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