/*
 * 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 <stdint.h>

#include "libavutil/attributes.h"
#include "libavutil/common.h"
#include "config.h"
#include "h263dsp.h"

const uint8_t ff_h263_loop_filter_strength[32]={
//  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
    0, 1, 1, 2, 2, 3, 3, 4, 4, 4, 5, 5, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9,10,10,10,11,11,11,12,12,12
};

static void h263_h_loop_filter_c(uint8_t *src, int stride, int qscale){
    int y;
    const int strength= ff_h263_loop_filter_strength[qscale];

    for(y=0; y<8; y++){
        int d1, d2, ad1;
        int p0= src[y*stride-2];
        int p1= src[y*stride-1];
        int p2= src[y*stride+0];
        int p3= src[y*stride+1];
        int d = (p0 - p3 + 4*(p2 - p1)) / 8;

        if     (d<-2*strength) d1= 0;
        else if(d<-  strength) d1=-2*strength - d;
        else if(d<   strength) d1= d;
        else if(d< 2*strength) d1= 2*strength - d;
        else                   d1= 0;

        p1 += d1;
        p2 -= d1;
        if(p1&256) p1= ~(p1>>31);
        if(p2&256) p2= ~(p2>>31);

        src[y*stride-1] = p1;
        src[y*stride+0] = p2;

        ad1= FFABS(d1)>>1;

        d2= av_clip((p0-p3)/4, -ad1, ad1);

        src[y*stride-2] = p0 - d2;
        src[y*stride+1] = p3 + d2;
    }
}

static void h263_v_loop_filter_c(uint8_t *src, int stride, int qscale){
    int x;
    const int strength= ff_h263_loop_filter_strength[qscale];

    for(x=0; x<8; x++){
        int d1, d2, ad1;
        int p0= src[x-2*stride];
        int p1= src[x-1*stride];
        int p2= src[x+0*stride];
        int p3= src[x+1*stride];
        int d = (p0 - p3 + 4*(p2 - p1)) / 8;

        if     (d<-2*strength) d1= 0;
        else if(d<-  strength) d1=-2*strength - d;
        else if(d<   strength) d1= d;
        else if(d< 2*strength) d1= 2*strength - d;
        else                   d1= 0;

        p1 += d1;
        p2 -= d1;
        if(p1&256) p1= ~(p1>>31);
        if(p2&256) p2= ~(p2>>31);

        src[x-1*stride] = p1;
        src[x+0*stride] = p2;

        ad1= FFABS(d1)>>1;

        d2= av_clip((p0-p3)/4, -ad1, ad1);

        src[x-2*stride] = p0 - d2;
        src[x+  stride] = p3 + d2;
    }
}

av_cold void ff_h263dsp_init(H263DSPContext *ctx)
{
    ctx->h263_h_loop_filter = h263_h_loop_filter_c;
    ctx->h263_v_loop_filter = h263_v_loop_filter_c;

    if (ARCH_X86)
        ff_h263dsp_init_x86(ctx);
}