[x265] [PATCH] SAO: modified SignOf2()

[chen]

At 2016-02-16 23:11:19,ashok at multicorewareinc.com wrote:
># HG changeset patch
># User Ashok Kumar Mishra<ashok at multicorewareinc.com>
># Date 1455633534 -19800
>#      Tue Feb 16 20:08:54 2016 +0530
># Node ID 5f1817e5ff55689c45b12e1982a4c4fc46201382
># Parent  a26f3d8c9758c1ee510c75518304d4c9445a202b
>SAO: modified SignOf2()
>Both SignOf and SignOf2 can be written as macro instead of using a separate namespace
>estSaoDist() is used for sao distortion calculation, it should be part of sao class
>
>diff -r a26f3d8c9758 -r 5f1817e5ff55 source/encoder/sao.cpp
>--- a/source/encoder/sao.cpp	Tue Feb 16 20:00:33 2016 +0530
>+++ b/source/encoder/sao.cpp	Tue Feb 16 20:08:54 2016 +0530
>@@ -29,6 +29,10 @@
> #include "picyuv.h"
> #include "sao.h"
> 
>+/* get the sign of input variable */
>+#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)
>@@ -36,27 +40,6 @@
>     return num >= 0 ? ((num * 2 + den) / (den * 2)) : -((-num * 2 + den) / (den * 2));
> }
> 
>-/* get the sign of input variable (TODO: this is a dup, make common) */
>-inline int8_t signOf(int x)
>-{
>-    return (x >> 31) | ((int)((((uint32_t)-x)) >> 31));
>-}
>-
>-inline int signOf2(const int a, const int b)
>-{
>-    // NOTE: don't reorder below compare, both ICL, VC, GCC optimize strong depends on order!
>-    int r = 0;
>-    if (a < b)
>-        r = -1;
>-    if (a > b)
>-        r = 1;
>-    return r;
>-}
>-
>-inline int64_t estSaoDist(int32_t count, int offset, int32_t offsetOrg)
>-{
>-    return (count * offset - offsetOrg * 2) * offset;
>-}
> } // end anonymous namespace
> 
> 
>@@ -1413,7 +1396,12 @@
>     }
> }
> 
>-inline int SAO::estIterOffset(int typeIdx, double lambda, int offset, int32_t count, int32_t offsetOrg, int& distBOClasses, double& costBOClasses)
>+inline int64_t SAO::estSaoDist(int32_t count, int offset, int32_t offsetOrg)

This modify will made a real function call, the call/ret cost more than compute cost.

>+{
>+    return (count * offset - offsetOrg * 2) * offset;
>+}
>+
>+int SAO::estIterOffset(int typeIdx, double lambda, int offset, int32_t count, int32_t offsetOrg, int& distBOClasses, double& costBOClasses)
> {
>     int bestOffset = 0;
> 
>@@ -1740,7 +1728,6 @@
>         for (int x = 0; x < endX; x++)
>         {
>             int signRight = signOf2(rec[x], rec[x + 1]);
>-            X265_CHECK(signRight == signOf(rec[x] - rec[x + 1]), "signDown check failure\n");

Why remove self verify condition?

>             uint32_t edgeType = signRight + signLeft + 2;
>             signLeft = -signRight;
> 

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