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Code from Rene Dudfield

SDL_blit_A.c (text/plain), 24.11 KB, created by Sam Lantinga on 2006-01-24 01:41:38 UTC

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Filename:

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Creator: Sam Lantinga

Created: 2006-01-24 01:41:38 UTC

Size: 24.11 KB

patch

obsolete

>/*
>    SDL - Simple DirectMedia Layer
>    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  Sam Lantinga
>
>    This library is free software; you can redistribute it and/or
>    modify it under the terms of the GNU Library General Public
>    License as published by the Free Software Foundation; either
>    version 2 of the License, or (at your option) any later version.
>
>    This library 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
>    Library General Public License for more details.
>
>    You should have received a copy of the GNU Library General Public
>    License along with this library; if not, write to the Free
>    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
>
>    Sam Lantinga
>    slouken@libsdl.org
>*/
>
>#ifdef SAVE_RCSID
>static char rcsid =
> "@(#) $Id: SDL_blit_A.c,v 1.4 2002/03/06 11:23:02 slouken Exp $";
>#endif
>
>#include <stdio.h>
>
>#include "SDL_types.h"
>#include "SDL_video.h"
>#include "SDL_blit.h"
>
>
>//#define PRINT_LINE printf("%d\n",__LINE__);
>#define PRINT_LINE 
>
>
>/* Functions to perform alpha blended blitting */
>
>/* N->1 blending with per-surface alpha */
>static void BlitNto1SurfaceAlpha(SDL_BlitInfo *info)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint8 *src = info->s_pixels;
>	int srcskip = info->s_skip;
>	Uint8 *dst = info->d_pixels;
>	int dstskip = info->d_skip;
>	Uint8 *palmap = info->table;
>	SDL_PixelFormat *srcfmt = info->src;
>	SDL_PixelFormat *dstfmt = info->dst;
>	int srcbpp = srcfmt->BytesPerPixel;
>
>	const unsigned A = srcfmt->alpha;
>	PRINT_LINE
>
>	while ( height-- ) {
>	    DUFFS_LOOP4(
>	    {
>		Uint32 pixel;
>		unsigned sR;
>		unsigned sG;
>		unsigned sB;
>		unsigned dR;
>		unsigned dG;
>		unsigned dB;
>		DISEMBLE_RGB(src, srcbpp, srcfmt, pixel, sR, sG, sB);
>		dR = dstfmt->palette->colors[*dst].r;
>		dG = dstfmt->palette->colors[*dst].g;
>		dB = dstfmt->palette->colors[*dst].b;
>		ALPHA_BLEND(sR, sG, sB, A, dR, dG, dB);
>		dR &= 0xff;
>		dG &= 0xff;
>		dB &= 0xff;
>		/* Pack RGB into 8bit pixel */
>		if ( palmap == NULL ) {
>		    *dst =((dR>>5)<<(3+2))|
>			  ((dG>>5)<<(2))|
>			  ((dB>>6)<<(0));
>		} else {
>		    *dst = palmap[((dR>>5)<<(3+2))|
>				  ((dG>>5)<<(2))  |
>				  ((dB>>6)<<(0))];
>		}
>		dst++;
>		src += srcbpp;
>	    },
>	    width);
>	    src += srcskip;
>	    dst += dstskip;
>	}
>}
>
>/* N->1 blending with pixel alpha */
>static void BlitNto1PixelAlpha(SDL_BlitInfo *info)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint8 *src = info->s_pixels;
>	int srcskip = info->s_skip;
>	Uint8 *dst = info->d_pixels;
>	int dstskip = info->d_skip;
>	Uint8 *palmap = info->table;
>	SDL_PixelFormat *srcfmt = info->src;
>	SDL_PixelFormat *dstfmt = info->dst;
>	int srcbpp = srcfmt->BytesPerPixel;
>
>	PRINT_LINE
>	/* FIXME: fix alpha bit field expansion here too? */
>	while ( height-- ) {
>	    DUFFS_LOOP4(
>	    {
>		Uint32 pixel;
>		unsigned sR;
>		unsigned sG;
>		unsigned sB;
>		unsigned sA;
>		unsigned dR;
>		unsigned dG;
>		unsigned dB;
>		DISEMBLE_RGBA(src,srcbpp,srcfmt,pixel,sR,sG,sB,sA);
>		dR = dstfmt->palette->colors[*dst].r;
>		dG = dstfmt->palette->colors[*dst].g;
>		dB = dstfmt->palette->colors[*dst].b;
>		ALPHA_BLEND(sR, sG, sB, sA, dR, dG, dB);
>		dR &= 0xff;
>		dG &= 0xff;
>		dB &= 0xff;
>		/* Pack RGB into 8bit pixel */
>		if ( palmap == NULL ) {
