FFmpeg/libswscale/hscale_fast_bilinear.c

/*
 * Copyright (C) 2001-2011 Michael Niedermayer <michaelni@gmx.at>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "swscale_internal.h"

void ff_hyscale_fast_c(SwsContext *c, int16_t *dst, int dstWidth,
                           const uint8_t *src, int srcW, int xInc)
{
    int i;
    unsigned int xpos = 0;
    for (i = 0; i < dstWidth; i++) {
        register unsigned int xx     = xpos >> 16;
        register unsigned int xalpha = (xpos & 0xFFFF) >> 9;
        dst[i] = (src[xx] << 7) + (src[xx + 1] - src[xx]) * xalpha;
        xpos  += xInc;
    }
    for (i=dstWidth-1; (i*xInc)>>16 >=srcW-1; i--)
        dst[i] = src[srcW-1]*128;
}

void ff_hcscale_fast_c(SwsContext *c, int16_t *dst1, int16_t *dst2,
                           int dstWidth, const uint8_t *src1,
                           const uint8_t *src2, int srcW, int xInc)
{
    int i;
    unsigned int xpos = 0;
    for (i = 0; i < dstWidth; i++) {
        register unsigned int xx     = xpos >> 16;
        register unsigned int xalpha = (xpos & 0xFFFF) >> 9;
        dst1[i] = (src1[xx] * (xalpha ^ 127) + src1[xx + 1] * xalpha);
        dst2[i] = (src2[xx] * (xalpha ^ 127) + src2[xx + 1] * xalpha);
        xpos   += xInc;
    }
    for (i=dstWidth-1; (i*xInc)>>16 >=srcW-1; i--) {
        dst1[i] = src1[srcW-1]*128;
        dst2[i] = src2[srcW-1]*128;
    }
}