dolphin/Source/Core/VideoCommon/TextureDecoder_Generic.cpp

// Copyright 2014 Dolphin Emulator Project
// Licensed under GPLv2
// Refer to the license.txt file included.

#include <algorithm>
#include <cmath>

#include "Common/Common.h"
#include "Common/CPUDetect.h"
#include "VideoCommon/LookUpTables.h"
#include "VideoCommon/TextureDecoder.h"
//#include "VideoCommon/VideoCommon.h" // to get debug logs
#include "VideoCommon/VideoConfig.h"

// GameCube/Wii texture decoder

// Decodes all known GameCube/Wii texture formats.
// by ector

static inline u32 decode5A3RGBA(u16 val)
{
	int r,g,b,a;
	if ((val&0x8000))
	{
		r=Convert5To8((val>>10) & 0x1f);
		g=Convert5To8((val>>5 ) & 0x1f);
		b=Convert5To8((val    ) & 0x1f);
		a=0xFF;
	}
	else
	{
		a=Convert3To8((val>>12) & 0x7);
		r=Convert4To8((val>>8 ) & 0xf);
		g=Convert4To8((val>>4 ) & 0xf);
		b=Convert4To8((val    ) & 0xf);
	}
	return r | (g<<8) | (b << 16) | (a << 24);
}

static inline u32 decode565RGBA(u16 val)
{
	int r,g,b,a;
	r=Convert5To8((val>>11) & 0x1f);
	g=Convert6To8((val>>5 ) & 0x3f);
	b=Convert5To8((val    ) & 0x1f);
	a=0xFF;
	return  r | (g<<8) | (b << 16) | (a << 24);
}
static inline u32 decodeIA8Swapped(u16 val)
{
	int a = val & 0xFF;
	int i = val >> 8;
	return i | (i<<8) | (i<<16) | (a<<24);
}

struct DXTBlock
{
	u16 color1;
	u16 color2;
	u8 lines[4];
};

static inline void decodebytesC4_5A3_To_rgba32(u32 *dst, const u8 *src, const u8* tlut_)
{
	const u16* tlut = (u16*) tlut_;
	for (int x = 0; x < 4; x++)
	{
		u8 val = src[x];
		*dst++ = decode5A3RGBA(Common::swap16(tlut[val >> 4]));
		*dst++ = decode5A3RGBA(Common::swap16(tlut[val & 0xF]));
	}
}

static inline void decodebytesC4IA8_To_RGBA(u32* dst, const u8* src, const u8* tlut_)
{
	const u16* tlut = (u16*) tlut_;
	for (int x = 0; x < 4; x++)
	{
		u8 val = src[x];
		*dst++ = decodeIA8Swapped(tlut[val >> 4]);
		*dst++ = decodeIA8Swapped(tlut[val & 0xF]);
	}
}

static inline void decodebytesC4RGB565_To_RGBA(u32* dst, const u8* src, const u8* tlut_)
{
	const u16* tlut = (u16*) tlut_;
	for (int x = 0; x < 4; x++)
	{
		u8 val = src[x];
		*dst++ = decode565RGBA(Common::swap16(tlut[val >> 4]));
		*dst++ = decode565RGBA(Common::swap16(tlut[val & 0xF]));
	}
}

static inline void decodebytesC8_5A3_To_RGBA32(u32 *dst, const u8 *src, const u8* tlut_)
{
	const u16* tlut = (u16*) tlut_;
	for (int x = 0; x < 8; x++)
	{
		u8 val = src[x];
		*dst++ = decode5A3RGBA(Common::swap16(tlut[val]));
	}
}

static inline void decodebytesC8IA8_To_RGBA(u32* dst, const u8* src, const u8* tlut_)
{
	const u16* tlut = (u16*) tlut_;
	for (int x = 0; x < 8; x++)
	{
		*dst++ = decodeIA8Swapped(tlut[src[x]]);
	}
}

