail.com>
---
 libavcodec/mpeg4videodec.c |  4 ++--
 libavcodec/vp3.c           | 16 ++++++++--------
 libavcodec/vp56.c          |  4 ++--
 libavutil/common.h         |  2 +-
 4 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
index f44ee76bd4..5d63ba12ba 100644
--- a/libavcodec/mpeg4videodec.c
+++ b/libavcodec/mpeg4videodec.c
@@ -601,7 +601,7 @@ static inline int get_amv(Mpeg4DecContext *ctx, int n)
         if (ctx->divx_version == 500 && ctx->divx_build == 413 && a >= s->quarter_sample)
             sum = s->sprite_offset[0][n] / (1 << (a - s->quarter_sample));
         else
-            sum = RSHIFT(s->sprite_offset[0][n] * (1 << s->quarter_sample), a);
+            sum = ROUNDED_RSHIFT(s->sprite_offset[0][n] * (1 << s->quarter_sample), a);
     } else {
         dx    = s->sprite_delta[n][0];
         dy    = s->sprite_delta[n][1];
@@ -623,7 +623,7 @@ static inline int get_amv(Mpeg4DecContext *ctx, int n)
                 v   += dx;
             }
         }
-        sum = RSHIFT(sum, a + 8 - s->quarter_sample);
+        sum = ROUNDED_RSHIFT(sum, a + 8 - s->quarter_sample);
     }
 
     if (sum < -len)
diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
index a5d8c2ed0b..13b3d6e22a 100644
--- a/libavcodec/vp3.c
+++ b/libavcodec/vp3.c
@@ -861,10 +861,10 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb)
 
                 if (s->chroma_y_shift) {
                     if (s->macroblock_coding[current_macroblock] == MODE_INTER_FOURMV) {
-                        motion_x[0] = RSHIFT(motion_x[0] + motion_x[1] +
-                                             motion_x[2] + motion_x[3], 2);
-                        motion_y[0] = RSHIFT(motion_y[0] + motion_y[1] +
-                                             motion_y[2] + motion_y[3], 2);
+                        motion_x[0] = ROUNDED_RSHIFT(motion_x[0] + motion_x[1] +
+                                                     motion_x[2] + motion_x[3], 2);
+                        motion_y[0] = ROUNDED_RSHIFT(motion_y[0] + motion_y[1] +
+                                                     motion_y[2] + motion_y[3], 2);
                     }
                     motion_x[0] = (motion_x[0] >> 1) | (motion_x[0] & 1);
                     motion_y[0] = (motion_y[0] >> 1) | (motion_y[0] & 1);
@@ -873,10 +873,10 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb)
                     s->motion_val[1][frag][1] = motion_y[0];
                 } else if (s->chroma_x_shift) {
                     if (s->macroblock_coding[current_macroblock] == MODE_INTER_FOURMV) {
-                        motion_x[0] = RSHIFT(motion_x[0] + motion_x[1], 1);
-                        motion_y[0] = RSHIFT(motion_y[0] + motion_y[1], 1);
-                        motion_x[1] = RSHIFT(motion_x[2] + motion_x[3], 1);
-                        motion_y[1] = RSHIFT(motion_y[2] + motion_y[3], 1);
+                        motion_x[0] = ROUNDED_RSHIFT(motion_x[0] + motion_x[1], 1);
+                        motion_y[0] = ROUNDED_RSHIFT(motion_y[0] + motion_y[1], 1);
+                        motion_x[1] = ROUNDED_RSHIFT(motion_x[2] + motion_x[3], 1);
+                        motion_y[1] = ROUNDED_RSHIFT(motion_y[2] + motion_y[3], 1);
                     } else {
                         motion_x[1] = motion_x[0];
                         motion_y[1] = motion_y[0];
diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c
index b69fe6c176..9359b48bc6 100644
--- a/libavcodec/vp56.c
+++ b/libavcodec/vp56.c
@@ -197,8 +197,8 @@ static void vp56_decode_4mv(VP56Context *s, int row, int col)
 
     /* chroma vectors are average luma vectors */
     if (s->avctx->codec->id == AV_CODEC_ID_VP5) {
-        s->mv[4].x = s->mv[5].x = RSHIFT(mv.x,2);
-        s->mv[4].y = s->mv[5].y = RSHIFT(mv.y,2);
+        s->mv[4].x = s->mv[5].x = ROUNDED_RSHIFT(mv.x,2);
+        s->mv[4].y = s->mv[5].y = ROUNDED_RSHIFT(mv.y,2);
     } else {
         s->mv[4] = s->mv[5] = (VP56mv) {mv.x/4, mv.y/4};
     }
diff --git a/libavutil/common.h b/libavutil/common.h
index 8db0291170..0bff7f8f72 100644
--- a/libavutil/common.h
+++ b/libavutil/common.h
@@ -51,7 +51,7 @@
 #endif
 
 //rounded division & shift
-#define RSHIFT(a,b) ((a) > 0 ? ((a) + ((1<<(b))>>1))>>(b) : ((a) + ((1<<(b))>>1)-1)>>(b))
+#define ROUNDED_RSHIFT(a,b) ((a) > 0 ? ((a) + ((1<<(b))>>1))>>(b) : ((a) + ((1<<(b))>>1)-1)>>(b))
 /* assume b>0 */
 #define ROUNDED_DIV(a,b) (((a)>0 ? (a) + ((b)>>1) : (a) - ((b)>>1))/(b))
 /* Fast a/(1<<b) rounded toward +inf. Assume a>=0 and b>=0 */
-- 
2.20.1