FFmpeg/libavcodec/vulkan/ffv1_enc_ac.comp

/*
 * Copyright (c) 2024 Lynne <dev@lynne.ee>
 *
 * 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
 */

void put_rac(inout RangeCoder c, uint64_t state, bool bit)
{
    put_rac_norenorm(c, state, bit);
    if (c.range < 0x100)
        renorm_encoder(c);
}

/* Note - only handles signed values */
void put_symbol(inout RangeCoder c, uint64_t state, int v)
{
    bool is_nil = (v == 0);
    put_rac(c, state, is_nil);
    if (is_nil)
        return;

    const int a = abs(v);
    const int e = findMSB(a);

    state += 1;
    for (int i = 0; i < e; i++)
        put_rac(c, state + min(i, 9), true);
    put_rac(c, state + min(e, 9), false);

    state += 21;
    for (int i = e - 1; i >= 0; i--)
        put_rac(c, state + min(i, 9), bool(bitfieldExtract(a, i, 1)));

    put_rac(c, state - 11 + min(e, 10), v < 0);
}

void encode_line_pcm(inout SliceContext sc, int y, int p, int comp,
                     int bits)
{
    ivec2 sp = sc.slice_pos;
    int w = sc.slice_dim.x;
    if (p > 0 && p < 3) {
        w >>= chroma_shift.x;
        sp >>= chroma_shift;
    }

    for (int x = 0; x < w; x++) {
        uint v = imageLoad(src[p], (sp + ivec2(x, y)))[comp];
        for (int i = (bits - 1); i >= 0; i--)
            put_rac_equi(sc.c, bool(bitfieldExtract(v, i, 1)));
    }
}

void encode_line(inout SliceContext sc, uint64_t state,
                 int y, int p, int comp, int bits, const int run_index)
{
    ivec2 sp = sc.slice_pos;

    int w = sc.slice_dim.x;
    if (p > 0 && p < 3) {
        w >>= chroma_shift.x;
        sp >>= chroma_shift;
    }

    for (int x = 0; x < w; x++) {
        const ivec2 d = get_diff(sp + ivec2(x, y), ivec2(x, y), p, comp, w, bits);
        put_symbol(sc.c, state + CONTEXT_SIZE*d[0], d[1]);
    }
}