static inline void decodebytesC8RGB565_To_RGBA(u32* dst, const u8* src, const u8* tlut_)
{
	const u16* tlut = (u16*) tlut_;
	for (int x = 0; x < 8; x++)
	{
		*dst++ = decode565RGBA(Common::swap16(tlut[src[x]]));
	}
}

static inline void decodebytesC14X2_5A3_To_RGBA(u32 *dst, const u16 *src, const u8* tlut_)
{
	const u16* tlut = (u16*) tlut_;
	for (int x = 0; x < 4; x++)
	{
		u16 val = Common::swap16(src[x]);
		*dst++ = decode5A3RGBA(Common::swap16(tlut[(val & 0x3FFF)]));
	}
}

static inline void decodebytesC14X2IA8_To_RGBA(u32* dst, const u16* src, const u8* tlut_)
{
	const u16* tlut = (u16*) tlut_;
	for (int x = 0; x < 4; x++)
	{
		u16 val = Common::swap16(src[x]);
		*dst++ = decodeIA8Swapped(tlut[(val & 0x3FFF)]);
	}
}

static inline void decodebytesC14X2rgb565_To_RGBA(u32* dst, const u16* src, const u8* tlut_)
{
	const u16* tlut = (u16*) tlut_;
	for (int x = 0; x < 4; x++)
	{
		u16 val = Common::swap16(src[x]);
		*dst++ = decode565RGBA(Common::swap16(tlut[(val & 0x3FFF)]));
	}
}

static inline void decodebytesIA4RGBA(u32 *dst, const u8 *src)
{
	for (int x = 0; x < 8; x++)
	{
		const u8 val = src[x];
		u8 a = Convert4To8(val >> 4);
		u8 l = Convert4To8(val & 0xF);
		dst[x] = (a << 24) | l << 16 | l << 8 | l;
	}
}

static inline void decodebytesRGB5A3rgba(u32 *dst, const u16 *src)
{
#if 0
	for (int x = 0; x < 4; x++)
		dst[x] = decode5A3RGBA(Common::swap16(src[x]));
#else
	dst[0] = decode5A3RGBA(Common::swap16(src[0]));
	dst[1] = decode5A3RGBA(Common::swap16(src[1]));
	dst[2] = decode5A3RGBA(Common::swap16(src[2]));
	dst[3] = decode5A3RGBA(Common::swap16(src[3]));
#endif
}

static inline void decodebytesARGB8_4ToRgba(u32 *dst, const u16 *src, const u16 * src2)
{
#if 0
	for (int x = 0; x < 4; x++)
	{
		dst[x] =  ((src[x] & 0xFF) << 24) | ((src[x] & 0xFF00)>>8)  | (src2[x] << 8);
	}
#else
	dst[0] =  ((src[0] & 0xFF) << 24) | ((src[0] & 0xFF00)>>8)  | (src2[0] << 8);
	dst[1] =  ((src[1] & 0xFF) << 24) | ((src[1] & 0xFF00)>>8)  | (src2[1] << 8);
	dst[2] =  ((src[2] & 0xFF) << 24) | ((src[2] & 0xFF00)>>8)  | (src2[2] << 8);
	dst[3] =  ((src[3] & 0xFF) << 24) | ((src[3] & 0xFF00)>>8)  | (src2[3] << 8);
#endif
}

static inline u32 makeRGBA(int r, int g, int b, int a)
{
	return (a<<24)|(b<<16)|(g<<8)|r;
}

