--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/video/SDL_RLEaccel.c	Thu Apr 26 16:45:43 2001 +0000
@@ -0,0 +1,1547 @@
+/*
+    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
+
+/*
+ * RLE encoding for software colorkey and alpha-channel acceleration
+ *
+ * Original version by Sam Lantinga
+ *
+ * Mattias Engdegård (Yorick): Rewrite. New encoding format, encoder and
+ * decoder. Added per-surface alpha blitter. Added per-pixel alpha
+ * format, encoder and blitter.
+ *
+ * Many thanks to Xark and johns for hints, benchmarks and useful comments
+ * leading to this code.
+ *
+ * Welcome to Macro Mayhem.
+ */
+
+/*
+ * The encoding translates the image data to a stream of segments of the form
+ *
+ * <skip> <run> <data>
+ *
+ * where <skip> is the number of transparent pixels to skip,
+ *       <run>  is the number of opaque pixels to blit,
+ * and   <data> are the pixels themselves.
+ *
+ * This basic structure is used both for colorkeyed surfaces, used for simple
+ * binary transparency and for per-surface alpha blending, and for surfaces
+ * with per-pixel alpha. The details differ, however:
+ *
+ * Encoding of colorkeyed surfaces:
+ *
+ *   Encoded pixels always have the same format as the target surface.
+ *   <skip> and <run> are unsigned 8 bit integers, except for 32 bit depth
+ *   where they are 16 bit. This makes the pixel data aligned at all times.
+ *   Segments never wrap around from one scan line to the next.
+ *
+ *   The end of the sequence is marked by a zero <skip>,<run> pair at the *
+ *   beginning of a line.
+ *
+ * Encoding of surfaces with per-pixel alpha:
+ *
+ *   The sequence begins with a struct RLEDestFormat describing the target
+ *   pixel format, to provide reliable un-encoding.
+ *
+ *   Each scan line is encoded twice: First all completely opaque pixels,
+ *   encoded in the target format as described above, and then all
+ *   partially transparent (translucent) pixels (where 1 <= alpha <= 254),
+ *   in the following 32-bit format:
+ *
+ *   For 32-bit targets, each pixel has the target RGB format but with
+ *   the alpha value occupying the highest 8 bits. The <skip> and <run>
+ *   counts are 16 bit.
+ * 
+ *   For 16-bit targets, each pixel has the target RGB format, but with
+ *   the middle component (usually green) shifted 16 steps to the left,
+ *   and the hole filled with the 5 most significant bits of the alpha value.
+ *   i.e. if the target has the format         rrrrrggggggbbbbb,
+ *   the encoded pixel will be 00000gggggg00000rrrrr0aaaaabbbbb.
+ *   The <skip> and <run> counts are 8 bit for the opaque lines, 16 bit
+ *   for the translucent lines. Two padding bytes may be inserted
+ *   before each translucent line to keep them 32-bit aligned.
+ *
+ *   The end of the sequence is marked by a zero <skip>,<run> pair at the
+ *   beginning of an opaque line.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "SDL_types.h"
+#include "SDL_video.h"
+#include "SDL_error.h"
+#include "SDL_sysvideo.h"
+#include "SDL_blit.h"
+#include "SDL_memops.h"
+#include "SDL_RLEaccel_c.h"
+
+#ifndef MAX
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#endif
+#ifndef MIN
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
+/*
+ * Various colorkey blit methods, for opaque and per-surface alpha
+ */
+
+#define OPAQUE_BLIT(to, from, length, bpp, alpha)	\
+    SDL_memcpy(to, from, (unsigned)(length * bpp))
+
+/*
+ * For 32bpp pixels on the form 0x00rrggbb:
+ * If we treat the middle component separately, we can process the two
+ * remaining in parallel. This is safe to do because of the gap to the left
+ * of each component, so the bits from the multiplication don't collide.
+ * This can be used for any RGB permutation of course.
+ */
+#define ALPHA_BLIT32_888(to, from, length, bpp, alpha)		\
+    do {							\
+        int i;							\
+	Uint32 *src = (Uint32 *)(from);				\
+	Uint32 *dst = (Uint32 *)(to);				\
+	for(i = 0; i < (int)(length); i++) {			\
+	    Uint32 s = *src++;					\
+	    Uint32 d = *dst;					\
+	    Uint32 s1 = s & 0xff00ff;				\
+	    Uint32 d1 = d & 0xff00ff;				\
+	    d1 = (d1 + ((s1 - d1) * alpha >> 8)) & 0xff00ff;	\
+	    s &= 0xff00;					\
+	    d &= 0xff00;					\
+	    d = (d + ((s - d) * alpha >> 8)) & 0xff00;		\
+	    *dst++ = d1 | d;					\
+	}							\
+    } while(0)
+
+/*
+ * For 16bpp pixels we can go a step further: put the middle component
+ * in the high 16 bits of a 32 bit word, and process all three RGB
+ * components at the same time. Since the smallest gap is here just
+ * 5 bits, we have to scale alpha down to 5 bits as well.
+ */
+#define ALPHA_BLIT16_565(to, from, length, bpp, alpha)	\
+    do {						\
+        int i;						\
+	Uint16 *src = (Uint16 *)(from);			\
+	Uint16 *dst = (Uint16 *)(to);			\
+	for(i = 0; i < (int)(length); i++) {		\
+	    Uint32 s = *src++;				\
+	    Uint32 d = *dst;				\
+	    s = (s | s << 16) & 0x07e0f81f;		\
+	    d = (d | d << 16) & 0x07e0f81f;		\
+	    d += (s - d) * alpha >> 5;			\
+	    d &= 0x07e0f81f;				\
+	    *dst++ = d | d >> 16;			\
+	}						\
+    } while(0)
+
+#define ALPHA_BLIT16_555(to, from, length, bpp, alpha)	\
+    do {						\
+        int i;						\
+	Uint16 *src = (Uint16 *)(from);			\
+	Uint16 *dst = (Uint16 *)(to);			\
+	for(i = 0; i < (int)(length); i++) {		\
+	    Uint32 s = *src++;				\
+	    Uint32 d = *dst;				\
+	    s = (s | s << 16) & 0x03e07c1f;		\
+	    d = (d | d << 16) & 0x03e07c1f;		\
+	    d += (s - d) * alpha >> 5;			\
+	    d &= 0x03e07c1f;				\
+	    *dst++ = d | d >> 16;			\
+	}						\
+    } while(0)
+
+/*
+ * The general slow catch-all function, for remaining depths and formats
+ */
+#define ALPHA_BLIT_ANY(to, from, length, bpp, alpha)			\
+    do {								\
+        int i;								\
+	Uint8 *src = from;						\
+	Uint8 *dst = to;						\
+	for(i = 0; i < (int)(length); i++) {				\
+	    Uint32 s, d;						\
+	    unsigned rs, gs, bs, rd, gd, bd;				\
+	    switch(bpp) {						\
+	    case 2:							\
+		s = *(Uint16 *)src;					\
+		d = *(Uint16 *)dst;					\
+		break;							\
+	    case 3:							\
+		if(SDL_BYTEORDER == SDL_BIG_ENDIAN) {			\
+		    s = (src[0] << 16) | (src[1] << 8) | src[2];	\
+		    d = (dst[0] << 16) | (dst[1] << 8) | dst[2];	\
+		} else {						\
+		    s = (src[2] << 16) | (src[1] << 8) | src[0];	\
+		    d = (dst[2] << 16) | (dst[1] << 8) | dst[0];	\
+		}							\
+		break;							\
+	    case 4:							\
+		s = *(Uint32 *)src;					\
+		d = *(Uint32 *)dst;					\
+		break;							\
+	    }								\
+	    RGB_FROM_PIXEL(s, fmt, rs, gs, bs);				\
+	    RGB_FROM_PIXEL(d, fmt, rd, gd, bd);				\
+	    rd += (rs - rd) * alpha >> 8;				\
+	    gd += (gs - gd) * alpha >> 8;				\
+	    bd += (bs - bd) * alpha >> 8;				\
+	    PIXEL_FROM_RGB(d, fmt, rd, gd, bd);				\
+	    switch(bpp) {						\
+	    case 2:							\
+		*(Uint16 *)dst = d;					\
+		break;							\
+	    case 3:							\
+		if(SDL_BYTEORDER == SDL_BIG_ENDIAN) {			\
+		    dst[0] = d >> 16;					\
+		    dst[1] = d >> 8;					\
+		    dst[2] = d;						\
+		} else {						\
+		    dst[0] = d;						\
+		    dst[1] = d >> 8;					\
+		    dst[2] = d >> 16;					\
+		}							\
+		break;							\
+	    case 4:							\
+		*(Uint32 *)dst = d;					\
+		break;							\
+	    }								\
+	    src += bpp;							\
+	    dst += bpp;							\
+	}								\
+    } while(0)
+
+
+/*
+ * Special case: 50% alpha (alpha=128)
+ * This is treated specially because it can be optimized very well, and
+ * since it is good for many cases of semi-translucency.
