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