sdl_surface.c

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		}
		maxh = src->h - srcy;
		if(maxh < h)
			h = maxh;
	    
	} else {
	        srcx = srcy = 0;
		w = src->w;
		h = src->h;
	}

	/* clip the destination rectangle against the clip rectangle */
	{
	        SDL_Rect *clip = &dst->clip_rect;
		int dx, dy;

		dx = clip->x - dstrect->x;
		if(dx > 0) {
			w -= dx;
			dstrect->x += dx;
			srcx += dx;
		}
		dx = dstrect->x + w - clip->x - clip->w;
		if(dx > 0)
			w -= dx;

		dy = clip->y - dstrect->y;
		if(dy > 0) {
			h -= dy;
			dstrect->y += dy;
			srcy += dy;
		}
		dy = dstrect->y + h - clip->y - clip->h;
		if(dy > 0)
			h -= dy;
	}

	if(w > 0 && h > 0) {
	        SDL_Rect sr;
	        sr.x = srcx;
		sr.y = srcy;
		sr.w = dstrect->w = w;
		sr.h = dstrect->h = h;
		return SDL_LowerBlit(src, &sr, dst, dstrect);
	}
	dstrect->w = dstrect->h = 0;
	return 0;
}

/* 
 * This function performs a fast fill of the given rectangle with 'color'
 */
int SDL_FillRect(SDL_Surface *dst, SDL_Rect *dstrect, Uint32 color)
{
	SDL_VideoDevice *video = current_video;
	SDL_VideoDevice *this  = current_video;
	int x, y;
	Uint8 *row;

	/* If 'dstrect' == NULL, then fill the whole surface */
	if ( dstrect ) {
		/* Perform clipping */
		if ( !SDL_IntersectRect(dstrect, &dst->clip_rect, dstrect) ) {
			return(0);
		}
	} else {
		dstrect = &dst->clip_rect;
	}

	/* Check for hardware acceleration */
	if ( ((dst->flags & SDL_HWSURFACE) == SDL_HWSURFACE) &&
					video->info.blit_fill ) {
		return(video->FillHWRect(this, dst, dstrect, color));
	}

	/* Perform software fill */
	if ( SDL_LockSurface(dst) != 0 ) {
		return(-1);
	}
	row = (Uint8 *)dst->pixels+dstrect->y*dst->pitch+
			dstrect->x*dst->format->BytesPerPixel;
	if ( dst->format->palette || (color == 0) ) {
		x = dstrect->w*dst->format->BytesPerPixel;
		if ( !color && !((long)row&3) && !(x&3) && !(dst->pitch&3) ) {
			int n = x >> 2;
			for ( y=dstrect->h; y; --y ) {
				SDL_memset4(row, 0, n);
				row += dst->pitch;
			}
		} else {
#ifdef __powerpc__
			/*
			 * memset() on PPC (both glibc and codewarrior) uses
			 * the dcbz (Data Cache Block Zero) instruction, which
			 * causes an alignment exception if the destination is
			 * uncachable, so only use it on software surfaces
			 */
			if((dst->flags & SDL_HWSURFACE) == SDL_HWSURFACE) {
				if(dstrect->w >= 8) {
					/*
					 * 64-bit stores are probably most
					 * efficient to uncached video memory
					 */
					double fill;
					memset(&fill, color, (sizeof fill));
					for(y = dstrect->h; y; y--) {
						Uint8 *d = row;
						unsigned n = x;
						unsigned nn;
						Uint8 c = color;
						double f = fill;
						while((unsigned long)d
						      & (sizeof(double) - 1)) {
							*d++ = c;
							n--;
						}
						nn = n / (sizeof(double) * 4);
						while(nn) {
							((double *)d)[0] = f;
							((double *)d)[1] = f;
							((double *)d)[2] = f;
							((double *)d)[3] = f;
							d += 4*sizeof(double);
							nn--;
						}
						n &= ~(sizeof(double) * 4 - 1);
						nn = n / sizeof(double);
						while(nn) {
							*(double *)d = f;
							d += sizeof(double);
							nn--;
						}
						n &= ~(sizeof(double) - 1);
						while(n) {
							*d++ = c;
							n--;
						}
						row += dst->pitch;
					}
				} else {
					/* narrow boxes */
					for(y = dstrect->h; y; y--) {
						Uint8 *d = row;
						Uint8 c = color;
						int n = x;
						while(n) {
							*d++ = c;
							n--;
						}
						row += dst->pitch;
					}
				}
			} else
#endif /* __powerpc__ */
			{
				for(y = dstrect->h; y; y--) {
					memset(row, color, x);
					row += dst->pitch;
				}
			}
		}
	} else {
		switch (dst->format->BytesPerPixel) {
		    case 2:
			for ( y=dstrect->h; y; --y ) {
				Uint16 *pixels = (Uint16 *)row;
				Uint16 c = color;
				Uint32 cc = (Uint32)c << 16 | c;
				int n = dstrect->w;
				if((unsigned long)pixels & 3) {
					*pixels++ = c;
					n--;
				}
				if(n >> 1)
					SDL_memset4(pixels, cc, n >> 1);
				if(n & 1)
					pixels[n - 1] = c;
				row += dst->pitch;
			}
			break;