+ * The theory is to do all three components at the same time:
+ * First zero the lowest bit of each component, which gives us room to
+ * add them. Then shift right and add the sum of the lowest bits.
+ */
+#define ALPHA_BLIT32_888_50(to, from, length, bpp, alpha)		\
+    do {								\
+        int i;								\
+	Uint32 *src = (Uint32 *)(from);					\
+	Uint32 *dst = (Uint32 *)(to);					\
+	for(i = 0; i < (int)(length); i++) {				\
+	    Uint32 s = *src++;						\
+	    Uint32 d = *dst;						\
+	    *dst++ = (((s & 0x00fefefe) + (d & 0x00fefefe)) >> 1)	\
+		     + (s & d & 0x00010101);				\
+	}								\
+    } while(0)
+
+/*
+ * For 16bpp, we can actually blend two pixels in parallel, if we take
+ * care to shift before we add, not after.
+ */
+
+/* helper: blend a single 16 bit pixel at 50% */
+#define BLEND16_50(dst, src, mask)			\
+    do {						\
+        Uint32 s = *src++;				\
+	Uint32 d = *dst;				\
+	*dst++ = (((s & mask) + (d & mask)) >> 1)	\
+	         + (s & d & (~mask & 0xffff));		\
+    } while(0)
+
+/* basic 16bpp blender. mask is the pixels to keep when adding. */
+#define ALPHA_BLIT16_50(to, from, length, bpp, alpha, mask)		\
+    do {								\
+	unsigned n = (length);						\
+	Uint16 *src = (Uint16 *)(from);					\
+	Uint16 *dst = (Uint16 *)(to);					\
+	if(((unsigned long)src ^ (unsigned long)dst) & 3) {		\
+	    /* source and destination not in phase, blit one by one */	\
+	    while(n--)							\
+		BLEND16_50(dst, src, mask);				\
+	} else {							\
+	    if((unsigned long)src & 3) {				\
+		/* first odd pixel */					\
+		BLEND16_50(dst, src, mask);				\
+		n--;							\
+	    }								\
+	    for(; n > 1; n -= 2) {					\
+		Uint32 s = *(Uint32 *)src;				\
+		Uint32 d = *(Uint32 *)dst;				\
+		*(Uint32 *)dst = ((s & (mask | mask << 16)) >> 1)	\
+		               + ((d & (mask | mask << 16)) >> 1)	\
+		               + (s & d & (~(mask | mask << 16)));	\
+		src += 2;						\
+		dst += 2;						\
+	    }								\
+	    if(n)							\
+		BLEND16_50(dst, src, mask); /* last odd pixel */	\
+	}								\
+    } while(0)
+
+#define ALPHA_BLIT16_565_50(to, from, length, bpp, alpha)	\
+    ALPHA_BLIT16_50(to, from, length, bpp, alpha, 0xf7de)
+
+#define ALPHA_BLIT16_555_50(to, from, length, bpp, alpha)	\
+    ALPHA_BLIT16_50(to, from, length, bpp, alpha, 0xfbde)
+
+
+#define CHOOSE_BLIT(blitter, alpha, fmt)				\
+    do {								\
+        if(alpha == 255) {						\
+	    switch(fmt->BytesPerPixel) {				\
+	    case 1: blitter(1, Uint8, OPAQUE_BLIT); break;		\
+	    case 2: blitter(2, Uint8, OPAQUE_BLIT); break;		\
+	    case 3: blitter(3, Uint8, OPAQUE_BLIT); break;		\
+	    case 4: blitter(4, Uint16, OPAQUE_BLIT); break;		\
+	    }								\
+	} else {							\
+	    switch(fmt->BytesPerPixel) {				\
+	    case 1:							\
+		/* No 8bpp alpha blitting */				\
+		break;							\
+									\
+	    case 2:							\
+		switch(fmt->Rmask | fmt->Gmask | fmt->Bmask) {		\
+		case 0xffff:						\
+		    if(fmt->Gmask == 0x07e0				\
+		       || fmt->Rmask == 0x07e0				\
+		       || fmt->Bmask == 0x07e0) {			\
+			if(alpha == 128)				\
+			    blitter(2, Uint8, ALPHA_BLIT16_565_50);	\
+			else {						\
+			    alpha >>= 3; /* use 5 bit alpha */		\
+			    blitter(2, Uint8, ALPHA_BLIT16_565);	\
+			}						\
+		    } else						\
+			goto general16;					\
+		    break;						\
+									\
+		case 0x7fff:						\
+		    if(fmt->Gmask == 0x03e0				\
+		       || fmt->Rmask == 0x03e0				\
+		       || fmt->Bmask == 0x03e0) {			\
+			if(alpha == 128)				\
+			    blitter(2, Uint8, ALPHA_BLIT16_555_50);	\
+			else {						\
+			    alpha >>= 3; /* use 5 bit alpha */		\
+			    blitter(2, Uint8, ALPHA_BLIT16_555);	\
+			}						\
+			break;						\
+		    }							\
+		    /* fallthrough */					\
+									\
+		default:						\
+		general16:						\
+		    blitter(2, Uint8, ALPHA_BLIT_ANY);			\
+		}							\
+		break;							\
+									\
+	    case 3:							\
+		blitter(3, Uint8, ALPHA_BLIT_ANY);			\
+		break;							\
+									\
+	    case 4:							\
+		if((fmt->Rmask | fmt->Gmask | fmt->Bmask) == 0x00ffffff	\
+		   && (fmt->Gmask == 0xff00 || fmt->Rmask == 0xff00	\
+		       || fmt->Bmask == 0xff00)) {			\
+		    if(alpha == 128)					\
+			blitter(4, Uint16, ALPHA_BLIT32_888_50);	\
+		    else						\
+			blitter(4, Uint16, ALPHA_BLIT32_888);		\
+		} else							\
+		    blitter(4, Uint16, ALPHA_BLIT_ANY);			\
+		break;							\
+	    }								\
+	}								\
+    } while(0)
+
+
+/*
+ * This takes care of the case when the surface is clipped on the left and/or
+ * right. Top clipping has already been taken care of.
