ppsspp/GPU/Common/TextureDecoder.cpp

// Copyright (c) 2012- PPSSPP Project.

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 2.0 or later versions.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official git repository and contact information can be found at
// https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.

#include "Common/CPUDetect.h"
#include "GPU/Common/TextureDecoder.h"
// NEON is in a separate file so that it can be compiled with a runtime check.
#include "GPU/Common/TextureDecoderNEON.h"

// TODO: Move some common things into here.

#ifdef _M_SSE
#include <xmmintrin.h>
#endif

static u32 QuickTexHashSSE2(const void *checkp, u32 size) {
	u32 check = 0;

#ifdef _M_SSE
	if (((intptr_t)checkp & 0xf) == 0 && (size & 0x3f) == 0) {
		__m128i cursor = _mm_set1_epi32(0);
		__m128i cursor2 = _mm_set_epi16(0x0001U, 0x0083U, 0x4309U, 0x4d9bU, 0xb651U, 0x4b73U, 0x9bd9U, 0xc00bU);
		__m128i update = _mm_set1_epi16(0x2455U);
		const __m128i *p = (const __m128i *)checkp;
		for (u32 i = 0; i < size / 16; i += 4) {
			__m128i chunk = _mm_mullo_epi16(_mm_load_si128(&p[i]), cursor2);
			cursor = _mm_add_epi32(cursor, chunk);
			cursor = _mm_xor_si128(cursor, _mm_load_si128(&p[i + 1]));
			cursor = _mm_add_epi32(cursor, _mm_load_si128(&p[i + 2]));
			chunk = _mm_mullo_epi16(_mm_load_si128(&p[i + 3]), cursor2);
			cursor = _mm_xor_si128(cursor, chunk);
			cursor2 = _mm_add_epi16(cursor2, update);
		}
		cursor = _mm_add_epi32(cursor, cursor2);
		// Add the four parts into the low i32.
		cursor = _mm_add_epi32(cursor, _mm_srli_si128(cursor, 8));
		cursor = _mm_add_epi32(cursor, _mm_srli_si128(cursor, 4));
		check = _mm_cvtsi128_si32(cursor);
	} else {
#else
	{
#endif
		const u32 *p = (const u32 *)checkp;
		for (u32 i = 0; i < size / 8; ++i) {
			check += *p++;
			check ^= *p++;
		}
	}

	return check;
}

static u32 QuickTexHashBasic(const void *checkp, u32 size) {
#if defined(ARM) && defined(__GNUC__)
	__builtin_prefetch(checkp, 0, 0);

	u32 check;
	asm volatile (
		// Let's change size to the end address.
		"add %1, %1, %2\n"
		"mov r6, #0\n"

		// If we have zero sized input, we'll return garbage.  Oh well, shouldn't happen.
		"QuickTexHashBasic_next:\n"
		"ldmia %2!, {r2-r5}\n"
		"add r6, r6, r2\n"
		"eor r6, r6, r3\n"
		"cmp %2, %1\n"
		"add r6, r6, r4\n"
		"eor r6, r6, r5\n"
		"blo QuickTexHashBasic_next\n"

		"QuickTexHashBasic_done:\n"
		"mov %0, r6\n"

		: "=r"(check)
		: "r"(size), "r"(checkp)
		: "r2", "r3", "r4", "r5", "r6"
	);
#else
	u32 check = 0;
	const u32 size_u32 = size / 4;
	const u32 *p = (const u32 *)checkp;
	for (u32 i = 0; i < size_u32; i += 4) {
		check += p[i + 0];
		check ^= p[i + 1];
		check += p[i + 2];
		check ^= p[i + 3];
	}
#endif

	return check;
}

QuickTexHashFunc DoQuickTexHash = &QuickTexHashBasic;

// This has to be done after CPUDetect has done its magic.
void SetupQuickTexHash() {
#ifdef ARMV7
	if (cpu_info.bNEON)
		DoQuickTexHash = &QuickTexHashNEON;
#else
	if (cpu_info.bSSE2)
		DoQuickTexHash = &QuickTexHashSSE2;
#endif
}

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

// This could probably be done faster by decoding two or four blocks at a time with SSE/NEON.
void DecodeDXT1Block(u32 *dst, const DXT1Block *src, int pitch, bool ignore1bitAlpha) {
	// S3TC Decoder
	// Needs more speed and debugging.
	u16 c1 = (src->color1);
	u16 c2 = (src->color2);
	int red1 = Convert5To8(c1 & 0x1F);
	int red2 = Convert5To8(c2 & 0x1F);
	int green1 = Convert6To8((c1 >> 5) & 0x3F);
	int green2 = Convert6To8((c2 >> 5) & 0x3F);
	int blue1 = Convert5To8((c1 >> 11) & 0x1F);
	int blue2 = Convert5To8((c2 >> 11) & 0x1F);

	u32 colors[4];
	colors[0] = makecol(red1, green1, blue1, 255);
	colors[1] = makecol(red2, green2, blue2, 255);
	if (c1 > c2 || ignore1bitAlpha) {
		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] = makecol(red1 + red3, green1 + green3, blue1 + blue3, 255);
		colors[3] = makecol(red2 - red3, green2 - green3, blue2 - blue3, 255);
	} else {
		colors[2] = makecol((red1 + red2 + 1) / 2, // Average
			(green1 + green2 + 1) / 2,
			(blue1 + blue2 + 1) / 2, 255);
		colors[3] = makecol(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 & 3];
			val >>= 2;
		}
		dst += pitch;
	}
}

void DecodeDXT3Block(u32 *dst, const DXT3Block *src, int pitch)
{
	DecodeDXT1Block(dst, &src->color, pitch, true);

	for (int y = 0; y < 4; y++) {
		u32 line = src->alphaLines[y];
		for (int x = 0; x < 4; x++) {
			const u8 a4 = line & 0xF;
			dst[x] = (dst[x] & 0xFFFFFF) | (a4 << 24) | (a4 << 28);
			line >>= 4;
		}
		dst += pitch;
	}
}

static inline u8 lerp8(const DXT5Block *src, int n) {
	float d = n / 7.0f;
	return (u8)(src->alpha1 + (src->alpha2 - src->alpha1) * d);
}

static inline u8 lerp6(const DXT5Block *src, int n) {
	float d = n / 5.0f;
	return (u8)(src->alpha1 + (src->alpha2 - src->alpha1) * d);
}

// The alpha channel is not 100% correct 
void DecodeDXT5Block(u32 *dst, const DXT5Block *src, int pitch) {
	DecodeDXT1Block(dst, &src->color, pitch, true);
	u8 alpha[8];

	alpha[0] = src->alpha1;
	alpha[1] = src->alpha2;
	if (alpha[0] > alpha[1]) {
		alpha[2] = lerp8(src, 1);
		alpha[3] = lerp8(src, 2);
		alpha[4] = lerp8(src, 3);
		alpha[5] = lerp8(src, 4);
		alpha[6] = lerp8(src, 5);
		alpha[7] = lerp8(src, 6);
	} else {
		alpha[2] = lerp6(src, 1);
		alpha[3] = lerp6(src, 2);
		alpha[4] = lerp6(src, 3);
		alpha[5] = lerp6(src, 4);
		alpha[6] = 0;
		alpha[7] = 255;
	}

	u64 data = ((u64)(u16)src->alphadata1 << 32) | (u32)src->alphadata2;

	for (int y = 0; y < 4; y++) {
		for (int x = 0; x < 4; x++) {
			dst[x] = (dst[x] & 0xFFFFFF) | (alpha[data & 7] << 24);
			data >>= 3;
		}
		dst += pitch;
	}
}