/* * FFv1 codec * * 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 */ uint slice_coord(uint width, uint sx, uint num_h_slices, uint chroma_shift){    uint mpw = 1 << chroma_shift;    uint awidth = align(width, mpw);     if ((version < 4) || ((version == 4) && (micro_version < 3)))        return width * sx / num_h_slices;     sx = (2 * awidth * sx + num_h_slices * mpw) / (2 * num_h_slices * mpw) * mpw;    if (sx == awidth)        sx = width;     return sx;} void init_slice(out SliceContext sc, const uint slice_idx){    /* Set coordinates */    uvec2 img_size = imageSize(src[0]);    uint sxs = slice_coord(img_size.x, gl_WorkGroupID.x + 0,                           gl_NumWorkGroups.x, chroma_shift.x);    uint sxe = slice_coord(img_size.x, gl_WorkGroupID.x + 1,                           gl_NumWorkGroups.x, chroma_shift.x);    uint sys = slice_coord(img_size.y, gl_WorkGroupID.y + 0,                           gl_NumWorkGroups.y, chroma_shift.y);    uint sye = slice_coord(img_size.y, gl_WorkGroupID.y + 1,                           gl_NumWorkGroups.y, chroma_shift.y);     sc.slice_pos = ivec2(sxs, sys);    sc.slice_dim = ivec2(sxe - sxs, sye - sys);    sc.slice_rct_coef = ivec2(1, 1);    sc.slice_coding_mode = int(force_pcm == 1);     rac_init(sc.c,             OFFBUF(u8buf, out_data, slice_idx * slice_size_max),             slice_size_max);} void put_rac_full(inout RangeCoder c, uint64_t state, bool bit){    put_rac_norenorm(c, state, bit);    if (c.range < 0x100)        renorm_encoder_full(c);} void put_symbol_unsigned(inout RangeCoder c, uint64_t state, uint v){    bool is_nil = (v == 0);    put_rac_full(c, state, is_nil);    if (is_nil)        return;     const int e = findMSB(v);     state += 1;    for (int i = 0; i < e; i++)        put_rac_full(c, state + min(i, 9), true);    put_rac_full(c, state + min(e, 9), false);     state += 21;    for (int i = e - 1; i >= 0; i--)        put_rac_full(c, state + min(i, 9), bool(bitfieldExtract(v, i, 1)));} void write_slice_header(inout SliceContext sc, uint64_t state){    u8buf sb = u8buf(state);     [[unroll]]    for (int i = 0; i < CONTEXT_SIZE; i++)        sb[i].v = uint8_t(128);     put_symbol_unsigned(sc.c, state, gl_WorkGroupID.x);    put_symbol_unsigned(sc.c, state, gl_WorkGroupID.y);    put_symbol_unsigned(sc.c, state, 0);    put_symbol_unsigned(sc.c, state, 0);     for (int i = 0; i < codec_planes; i++)        put_symbol_unsigned(sc.c, state, context_model);     put_symbol_unsigned(sc.c, state, pic_mode);    put_symbol_unsigned(sc.c, state, sar.x);    put_symbol_unsigned(sc.c, state, sar.y);     if (version >= 4) {        put_rac_full(sc.c, state, sc.slice_coding_mode == 1);        put_symbol_unsigned(sc.c, state, sc.slice_coding_mode);        if (sc.slice_coding_mode != 1 && colorspace == 1) {            put_symbol_unsigned(sc.c, state, sc.slice_rct_coef.y);            put_symbol_unsigned(sc.c, state, sc.slice_rct_coef.x);        }    }} void write_frame_header(inout SliceContext sc, uint64_t state){    u8buf sb = u8buf(state);    sb.v = uint8_t(128);    put_rac_full(sc.c, state, bool(key_frame));} #ifdef GOLOMBvoid init_golomb(inout SliceContext sc){    sc.hdr_len = rac_terminate(sc.c);    init_put_bits(sc.pb,                  OFFBUF(u8buf, sc.c.bytestream_start, sc.hdr_len),                  slice_size_max - sc.hdr_len);}#endif void main(void){    const uint slice_idx = gl_WorkGroupID.y*gl_NumWorkGroups.x + gl_WorkGroupID.x;     /* Write slice data */    uint64_t scratch_state = uint64_t(scratch_data) + slice_idx*CONTEXT_SIZE;    u8buf sb = u8buf(scratch_state);     init_slice(slice_ctx[slice_idx], slice_idx);     if (slice_idx == 0)        write_frame_header(slice_ctx[slice_idx], scratch_state);     write_slice_header(slice_ctx[slice_idx], scratch_state); #ifdef GOLOMB    init_golomb(slice_ctx[slice_idx]);#endif}