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view src/video/SDL_blit_1.c @ 2042:3908e1f808e1

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Fixed bug #292 I might be on crack here. It looks like SDL_ConvertMono() in src/audio/SDL_audiocvt.c adds the left and right channels of a stereo stream together, and clamps the new mono channel if it would overflow. Shouldn't it be dividing by 2 to average the two sample points instead of clamping? Otherwise the mono sample point's volume doubles in the conversion. This would also make the conversion faster, as it replaces two branches per sample frame with a bitwise shift. --ryan.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 24 Sep 2006 15:56:36 +0000
parents c121d94672cb
children 340942cfda48
line wrap: on
line source

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

#include "SDL_video.h"
#include "SDL_blit.h"
#include "SDL_sysvideo.h"
#include "SDL_endian.h"

/* Functions to blit from 8-bit surfaces to other surfaces */

static void
Blit1to1(SDL_BlitInfo * info)
{
#ifndef USE_DUFFS_LOOP
    int c;
#endif
    int width, height;
    Uint8 *src, *map, *dst;
    int srcskip, dstskip;

    /* Set up some basic variables */
    width = info->d_width;
    height = info->d_height;
    src = info->s_pixels;
    srcskip = info->s_skip;
    dst = info->d_pixels;
    dstskip = info->d_skip;
    map = info->table;

    while (height--) {
#ifdef USE_DUFFS_LOOP
        /* *INDENT-OFF* */
		DUFFS_LOOP(
			{
			  *dst = map[*src];
			}
			dst++;
			src++;
		, width);
        /* *INDENT-ON* */
#else
        for (c = width; c; --c) {
            *dst = map[*src];
            dst++;
            src++;
        }
#endif
        src += srcskip;
        dst += dstskip;
    }
}

/* This is now endian dependent */
#if ( SDL_BYTEORDER == SDL_LIL_ENDIAN )
#define HI	1
#define LO	0
#else /* ( SDL_BYTEORDER == SDL_BIG_ENDIAN ) */
#define HI	0
#define LO	1
#endif
static void
Blit1to2(SDL_BlitInfo * info)
{
#ifndef USE_DUFFS_LOOP
    int c;
#endif
    int width, height;
    Uint8 *src, *dst;
    Uint16 *map;
    int srcskip, dstskip;

    /* Set up some basic variables */
    width = info->d_width;
    height = info->d_height;
    src = info->s_pixels;
    srcskip = info->s_skip;
    dst = info->d_pixels;
    dstskip = info->d_skip;
    map = (Uint16 *) info->table;

#ifdef USE_DUFFS_LOOP
    while (height--) {
		/* *INDENT-OFF* */
		DUFFS_LOOP(
		{
			*(Uint16 *)dst = map[*src++];
			dst += 2;
		},
		width);
		/* *INDENT-ON* */
        src += srcskip;
        dst += dstskip;
    }
#else
    /* Memory align at 4-byte boundary, if necessary */
    if ((long) dst & 0x03) {
        /* Don't do anything if width is 0 */
        if (width == 0) {
            return;
        }
        --width;

        while (height--) {
            /* Perform copy alignment */
            *(Uint16 *) dst = map[*src++];
            dst += 2;

            /* Copy in 4 pixel chunks */
            for (c = width / 4; c; --c) {
                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
                src += 2;
                dst += 4;
                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
                src += 2;
                dst += 4;
            }
            /* Get any leftovers */
            switch (width & 3) {
            case 3:
                *(Uint16 *) dst = map[*src++];
                dst += 2;
            case 2:
                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
                src += 2;
                dst += 4;
                break;
            case 1:
                *(Uint16 *) dst = map[*src++];
                dst += 2;
                break;
            }
            src += srcskip;
            dst += dstskip;
        }
    } else {
        while (height--) {
            /* Copy in 4 pixel chunks */
            for (c = width / 4; c; --c) {
                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
                src += 2;
                dst += 4;
                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
                src += 2;
                dst += 4;
            }
            /* Get any leftovers */
            switch (width & 3) {
            case 3:
                *(Uint16 *) dst = map[*src++];
                dst += 2;
            case 2:
                *(Uint32 *) dst = (map[src[HI]] << 16) | (map[src[LO]]);
                src += 2;
                dst += 4;
                break;
            case 1:
                *(Uint16 *) dst = map[*src++];
                dst += 2;
                break;
            }
            src += srcskip;
            dst += dstskip;
        }
    }
#endif /* USE_DUFFS_LOOP */
}
static void
Blit1to3(SDL_BlitInfo * info)
{
#ifndef USE_DUFFS_LOOP
    int c;
#endif
    int o;
    int width, height;
    Uint8 *src, *map, *dst;
    int srcskip, dstskip;