>		    *dst =((dR>>5)<<(3+2))|
>			  ((dG>>5)<<(2))|
>			  ((dB>>6)<<(0));
>		} else {
>		    *dst = palmap[((dR>>5)<<(3+2))|
>				  ((dG>>5)<<(2))  |
>				  ((dB>>6)<<(0))  ];
>		}
>		dst++;
>		src += srcbpp;
>	    },
>	    width);
>	    src += srcskip;
>	    dst += dstskip;
>	}
>}
>
>/* colorkeyed N->1 blending with per-surface alpha */
>static void BlitNto1SurfaceAlphaKey(SDL_BlitInfo *info)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint8 *src = info->s_pixels;
>	int srcskip = info->s_skip;
>	Uint8 *dst = info->d_pixels;
>	int dstskip = info->d_skip;
>	Uint8 *palmap = info->table;
>	SDL_PixelFormat *srcfmt = info->src;
>	SDL_PixelFormat *dstfmt = info->dst;
>	int srcbpp = srcfmt->BytesPerPixel;
>	Uint32 ckey = srcfmt->colorkey;
>
>	const int A = srcfmt->alpha;
>
>	PRINT_LINE
>	while ( height-- ) {
>	    DUFFS_LOOP(
>	    {
>		Uint32 pixel;
>		unsigned sR;
>		unsigned sG;
>		unsigned sB;
>		unsigned dR;
>		unsigned dG;
>		unsigned dB;
>		DISEMBLE_RGB(src, srcbpp, srcfmt, pixel, sR, sG, sB);
>		if ( pixel != ckey ) {
>		    dR = dstfmt->palette->colors[*dst].r;
>		    dG = dstfmt->palette->colors[*dst].g;
>		    dB = dstfmt->palette->colors[*dst].b;
>		    ALPHA_BLEND(sR, sG, sB, A, dR, dG, dB);
>		    dR &= 0xff;
>		    dG &= 0xff;
>		    dB &= 0xff;
>		    /* Pack RGB into 8bit pixel */
>		    if ( palmap == NULL ) {
>			*dst =((dR>>5)<<(3+2))|
>			      ((dG>>5)<<(2)) |
>			      ((dB>>6)<<(0));
>		    } else {
>			*dst = palmap[((dR>>5)<<(3+2))|
>				      ((dG>>5)<<(2))  |
>				      ((dB>>6)<<(0))  ];
>		    }
>		}
>		dst++;
>		src += srcbpp;
>	    },
>	    width);
>	    src += srcskip;
>	    dst += dstskip;
>	}
>}
>
>/* fast RGB888->(A)RGB888 blending with surface alpha=128 special case */
>static void BlitRGBtoRGBSurfaceAlpha128(SDL_BlitInfo *info)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint32 *srcp = (Uint32 *)info->s_pixels;
>	int srcskip = info->s_skip >> 2;
>	Uint32 *dstp = (Uint32 *)info->d_pixels;
>	int dstskip = info->d_skip >> 2;
>
>	PRINT_LINE
>	while(height--) {
>	    DUFFS_LOOP4({
>		    Uint32 s = *srcp++;
>		    Uint32 d = *dstp;
>		    *dstp++ = ((((s & 0x00fefefe) + (d & 0x00fefefe)) >> 1)
>			       + (s & d & 0x00010101)) | 0xff000000;
>	    }, width);
>	    srcp += srcskip;
>	    dstp += dstskip;
>	}
>}
>
>/* fast RGB888->(A)RGB888 blending with surface alpha */
>static void BlitRGBtoRGBSurfaceAlpha(SDL_BlitInfo *info)
>{
>	unsigned alpha = info->src->alpha;
>	PRINT_LINE
>	if(alpha == 128) {
>		BlitRGBtoRGBSurfaceAlpha128(info);
>	} else {
>		int width = info->d_width;
>		int height = info->d_height;
>		Uint32 *srcp = (Uint32 *)info->s_pixels;
>		int srcskip = info->s_skip >> 2;
>		Uint32 *dstp = (Uint32 *)info->d_pixels;
>		int dstskip = info->d_skip >> 2;
>
>		while(height--) {
>			DUFFS_LOOP4({
>				Uint32 s;
>				Uint32 d;
>				Uint32 s1;
>				Uint32 d1;
>				s = *srcp;
>				d = *dstp;
>				s1 = s & 0xff00ff;
>				d1 = d & 0xff00ff;
>				d1 = (d1 + ((s1 - d1) * alpha >> 8))
>				     & 0xff00ff;
>				s &= 0xff00;
>				d &= 0xff00;
>				d = (d + ((s - d) * alpha >> 8)) & 0xff00;
>				*dstp = d1 | d | 0xff000000;
>				++srcp;
>				++dstp;
>			}, width);
>			srcp += srcskip;
>			dstp += dstskip;
>		}
>	}
>}
>
>
>
>
>
>
>#define PHEX(A) printf(#A " %u:0x%X\n", A, A);
>//#define PHEX(A)
>
>
>
>inline Uint32 alpha_blend_mmx_pointer(Uint32 *src, Uint32 *dst)
>{
>    // s[r,g,b] = a * p[r,g,b] + (1 - a) * q[r,g,b]
>    //
>    //
>    //  Implements this algo:
>    //
>    // dstR = (((src_R-dst_R)*(src_A))>>8)+dst_R;
>    // dstG = (((src_G-dst_G)*(src_A))>>8)+dst_G;
>    // dstR = (((src_B-dst_B)*(src_B))>>8)+dst_B;
>    
>    Uint32 dummy_return;
>
>
>
>    __asm__ (
>    "emms\n"
>
>    // make mm6 all zeros.
