1 // Copyright 2014 Citra Emulator Project
2 // Licensed under GPLv2 or any later version
3 // Refer to the license.txt file included.
4
5 #pragma once
6
7 #include "common/common_types.h"
8
9 namespace VideoCore {
10
11 // 8x8 Z-Order coordinate from 2D coordinates
MortonInterleave(u32 x,u32 y)12 static constexpr u32 MortonInterleave(u32 x, u32 y) {
13 constexpr u32 xlut[] = {0x00, 0x01, 0x04, 0x05, 0x10, 0x11, 0x14, 0x15};
14 constexpr u32 ylut[] = {0x00, 0x02, 0x08, 0x0a, 0x20, 0x22, 0x28, 0x2a};
15 return xlut[x % 8] + ylut[y % 8];
16 }
17
18 /**
19 * Calculates the offset of the position of the pixel in Morton order
20 */
GetMortonOffset(u32 x,u32 y,u32 bytes_per_pixel)21 static inline u32 GetMortonOffset(u32 x, u32 y, u32 bytes_per_pixel) {
22 // Images are split into 8x8 tiles. Each tile is composed of four 4x4 subtiles each
23 // of which is composed of four 2x2 subtiles each of which is composed of four texels.
24 // Each structure is embedded into the next-bigger one in a diagonal pattern, e.g.
25 // texels are laid out in a 2x2 subtile like this:
26 // 2 3
27 // 0 1
28 //
29 // The full 8x8 tile has the texels arranged like this:
30 //
31 // 42 43 46 47 58 59 62 63
32 // 40 41 44 45 56 57 60 61
33 // 34 35 38 39 50 51 54 55
34 // 32 33 36 37 48 49 52 53
35 // 10 11 14 15 26 27 30 31
36 // 08 09 12 13 24 25 28 29
37 // 02 03 06 07 18 19 22 23
38 // 00 01 04 05 16 17 20 21
39 //
40 // This pattern is what's called Z-order curve, or Morton order.
41
42 const unsigned int block_height = 8;
43 const unsigned int coarse_x = x & ~7;
44
45 u32 i = VideoCore::MortonInterleave(x, y);
46
47 const unsigned int offset = coarse_x * block_height;
48
49 return (i + offset) * bytes_per_pixel;
50 }
51
52 } // namespace VideoCore
53