    /* Set up some basic variables */
    width = info->d_width;
    height = info->d_height;
    src = info->s_pixels;
    srcskip = info->s_skip;
    dst = info->d_pixels;
    dstskip = info->d_skip;
    map = info->table;

    while (height--) {
#ifdef USE_DUFFS_LOOP
		/* *INDENT-OFF* */
		DUFFS_LOOP(
			{
				o = *src * 4;
				dst[0] = map[o++];
				dst[1] = map[o++];
				dst[2] = map[o++];
			}
			src++;
			dst += 3;
		, width);
		/* *INDENT-ON* */
#else
        for (c = width; c; --c) {
            o = *src * 4;
            dst[0] = map[o++];
            dst[1] = map[o++];
            dst[2] = map[o++];
            src++;
            dst += 3;
        }
#endif /* USE_DUFFS_LOOP */
        src += srcskip;
        dst += dstskip;
    }
}
static void
Blit1to4(SDL_BlitInfo * info)
{
#ifndef USE_DUFFS_LOOP
    int c;
#endif
    int width, height;
    Uint8 *src;
    Uint32 *map, *dst;
    int srcskip, dstskip;

    /* Set up some basic variables */
    width = info->d_width;
    height = info->d_height;
    src = info->s_pixels;
    srcskip = info->s_skip;
    dst = (Uint32 *) info->d_pixels;
    dstskip = info->d_skip / 4;
    map = (Uint32 *) info->table;

    while (height--) {
#ifdef USE_DUFFS_LOOP
		/* *INDENT-OFF* */
		DUFFS_LOOP(
			*dst++ = map[*src++];
		, width);
		/* *INDENT-ON* */
#else
        for (c = width / 4; c; --c) {
            *dst++ = map[*src++];
            *dst++ = map[*src++];
            *dst++ = map[*src++];
            *dst++ = map[*src++];
        }
        switch (width & 3) {
        case 3:
            *dst++ = map[*src++];
        case 2:
            *dst++ = map[*src++];
        case 1:
            *dst++ = map[*src++];
        }
#endif /* USE_DUFFS_LOOP */
        src += srcskip;
        dst += dstskip;
    }
}

static void
Blit1to1Key(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;
    Uint32 ckey = info->src->colorkey;

    if (palmap) {
        while (height--) {
			/* *INDENT-OFF* */
			DUFFS_LOOP(
			{
				if ( *src != ckey ) {
				  *dst = palmap[*src];
				}
				dst++;
				src++;
			},
			width);
			/* *INDENT-ON* */
            src += srcskip;
            dst += dstskip;
        }
    } else {
        while (height--) {
			/* *INDENT-OFF* */
			DUFFS_LOOP(
			{
				if ( *src != ckey ) {
				  *dst = *src;
				}
				dst++;
				src++;
			},
			width);
			/* *INDENT-ON* */
            src += srcskip;
            dst += dstskip;
        }
    }
}

static void
Blit1to2Key(SDL_BlitInfo * info)
{
    int width = info->d_width;
    int height = info->d_height;
    Uint8 *src = info->s_pixels;
    int srcskip = info->s_skip;
    Uint16 *dstp = (Uint16 *) info->d_pixels;
    int dstskip = info->d_skip;
    Uint16 *palmap = (Uint16 *) info->table;
    Uint32 ckey = info->src->colorkey;

    /* Set up some basic variables */
    dstskip /= 2;

    while (height--) {
		/* *INDENT-OFF* */
		DUFFS_LOOP(
		{
			if ( *src != ckey ) {
				*dstp=palmap[*src];
			}
			src++;
			dstp++;
		},
		width);
		/* *INDENT-ON* */
        src += srcskip;
        dstp += dstskip;
    }
}

static void
Blit1to3Key(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;
    Uint32 ckey = info->src->colorkey;
    int o;

    while (height--) {
		/* *INDENT-OFF* */
		DUFFS_LOOP(
		{
			if ( *src != ckey ) {
				o = *src * 4;
				dst[0] = palmap[o++];
				dst[1] = palmap[o++];
				dst[2] = palmap[o++];
			}
			src++;
			dst += 3;
		},
		width);
		/* *INDENT-ON* */
        src += srcskip;
        dst += dstskip;
    }
}

static void
Blit1to4Key(SDL_BlitInfo * info)
{
    int width = info->d_width;
    int height = info->d_height;
    Uint8 *src = info->s_pixels;
    int srcskip = info->s_skip;
    Uint32 *dstp = (Uint32 *) info->d_pixels;
    int dstskip = info->d_skip;
    Uint32 *palmap = (Uint32 *) info->table;
    Uint32 ckey = info->src->colorkey;