+ */
+static void RLEClipBlit(int w, Uint8 *srcbuf, SDL_Surface *dst,
+			Uint8 *dstbuf, SDL_Rect *srcrect, unsigned alpha)
+{
+    SDL_PixelFormat *fmt = dst->format;
+
+#define RLECLIPBLIT(bpp, Type, do_blit)					   \
+    do {								   \
+	int linecount = srcrect->h;					   \
+	int ofs = 0;							   \
+	int left = srcrect->x;						   \
+	int right = left + srcrect->w;					   \
+	dstbuf -= left * bpp;						   \
+	for(;;) {							   \
+	    int run;							   \
+	    ofs += *(Type *)srcbuf;					   \
+	    run = ((Type *)srcbuf)[1];					   \
+	    srcbuf += 2 * sizeof(Type);					   \
+	    if(run) {							   \
+		/* clip to left and right borders */			   \
+		if(ofs < right) {					   \
+		    int start = 0;					   \
+		    int len = run;					   \
+		    int startcol;					   \
+		    if(left - ofs > 0) {				   \
+			start = left - ofs;				   \
+			len -= start;					   \
+			if(len <= 0)					   \
+			    goto nocopy ## bpp ## do_blit;		   \
+		    }							   \
+		    startcol = ofs + start;				   \
+		    if(len > right - startcol)				   \
+			len = right - startcol;				   \
+		    do_blit(dstbuf + startcol * bpp, srcbuf + start * bpp, \
+			    len, bpp, alpha);				   \
+		}							   \
+	    nocopy ## bpp ## do_blit:					   \
+		srcbuf += run * bpp;					   \
+		ofs += run;						   \
+	    } else if(!ofs)						   \
+		break;							   \
+	    if(ofs == w) {						   \
+		ofs = 0;						   \
+		dstbuf += dst->pitch;					   \
+		if(!--linecount)					   \
+		    break;						   \
+	    }								   \
+	}								   \
+    } while(0)
+
+    CHOOSE_BLIT(RLECLIPBLIT, alpha, fmt);
+
+#undef RLECLIPBLIT
+
+}
+
+
+/* blit a colorkeyed RLE surface */
+int SDL_RLEBlit(SDL_Surface *src, SDL_Rect *srcrect,
+		SDL_Surface *dst, SDL_Rect *dstrect)
+{
+	Uint8 *dstbuf;
+	Uint8 *srcbuf;
+	int x, y;
+	int w = src->w;
+	unsigned alpha;
+
+	/* Lock the destination if necessary */
+	if ( dst->flags & (SDL_HWSURFACE|SDL_ASYNCBLIT) ) {
+		SDL_VideoDevice *video = current_video;
+		SDL_VideoDevice *this  = current_video;
+		if ( video->LockHWSurface(this, dst) < 0 ) {
+			return(-1);
+		}
+	}
+
+	/* Set up the source and destination pointers */
+	x = dstrect->x;
+	y = dstrect->y;
+	dstbuf = (Uint8 *)dst->pixels + dst->offset
+	         + y * dst->pitch + x * src->format->BytesPerPixel;
+	srcbuf = (Uint8 *)src->map->sw_data->aux_data;
+
+	{
+	    /* skip lines at the top if neccessary */
+	    int vskip = srcrect->y;
+	    int ofs = 0;
+	    if(vskip) {
+
+#define RLESKIP(bpp, Type)			\
+		for(;;) {			\
+		    int run;			\
+		    ofs += *(Type *)srcbuf;	\
+		    run = ((Type *)srcbuf)[1];	\
+		    srcbuf += sizeof(Type) * 2;	\
+		    if(run) {			\
+			srcbuf += run * bpp;	\
+			ofs += run;		\
+		    } else if(!ofs)		\
+			goto done;		\
+		    if(ofs == w) {		\
+			ofs = 0;		\
+			if(!--vskip)		\
+			    break;		\
+		    }				\
+		}
+
+		switch(src->format->BytesPerPixel) {
+		case 1: RLESKIP(1, Uint8); break;
+		case 2: RLESKIP(2, Uint8); break;
+		case 3: RLESKIP(3, Uint8); break;
+		case 4: RLESKIP(4, Uint16); break;
+		}
+
+#undef RLESKIP
+
+	    }
+	}
+
+	alpha = (src->flags & SDL_SRCALPHA) == SDL_SRCALPHA
+	        ? src->format->alpha : 255;
+	/* if left or right edge clipping needed, call clip blit */
+	if ( srcrect->x || srcrect->w != src->w ) {
+	    RLEClipBlit(w, srcbuf, dst, dstbuf, srcrect, alpha);
+	} else {
+	    SDL_PixelFormat *fmt = src->format;
+
+#define RLEBLIT(bpp, Type, do_blit)					      \
+	    do {							      \
+		int linecount = srcrect->h;				      \
+		int ofs = 0;						      \
+		for(;;) {						      \
+		    unsigned run;					      \
+		    ofs += *(Type *)srcbuf;				      \
+		    run = ((Type *)srcbuf)[1];				      \
+		    srcbuf += 2 * sizeof(Type);				      \
+		    if(run) {						      \
+			do_blit(dstbuf + ofs * bpp, srcbuf, run, bpp, alpha); \
+			srcbuf += run * bpp;				      \
+			ofs += run;					      \
+		    } else if(!ofs)					      \
+			break;						      \
+		    if(ofs == w) {					      \
+			ofs = 0;					      \
+			dstbuf += dst->pitch;				      \
+			if(!--linecount)				      \
+			    break;					      \
+		    }							      \
+		}							      \
+	    } while(0)
+
+	    CHOOSE_BLIT(RLEBLIT, alpha, fmt);
+
+#undef RLEBLIT
+	}
+
+done:
+	/* Unlock the destination if necessary */
+	if ( dst->flags & (SDL_HWSURFACE|SDL_ASYNCBLIT) ) {
+		SDL_VideoDevice *video = current_video;
+		SDL_VideoDevice *this  = current_video;
+		video->UnlockHWSurface(this, dst);
+	}
+	return(0);
+}
+
+#undef OPAQUE_BLIT
+
+/*
+ * Per-pixel blitting macros for translucent pixels:
+ * These use the same techniques as the per-surface blitting macros
+ */
+
+/*
+ * For 32bpp pixels, we have made sure the alpha is stored in the top
+ * 8 bits, so proceed as usual
+ */
+#define BLIT_TRANSL_888(src, dst)				\
+    do {							\
+        Uint32 s = src;						\
+	Uint32 d = dst;						\
+	unsigned alpha = s >> 24;				\
+	Uint32 s1 = s & 0xff00ff;				\
+	Uint32 d1 = d & 0xff00ff;				\
+	d1 = (d1 + ((s1 - d1) * alpha >> 8)) & 0xff00ff;	\
+	s &= 0xff00;						\
+	d &= 0xff00;						\
+	d = (d + ((s - d) * alpha >> 8)) & 0xff00;		\
+	dst = d1 | d;						\
+    } while(0)
+
+/*
+ * For 16bpp pixels, we have stored the 5 most significant alpha bits in
+ * bits 5-10. As before, we can process all 3 RGB components at the same time.