static void decodeDXTBlockRGBA(u32 *dst, const DXTBlock *src, int pitch)
{
	// S3TC Decoder (Note: GCN decodes differently from PC so we can't use native support)
	// Needs more speed.
	u16 c1 = Common::swap16(src->color1);
	u16 c2 = Common::swap16(src->color2);
	int blue1 = Convert5To8(c1 & 0x1F);
	int blue2 = Convert5To8(c2 & 0x1F);
	int green1 = Convert6To8((c1 >> 5) & 0x3F);
	int green2 = Convert6To8((c2 >> 5) & 0x3F);
	int red1 = Convert5To8((c1 >> 11) & 0x1F);
	int red2 = Convert5To8((c2 >> 11) & 0x1F);
	int colors[4];
	colors[0] = makeRGBA(red1, green1, blue1, 255);
	colors[1] = makeRGBA(red2, green2, blue2, 255);
	if (c1 > c2)
	{
		int blue3 = ((blue2 - blue1) >> 1) - ((blue2 - blue1) >> 3);
		int green3 = ((green2 - green1) >> 1) - ((green2 - green1) >> 3);
		int red3 = ((red2 - red1) >> 1) - ((red2 - red1) >> 3);
		colors[2] = makeRGBA(red1 + red3, green1 + green3, blue1 + blue3, 255);
		colors[3] = makeRGBA(red2 - red3, green2 - green3, blue2 - blue3, 255);
	}
	else
	{
		colors[2] = makeRGBA((red1 + red2 + 1) / 2, // Average
							(green1 + green2 + 1) / 2,
							(blue1 + blue2 + 1) / 2, 255);
		colors[3] = makeRGBA(red2, green2, blue2, 0);  // Color2 but transparent
	}

	for (int y = 0; y < 4; y++)
	{
		int val = src->lines[y];
		for (int x = 0; x < 4; x++)
		{
			dst[x] = colors[(val >> 6) & 3];
			val <<= 2;
		}
		dst += pitch;
	}
}

// JSD 01/06/11:
// TODO: we really should ensure BOTH the source and destination addresses are aligned to 16-byte boundaries to
// squeeze out a little more performance. _mm_loadu_si128/_mm_storeu_si128 is slower than _mm_load_si128/_mm_store_si128
// because they work on unaligned addresses. The processor is free to make the assumption that addresses are multiples
// of 16 in the aligned case.
// TODO: complete SSE2 optimization of less often used texture formats.
// TODO: refactor algorithms using _mm_loadl_epi64 unaligned loads to prefer 128-bit aligned loads.

PC_TexFormat _TexDecoder_DecodeImpl(u32 * dst, const u8 * src, int width, int height, int texformat, const u8* tlut, TlutFormat tlutfmt)
{

	const int Wsteps4 = (width + 3) / 4;
	const int Wsteps8 = (width + 7) / 8;

	switch (texformat)
	{
	case GX_TF_C4:
		if (tlutfmt == GX_TL_RGB5A3)
		{
			// Special decoding is required for TLUT format 5A3
			for (int y = 0; y < height; y += 8)
				for (int x = 0, yStep = (y / 8) * Wsteps8; x < width; x += 8,yStep++)
					for (int iy = 0, xStep =  8 * yStep; iy < 8; iy++,xStep++)
						decodebytesC4_5A3_To_rgba32(dst + (y + iy) * width + x, src + 4 * xStep, tlut);
		}
		else if (tlutfmt == GX_TL_IA8)
		{
			for (int y = 0; y < height; y += 8)
				for (int x = 0, yStep = (y / 8) * Wsteps8; x < width; x += 8,yStep++)
					for (int iy = 0, xStep =  8 * yStep; iy < 8; iy++,xStep++)
						decodebytesC4IA8_To_RGBA(dst + (y + iy) * width + x, src + 4 * xStep, tlut);
		}
		else if (tlutfmt == GX_TL_RGB565)
		{
			for (int y = 0; y < height; y += 8)
				for (int x = 0, yStep = (y / 8) * Wsteps8; x < width; x += 8,yStep++)
					for (int iy = 0, xStep =  8 * yStep; iy < 8; iy++,xStep++)
						decodebytesC4RGB565_To_RGBA(dst + (y + iy) * width + x, src  + 4 * xStep, tlut);
		}
		break;
	case GX_TF_I4:
		{
			// Reference C implementation:
			for (int y = 0; y < height; y += 8)
				for (int x = 0; x < width; x += 8)
					for (int iy = 0; iy < 8; iy++, src += 4)
						for (int ix = 0; ix < 4; ix++)
						{
							int val = src[ix];
							u8 i1 = Convert4To8(val >> 4);
							u8 i2 = Convert4To8(val & 0xF);
							memset(dst+(y + iy) * width + x + ix * 2 , i1,4);
							memset(dst+(y + iy) * width + x + ix * 2 + 1 , i2,4);
						}
		}
		break;
	case GX_TF_I8:  // speed critical
		{
			// Reference C implementation
			for (int y = 0; y < height; y += 4)
				for (int x = 0; x < width; x += 8)
					for (int iy = 0; iy < 4; ++iy, src += 8)
					{
						u32 *  newdst = dst + (y + iy)*width+x;
						const u8 *  newsrc = src;
						u8 srcval;

