src/third_party/libvpx/vp8/common/loopfilter_filters.c

/*
 *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */


#include <stdlib.h>
#include "loopfilter.h"
#include "onyxc_int.h"

typedef unsigned char uc;

static signed char vp8_signed_char_clamp(int t)
{
    t = (t < -128 ? -128 : t);
    t = (t > 127 ? 127 : t);
    return (signed char) t;
}


/* should we apply any filter at all ( 11111111 yes, 00000000 no) */
static signed char vp8_filter_mask(uc limit, uc blimit,
                            uc p3, uc p2, uc p1, uc p0,
                            uc q0, uc q1, uc q2, uc q3)
{
    signed char mask = 0;
    mask |= (abs(p3 - p2) > limit);
    mask |= (abs(p2 - p1) > limit);
    mask |= (abs(p1 - p0) > limit);
    mask |= (abs(q1 - q0) > limit);
    mask |= (abs(q2 - q1) > limit);
    mask |= (abs(q3 - q2) > limit);
    mask |= (abs(p0 - q0) * 2 + abs(p1 - q1) / 2  > blimit);
    return mask - 1;
}

/* is there high variance internal edge ( 11111111 yes, 00000000 no) */
static signed char vp8_hevmask(uc thresh, uc p1, uc p0, uc q0, uc q1)
{
    signed char hev = 0;
    hev  |= (abs(p1 - p0) > thresh) * -1;
    hev  |= (abs(q1 - q0) > thresh) * -1;
    return hev;
}

static void vp8_filter(signed char mask, uc hev, uc *op1,
        uc *op0, uc *oq0, uc *oq1)

{
    signed char ps0, qs0;
    signed char ps1, qs1;
    signed char filter_value, Filter1, Filter2;
    signed char u;

    ps1 = (signed char) * op1 ^ 0x80;
    ps0 = (signed char) * op0 ^ 0x80;
    qs0 = (signed char) * oq0 ^ 0x80;
    qs1 = (signed char) * oq1 ^ 0x80;

    /* add outer taps if we have high edge variance */
    filter_value = vp8_signed_char_clamp(ps1 - qs1);
    filter_value &= hev;

    /* inner taps */
    filter_value = vp8_signed_char_clamp(filter_value + 3 * (qs0 - ps0));
    filter_value &= mask;

    /* save bottom 3 bits so that we round one side +4 and the other +3
     * if it equals 4 we'll set to adjust by -1 to account for the fact
     * we'd round 3 the other way
     */
    Filter1 = vp8_signed_char_clamp(filter_value + 4);
    Filter2 = vp8_signed_char_clamp(filter_value + 3);
    Filter1 >>= 3;
    Filter2 >>= 3;
    u = vp8_signed_char_clamp(qs0 - Filter1);
    *oq0 = u ^ 0x80;
    u = vp8_signed_char_clamp(ps0 + Filter2);
    *op0 = u ^ 0x80;
    filter_value = Filter1;

    /* outer tap adjustments */
    filter_value += 1;
    filter_value >>= 1;
    filter_value &= ~hev;

    u = vp8_signed_char_clamp(qs1 - filter_value);
    *oq1 = u ^ 0x80;
    u = vp8_signed_char_clamp(ps1 + filter_value);
    *op1 = u ^ 0x80;

}
void vp8_loop_filter_horizontal_edge_c
(
    unsigned char *s,
    int p, /* pitch */
    const unsigned char *blimit,
    const unsigned char *limit,
    const unsigned char *thresh,
    int count
)
{
    int  hev = 0; /* high edge variance */
    signed char mask = 0;
    int i = 0;

    /* loop filter designed to work using chars so that we can make maximum use
     * of 8 bit simd instructions.
     */
    do
    {
        mask = vp8_filter_mask(limit[0], blimit[0],
                               s[-4*p], s[-3*p], s[-2*p], s[-1*p],
                               s[0*p], s[1*p], s[2*p], s[3*p]);

        hev = vp8_hevmask(thresh[0], s[-2*p], s[-1*p], s[0*p], s[1*p]);

        vp8_filter(mask, hev, s - 2 * p, s - 1 * p, s, s + 1 * p);