>    "pxor       %%mm6, %%mm6\n"
>    
>    // Make a mask to preserve the alpha.
>    "pcmpeqb   %%mm7, %%mm7\n\t"            // mm7(s) = FF FF FF FF | FF FF FF FF
>    "psrlq     $16, %%mm7\n\t"		    // mm7(s) = 00 00 FF FF | FF FF FF FF
>
>    // load in the source, and dst.
>
>    "movd      (%1), %%mm0\n"		    // mm0(s) = 0 0 0 0 | As Rs Gs Bs
>    "movd      (%2), %%mm1\n"		    // mm1(d) = 0 0 0 0 | Ad Rd Gd Bd
>
>
>    // Move the src alpha into mm2
>
>    // if supporting pshufw
>    "pshufw     $0x55, %%mm0, %%mm2\n"    // mm2 = 0 As 0 As |  0 As  0  As
>    "psrlw     $8, %%mm2\n"
>    
>    // else:
>    //"psrld     $24, %%mm2\n"                // mm2 = 0 0 0 0 | 0  0  0  As
>    //"punpcklwd	%%mm2, %%mm2\n"
>    //"punpckldq	%%mm2, %%mm2\n"             // mm2 = 0 As 0 As |  0 As  0  As
>
>
>
>    // move the colors into words.
>    
>    "punpcklbw %%mm6, %%mm0\n"		    // mm0 = 0 As 0 Rs | 0 Gs 0 Bs
>    "punpcklbw %%mm6, %%mm1\n"              // mm0 = 0 Ad 0 Rd | 0 Gd 0 Bd
>
>
>    // src - dst
>    "psubw    %%mm1, %%mm0\n"		    // mm0 = As-Ad Rs-Rd | Gs-Gd  Bs-Bd
>
>    // A * (src-dst)
>    "pmullw    %%mm2, %%mm0\n"		    // mm0 = As*As-d As*Rs-d | As*Gs-d  As*Bs-d
>    "psrlw     $8,    %%mm0\n"		    // mm0 = Ac>>8 Rc>>8 | Gc>>8  Bc>>8
>    "pand      %%mm7, %%mm0\n"              // to preserve dest alpha
>    "paddsb    %%mm1, %%mm0\n"		    // mm0 = Ac+Ad Rc+Rd | Gc+Gd  Bc+Bd
>
>    "packuswb  %%mm0, %%mm0\n"              // mm0 =             | Ac Rc Gc Bc
>    
>    
>    
>    "movd      %%mm0, (%0)\n"    // result in mm0 
>    "emms\n"
>
>     : : "r" (&dummy_return), "r" (src), "r" (dst) );
>     //: "=r" (dummy_return) : "r" (src), "r" (dst) );
>    
>    return dummy_return;
>}
>
>
>
>
>
>/* fast ARGB888->(A)RGB888 blending with pixel alpha */
>inline static void BlitRGBtoRGBPixelAlpha(SDL_BlitInfo *info)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint32 *srcp = (Uint32 *)info->s_pixels;
>	int srcskip = info->s_skip >> 2;
>	Uint32 *dstp = (Uint32 *)info->d_pixels;
>	int dstskip = info->d_skip >> 2;
>
>	/*
>	Uint32 dalpha;
>	Uint32 d;
>	Uint32 s1;
>	Uint32 d1;
>	*/
>
>	Uint32 s;
>	Uint32 alpha;
>
>	__asm__ (
>	"emms\n"
>
>	// make mm6 all zeros.
>	"pxor       %%mm6, %%mm6\n"
>	
>	// Make a mask to preserve the alpha.