+ */
+#define BLIT_TRANSL_565(src, dst)		\
+    do {					\
+        Uint32 s = src;				\
+	Uint32 d = dst;				\
+	unsigned alpha = (s & 0x3e0) >> 5;	\
+	s &= 0x07e0f81f;			\
+	d = (d | d << 16) & 0x07e0f81f;		\
+	d += (s - d) * alpha >> 5;		\
+	d &= 0x07e0f81f;			\
+	dst = d | d >> 16;			\
+    } while(0)
+
+#define BLIT_TRANSL_555(src, dst)		\
+    do {					\
+        Uint32 s = src;				\
+	Uint32 d = dst;				\
+	unsigned alpha = (s & 0x3e0) >> 5;	\
+	s &= 0x03e07c1f;			\
+	d = (d | d << 16) & 0x03e07c1f;		\
+	d += (s - d) * alpha >> 5;		\
+	d &= 0x03e07c1f;			\
+	dst = d | d >> 16;			\
+    } while(0)
+
+/* used to save the destination format in the encoding. Designed to be
+   macro-compatible with SDL_PixelFormat but without the unneeded fields */
+typedef struct {
+    	Uint8  BytesPerPixel;
+	Uint8  Rloss;
+	Uint8  Gloss;
+	Uint8  Bloss;
+	Uint8  Rshift;
+	Uint8  Gshift;
+	Uint8  Bshift;
+	Uint8  Ashift;
+	Uint32 Rmask;
+	Uint32 Gmask;
+	Uint32 Bmask;
+	Uint32 Amask;
+} RLEDestFormat;
+
+/* blit a pixel-alpha RLE surface clipped at the right and/or left edges */
+static void RLEAlphaClipBlit(int w, Uint8 *srcbuf, SDL_Surface *dst,
+			     Uint8 *dstbuf, SDL_Rect *srcrect)
+{
+    SDL_PixelFormat *df = dst->format;
+    /*
+     * clipped blitter: Ptype is the destination pixel type,
+     * Ctype the translucent count type, and do_blend the macro
+     * to blend one pixel.
+     */
+#define RLEALPHACLIPBLIT(Ptype, Ctype, do_blend)			  \
+    do {								  \
+	int linecount = srcrect->h;					  \
+	int left = srcrect->x;						  \
+	int right = left + srcrect->w;					  \
+	dstbuf -= left * sizeof(Ptype);					  \
+	do {								  \
+	    int ofs = 0;						  \
+	    /* blit opaque pixels on one line */			  \
+	    do {							  \
+		unsigned run;						  \
+		ofs += ((Ctype *)srcbuf)[0];				  \
+		run = ((Ctype *)srcbuf)[1];				  \
+		srcbuf += 2 * sizeof(Ctype);				  \
+		if(run) {						  \
+		    /* clip to left and right borders */		  \
+		    int cofs = ofs;					  \
+		    int crun = run;					  \
+		    if(left - cofs > 0) {				  \
+			crun -= left - cofs;				  \
+			cofs = left;					  \
+		    }							  \
+		    if(crun > right - cofs)				  \
+			crun = right - cofs;				  \
+		    if(crun > 0)					  \
+			SDL_memcpy(dstbuf + cofs * sizeof(Ptype),	  \
+				   srcbuf + (cofs - ofs) * sizeof(Ptype), \
+				   (unsigned)crun * sizeof(Ptype));	  \
+		    srcbuf += run * sizeof(Ptype);			  \
+		    ofs += run;						  \
+		} else if(!ofs)						  \
+		    return;						  \
+	    } while(ofs < w);						  \
+	    /* skip padding if necessary */				  \
+	    if(sizeof(Ptype) == 2)					  \
+		srcbuf += (unsigned long)srcbuf & 2;			  \
+	    /* blit translucent pixels on the same line */		  \
+	    ofs = 0;							  \
+	    do {							  \
+		unsigned run;						  \
+		ofs += ((Uint16 *)srcbuf)[0];				  \
+		run = ((Uint16 *)srcbuf)[1];				  \
+		srcbuf += 4;						  \
+		if(run) {						  \
+		    /* clip to left and right borders */		  \
+		    int cofs = ofs;					  \
+		    int crun = run;					  \
+		    if(left - cofs > 0) {				  \
+			crun -= left - cofs;				  \
+			cofs = left;					  \
+		    }							  \
+		    if(crun > right - cofs)				  \
+			crun = right - cofs;				  \
+		    if(crun > 0) {					  \
+			Ptype *dst = (Ptype *)dstbuf + cofs;		  \
+			Uint32 *src = (Uint32 *)srcbuf + (cofs - ofs);	  \
+			int i;						  \
+			for(i = 0; i < crun; i++)			  \
+			    do_blend(src[i], dst[i]);			  \
+		    }							  \
+		    srcbuf += run * 4;					  \
+		    ofs += run;						  \
+		}							  \
+	    } while(ofs < w);						  \
+	    dstbuf += dst->pitch;					  \
+	} while(--linecount);						  \
+    } while(0)
+
+    switch(df->BytesPerPixel) {
+    case 2:
+	if(df->Gmask == 0x07e0 || df->Rmask == 0x07e0
+	   || df->Bmask == 0x07e0)
+	    RLEALPHACLIPBLIT(Uint16, Uint8, BLIT_TRANSL_565);
+	else
+	    RLEALPHACLIPBLIT(Uint16, Uint8, BLIT_TRANSL_555);
+	break;
+    case 4:
+	RLEALPHACLIPBLIT(Uint32, Uint16, BLIT_TRANSL_888);
+	break;
+    }
+}
+
+/* blit a pixel-alpha RLE surface */
+int SDL_RLEAlphaBlit(SDL_Surface *src, SDL_Rect *srcrect,
+		     SDL_Surface *dst, SDL_Rect *dstrect)
+{
+    int x, y;
+    int w = src->w;
+    Uint8 *srcbuf, *dstbuf;
+    SDL_PixelFormat *df = dst->format;
+
+    /* Lock the destination if necessary */
+    if(dst->flags & (SDL_HWSURFACE|SDL_ASYNCBLIT)) {
+	SDL_VideoDevice *video = current_video;
+	SDL_VideoDevice *this  = current_video;
+	if(video->LockHWSurface(this, dst) < 0) {
+	    return -1;
+	}
+    }
+
+    x = dstrect->x;
+    y = dstrect->y;
+    dstbuf = (Uint8 *)dst->pixels + dst->offset
+	     + y * dst->pitch + x * df->BytesPerPixel;
+    srcbuf = (Uint8 *)src->map->sw_data->aux_data + sizeof(RLEDestFormat);
+
+    {
+	/* skip lines at the top if necessary */
+	int vskip = srcrect->y;
+	if(vskip) {
+	    int ofs;
+	    if(df->BytesPerPixel == 2) {
+		/* the 16/32 interleaved format */
+		do {
+		    /* skip opaque line */
+		    ofs = 0;
+		    do {
+			int run;
+			ofs += srcbuf[0];
+			run = srcbuf[1];
+			srcbuf += 2;
+			if(run) {
+			    srcbuf += 2 * run;
+			    ofs += run;
+			} else if(!ofs)
+			    goto done;
+		    } while(ofs < w);
+
+		    /* skip padding */
+		    srcbuf += (unsigned long)srcbuf & 2;
+
+		    /* skip translucent line */
+		    ofs = 0;
+		    do {
+			int run;
+			ofs += ((Uint16 *)srcbuf)[0];
+			run = ((Uint16 *)srcbuf)[1];
+			srcbuf += 4 * (run + 1);
+			ofs += run;
+		    } while(ofs < w);
+		} while(--vskip);
+	    } else {
+		/* the 32/32 interleaved format */
+		vskip <<= 1;	/* opaque and translucent have same format */
+		do {
+		    ofs = 0;
+		    do {
+			int run;
+			ofs += ((Uint16 *)srcbuf)[0];
+			run = ((Uint16 *)srcbuf)[1];
+			srcbuf += 4;
+			if(run) {
+			    srcbuf += 4 * run;
+			    ofs += run;
+			} else if(!ofs)
+			    goto done;
+		    } while(ofs < w);
+		} while(--vskip);
+	    }
+	}
+    }
+
+    /* if left or right edge clipping needed, call clip blit */
+    if(srcrect->x || srcrect->w != src->w) {
+	RLEAlphaClipBlit(w, srcbuf, dst, dstbuf, srcrect);
+    } else {
+
+	/*
+	 * non-clipped blitter. Ptype is the destination pixel type,
+	 * Ctype the translucent count type, and do_blend the
+	 * macro to blend one pixel.
