From dc9e604ef16ee19cf7480325100e6edd768dbb16 Mon Sep 17 00:00:00 2001
From: Mathias Fröhlich <mathias.froehlich@web.de>
Date: Sun, 22 May 2016 14:10:19 +0200
Subject: mesa: Use bitmask/ffs to iterate enabled clip planes.
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Replaces an iterate and test bit in a bitmask loop by a
loop only iterating over the bits set in the bitmask.

v2: Use _mesa_bit_scan{,64} instead of open coding.
v3: Use u_bit_scan{,64} instead of _mesa_bit_scan{,64}.

Reviewed-by: Brian Paul <brianp@vmware.com>
Signed-off-by: Mathias Fröhlich <Mathias.Froehlich@web.de>
---
 src/mesa/tnl/t_vb_vertex.c | 59 +++++++++++++++++++++++-----------------------
 1 file changed, 30 insertions(+), 29 deletions(-)

(limited to 'src/mesa/tnl/t_vb_vertex.c')

diff --git a/src/mesa/tnl/t_vb_vertex.c b/src/mesa/tnl/t_vb_vertex.c
index b56d6803c99..71a32b49528 100644
--- a/src/mesa/tnl/t_vb_vertex.c
+++ b/src/mesa/tnl/t_vb_vertex.c
@@ -33,6 +33,8 @@
 
 #include "math/m_xform.h"
 
+#include "util/bitscan.h"
+
 #include "t_context.h"
 #include "t_pipeline.h"
 
@@ -63,40 +65,39 @@ static void NAME( struct gl_context *ctx,				\
 		  GLubyte *clipormask,				\
 		  GLubyte *clipandmask )			\
 {								\
-   GLuint p;							\
-								\
-   for (p = 0; p < ctx->Const.MaxClipPlanes; p++)		\
-      if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {	\
-	 GLuint nr, i;						\
-	 const GLfloat a = ctx->Transform._ClipUserPlane[p][0];	\
-	 const GLfloat b = ctx->Transform._ClipUserPlane[p][1];	\
-	 const GLfloat c = ctx->Transform._ClipUserPlane[p][2];	\
-	 const GLfloat d = ctx->Transform._ClipUserPlane[p][3];	\
-         GLfloat *coord = (GLfloat *)clip->data;		\
-         GLuint stride = clip->stride;				\
-         GLuint count = clip->count;				\
+   GLbitfield mask = ctx->Transform.ClipPlanesEnabled;          \
+   while (mask) {                                               \
+      const int p = u_bit_scan(&mask);                          \
+      GLuint nr, i;						\
+      const GLfloat a = ctx->Transform._ClipUserPlane[p][0];	\
+      const GLfloat b = ctx->Transform._ClipUserPlane[p][1];	\
+      const GLfloat c = ctx->Transform._ClipUserPlane[p][2];	\
+      const GLfloat d = ctx->Transform._ClipUserPlane[p][3];	\
+      GLfloat *coord = (GLfloat *)clip->data;                   \
+      GLuint stride = clip->stride;				\
+      GLuint count = clip->count;				\
 								\
-	 for (nr = 0, i = 0 ; i < count ; i++) {		\
-	    GLfloat dp = coord[0] * a + coord[1] * b;		\
-	    if (SZ > 2) dp += coord[2] * c;			\
-	    if (SZ > 3) dp += coord[3] * d; else dp += d;	\
+      for (nr = 0, i = 0 ; i < count ; i++) {                   \
+         GLfloat dp = coord[0] * a + coord[1] * b;		\
+         if (SZ > 2) dp += coord[2] * c;			\
+         if (SZ > 3) dp += coord[3] * d; else dp += d;          \
 								\
-	    if (dp < 0) {					\
-	       nr++;						\
-	       clipmask[i] |= CLIP_USER_BIT;			\
-	    }							\
+         if (dp < 0) {                                          \
+            nr++;						\
+            clipmask[i] |= CLIP_USER_BIT;			\
+         }							\
 								\
-	    STRIDE_F(coord, stride);				\
-	 }							\
+         STRIDE_F(coord, stride);				\
+      }                                                         \
 								\
-	 if (nr > 0) {						\
-	    *clipormask |= CLIP_USER_BIT;			\
-	    if (nr == count) {					\
-	       *clipandmask |= CLIP_USER_BIT;			\
-	       return;						\
-	    }							\
-	 }							\
+      if (nr > 0) {						\
+         *clipormask |= CLIP_USER_BIT;                          \
+         if (nr == count) {					\
+            *clipandmask |= CLIP_USER_BIT;			\
+            return;						\
+         }							\
       }								\
+   }								\
 }
 
 
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