>	"pcmpeqb   %%mm7, %%mm7\n\t"            // mm7(s) = FF FF FF FF | FF FF FF FF
>	"psrlq     $16, %%mm7\n\t"		    // mm7(s) = 00 00 FF FF | FF FF FF FF
>
>		: );
>
>
>
>	PRINT_LINE
>	while(height--) {
>
>/*
>	    __asm__ (
>	    "prefetch 64(%0)\n"
>	    "prefetchw 64(%1)\n"
>		    : : "r" (srcp), "r" (dstp) );
>*/
>
>	    DUFFS_LOOP4({
>
>		//*dstp = alpha_blend_mmx_pointer(srcp, dstp);
>
>
>		__asm__ (
>		"prefetch 64(%0)\n"
>		"prefetch 64(%1)\n"
>			: : "r" (srcp), "r" (dstp) );
>
>		s = *srcp;
>		alpha = s >> 24;
>		// FIXME: Here we special-case opaque alpha since the
>		//   compositioning used (>>8 instead of /255) doesn't handle
>		//   it correctly. Also special-case alpha=0 for speed?
>		//   Benchmark this! 
>		
>		if(alpha == SDL_ALPHA_OPAQUE) {
>		    *dstp = (s & 0x00ffffff) | (*dstp & 0xff000000);
>		} 
>		else if (alpha == SDL_ALPHA_TRANSPARENT)
>		{
>		    // source fully transparent, use the destinations for it.
>		    //*dstp = (s & 0xff000000) | (*dstp & 0x00ffffff);
>		}
>		/*
>		else if (alpha == 127)
>		{
>		    // source half transparent, use the destinations for it.
>		    *dstp = (s & 0xff777777) | (*dstp & 0x00777777);
>		}
>		*/
>
>		else {
>		    //
>		    // take out the middle component (green), and process
>		    // the other two in parallel. One multiply less.
>		    // 
>		    //
>		    
>		    //PHEX(srcp)
>		    //PHEX(dstp)
>		    //printf("\n");
>
>		    //*dstp = alpha_blend_mmx_pointer(srcp, dstp);
>
>
>		    __asm__ (
>
>		    // load in the source, and dst.
>
>		    "movd      (%0), %%mm0\n"		    // mm0(s) = 0 0 0 0 | As Rs Gs Bs
>		    "movd      (%1), %%mm1\n"		    // mm1(d) = 0 0 0 0 | Ad Rd Gd Bd
>
>
>		    // Move the src alpha into mm2
>
>		    // if supporting pshufw
>		    //"pshufw     $0x55, %%mm0, %%mm2\n"    // mm2 = 0 As 0 As |  0 As  0  As
>		    //"psrlw     $8, %%mm2\n"
>		    
>		    // else:
>		    "movq      %%mm0, %%mm2\n"
>		    "psrld     $24, %%mm2\n"                // mm2 = 0 0 0 0 | 0  0  0  As
>		    "punpcklwd	%%mm2, %%mm2\n"
>		    "punpckldq	%%mm2, %%mm2\n"             // mm2 = 0 As 0 As |  0 As  0  As
>
>
>
>
>		    // move the colors into words.
>		    
>		    "punpcklbw %%mm6, %%mm0\n"		    // mm0 = 0 As 0 Rs | 0 Gs 0 Bs
>		    "punpcklbw %%mm6, %%mm1\n"              // mm0 = 0 Ad 0 Rd | 0 Gd 0 Bd
>
>
>		    // src - dst
>		    "psubw    %%mm1, %%mm0\n"		    // mm0 = As-Ad Rs-Rd | Gs-Gd  Bs-Bd
>
>		    // A * (src-dst)
>		    "pmullw    %%mm2, %%mm0\n"		    // mm0 = As*As-d As*Rs-d | As*Gs-d  As*Bs-d
>		    "pand      %%mm7, %%mm0\n"              // to preserve dest alpha
>		    "psrlw     $8,    %%mm0\n"		    // mm0 = Ac>>8 Rc>>8 | Gc>>8  Bc>>8
>		    "paddsb    %%mm1, %%mm0\n"		    // mm0 = Ac+Ad Rc+Rd | Gc+Gd  Bc+Bd
>
>		    "packuswb  %%mm0, %%mm0\n"              // mm0 =             | Ac Rc Gc Bc
>		    
>		    
>		    
>		    "movd      %%mm0, (%1)\n"    // result in mm0 
>
>		     : : "r" (srcp), "r" (dstp) );
>
>		    //PHEX(*dstp)
>		    //printf("\n");
>		    
>		    /*
>
>		     
>		    d = *dstp;
>		    dalpha = d & 0xff000000;
>		    // store 00RR00BB in s1
>		    s1 = s & 0xff00ff;
>		    // store 00RR00BB in d1
>		    d1 = d & 0xff00ff;
>		    d1 = (d1 + ((s1 - d1) * alpha >> 8)) & 0xff00ff;
>		    s &= 0xff00;
>		    d &= 0xff00;
>		    d = (d + ((s - d) * alpha >> 8)) & 0xff00;
>		    *dstp = d1 | d | dalpha;
>		    */
>		}
>
>
>		++srcp;
>		++dstp;
>	    }, width);
>	    srcp += srcskip;
>	    dstp += dstskip;