+	 */
+#define RLEALPHABLIT(Ptype, Ctype, do_blend)				 \
+	do {								 \
+	    int linecount = srcrect->h;					 \
+	    do {							 \
+		int ofs = 0;						 \
+		/* blit opaque pixels on one line */			 \
+		do {							 \
+		    unsigned run;					 \
+		    ofs += ((Ctype *)srcbuf)[0];			 \
+		    run = ((Ctype *)srcbuf)[1];				 \
+		    srcbuf += 2 * sizeof(Ctype);			 \
+		    if(run) {						 \
+			SDL_memcpy(dstbuf + ofs * sizeof(Ptype), srcbuf, \
+				   run * sizeof(Ptype));		 \
+			srcbuf += run * sizeof(Ptype);			 \
+			ofs += run;					 \
+		    } else if(!ofs)					 \
+			goto done;					 \
+		} while(ofs < w);					 \
+		/* skip padding if necessary */				 \
+		if(sizeof(Ptype) == 2)					 \
+		    srcbuf += (unsigned long)srcbuf & 2;		 \
+		/* blit translucent pixels on the same line */		 \
+		ofs = 0;						 \
+		do {							 \
+		    unsigned run;					 \
+		    ofs += ((Uint16 *)srcbuf)[0];			 \
+		    run = ((Uint16 *)srcbuf)[1];			 \
+		    srcbuf += 4;					 \
+		    if(run) {						 \
+			Ptype *dst = (Ptype *)dstbuf + ofs;		 \
+			unsigned i;					 \
+			for(i = 0; i < run; i++) {			 \
+			    Uint32 src = *(Uint32 *)srcbuf;		 \
+			    do_blend(src, *dst);			 \
+			    srcbuf += 4;				 \
+			    dst++;					 \
+			}						 \
+			ofs += run;					 \
+		    }							 \
+		} while(ofs < w);					 \
+		dstbuf += dst->pitch;					 \
+	    } while(--linecount);					 \
+	} while(0)
+
+	switch(df->BytesPerPixel) {
+	case 2:
+	    if(df->Gmask == 0x07e0 || df->Rmask == 0x07e0
+	       || df->Bmask == 0x07e0)
+		RLEALPHABLIT(Uint16, Uint8, BLIT_TRANSL_565);
+	    else
+		RLEALPHABLIT(Uint16, Uint8, BLIT_TRANSL_555);
+	    break;
+	case 4:
+	    RLEALPHABLIT(Uint32, Uint16, BLIT_TRANSL_888);
+	    break;
+	}
+    }
+
+ done:
+    /* Unlock the destination if necessary */
+    if(dst->flags & (SDL_HWSURFACE|SDL_ASYNCBLIT)) {
+	SDL_VideoDevice *video = current_video;
+	SDL_VideoDevice *this  = current_video;
+	video->UnlockHWSurface(this, dst);
+    }
+    return 0;
+}
+
+/*
+ * Auxiliary functions:
+ * The encoding functions take 32bpp rgb + a, and
+ * return the number of bytes copied to the destination.
+ * The decoding functions copy to 32bpp rgb + a, and
+ * return the number of bytes copied from the source.
+ * These are only used in the encoder and un-RLE code and are therefore not
+ * highly optimised.
+ */
+
+/* encode 32bpp rgb + a into 16bpp rgb, losing alpha */
+static int copy_opaque_16(void *dst, Uint32 *src, int n,
+			  SDL_PixelFormat *sfmt, SDL_PixelFormat *dfmt)
+{
+    int i;
+    Uint16 *d = dst;
+    for(i = 0; i < n; i++) {
+	unsigned r, g, b;
+	RGB_FROM_PIXEL(*src, sfmt, r, g, b);
+	PIXEL_FROM_RGB(*d, dfmt, r, g, b);
+	src++;
+	d++;
+    }
+    return n * 2;
+}
+
+/* decode opaque pixels from 16bpp to 32bpp rgb + a */
+static int uncopy_opaque_16(Uint32 *dst, void *src, int n,
+			    RLEDestFormat *sfmt, SDL_PixelFormat *dfmt)
+{
+    int i;
+    Uint16 *s = src;
+    unsigned alpha = dfmt->Amask ? 255 : 0;
+    for(i = 0; i < n; i++) {
+	unsigned r, g, b;
+	RGB_FROM_PIXEL(*s, sfmt, r, g, b);
+	PIXEL_FROM_RGBA(*dst, dfmt, r, g, b, alpha);
+	s++;
+	dst++;
+    }
+    return n * 2;
+}
+
+
+
+/* encode 32bpp rgb + a into 32bpp G0RAB format for blitting into 565 */
+static int copy_transl_565(void *dst, Uint32 *src, int n,
+			   SDL_PixelFormat *sfmt, SDL_PixelFormat *dfmt)
+{
+    int i;
+    Uint32 *d = dst;
+    for(i = 0; i < n; i++) {
+	unsigned r, g, b, a;
+	Uint16 pix;
+	RGBA_FROM_8888(*src, sfmt, r, g, b, a);
+	PIXEL_FROM_RGB(pix, dfmt, r, g, b);
+	*d = ((pix & 0x7e0) << 16) | (pix & 0xf81f) | ((a << 2) & 0x7e0);
+	src++;
+	d++;
+    }
+    return n * 4;
+}
+
+/* encode 32bpp rgb + a into 32bpp G0RAB format for blitting into 555 */
+static int copy_transl_555(void *dst, Uint32 *src, int n,
+			   SDL_PixelFormat *sfmt, SDL_PixelFormat *dfmt)
+{
+    int i;
+    Uint32 *d = dst;
+    for(i = 0; i < n; i++) {
+	unsigned r, g, b, a;
+	Uint16 pix;
+	RGBA_FROM_8888(*src, sfmt, r, g, b, a);
+	PIXEL_FROM_RGB(pix, dfmt, r, g, b);
+	*d = ((pix & 0x3e0) << 16) | (pix & 0xfc1f) | ((a << 2) & 0x3e0);
+	src++;
+	d++;
+    }
+    return n * 4;
+}
+
+/* decode translucent pixels from 32bpp GORAB to 32bpp rgb + a */
+static int uncopy_transl_16(Uint32 *dst, void *src, int n,
+			    RLEDestFormat *sfmt, SDL_PixelFormat *dfmt)
+{
+    int i;
+    Uint32 *s = src;
+    for(i = 0; i < n; i++) {
+	unsigned r, g, b, a;
+	Uint32 pix = *s++;
+	a = (pix & 0x3e0) >> 2;
+	pix = (pix & ~0x3e0) | pix >> 16;
+	RGB_FROM_PIXEL(pix, sfmt, r, g, b);
+	PIXEL_FROM_RGBA(*dst, dfmt, r, g, b, a);
+	dst++;
+    }
+    return n * 4;
+}
+
+/* encode 32bpp rgba into 32bpp rgba, keeping alpha (dual purpose) */
+static int copy_32(void *dst, Uint32 *src, int n,
+		   SDL_PixelFormat *sfmt, SDL_PixelFormat *dfmt)
+{
+    int i;
+    Uint32 *d = dst;
+    for(i = 0; i < n; i++) {
+	unsigned r, g, b, a;
+	Uint32 pixel;
+	RGBA_FROM_8888(*src, sfmt, r, g, b, a);