						srcval = (newsrc++)[0]; (newdst++)[0] = srcval | (srcval << 8) | (srcval << 16) | (srcval << 24);
						srcval = (newsrc++)[0]; (newdst++)[0] = srcval | (srcval << 8) | (srcval << 16) | (srcval << 24);
						srcval = (newsrc++)[0]; (newdst++)[0] = srcval | (srcval << 8) | (srcval << 16) | (srcval << 24);
						srcval = (newsrc++)[0]; (newdst++)[0] = srcval | (srcval << 8) | (srcval << 16) | (srcval << 24);
						srcval = (newsrc++)[0]; (newdst++)[0] = srcval | (srcval << 8) | (srcval << 16) | (srcval << 24);
						srcval = (newsrc++)[0]; (newdst++)[0] = srcval | (srcval << 8) | (srcval << 16) | (srcval << 24);
						srcval = (newsrc++)[0]; (newdst++)[0] = srcval | (srcval << 8) | (srcval << 16) | (srcval << 24);
						srcval = newsrc[0]; newdst[0] = srcval | (srcval << 8) | (srcval << 16) | (srcval << 24);
					}
		}
		break;
	case GX_TF_C8:
		if (tlutfmt == GX_TL_RGB5A3)
		{
			// Special decoding is required for TLUT format 5A3
			for (int y = 0; y < height; y += 4)
				for (int x = 0, yStep = (y / 4) * Wsteps8; x < width; x += 8, yStep++)
					for (int iy = 0, xStep = 4 * yStep; iy < 4; iy++, xStep++)
						decodebytesC8_5A3_To_RGBA32((u32*)dst + (y + iy) * width + x, src + 8 * xStep, tlut);
		}
		else if (tlutfmt == GX_TL_IA8)
		{
			for (int y = 0; y < height; y += 4)
				for (int x = 0, yStep = (y / 4) * Wsteps8; x < width; x += 8, yStep++)
					for (int iy = 0, xStep = 4 * yStep; iy < 4; iy++, xStep++)
						decodebytesC8IA8_To_RGBA(dst + (y + iy) * width + x, src + 8 * xStep, tlut);
		}
		else if (tlutfmt == GX_TL_RGB565)
		{
			for (int y = 0; y < height; y += 4)
				for (int x = 0, yStep = (y / 4) * Wsteps8; x < width; x += 8, yStep++)
					for (int iy = 0, xStep = 4 * yStep; iy < 4; iy++, xStep++)
						decodebytesC8RGB565_To_RGBA(dst + (y + iy) * width + x, src + 8 * xStep, tlut);