>	}
>
>
>	__asm__ (
>	"emms\n"
>		:   );
>
>
>
>}
>
>/* 16bpp special case for per-surface alpha=50%: blend 2 pixels in parallel */
>
>/* blend a single 16 bit pixel at 50% */
>#define BLEND16_50(d, s, mask)						\
>	((((s & mask) + (d & mask)) >> 1) + (s & d & (~mask & 0xffff)))
>
>/* blend two 16 bit pixels at 50% */
>#define BLEND2x16_50(d, s, mask)					     \
>	(((s & (mask | mask << 16)) >> 1) + ((d & (mask | mask << 16)) >> 1) \
>	 + (s & d & (~(mask | mask << 16))))
>
>static void Blit16to16SurfaceAlpha128(SDL_BlitInfo *info, Uint16 mask)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint16 *srcp = (Uint16 *)info->s_pixels;
>	int srcskip = info->s_skip >> 1;
>	Uint16 *dstp = (Uint16 *)info->d_pixels;
>	int dstskip = info->d_skip >> 1;
>
>	PRINT_LINE
>	while(height--) {
>		if(((unsigned long)srcp ^ (unsigned long)dstp) & 2) {
>			/*
>			 * Source and destination not aligned, pipeline it.
>			 * This is mostly a win for big blits but no loss for
>			 * small ones
>			 */
>			Uint32 prev_sw;
>			int w = width;
>
>			/* handle odd destination */
>			if((unsigned long)dstp & 2) {
>				Uint16 d = *dstp, s = *srcp;
>				*dstp = BLEND16_50(d, s, mask);
>				dstp++;
>				srcp++;
>				w--;
>			}
>			srcp++;	/* srcp is now 32-bit aligned */
>
>			/* bootstrap pipeline with first halfword */
>			prev_sw = ((Uint32 *)srcp)[-1];
>
>			while(w > 1) {
>				Uint32 sw, dw, s;
>				sw = *(Uint32 *)srcp;
>				dw = *(Uint32 *)dstp;
>				if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
>					s = (prev_sw << 16) + (sw >> 16);
>				else
>					s = (prev_sw >> 16) + (sw << 16);
>				prev_sw = sw;
>				*(Uint32 *)dstp = BLEND2x16_50(dw, s, mask);
>				dstp += 2;
>				srcp += 2;
>				w -= 2;
>			}
>
>			/* final pixel if any */
>			if(w) {
>				Uint16 d = *dstp, s;
>				if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
>					s = prev_sw;
>				else
>					s = prev_sw >> 16;
>				*dstp = BLEND16_50(d, s, mask);
>				srcp++;
>				dstp++;
>			}
>			srcp += srcskip - 1;
>			dstp += dstskip;
>		} else {
>			/* source and destination are aligned */
>			int w = width;
>
>			/* first odd pixel? */
>			if((unsigned long)srcp & 2) {
>				Uint16 d = *dstp, s = *srcp;
>				*dstp = BLEND16_50(d, s, mask);
>				srcp++;
>				dstp++;
>				w--;
>			}
>			/* srcp and dstp are now 32-bit aligned */
>
>			while(w > 1) {
>				Uint32 sw = *(Uint32 *)srcp;
>				Uint32 dw = *(Uint32 *)dstp;
>				*(Uint32 *)dstp = BLEND2x16_50(dw, sw, mask);
>				srcp += 2;
>				dstp += 2;
>				w -= 2;
>			}
>
>			/* last odd pixel? */
>			if(w) {
>				Uint16 d = *dstp, s = *srcp;
>				*dstp = BLEND16_50(d, s, mask);
>				srcp++;
>				dstp++;
>			}
>			srcp += srcskip;
>			dstp += dstskip;
>		}
>	}
>}
>
>/* fast RGB565->RGB565 blending with surface alpha */
>static void Blit565to565SurfaceAlpha(SDL_BlitInfo *info)
>{
>	unsigned alpha = info->src->alpha;
>	PRINT_LINE
>	if(alpha == 128) {
>		Blit16to16SurfaceAlpha128(info, 0xf7de);
>	} else {
>		int width = info->d_width;
>		int height = info->d_height;
>		Uint16 *srcp = (Uint16 *)info->s_pixels;
>		int srcskip = info->s_skip >> 1;
>		Uint16 *dstp = (Uint16 *)info->d_pixels;
>		int dstskip = info->d_skip >> 1;
>		alpha >>= 3;	/* downscale alpha to 5 bits */
>
>		while(height--) {
>			DUFFS_LOOP4({
>				Uint32 s = *srcp++;
>				Uint32 d = *dstp;
>				/*
>				 * shift out the middle component (green) to
>				 * the high 16 bits, and process all three RGB
>				 * components at the same time.
