From aa89dc67256f555cb48e391959bc5e4aa737f20f Mon Sep 17 00:00:00 2001
From: helixhorned <helixhorned@1a8010ca-5511-0410-912e-c29ae57300e0>
Date: Wed, 7 Mar 2012 19:42:20 +0000
Subject: [PATCH] Optimize 'rainbow' background drawing in the editor with
 8-bit renderer.

git-svn-id: https://svn.eduke32.com/eduke32@2423 1a8010ca-5511-0410-912e-c29ae57300e0
---
 polymer/eduke32/build/src/engine.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/polymer/eduke32/build/src/engine.c b/polymer/eduke32/build/src/engine.c
index 2e03e27c0..da3725905 100644
--- a/polymer/eduke32/build/src/engine.c
+++ b/polymer/eduke32/build/src/engine.c
@@ -983,11 +983,18 @@ void yax_drawrooms(void (*ExtAnalyzeSprites)(void), int32_t horiz, int16_t sectn
         if (getrendermode()==0)
         {
             begindrawing();
-            j = 0;
-            for (i=0; i<xdimen*ydimen; i++)
             {
-                *((char *)frameplace + i) = (char)j;
-                j = (j+1)%xdimen;
+                const int32_t dimenprod = xdimen*ydimen;
+                char *const p = (char *)frameplace;
+
+                j = 0;
+                for (i=0; i<dimenprod; i++)
+                {
+                    p[i] = (char)j;
+                    j++;
+                    if (j >= xdimen)
+                        j = 0;
+                }
             }
             enddrawing();
         }