		}
		break;
	case GX_TF_IA4:
		{
			for (int y = 0; y < height; y += 4)
				for (int x = 0, yStep = (y / 4) * Wsteps8; x < width; x += 8, yStep++)
					for (int iy = 0, xStep = 4 * yStep; iy < 4; iy++, xStep++)
						decodebytesIA4RGBA(dst + (y + iy) * width + x, src + 8 * xStep);
		}
		break;
	case GX_TF_IA8:
		{
			// Reference C implementation:
			for (int y = 0; y < height; y += 4)
				for (int x = 0; x < width; x += 4)
					for (int iy = 0; iy < 4; iy++, src += 8)
					{
						u32 *ptr = dst + (y + iy) * width + x;
						u16 *s = (u16 *)src;
						ptr[0] = decodeIA8Swapped(s[0]);
						ptr[1] = decodeIA8Swapped(s[1]);
						ptr[2] = decodeIA8Swapped(s[2]);
						ptr[3] = decodeIA8Swapped(s[3]);
					}
		}
		break;
	case GX_TF_C14X2:
		if (tlutfmt == GX_TL_RGB5A3)
		{
			// Special decoding is required for TLUT format 5A3
			for (int y = 0; y < height; y += 4)
				for (int x = 0, yStep = (y / 4) * Wsteps4; x < width; x += 4, yStep++)
					for (int iy = 0, xStep = 4 * yStep; iy < 4; iy++, xStep++)
						decodebytesC14X2_5A3_To_RGBA(dst + (y + iy) * width + x, (u16*)(src + 8 * xStep), tlut);
		}
		else if (tlutfmt == GX_TL_IA8)
		{
			for (int y = 0; y < height; y += 4)
				for (int x = 0, yStep = (y / 4) * Wsteps4; x < width; x += 4, yStep++)
					for (int iy = 0, xStep = 4 * yStep; iy < 4; iy++, xStep++)
						decodebytesC14X2IA8_To_RGBA(dst + (y + iy) * width + x,  (u16*)(src + 8 * xStep), tlut);
		}
		else if (tlutfmt == GX_TL_RGB565)
		{
			for (int y = 0; y < height; y += 4)
				for (int x = 0, yStep = (y / 4) * Wsteps4; x < width; x += 4, yStep++)
					for (int iy = 0, xStep = 4 * yStep; iy < 4; iy++, xStep++)
						decodebytesC14X2rgb565_To_RGBA(dst + (y + iy) * width + x, (u16*)(src + 8 * xStep), tlut);
		}
		break;
	case GX_TF_RGB565:
		{
			// Reference C implementation.
			for (int y = 0; y < height; y += 4)
				for (int x = 0; x < width; x += 4)
					for (int iy = 0; iy < 4; iy++, src += 8)
					{
						u32 *ptr = dst + (y + iy) * width + x;
						u16 *s = (u16 *)src;
						for (int j = 0; j < 4; j++)
							*ptr++ = decode565RGBA(Common::swap16(*s++));
					}
		}
		break;
	case GX_TF_RGB5A3:
		{
			// Reference C implementation:
			for (int y = 0; y < height; y += 4)
				for (int x = 0; x < width; x += 4)
					for (int iy = 0; iy < 4; iy++, src += 8)
						decodebytesRGB5A3rgba(dst+(y+iy)*width+x, (u16*)src);
		}
		break;
	case GX_TF_RGBA8:  // speed critical
		{
			// Reference C implementation.
			for (int y = 0; y < height; y += 4)
				for (int x = 0; x < width; x += 4)
				{
					for (int iy = 0; iy < 4; iy++)
						decodebytesARGB8_4ToRgba(dst + (y+iy)*width + x, (u16*)src + 4 * iy, (u16*)src + 4 * iy + 16);
					src += 64;
				}
		}
		break;
	case GX_TF_CMPR:  // speed critical
		// The metroid games use this format almost exclusively.
		{
			for (int y = 0; y < height; y += 8)
			{
				for (int x = 0; x < width; x += 8)
				{
					decodeDXTBlockRGBA((u32*)dst + y * width + x, (DXTBlock*)src, width);
										src += sizeof(DXTBlock);
					decodeDXTBlockRGBA((u32*)dst + y * width + x + 4, (DXTBlock*)src, width);
										src += sizeof(DXTBlock);
					decodeDXTBlockRGBA((u32*)dst + (y + 4) * width + x, (DXTBlock*)src, width);
										src += sizeof(DXTBlock);
					decodeDXTBlockRGBA((u32*)dst + (y + 4) * width + x + 4, (DXTBlock*)src, width);
										src += sizeof(DXTBlock);
				}
			}
			break;
		}
	}

	// The "copy" texture formats, too?
	return PC_TEX_FMT_RGBA32;
}