[x265] [PATCH] SAO: modified IDBI()

[chen]

At 2016-02-16 23:11:37,ashok at multicorewareinc.com wrote:
># HG changeset patch
># User Ashok Kumar Mishra<ashok at multicorewareinc.com>
># Date 1455633570 -19800
>#      Tue Feb 16 20:09:30 2016 +0530
># Node ID 33b02e2af5a4b38cd54d3f94f163aae640855dbf
># Parent  5f1817e5ff55689c45b12e1982a4c4fc46201382
>SAO: modified IDBI()
>
>diff -r 5f1817e5ff55 -r 33b02e2af5a4 source/common/common.h
>--- a/source/common/common.h	Tue Feb 16 20:08:54 2016 +0530
>+++ b/source/common/common.h	Tue Feb 16 20:09:30 2016 +0530
>@@ -168,6 +168,9 @@
> template<typename T>
> inline T x265_clip3(T minVal, T maxVal, T a) { return x265_min(x265_max(minVal, a), maxVal); }
> 
>+template<typename T>
>+inline T x265_abs(T a) { return (a < 0) ? -a : a;}
>+
> template<typename T> /* clip to pixel range, 0..255 or 0..1023 */
> inline pixel x265_clip(T x) { return (pixel)x265_min<T>(T((1 << X265_DEPTH) - 1), x265_max<T>(T(0), x)); }
> 
>diff -r 5f1817e5ff55 -r 33b02e2af5a4 source/encoder/sao.cpp
>--- a/source/encoder/sao.cpp	Tue Feb 16 20:08:54 2016 +0530
>+++ b/source/encoder/sao.cpp	Tue Feb 16 20:09:30 2016 +0530
>@@ -33,16 +33,6 @@
> #define signOf(X) (((X) >> 31) | (((uint32_t)-(X)) >> 31))
> #define signOf2(A, B) (((A) < (B)) ? -1 : ((A) > (B)) ? 1 : 0)
> 
>-namespace {
>-
>-inline int32_t roundIBDI(int32_t num, int32_t den)
>-{
>-    return num >= 0 ? ((num * 2 + den) / (den * 2)) : -((-num * 2 + den) / (den * 2));
>-}
>-
>-} // end anonymous namespace
>-
>-
> namespace X265_NS {
> 
> const uint32_t SAO::s_eoTable[NUM_EDGETYPE] =
>@@ -1366,8 +1356,10 @@
> 
>                 if (count)
>                 {
>-                    offsetOut = roundIBDI(offsetOrg, count << SAO_BIT_INC);
>-                    offsetOut = x265_clip3(-OFFSET_THRESH + 1, OFFSET_THRESH - 1, offsetOut);
>+                    int absOffset = (x265_abs(offsetOrg) + ((count << SAO_BIT_INC) >> 1)) / count;
>+                    offsetOut = x265_min(OFFSET_THRESH - 1, absOffset);
>+                    offsetOut = offsetOrg < 0 ? -offsetOut : offsetOut;

origin code is more clear, the new one we will difficult to know what to get in this step.
if you just want to share abs(), you may modify roundIBDI, of course, the generate code will slower since there no hardware ABS instruction
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