From 876aa82c29d2e17f8b5a4f74155971cba78c00b6 Mon Sep 17 00:00:00 2001
From: Huw Pascoe <huw.pascoe@gmail.com>
Date: Sun, 24 Sep 2017 22:24:45 +0100
Subject: Optimized Morton

---
 src/video_core/utils.h | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

(limited to 'src')

diff --git a/src/video_core/utils.h b/src/video_core/utils.h
index 7ce83a055..d8567f314 100644
--- a/src/video_core/utils.h
+++ b/src/video_core/utils.h
@@ -8,17 +8,11 @@
 
 namespace VideoCore {
 
-/**
- * Interleave the lower 3 bits of each coordinate to get the intra-block offsets, which are
- * arranged in a Z-order curve. More details on the bit manipulation at:
- * https://fgiesen.wordpress.com/2009/12/13/decoding-morton-codes/
- */
+// 8x8 Z-Order coordinate from 2D coordinates
 static inline u32 MortonInterleave(u32 x, u32 y) {
-    u32 i = (x & 7) | ((y & 7) << 8); // ---- -210
-    i = (i ^ (i << 2)) & 0x1313;      // ---2 --10
-    i = (i ^ (i << 1)) & 0x1515;      // ---2 -1-0
-    i = (i | (i >> 7)) & 0x3F;
-    return i;
+    static const u32 xlut[] = {0x00, 0x01, 0x04, 0x05, 0x10, 0x11, 0x14, 0x15};
+    static const u32 ylut[] = {0x00, 0x02, 0x08, 0x0a, 0x20, 0x22, 0x28, 0x2a};
+    return xlut[x % 8] + ylut[y % 8];
 }
 
 /**
-- 
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