>				 */
>				s = (s | s << 16) & 0x07e0f81f;
>				d = (d | d << 16) & 0x07e0f81f;
>				d += (s - d) * alpha >> 5;
>				d &= 0x07e0f81f;
>				*dstp++ = d | d >> 16;
>			}, width);
>			srcp += srcskip;
>			dstp += dstskip;
>		}
>	}
>}
>
>/* fast RGB555->RGB555 blending with surface alpha */
>static void Blit555to555SurfaceAlpha(SDL_BlitInfo *info)
>{
>	unsigned alpha = info->src->alpha; /* downscale alpha to 5 bits */
>	PRINT_LINE
>	if(alpha == 128) {
>		Blit16to16SurfaceAlpha128(info, 0xfbde);
>	} else {
>		int width = info->d_width;
>		int height = info->d_height;
>		Uint16 *srcp = (Uint16 *)info->s_pixels;
>		int srcskip = info->s_skip >> 1;
>		Uint16 *dstp = (Uint16 *)info->d_pixels;
>		int dstskip = info->d_skip >> 1;
>		alpha >>= 3;		/* downscale alpha to 5 bits */
>
>		while(height--) {
>			DUFFS_LOOP4({
>				Uint32 s = *srcp++;
>				Uint32 d = *dstp;
>				/*
>				 * shift out the middle component (green) to
>				 * the high 16 bits, and process all three RGB
>				 * components at the same time.
>				 */
>				s = (s | s << 16) & 0x03e07c1f;
>				d = (d | d << 16) & 0x03e07c1f;
>				d += (s - d) * alpha >> 5;
>				d &= 0x03e07c1f;
>				*dstp++ = d | d >> 16;
>			}, width);
>			srcp += srcskip;
>			dstp += dstskip;
>		}
>	}
>}
>
>/* fast ARGB8888->RGB565 blending with pixel alpha */
>static void BlitARGBto565PixelAlpha(SDL_BlitInfo *info)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint32 *srcp = (Uint32 *)info->s_pixels;
>	int srcskip = info->s_skip >> 2;
>	Uint16 *dstp = (Uint16 *)info->d_pixels;
>	int dstskip = info->d_skip >> 1;
>
>	PRINT_LINE
>	while(height--) {
>	    DUFFS_LOOP4({
>		Uint32 s = *srcp;
>		unsigned alpha = s >> 27; /* downscale alpha to 5 bits */
>		/* FIXME: Here we special-case opaque alpha since the
>		   compositioning used (>>8 instead of /255) doesn't handle
>		   it correctly. Also special-case alpha=0 for speed?
>		   Benchmark this! */
>		if(alpha == (SDL_ALPHA_OPAQUE >> 3)) {
>		    *dstp = (s >> 8 & 0xf800) + (s >> 5 & 0x7e0)
>			  + (s >> 3  & 0x1f);
>		} else {
>		    Uint32 d = *dstp;
>		    /*
>		     * convert source and destination to G0RAB65565
>		     * and blend all components at the same time
>		     */
>		    s = ((s & 0xfc00) << 11) + (s >> 8 & 0xf800)
>		      + (s >> 3 & 0x1f);
>		    d = (d | d << 16) & 0x07e0f81f;
>		    d += (s - d) * alpha >> 5;
>		    d &= 0x07e0f81f;
>		    *dstp = d | d >> 16;
>		}
>		srcp++;
>		dstp++;
>	    }, width);
>	    srcp += srcskip;
>	    dstp += dstskip;
>	}
>}
>
>/* fast ARGB8888->RGB555 blending with pixel alpha */
>static void BlitARGBto555PixelAlpha(SDL_BlitInfo *info)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint32 *srcp = (Uint32 *)info->s_pixels;
>	int srcskip = info->s_skip >> 2;
>	Uint16 *dstp = (Uint16 *)info->d_pixels;
>	int dstskip = info->d_skip >> 1;
>
>	PRINT_LINE
>	while(height--) {
>	    DUFFS_LOOP4({
>		unsigned alpha;
>		Uint32 s = *srcp;
>		alpha = s >> 27; /* downscale alpha to 5 bits */
>		/* FIXME: Here we special-case opaque alpha since the
>		   compositioning used (>>8 instead of /255) doesn't handle
>		   it correctly. Also special-case alpha=0 for speed?