        ++s;
    }
    while (++i < count * 8);
}

void vp8_loop_filter_vertical_edge_c
(
    unsigned char *s,
    int p,
    const unsigned char *blimit,
    const unsigned char *limit,
    const unsigned char *thresh,
    int count
)
{
    int  hev = 0; /* high edge variance */
    signed char mask = 0;
    int i = 0;

    /* loop filter designed to work using chars so that we can make maximum use
     * of 8 bit simd instructions.
     */
    do
    {
        mask = vp8_filter_mask(limit[0], blimit[0],
                               s[-4], s[-3], s[-2], s[-1], s[0], s[1], s[2], s[3]);

        hev = vp8_hevmask(thresh[0], s[-2], s[-1], s[0], s[1]);

        vp8_filter(mask, hev, s - 2, s - 1, s, s + 1);

        s += p;
    }
    while (++i < count * 8);
}

static void vp8_mbfilter(signed char mask, uc hev,
                           uc *op2, uc *op1, uc *op0, uc *oq0, uc *oq1, uc *oq2)
{
    signed char s, u;
    signed char filter_value, Filter1, Filter2;
    signed char ps2 = (signed char) * op2 ^ 0x80;
    signed char ps1 = (signed char) * op1 ^ 0x80;
    signed char ps0 = (signed char) * op0 ^ 0x80;
    signed char qs0 = (signed char) * oq0 ^ 0x80;
    signed char qs1 = (signed char) * oq1 ^ 0x80;
    signed char qs2 = (signed char) * oq2 ^ 0x80;

    /* add outer taps if we have high edge variance */
    filter_value = vp8_signed_char_clamp(ps1 - qs1);
    filter_value = vp8_signed_char_clamp(filter_value + 3 * (qs0 - ps0));
    filter_value &= mask;

    Filter2 = filter_value;
    Filter2 &= hev;

    /* save bottom 3 bits so that we round one side +4 and the other +3 */
    Filter1 = vp8_signed_char_clamp(Filter2 + 4);
    Filter2 = vp8_signed_char_clamp(Filter2 + 3);
    Filter1 >>= 3;
    Filter2 >>= 3;
    qs0 = vp8_signed_char_clamp(qs0 - Filter1);
    ps0 = vp8_signed_char_clamp(ps0 + Filter2);


    /* only apply wider filter if not high edge variance */
    filter_value &= ~hev;
    Filter2 = filter_value;

    /* roughly 3/7th difference across boundary */
    u = vp8_signed_char_clamp((63 + Filter2 * 27) >> 7);
    s = vp8_signed_char_clamp(qs0 - u);
    *oq0 = s ^ 0x80;
    s = vp8_signed_char_clamp(ps0 + u);
    *op0 = s ^ 0x80;

    /* roughly 2/7th difference across boundary */
    u = vp8_signed_char_clamp((63 + Filter2 * 18) >> 7);
    s = vp8_signed_char_clamp(qs1 - u);
    *oq1 = s ^ 0x80;
    s = vp8_signed_char_clamp(ps1 + u);
    *op1 = s ^ 0x80;

    /* roughly 1/7th difference across boundary */
    u = vp8_signed_char_clamp((63 + Filter2 * 9) >> 7);
    s = vp8_signed_char_clamp(qs2 - u);
    *oq2 = s ^ 0x80;
    s = vp8_signed_char_clamp(ps2 + u);
    *op2 = s ^ 0x80;
}

void vp8_mbloop_filter_horizontal_edge_c
(
    unsigned char *s,
    int p,
    const unsigned char *blimit,
    const unsigned char *limit,
    const unsigned char *thresh,
    int count
)
{
    signed char hev = 0; /* high edge variance */
    signed char mask = 0;
    int i = 0;

    /* loop filter designed to work using chars so that we can make maximum use
     * of 8 bit simd instructions.
     */
    do
    {

        mask = vp8_filter_mask(limit[0], blimit[0],
                               s[-4*p], s[-3*p], s[-2*p], s[-1*p],
                               s[0*p], s[1*p], s[2*p], s[3*p]);

        hev = vp8_hevmask(thresh[0], s[-2*p], s[-1*p], s[0*p], s[1*p]);

        vp8_mbfilter(mask, hev, s - 3 * p, s - 2 * p, s - 1 * p, s, s + 1 * p, s + 2 * p);