		    case 3:
			if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
				color <<= 8;
			for ( y=dstrect->h; y; --y ) {
				Uint8 *pixels = row;
				for ( x=dstrect->w; x; --x ) {
					memcpy(pixels, &color, 3);
					pixels += 3;
				}
				row += dst->pitch;
			}
			break;

		    case 4:
			for(y = dstrect->h; y; --y) {
				SDL_memset4(row, color, dstrect->w);
				row += dst->pitch;
			}
			break;
		}
	}
	SDL_UnlockSurface(dst);

	/* We're done! */
	return(0);
}

/*
 * Lock a surface to directly access the pixels
 * -- Do not call this from any blit function, as SDL_DrawCursor() may recurse
 *    Instead, use:
 *    if ( (surface->flags & SDL_HWSURFACE) == SDL_HWSURFACE )
 *               video->LockHWSurface(video, surface);
 */
int SDL_LockSurface (SDL_Surface *surface)
{
	if ( ! surface->locked ) {
		/* Perform the lock */
		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);
			}
		}
		if ( surface->flags & SDL_RLEACCEL ) {
			SDL_UnRLESurface(surface, 1);
			surface->flags |= SDL_RLEACCEL;	/* save accel'd state */
		}
		/* This needs to be done here in case pixels changes value */
		surface->pixels = (Uint8 *)surface->pixels + surface->offset;
	}

	/* Increment the surface lock count, for recursive locks */
	++surface->locked;

	/* Ready to go.. */
	return(0);
}
/*
 * Unlock a previously locked surface
 * -- Do not call this from any blit function, as SDL_DrawCursor() may recurse
 *    Instead, use:
 *    if ( (surface->flags & SDL_HWSURFACE) == SDL_HWSURFACE )
 *               video->UnlockHWSurface(video, surface);
 */
void SDL_UnlockSurface (SDL_Surface *surface)
{
	/* Only perform an unlock if we are locked */
	if ( ! surface->locked || (--surface->locked > 0) ) {
		return;
	}

	/* Perform the unlock */
	surface->pixels = (Uint8 *)surface->pixels - surface->offset;

	/* Unlock hardware or accelerated surfaces */
	if ( surface->flags & (SDL_HWSURFACE|SDL_ASYNCBLIT) ) {
		SDL_VideoDevice *video = current_video;
		SDL_VideoDevice *this  = current_video;
		video->UnlockHWSurface(this, surface);
	} else {
		/* Update RLE encoded surface with new data */
		if ( (surface->flags & SDL_RLEACCEL) == SDL_RLEACCEL ) {
		        surface->flags &= ~SDL_RLEACCEL; /* stop lying */
			SDL_RLESurface(surface);
		}
	}
}

/* 
 * Convert a surface into the specified pixel format.
 */
SDL_Surface * SDL_ConvertSurface (SDL_Surface *surface,
					SDL_PixelFormat *format, Uint32 flags)
{
	SDL_Surface *convert;
	Uint32 colorkey = 0;
	Uint8 alpha = 0;
	Uint32 surface_flags;
	SDL_Rect bounds;

	/* Check for empty destination palette! (results in empty image) */
	if ( format->palette != NULL ) {
		int i;
		for ( i=0; i<format->palette->ncolors; ++i ) {
			if ( (format->palette->colors[i].r != 0) ||
			     (format->palette->colors[i].g != 0) ||
			     (format->palette->colors[i].b != 0) )
				break;
		}
		if ( i == format->palette->ncolors ) {
			SDL_SetError("Empty destination palette");
			return(NULL);
		}
	}