>		   Benchmark this! */
>		if(alpha == (SDL_ALPHA_OPAQUE >> 3)) {
>		    *dstp = (s >> 9 & 0x7c00) + (s >> 6 & 0x3e0)
>			  + (s >> 3  & 0x1f);
>		} else {
>		    Uint32 d = *dstp;
>		    /*
>		     * convert source and destination to G0RAB65565
>		     * and blend all components at the same time
>		     */
>		    s = ((s & 0xf800) << 10) + (s >> 9 & 0x7c00)
>		      + (s >> 3 & 0x1f);
>		    d = (d | d << 16) & 0x03e07c1f;
>		    d += (s - d) * alpha >> 5;
>		    d &= 0x03e07c1f;
>		    *dstp = d | d >> 16;
>		}
>		srcp++;
>		dstp++;
>	    }, width);
>	    srcp += srcskip;
>	    dstp += dstskip;
>	}
>}
>
>/* General (slow) N->N blending with per-surface alpha */
>static void BlitNtoNSurfaceAlpha(SDL_BlitInfo *info)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint8 *src = info->s_pixels;
>	int srcskip = info->s_skip;
>	Uint8 *dst = info->d_pixels;
>	int dstskip = info->d_skip;
>	SDL_PixelFormat *srcfmt = info->src;
>	SDL_PixelFormat *dstfmt = info->dst;
>	int srcbpp = srcfmt->BytesPerPixel;
>	int dstbpp = dstfmt->BytesPerPixel;
>	unsigned sA = srcfmt->alpha;
>	unsigned dA = dstfmt->Amask ? SDL_ALPHA_OPAQUE : 0;
>
>	PRINT_LINE
>	while ( height-- ) {
>	    DUFFS_LOOP4(
>	    {
>		Uint32 pixel;
>		unsigned sR;
>		unsigned sG;
>		unsigned sB;
>		unsigned dR;
>		unsigned dG;
>		unsigned dB;
>		DISEMBLE_RGB(src, srcbpp, srcfmt, pixel, sR, sG, sB);
>		DISEMBLE_RGB(dst, dstbpp, dstfmt, pixel, dR, dG, dB);
>		ALPHA_BLEND(sR, sG, sB, sA, dR, dG, dB);
>		ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
>		src += srcbpp;
>		dst += dstbpp;
>	    },
>	    width);
>	    src += srcskip;
>	    dst += dstskip;
>	}
>}
>
>/* General (slow) colorkeyed N->N blending with per-surface alpha */
>static void BlitNtoNSurfaceAlphaKey(SDL_BlitInfo *info)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint8 *src = info->s_pixels;
>	int srcskip = info->s_skip;
>	Uint8 *dst = info->d_pixels;
>	int dstskip = info->d_skip;
>	SDL_PixelFormat *srcfmt = info->src;
>	SDL_PixelFormat *dstfmt = info->dst;
>	Uint32 ckey = srcfmt->colorkey;
>	int srcbpp = srcfmt->BytesPerPixel;
>	int dstbpp = dstfmt->BytesPerPixel;
>	unsigned sA = srcfmt->alpha;
>	unsigned dA = dstfmt->Amask ? SDL_ALPHA_OPAQUE : 0;
>
>	PRINT_LINE
>	while ( height-- ) {
>	    DUFFS_LOOP4(
>	    {
>		Uint32 pixel;
>		unsigned sR;
>		unsigned sG;
>		unsigned sB;
>		unsigned dR;
>		unsigned dG;
>		unsigned dB;
>		RETRIEVE_RGB_PIXEL(src, srcbpp, pixel);
>		if(pixel != ckey) {
>		    RGB_FROM_PIXEL(pixel, srcfmt, sR, sG, sB);
>		    DISEMBLE_RGB(dst, dstbpp, dstfmt, pixel, dR, dG, dB);
>		    ALPHA_BLEND(sR, sG, sB, sA, dR, dG, dB);
>		    ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
>		}
>		src += srcbpp;
>		dst += dstbpp;
>	    },
>	    width);
>	    src += srcskip;
>	    dst += dstskip;
>	}
>}
>
>/* General (slow) N->N blending with pixel alpha */
>static void BlitNtoNPixelAlpha(SDL_BlitInfo *info)
>{
>	int width = info->d_width;
>	int height = info->d_height;
>	Uint8 *src = info->s_pixels;
>	int srcskip = info->s_skip;
>	Uint8 *dst = info->d_pixels;
>	int dstskip = info->d_skip;
>	SDL_PixelFormat *srcfmt = info->src;
>	SDL_PixelFormat *dstfmt = info->dst;
>
>	int  srcbpp;
>	int  dstbpp;
>
>	PRINT_LINE
>	/* Set up some basic variables */
>	srcbpp = srcfmt->BytesPerPixel;
>	dstbpp = dstfmt->BytesPerPixel;
>
>	/* FIXME: for 8bpp source alpha, this doesn't get opaque values
>	   quite right. for <8bpp source alpha, it gets them very wrong
>	   (check all macros!)