        ++s;
    }
    while (++i < count * 8);

}


void vp8_mbloop_filter_vertical_edge_c
(
    unsigned char *s,
    int p,
    const unsigned char *blimit,
    const unsigned char *limit,
    const unsigned char *thresh,
    int count
)
{
    signed char hev = 0; /* high edge variance */
    signed char mask = 0;
    int i = 0;

    do
    {

        mask = vp8_filter_mask(limit[0], blimit[0],
                               s[-4], s[-3], s[-2], s[-1], s[0], s[1], s[2], s[3]);

        hev = vp8_hevmask(thresh[0], s[-2], s[-1], s[0], s[1]);

        vp8_mbfilter(mask, hev, s - 3, s - 2, s - 1, s, s + 1, s + 2);

        s += p;
    }
    while (++i < count * 8);

}

/* should we apply any filter at all ( 11111111 yes, 00000000 no) */
static signed char vp8_simple_filter_mask(uc blimit, uc p1, uc p0, uc q0, uc q1)
{
/* Why does this cause problems for win32?
 * error C2143: syntax error : missing ';' before 'type'
 *  (void) limit;
 */
    signed char mask = (abs(p0 - q0) * 2 + abs(p1 - q1) / 2  <= blimit) * -1;
    return mask;
}

static void vp8_simple_filter(signed char mask, uc *op1, uc *op0, uc *oq0, uc *oq1)
{
    signed char filter_value, Filter1, Filter2;
    signed char p1 = (signed char) * op1 ^ 0x80;
    signed char p0 = (signed char) * op0 ^ 0x80;
    signed char q0 = (signed char) * oq0 ^ 0x80;
    signed char q1 = (signed char) * oq1 ^ 0x80;
    signed char u;

    filter_value = vp8_signed_char_clamp(p1 - q1);
    filter_value = vp8_signed_char_clamp(filter_value + 3 * (q0 - p0));
    filter_value &= mask;

    /* save bottom 3 bits so that we round one side +4 and the other +3 */
    Filter1 = vp8_signed_char_clamp(filter_value + 4);
    Filter1 >>= 3;
    u = vp8_signed_char_clamp(q0 - Filter1);
    *oq0  = u ^ 0x80;

    Filter2 = vp8_signed_char_clamp(filter_value + 3);
    Filter2 >>= 3;
    u = vp8_signed_char_clamp(p0 + Filter2);
    *op0 = u ^ 0x80;
}

void vp8_loop_filter_simple_horizontal_edge_c
(
    unsigned char *s,
    int p,
    const unsigned char *blimit
)
{
    signed char mask = 0;
    int i = 0;

    do
    {
        mask = vp8_simple_filter_mask(blimit[0], s[-2*p], s[-1*p], s[0*p], s[1*p]);
        vp8_simple_filter(mask, s - 2 * p, s - 1 * p, s, s + 1 * p);
        ++s;
    }
    while (++i < 16);
}

void vp8_loop_filter_simple_vertical_edge_c
(
    unsigned char *s,
    int p,
    const unsigned char *blimit
)
{
    signed char mask = 0;
    int i = 0;

    do
    {
        mask = vp8_simple_filter_mask(blimit[0], s[-2], s[-1], s[0], s[1]);
        vp8_simple_filter(mask, s - 2, s - 1, s, s + 1);
        s += p;
    }
    while (++i < 16);

}

/* Horizontal MB filtering */
void vp8_loop_filter_mbh_c(unsigned char *y_ptr, unsigned char *u_ptr,
                           unsigned char *v_ptr, int y_stride, int uv_stride,
                           loop_filter_info *lfi)
{
    vp8_mbloop_filter_horizontal_edge_c(y_ptr, y_stride, lfi->mblim, lfi->lim, lfi->hev_thr, 2);

    if (u_ptr)
        vp8_mbloop_filter_horizontal_edge_c(u_ptr, uv_stride, lfi->mblim, lfi->lim, lfi->hev_thr, 1);

    if (v_ptr)
        vp8_mbloop_filter_horizontal_edge_c(v_ptr, uv_stride, lfi->mblim, lfi->lim, lfi->hev_thr, 1);
}