+	PIXEL_FROM_RGB(pixel, dfmt, r, g, b);
+	*d++ = pixel | a << 24;
+	src++;
+    }
+    return n * 4;
+}
+
+/* decode 32bpp rgba into 32bpp rgba, keeping alpha (dual purpose) */
+static int uncopy_32(Uint32 *dst, void *src, int n,
+		     RLEDestFormat *sfmt, SDL_PixelFormat *dfmt)
+{
+    int i;
+    Uint32 *s = src;
+    for(i = 0; i < n; i++) {
+	unsigned r, g, b, a;
+	Uint32 pixel = *s++;
+	RGB_FROM_PIXEL(pixel, sfmt, r, g, b);
+	a = pixel >> 24;
+	PIXEL_FROM_RGBA(*dst, dfmt, r, g, b, a);
+	dst++;
+    }
+    return n * 4;
+}
+
+#define ISOPAQUE(pixel, fmt) ((((pixel) & fmt->Amask) >> fmt->Ashift) == 255)
+
+#define ISTRANSL(pixel, fmt)	\
+    ((unsigned)((((pixel) & fmt->Amask) >> fmt->Ashift) - 1U) < 254U)
+
+/* convert surface to be quickly alpha-blittable onto dest, if possible */
+static int RLEAlphaSurface(SDL_Surface *surface)
+{
+    SDL_Surface *dest;
+    SDL_PixelFormat *df;
+    int maxsize = 0;
+    int max_opaque_run;
+    int max_transl_run = 65535;
+    unsigned masksum;
+    Uint8 *rlebuf, *dst;
+    int (*copy_opaque)(void *, Uint32 *, int,
+		       SDL_PixelFormat *, SDL_PixelFormat *);
+    int (*copy_transl)(void *, Uint32 *, int,
+		       SDL_PixelFormat *, SDL_PixelFormat *);
+
+    dest = surface->map->dst;
+    if(!dest)
+	return -1;
+    df = dest->format;
+    if(surface->format->BitsPerPixel != 32)
+	return -1;		/* only 32bpp source supported */
+
+    /* find out whether the destination is one we support,
+       and determine the max size of the encoded result */
+    masksum = df->Rmask | df->Gmask | df->Bmask;
+    switch(df->BytesPerPixel) {
+    case 2:
+	/* 16bpp: only support 565 and 555 formats */
+	switch(masksum) {
+	case 0xffff:
+	    if(df->Gmask == 0x07e0
+	       || df->Rmask == 0x07e0 || df->Bmask == 0x07e0) {
+		copy_opaque = copy_opaque_16;
+		copy_transl = copy_transl_565;
+	    } else
+		return -1;
+	    break;
+	case 0x7fff:
+	    if(df->Gmask == 0x03e0
+	       || df->Rmask == 0x03e0 || df->Bmask == 0x03e0) {
+		copy_opaque = copy_opaque_16;
+		copy_transl = copy_transl_555;
+	    } else
+		return -1;
+	    break;
+	default:
+	    return -1;
+	}
+	max_opaque_run = 255;	/* runs stored as bytes */
+
+	/* worst case is alternating opaque and translucent pixels,
+	   with room for alignment padding between lines */
+	maxsize = surface->h * (2 + (4 + 2) * (surface->w + 1)) + 2;
+	break;
+    case 4:
+	if(masksum != 0x00ffffff)
+	    return -1;		/* requires unused high byte */
+	copy_opaque = copy_32;
+	copy_transl = copy_32;
+	max_opaque_run = 255;	/* runs stored as short ints */
+
+	/* worst case is alternating opaque and translucent pixels */
+	maxsize = surface->h * 2 * 4 * (surface->w + 1) + 4;
+	break;
+    default:
+	return -1;		/* anything else unsupported right now */
+    }
+
+    maxsize += sizeof(RLEDestFormat);
+    rlebuf = (Uint8 *)malloc(maxsize);
+    if(!rlebuf) {
+	SDL_OutOfMemory();
+	return -1;
+    }
+    {
+	/* save the destination format so we can undo the encoding later */
+	RLEDestFormat *r = (RLEDestFormat *)rlebuf;
+	r->BytesPerPixel = df->BytesPerPixel;
+	r->Rloss = df->Rloss;
+	r->Gloss = df->Gloss;
+	r->Bloss = df->Bloss;
+	r->Rshift = df->Rshift;
+	r->Gshift = df->Gshift;
+	r->Bshift = df->Bshift;
+	r->Ashift = df->Ashift;
+	r->Rmask = df->Rmask;
+	r->Gmask = df->Gmask;
+	r->Bmask = df->Bmask;
+	r->Amask = df->Amask;
+    }
+    dst = rlebuf + sizeof(RLEDestFormat);
+
+    /* Do the actual encoding */
+    {
+	int x, y;
+	int h = surface->h, w = surface->w;
+	SDL_PixelFormat *sf = surface->format;
+	Uint32 *src = (Uint32 *)((Uint8 *)surface->pixels + surface->offset);
+	Uint8 *lastline = dst;	/* end of last non-blank line */
+
+	/* opaque counts are 8 or 16 bits, depending on target depth */
+#define ADD_OPAQUE_COUNTS(n, m)			\
+	if(df->BytesPerPixel == 4) {		\
+	    ((Uint16 *)dst)[0] = n;		\
+	    ((Uint16 *)dst)[1] = m;		\
+	    dst += 4;				\
+	} else {				\
+	    dst[0] = n;				\
+	    dst[1] = m;				\
+	    dst += 2;				\
+	}
+
+	/* translucent counts are always 16 bit */
+#define ADD_TRANSL_COUNTS(n, m)		\
+	(((Uint16 *)dst)[0] = n, ((Uint16 *)dst)[1] = m, dst += 4)
+
+	for(y = 0; y < h; y++) {
+	    int runstart, skipstart;
+	    int blankline = 0;
+	    /* First encode all opaque pixels of a scan line */
+	    x = 0;
+	    do {
+		int run, skip, len;
+		skipstart = x;
+		while(x < w && !ISOPAQUE(src[x], sf))
+		    x++;
+		runstart = x;
+		while(x < w && ISOPAQUE(src[x], sf))
+		    x++;
+		skip = runstart - skipstart;
+		if(skip == w)
+		    blankline = 1;
+		run = x - runstart;
+		while(skip > max_opaque_run) {
+		    ADD_OPAQUE_COUNTS(max_opaque_run, 0);
+		    skip -= max_opaque_run;
+		}
+		len = MIN(run, max_opaque_run);
+		ADD_OPAQUE_COUNTS(skip, len);
+		dst += copy_opaque(dst, src + runstart, len, sf, df);
+		runstart += len;
+		run -= len;
+		while(run) {
+		    len = MIN(run, max_opaque_run);
+		    ADD_OPAQUE_COUNTS(0, len);