>	   It is unclear whether there is a good general solution that doesn't
>	   need a branch (or a divide). */
>	while ( height-- ) {
>	    DUFFS_LOOP4(
>	    {
>		Uint32 pixel;
>		unsigned sR;
>		unsigned sG;
>		unsigned sB;
>		unsigned dR;
>		unsigned dG;
>		unsigned dB;
>		unsigned sA;
>		unsigned dA;
>		DISEMBLE_RGBA(src, srcbpp, srcfmt, pixel, sR, sG, sB, sA);
>		DISEMBLE_RGBA(dst, dstbpp, dstfmt, pixel, dR, dG, dB, dA);
>		ALPHA_BLEND(sR, sG, sB, sA, dR, dG, dB);
>		ASSEMBLE_RGBA(dst, dstbpp, dstfmt, dR, dG, dB, dA);
>		src += srcbpp;
>		dst += dstbpp;
>	    },
>	    width);
>	    src += srcskip;
>	    dst += dstskip;
>	}
>}
>
>
>inline SDL_loblit SDL_CalculateAlphaBlit(SDL_Surface *surface, int blit_index)
>{
>    SDL_PixelFormat *sf = surface->format;
>    SDL_PixelFormat *df = surface->map->dst->format;
>
>	PRINT_LINE
>    if(sf->Amask == 0) {
>	if((surface->flags & SDL_SRCCOLORKEY) == SDL_SRCCOLORKEY) {
>	    if(df->BytesPerPixel == 1)
>		return BlitNto1SurfaceAlphaKey;
>	    else
>		return BlitNtoNSurfaceAlphaKey;
>	} else {
>	    /* Per-surface alpha blits */
>	    switch(df->BytesPerPixel) {
>	    case 1:
>		return BlitNto1SurfaceAlpha;
>
>	    case 2:
>		if(surface->map->identity) {
>		    if(df->Gmask == 0x7e0)
>			return Blit565to565SurfaceAlpha;
>		    else if(df->Gmask == 0x3e0)
>			return Blit555to555SurfaceAlpha;
>		}
>		return BlitNtoNSurfaceAlpha;
>
>	    case 4:
>		if(sf->Rmask == df->Rmask
>		   && sf->Gmask == df->Gmask
>		   && sf->Bmask == df->Bmask
>		   && (sf->Rmask | sf->Gmask | sf->Bmask) == 0xffffff
>		   && sf->BytesPerPixel == 4)
>		    return BlitRGBtoRGBSurfaceAlpha;
>		else
>		    return BlitNtoNSurfaceAlpha;
>
>	    case 3:
>	    default:
>		return BlitNtoNSurfaceAlpha;
>	    }
>	}
>    } else {
>	/* Per-pixel alpha blits */
>	switch(df->BytesPerPixel) {
>	case 1:
>	    return BlitNto1PixelAlpha;
>
>	case 2:
>	    if(sf->BytesPerPixel == 4 && sf->Amask == 0xff000000
>	       && sf->Gmask == 0xff00
>	       && ((sf->Rmask == 0xff && df->Rmask == 0x1f)
>		   || (sf->Bmask == 0xff && df->Bmask == 0x1f))) {
>		if(df->Gmask == 0x7e0)
>		    return BlitARGBto565PixelAlpha;
>		else if(df->Gmask == 0x3e0)
>		    return BlitARGBto555PixelAlpha;
>	    }
>	    return BlitNtoNPixelAlpha;
>
>	case 4:
>	    if(sf->Amask == 0xff000000
>	       && sf->Rmask == df->Rmask
>	       && sf->Gmask == df->Gmask
>	       && sf->Bmask == df->Bmask
>	       && sf->BytesPerPixel == 4)
>		return BlitRGBtoRGBPixelAlpha;
>	    return BlitNtoNPixelAlpha;
>
>	case 3:
>	default:
>	    return BlitNtoNPixelAlpha;
>	}
>    }
>}
>

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Attachments on bug 15: 32 | 81

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We are currently migrating Bugzilla to GitHub issues.
Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.
When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.