--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/video/SDL_blit_A.c	Thu Apr 26 16:45:43 2001 +0000
@@ -0,0 +1,633 @@
+/*
+    SDL - Simple DirectMedia Layer
+    Copyright (C) 1997, 1998, 1999, 2000, 2001  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@devolution.com
+*/
+
+#ifdef SAVE_RCSID
+static char rcsid =
+ "@(#) $Id$";
+#endif
+
+#include <stdio.h>
+
+#include "SDL_types.h"
+#include "SDL_video.h"
+#include "SDL_blit.h"
+
+/* 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;
+
+	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;
+
+	/* 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;
+
+	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 */
+static void BlitRGBtoRGBSurfaceAlpha(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;
+	SDL_PixelFormat *srcfmt = info->src;
+	unsigned alpha = srcfmt->alpha;
+
+	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;
+	}
+}
+
+/* fast ARGB888->(A)RGB888 blending with pixel alpha */
+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;
+
+	while(height--) {
+	    DUFFS_LOOP4({
+		Uint32 dalpha;
+		Uint32 d;
+		Uint32 s1;
+		Uint32 d1;
+		Uint32 s = *srcp;
+		Uint32 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 {
+		    /*
+		     * take out the middle component (green), and process
+		     * the other two in parallel. One multiply less.
+		     */
+		    d = *dstp;
+		    dalpha = d & 0xff000000;
+		    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 | dalpha;
+		}
+		++srcp;
+		++dstp;
+	    }, width);
+	    srcp += srcskip;
+	    dstp += dstskip;
+	}
+}
+
+/* fast RGB565->RGB565 blending with surface alpha */
+static void Blit565to565SurfaceAlpha(SDL_BlitInfo *info)
+{
+	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;
+	unsigned alpha = info->src->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)
+{
+	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;
+	unsigned alpha = info->src->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;
+
+	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;
+
+	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;
+
+	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;
+
+	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;
+
+	/* 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;
+	}
+}
+
+
+SDL_loblit SDL_CalculateAlphaBlit(SDL_Surface *surface, int blit_index)
+{
+    SDL_PixelFormat *sf = surface->format;
+    SDL_PixelFormat *df = surface->map->dst->format;
+
+    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;
+	}
+    }
+}
+