+		    dst += copy_opaque(dst, src + runstart, len, sf, df);
+		    runstart += len;
+		    run -= len;
+		}
+	    } while(x < w);
+
+	    /* Make sure the next output address is 32-bit aligned */
+	    dst += (unsigned long)dst & 2;
+
+	    /* Next, encode all translucent pixels of the same scan line */
+	    x = 0;
+	    do {
+		int run, skip, len;
+		skipstart = x;
+		while(x < w && !ISTRANSL(src[x], sf))
+		    x++;
+		runstart = x;
+		while(x < w && ISTRANSL(src[x], sf))
+		    x++;
+		skip = runstart - skipstart;
+		blankline &= (skip == w);
+		run = x - runstart;
+		while(skip > max_transl_run) {
+		    ADD_TRANSL_COUNTS(max_transl_run, 0);
+		    skip -= max_transl_run;
+		}
+		len = MIN(run, max_transl_run);
+		ADD_TRANSL_COUNTS(skip, len);
+		dst += copy_transl(dst, src + runstart, len, sf, df);
+		runstart += len;
+		run -= len;
+		while(run) {
+		    len = MIN(run, max_transl_run);
+		    ADD_TRANSL_COUNTS(0, len);
+		    dst += copy_transl(dst, src + runstart, len, sf, df);
+		    runstart += len;
+		    run -= len;
+		}
+		if(!blankline)
+		    lastline = dst;
+	    } while(x < w);
+
+	    src += surface->pitch >> 2;
+	}
+	dst = lastline;		/* back up past trailing blank lines */
+	ADD_OPAQUE_COUNTS(0, 0);
+    }
+
+#undef ADD_OPAQUE_COUNTS
+#undef ADD_TRANSL_COUNTS
+
+    /* Now that we have it encoded, release the original pixels */
+    if((surface->flags & SDL_PREALLOC) != SDL_PREALLOC
+       && (surface->flags & SDL_HWSURFACE) != SDL_HWSURFACE) {
+	free( surface->pixels );
+	surface->pixels = NULL;
+    }
+
+    /* realloc the buffer to release unused memory */
+    {
+	Uint8 *p = realloc(rlebuf, dst - rlebuf);
+	if(!p)
+	    p = rlebuf;
+	surface->map->sw_data->aux_data = p;
+    }
+
+    return 0;
+}
+
+static Uint32 getpix_8(Uint8 *srcbuf)
+{
+    return *srcbuf;
+}
+
+static Uint32 getpix_16(Uint8 *srcbuf)
+{
+    return *(Uint16 *)srcbuf;
+}
+
+static Uint32 getpix_24(Uint8 *srcbuf)
+{
+    if(SDL_BYTEORDER == SDL_LIL_ENDIAN)
+	return srcbuf[0] + (srcbuf[1] << 8) + (srcbuf[2] << 16);
+    else
+	return (srcbuf[0] << 16) + (srcbuf[1] << 8) + srcbuf[2];
+}
+
+static Uint32 getpix_32(Uint8 *srcbuf)
+{
+    return *(Uint32 *)srcbuf;
+}
+
+typedef Uint32 (*getpix_func)(Uint8 *);
+
+static getpix_func getpixes[4] = {
+    getpix_8, getpix_16, getpix_24, getpix_32
+};
+
+static int RLEColorkeySurface(SDL_Surface *surface)
+{
+        Uint8 *rlebuf, *dst;
+	int maxn;
+	int y;
+	Uint8 *srcbuf, *curbuf, *lastline;
+	int maxsize = 0;
+	int skip, run;
+	int bpp = surface->format->BytesPerPixel;
+	getpix_func getpix;
+	Uint32 ckey, rgbmask;
+	int w, h;
+
+	/* calculate the worst case size for the compressed surface */
+	switch(bpp) {
+	case 1:
+	    /* worst case is alternating opaque and transparent pixels,
+	       starting with an opaque pixel */
+	    maxsize = surface->h * 3 * (surface->w / 2 + 1) + 2;
+	    break;
+	case 2:
+	case 3:
+	    /* worst case is solid runs, at most 255 pixels wide */
+	    maxsize = surface->h * (2 * (surface->w / 255 + 1)
+				    + surface->w * bpp) + 2;
+	    break;
+	case 4:
+	    /* worst case is solid runs, at most 65535 pixels wide */
+	    maxsize = surface->h * (4 * (surface->w / 65535 + 1)
+				    + surface->w * 4) + 4;
+	    break;
+	}
+
+	rlebuf = (Uint8 *)malloc(maxsize);
+	if ( rlebuf == NULL ) {
+		SDL_OutOfMemory();
+		return(-1);
+	}
+
+	/* Set up the conversion */
+	srcbuf = (Uint8 *)surface->pixels+surface->offset;
+	curbuf = srcbuf;
+	maxn = bpp == 4 ? 65535 : 255;
+	skip = run = 0;
+	dst = rlebuf;
+	rgbmask = ~surface->format->Amask;
+	ckey = surface->format->colorkey & rgbmask;
+	lastline = dst;
+	getpix = getpixes[bpp - 1];
+	w = surface->w;
+	h = surface->h;
+
+#define ADD_COUNTS(n, m)			\
+	if(bpp == 4) {				\
+	    ((Uint16 *)dst)[0] = n;		\
+	    ((Uint16 *)dst)[1] = m;		\
+	    dst += 4;				\
+	} else {				\
+	    dst[0] = n;				\
+	    dst[1] = m;				\
+	    dst += 2;				\
+	}
+
+	for(y = 0; y < h; y++) {
+	    int x = 0;
+	    int blankline = 0;
+	    do {
+		int run, skip, len;
+		int runstart;
+		int skipstart = x;
+
+		/* find run of transparent, then opaque pixels */
+		while(x < w && (getpix(srcbuf + x * bpp) & rgbmask) == ckey)
+		    x++;
+		runstart = x;
+		while(x < w && (getpix(srcbuf + x * bpp) & rgbmask) != ckey)
+		    x++;
+		skip = runstart - skipstart;
+		if(skip == w)
+		    blankline = 1;
+		run = x - runstart;
+
+		/* encode segment */
+		while(skip > maxn) {
+		    ADD_COUNTS(maxn, 0);
+		    skip -= maxn;
+		}
+		len = MIN(run, maxn);
+		ADD_COUNTS(skip, len);
+		memcpy(dst, srcbuf + runstart * bpp, len * bpp);
+		dst += len * bpp;
+		run -= len;
+		runstart += len;
+		while(run) {
+		    len = MIN(run, maxn);
+		    ADD_COUNTS(0, len);
+		    memcpy(dst, srcbuf + runstart * bpp, len * bpp);
+		    dst += len * bpp;
+		    runstart += len;
+		    run -= len;
+		}
+		if(!blankline)
+		    lastline = dst;
+	    } while(x < w);
+
+	    srcbuf += surface->pitch;
+	}