/* Vertical MB Filtering */
void vp8_loop_filter_mbv_c(unsigned char *y_ptr, unsigned char *u_ptr,
                           unsigned char *v_ptr, int y_stride, int uv_stride,
                           loop_filter_info *lfi)
{
    vp8_mbloop_filter_vertical_edge_c(y_ptr, y_stride, lfi->mblim, lfi->lim, lfi->hev_thr, 2);

    if (u_ptr)
        vp8_mbloop_filter_vertical_edge_c(u_ptr, uv_stride, lfi->mblim, lfi->lim, lfi->hev_thr, 1);

    if (v_ptr)
        vp8_mbloop_filter_vertical_edge_c(v_ptr, uv_stride, lfi->mblim, lfi->lim, lfi->hev_thr, 1);
}

/* Horizontal B Filtering */
void vp8_loop_filter_bh_c(unsigned char *y_ptr, unsigned char *u_ptr,
                          unsigned char *v_ptr, int y_stride, int uv_stride,
                          loop_filter_info *lfi)
{
    vp8_loop_filter_horizontal_edge_c(y_ptr + 4 * y_stride, y_stride, lfi->blim, lfi->lim, lfi->hev_thr, 2);
    vp8_loop_filter_horizontal_edge_c(y_ptr + 8 * y_stride, y_stride, lfi->blim, lfi->lim, lfi->hev_thr, 2);
    vp8_loop_filter_horizontal_edge_c(y_ptr + 12 * y_stride, y_stride, lfi->blim, lfi->lim, lfi->hev_thr, 2);

    if (u_ptr)
        vp8_loop_filter_horizontal_edge_c(u_ptr + 4 * uv_stride, uv_stride, lfi->blim, lfi->lim, lfi->hev_thr, 1);

    if (v_ptr)
        vp8_loop_filter_horizontal_edge_c(v_ptr + 4 * uv_stride, uv_stride, lfi->blim, lfi->lim, lfi->hev_thr, 1);
}

void vp8_loop_filter_bhs_c(unsigned char *y_ptr, int y_stride,
                           const unsigned char *blimit)
{
    vp8_loop_filter_simple_horizontal_edge_c(y_ptr + 4 * y_stride, y_stride, blimit);
    vp8_loop_filter_simple_horizontal_edge_c(y_ptr + 8 * y_stride, y_stride, blimit);
    vp8_loop_filter_simple_horizontal_edge_c(y_ptr + 12 * y_stride, y_stride, blimit);
}

/* Vertical B Filtering */
void vp8_loop_filter_bv_c(unsigned char *y_ptr, unsigned char *u_ptr,
                          unsigned char *v_ptr, int y_stride, int uv_stride,
                          loop_filter_info *lfi)
{
    vp8_loop_filter_vertical_edge_c(y_ptr + 4, y_stride, lfi->blim, lfi->lim, lfi->hev_thr, 2);
    vp8_loop_filter_vertical_edge_c(y_ptr + 8, y_stride, lfi->blim, lfi->lim, lfi->hev_thr, 2);
    vp8_loop_filter_vertical_edge_c(y_ptr + 12, y_stride, lfi->blim, lfi->lim, lfi->hev_thr, 2);

    if (u_ptr)
        vp8_loop_filter_vertical_edge_c(u_ptr + 4, uv_stride, lfi->blim, lfi->lim, lfi->hev_thr, 1);

    if (v_ptr)
        vp8_loop_filter_vertical_edge_c(v_ptr + 4, uv_stride, lfi->blim, lfi->lim, lfi->hev_thr, 1);
}

void vp8_loop_filter_bvs_c(unsigned char *y_ptr, int y_stride,
                           const unsigned char *blimit)
{
    vp8_loop_filter_simple_vertical_edge_c(y_ptr + 4, y_stride, blimit);
    vp8_loop_filter_simple_vertical_edge_c(y_ptr + 8, y_stride, blimit);
    vp8_loop_filter_simple_vertical_edge_c(y_ptr + 12, y_stride, blimit);
}