	/* Only create hw surfaces with alpha channel if hw alpha blits
	   are supported */
	if(format->Amask != 0 && (flags & SDL_HWSURFACE)) {
		const SDL_VideoInfo *vi = SDL_GetVideoInfo();
		if(!vi || !vi->blit_hw_A)
			flags &= ~SDL_HWSURFACE;
	}

	/* Create a new surface with the desired format */
	convert = SDL_CreateRGBSurface(flags,
				surface->w, surface->h, format->BitsPerPixel,
		format->Rmask, format->Gmask, format->Bmask, format->Amask);
	if ( convert == NULL ) {
		return(NULL);
	}

	/* Copy the palette if any */
	if ( format->palette && convert->format->palette ) {
		memcpy(convert->format->palette->colors,
				format->palette->colors,
				format->palette->ncolors*sizeof(SDL_Color));
		convert->format->palette->ncolors = format->palette->ncolors;
	}

	/* Save the original surface color key and alpha */
	surface_flags = surface->flags;
	if ( (surface_flags & SDL_SRCCOLORKEY) == SDL_SRCCOLORKEY ) {
		/* Convert colourkeyed surfaces to RGBA if requested */
		if((flags & SDL_SRCCOLORKEY) != SDL_SRCCOLORKEY
		   && format->Amask) {
			surface_flags &= ~SDL_SRCCOLORKEY;
		} else {
			colorkey = surface->format->colorkey;
			SDL_SetColorKey(surface, 0, 0);
		}
	}
	if ( (surface_flags & SDL_SRCALPHA) == SDL_SRCALPHA ) {
		alpha = surface->format->alpha;
		SDL_SetAlpha(surface, 0, 0);
	}

	/* Copy over the image data */
	bounds.x = 0;
	bounds.y = 0;
	bounds.w = surface->w;
	bounds.h = surface->h;
	SDL_LowerBlit(surface, &bounds, convert, &bounds);

	/* Clean up the original surface, and update converted surface */
	if ( convert != NULL ) {
		SDL_SetClipRect(convert, &surface->clip_rect);
	}
	if ( (surface_flags & SDL_SRCCOLORKEY) == SDL_SRCCOLORKEY ) {
		Uint32 cflags = surface_flags&(SDL_SRCCOLORKEY|SDL_RLEACCELOK);
		if ( convert != NULL ) {
			Uint8 keyR, keyG, keyB;

			SDL_GetRGB(colorkey,surface->format,&keyR,&keyG,&keyB);
			SDL_SetColorKey(convert, cflags|(flags&SDL_RLEACCELOK),
				SDL_MapRGB(convert->format, keyR, keyG, keyB));
		}
		SDL_SetColorKey(surface, cflags, colorkey);
	}
	if ( (surface_flags & SDL_SRCALPHA) == SDL_SRCALPHA ) {
		Uint32 aflags = surface_flags&(SDL_SRCALPHA|SDL_RLEACCELOK);
		if ( convert != NULL ) {
		        SDL_SetAlpha(convert, aflags|(flags&SDL_RLEACCELOK),
				alpha);
		}
		SDL_SetAlpha(surface, aflags, alpha);
	}

	/* We're ready to go! */
	return(convert);
}

/*
 * Free a surface created by the above function.
 */
void SDL_FreeSurface (SDL_Surface *surface)
{
	/* Free anything that's not NULL, and not the screen surface */
	if ((surface == NULL) ||
	    (current_video &&
	    ((surface == SDL_ShadowSurface)||(surface == SDL_VideoSurface)))) {
		return;
	}
	if ( --surface->refcount > 0 ) {
		return;
	}
	if ( (surface->flags & SDL_RLEACCEL) == SDL_RLEACCEL ) {
	        SDL_UnRLESurface(surface, 0);
	}
	if ( surface->format ) {
		SDL_FreeFormat(surface->format);
		surface->format = NULL;
	}
	if ( surface->map != NULL ) {
		SDL_FreeBlitMap(surface->map);
		surface->map = NULL;
	}
	if ( (surface->flags & SDL_HWSURFACE) == SDL_HWSURFACE ) {
		SDL_VideoDevice *video = current_video;
		SDL_VideoDevice *this  = current_video;
		video->FreeHWSurface(this, surface);
	}
	if ( surface->pixels &&
	     ((surface->flags & SDL_PREALLOC) != SDL_PREALLOC) ) {
		free(surface->pixels);
	}
	free(surface);
#ifdef CHECK_LEAKS
	--surfaces_allocated;
#endif
}