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/*
* 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
*/
uint8_t setup_state[CONTEXT_SIZE];
uint get_usymbol(inout RangeCoder c)
{
if (get_rac_direct(c, setup_state[0]))
return 0;
int e = 0;
while (get_rac_direct(c, setup_state[1 + min(e, 9)])) { // 1..10
e++;
if (e > 31) {
corrupt = true;
return 0;
}
}
uint a = 1;
for (int i = e - 1; i >= 0; i--) {
a <<= 1;
a |= uint(get_rac_direct(c, setup_state[22 + min(i, 9)])); // 22..31
}
return a;
}
bool decode_slice_header(inout SliceContext sc)
{
[[unroll]]
for (int i = 0; i < CONTEXT_SIZE; i++)
setup_state[i] = uint8_t(128);
uint sx = get_usymbol(sc.c);
uint sy = get_usymbol(sc.c);
uint sw = get_usymbol(sc.c) + 1;
uint sh = get_usymbol(sc.c) + 1;
if (sx < 0 || sy < 0 || sw <= 0 || sh <= 0 ||
sx > (gl_NumWorkGroups.x - sw) || sy > (gl_NumWorkGroups.y - sh) ||
corrupt) {
return true;
}
/* Set coordinates */
uint sxs = slice_coord(img_size.x, sx , gl_NumWorkGroups.x, chroma_shift.x);
uint sxe = slice_coord(img_size.x, sx + sw, gl_NumWorkGroups.x, chroma_shift.x);
uint sys = slice_coord(img_size.y, sy , gl_NumWorkGroups.y, chroma_shift.y);
uint sye = slice_coord(img_size.y, sy + sh, 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(0);
for (uint i = 0; i < codec_planes; i++) {
uint idx = get_usymbol(sc.c);
if (idx >= quant_table_count)
return true;
sc.quant_table_idx[i] = uint8_t(idx);
}
get_usymbol(sc.c);
get_usymbol(sc.c);
get_usymbol(sc.c);
if (version >= 4) {
sc.slice_reset_contexts = get_rac_direct(sc.c, setup_state[0]);
sc.slice_coding_mode = get_usymbol(sc.c);
if (sc.slice_coding_mode != 1 && colorspace == 1) {
sc.slice_rct_coef.x = int(get_usymbol(sc.c));
sc.slice_rct_coef.y = int(get_usymbol(sc.c));
if (sc.slice_rct_coef.x + sc.slice_rct_coef.y > 4)
return true;
}
}
return false;
}
void golomb_init(inout SliceContext sc)
{
if (version == 3 && micro_version > 1 || version > 3) {
setup_state[0] = uint8_t(129);
get_rac_direct(sc.c, setup_state[0]);
}
uint64_t ac_byte_count = sc.c.bytestream - sc.c.bytestream_start - 1;
init_get_bits(sc.gb, u8buf(sc.c.bytestream_start + ac_byte_count),
int(sc.c.bytestream_end - sc.c.bytestream_start - ac_byte_count));
}
void main(void)
{
const uint slice_idx = gl_WorkGroupID.y*gl_NumWorkGroups.x + gl_WorkGroupID.x;
u8buf bs = u8buf(slice_data + slice_offsets[2*slice_idx + 0]);
uint32_t slice_size = slice_offsets[2*slice_idx + 1];
rac_init_dec(slice_ctx[slice_idx].c,
bs, slice_size);
if (slice_idx == (gl_NumWorkGroups.x*gl_NumWorkGroups.y - 1))
get_rac_equi(slice_ctx[slice_idx].c);
decode_slice_header(slice_ctx[slice_idx]);
if (golomb == 1)
golomb_init(slice_ctx[slice_idx]);
if (ec != 0 && check_crc != 0) {
uint32_t crc = crcref;
for (int i = 0; i < slice_size; i++)
crc = crc_ieee[(crc & 0xFF) ^ uint32_t(bs[i].v)] ^ (crc >> 8);
slice_status[2*slice_idx + 0] = crc;
}
slice_status[2*slice_idx + 1] = corrupt ? uint32_t(corrupt) : overread;
}
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