+	dst = lastline;		/* back up bast trailing blank lines */
+	ADD_COUNTS(0, 0);
+
+#undef ADD_COUNTS
+
+	/* Now that we have it encoded, release the original pixels */
+	if((surface->flags & SDL_PREALLOC) != SDL_PREALLOC
+	   && (surface->flags & SDL_HWSURFACE) != SDL_HWSURFACE) {
+	    free( surface->pixels );
+	    surface->pixels = NULL;
+	}
+
+	/* realloc the buffer to release unused memory */
+	{
+	    /* If realloc returns NULL, the original block is left intact */
+	    Uint8 *p = realloc(rlebuf, dst - rlebuf);
+	    if(!p)
+		p = rlebuf;
+	    surface->map->sw_data->aux_data = p;
+	}
+
+	return(0);
+}
+
+int SDL_RLESurface(SDL_Surface *surface)
+{
+	int retcode;
+
+	/* Clear any previous RLE conversion */
+	if ( (surface->flags & SDL_RLEACCEL) == SDL_RLEACCEL ) {
+		SDL_UnRLESurface(surface, 1);
+	}
+
+	/* We don't support RLE encoding of bitmaps */
+	if ( surface->format->BitsPerPixel < 8 ) {
+		return(-1);
+	}
+
+	/* Lock the surface if it's in hardware */
+	if ( surface->flags & (SDL_HWSURFACE|SDL_ASYNCBLIT) ) {
+		SDL_VideoDevice *video = current_video;
+		SDL_VideoDevice *this  = current_video;
+		if ( video->LockHWSurface(this, surface) < 0 ) {
+			return(-1);
+		}
+	}
+
+	/* Encode */
+	if((surface->flags & SDL_SRCCOLORKEY) == SDL_SRCCOLORKEY) {
+	    retcode = RLEColorkeySurface(surface);
+	} else {
+	    if((surface->flags & SDL_SRCALPHA) == SDL_SRCALPHA
+	       && surface->format->Amask != 0)
+		retcode = RLEAlphaSurface(surface);
+	    else
+		retcode = -1;	/* no RLE for per-surface alpha sans ckey */
+	}
+
+	/* Unlock the surface if it's in hardware */
+	if ( surface->flags & (SDL_HWSURFACE|SDL_ASYNCBLIT) ) {
+		SDL_VideoDevice *video = current_video;
+		SDL_VideoDevice *this  = current_video;
+		video->UnlockHWSurface(this, surface);
+	}
+
+	if(retcode < 0)
+	    return -1;
+
+	/* The surface is now accelerated */
+	surface->flags |= SDL_RLEACCEL;
+
+	return(0);
+}
+
+/*
+ * Un-RLE a surface with pixel alpha
+ * This may not give back exactly the image before RLE-encoding; all
+ * completely transparent pixels will be lost, and colour and alpha depth
+ * may have been reduced (when encoding for 16bpp targets).
+ */
+static void UnRLEAlpha(SDL_Surface *surface)
+{
+    Uint8 *srcbuf;
+    Uint32 *dst;
+    SDL_PixelFormat *sf = surface->format;
+    RLEDestFormat *df = surface->map->sw_data->aux_data;
+    int (*uncopy_opaque)(Uint32 *, void *, int,
+			 RLEDestFormat *, SDL_PixelFormat *);
+    int (*uncopy_transl)(Uint32 *, void *, int,
+			 RLEDestFormat *, SDL_PixelFormat *);
+    int w = surface->w;
+    int bpp = df->BytesPerPixel;
+
+    if(bpp == 2) {
+	uncopy_opaque = uncopy_opaque_16;
+	uncopy_transl = uncopy_transl_16;
+    } else {
+	uncopy_opaque = uncopy_transl = uncopy_32;
+    }
+
+    surface->pixels = malloc(surface->h * surface->pitch);
+    /* fill background with transparent pixels */
+    memset(surface->pixels, 0, surface->h * surface->pitch);
+
+    dst = surface->pixels;
+    srcbuf = (Uint8 *)(df + 1);
+    for(;;) {
+	/* copy opaque pixels */
+	int ofs = 0;
+	do {
+	    unsigned run;
+	    if(bpp == 2) {
+		ofs += srcbuf[0];
+		run = srcbuf[1];
+		srcbuf += 2;
+	    } else {
+		ofs += ((Uint16 *)srcbuf)[0];
+		run = ((Uint16 *)srcbuf)[1];
+		srcbuf += 4;
+	    }
+	    if(run) {
+		srcbuf += uncopy_opaque(dst + ofs, srcbuf, run, df, sf);
+		ofs += run;
+	    } else if(!ofs)
+		return;
+	} while(ofs < w);
+
+	/* skip padding if needed */
+	if(bpp == 2)
+	    srcbuf += (unsigned long)srcbuf & 2;
+	
+	/* copy translucent pixels */
+	ofs = 0;
+	do {
+	    unsigned run;
+	    ofs += ((Uint16 *)srcbuf)[0];
+	    run = ((Uint16 *)srcbuf)[1];
+	    srcbuf += 4;
+	    if(run) {
+		srcbuf += uncopy_transl(dst + ofs, srcbuf, run, df, sf);
+		ofs += run;
+	    }
+	} while(ofs < w);
+	dst += surface->pitch >> 2;
+    }
+}
+
+void SDL_UnRLESurface(SDL_Surface *surface, int recode)
+{
+    if ( (surface->flags & SDL_RLEACCEL) == SDL_RLEACCEL ) {
+	surface->flags &= ~SDL_RLEACCEL;
+
+	if(recode && (surface->flags & SDL_PREALLOC) != SDL_PREALLOC
+	   && (surface->flags & SDL_HWSURFACE) != SDL_HWSURFACE) {
+	    if((surface->flags & SDL_SRCCOLORKEY) == SDL_SRCCOLORKEY) {
+		SDL_Rect full;
+		unsigned alpha_flag;
+
+		/* re-create the original surface */
+		surface->pixels = malloc(surface->h * surface->pitch);
+
+		/* fill it with the background colour */
+		SDL_FillRect(surface, NULL, surface->format->colorkey);
+
+		/* now render the encoded surface */
+		full.x = full.y = 0;
+		full.w = surface->w;
+		full.h = surface->h;
+		alpha_flag = surface->flags & SDL_SRCALPHA;
+		surface->flags &= ~SDL_SRCALPHA; /* opaque blit */
+		SDL_RLEBlit(surface, &full, surface, &full);
+		surface->flags |= alpha_flag;
+	    } else
+		UnRLEAlpha(surface);
+	}
+
+	if ( surface->map && surface->map->sw_data->aux_data ) {
+	    free(surface->map->sw_data->aux_data);
+	    surface->map->sw_data->aux_data = NULL;
+	}
+    }
+}
+
+