    /* Set up some basic variables */
    dstskip /= 4;

    while (height--) {
		/* *INDENT-OFF* */
		DUFFS_LOOP(
		{
			if ( *src != ckey ) {
				*dstp = palmap[*src];
			}
			src++;
			dstp++;
		},
		width);
		/* *INDENT-ON* */
        src += srcskip;
        dstp += dstskip;
    }
}

static void
Blit1toNAlpha(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 *dstfmt = info->dst;
    const SDL_Color *srcpal = info->src->palette->colors;
    int dstbpp;
    const int A = info->src->alpha;

    /* Set up some basic variables */
    dstbpp = dstfmt->BytesPerPixel;

    while (height--) {
        int sR, sG, sB;
        int dR, dG, dB;
	    	/* *INDENT-OFF* */
	    	DUFFS_LOOP4(
			{
			        Uint32 pixel;
				sR = srcpal[*src].r;
				sG = srcpal[*src].g;
				sB = srcpal[*src].b;
				DISEMBLE_RGB(dst, dstbpp, dstfmt,
					     pixel, dR, dG, dB);
				ALPHA_BLEND(sR, sG, sB, A, dR, dG, dB);
			  	ASSEMBLE_RGB(dst, dstbpp, dstfmt, dR, dG, dB);
				src++;
				dst += dstbpp;
			},
			width);
	    	/* *INDENT-ON* */
        src += srcskip;
        dst += dstskip;
    }
}

static void
Blit1toNAlphaKey(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;
    const SDL_Color *srcpal = info->src->palette->colors;
    Uint32 ckey = srcfmt->colorkey;
    int dstbpp;
    const int A = srcfmt->alpha;

    /* Set up some basic variables */
    dstbpp = dstfmt->BytesPerPixel;

    while (height--) {
        int sR, sG, sB;
        int dR, dG, dB;
		/* *INDENT-OFF* */
		DUFFS_LOOP(
		{
			if ( *src != ckey ) {
			        Uint32 pixel;
				sR = srcpal[*src].r;
				sG = srcpal[*src].g;
				sB = srcpal[*src].b;
				DISEMBLE_RGB(dst, dstbpp, dstfmt,
							pixel, dR, dG, dB);
				ALPHA_BLEND(sR, sG, sB, A, dR, dG, dB);
			  	ASSEMBLE_RGB(dst, dstbpp, dstfmt, dR, dG, dB);
			}
			src++;
			dst += dstbpp;
		},
		width);
		/* *INDENT-ON* */
        src += srcskip;
        dst += dstskip;
    }
}

static SDL_loblit one_blit[] = {
    NULL, Blit1to1, Blit1to2, Blit1to3, Blit1to4
};

static SDL_loblit one_blitkey[] = {
    NULL, Blit1to1Key, Blit1to2Key, Blit1to3Key, Blit1to4Key
};

SDL_loblit
SDL_CalculateBlit1(SDL_Surface * surface, int blit_index)
{
    int which;
    SDL_PixelFormat *dstfmt;

    dstfmt = surface->map->dst->format;
    if (dstfmt->BitsPerPixel < 8) {
        which = 0;
    } else {
        which = dstfmt->BytesPerPixel;
    }
    switch (blit_index) {
    case 0:                    /* copy */
        return one_blit[which];

    case 1:                    /* colorkey */
        return one_blitkey[which];

    case 2:                    /* alpha */
        /* Supporting 8bpp->8bpp alpha is doable but requires lots of
           tables which consume space and takes time to precompute,
           so is better left to the user */
        return which >= 2 ? Blit1toNAlpha : NULL;

    case 3:                    /* alpha + colorkey */
        return which >= 2 ? Blit1toNAlphaKey : NULL;

    }
    return NULL;
}

/* vi: set ts=4 sw=4 expandtab: */