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Code Issues Releases Activity

avcodec/rv10: Avoid indirection when reading VLC codes

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Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-05-25 17:35:56 +02:00
parent c2e5f7466d
commit 01d6235fae
1 changed files with 13 additions and 18 deletions
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31
libavcodec/rv10.c
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@ -78,16 +78,16 @@ static const uint16_t rv_chrom_len_count[15] = {
1, 2, 4, 0, 8, 0, 16, 0, 32, 0, 64, 0, 128, 0, 256, 1, 2, 4, 0, 8, 0, 16, 0, 32, 0, 64, 0, 128, 0, 256,
}; };
static VLC rv_dc_lum, rv_dc_chrom; static VLCElem rv_dc_lum[1472], rv_dc_chrom[992];
int ff_rv_decode_dc(MpegEncContext *s, int n) int ff_rv_decode_dc(MpegEncContext *s, int n)
{ {
int code; int code;
if (n < 4) { if (n < 4) {
code = get_vlc2(&s->gb, rv_dc_lum.table, DC_VLC_BITS, 2); code = get_vlc2(&s->gb, rv_dc_lum, DC_VLC_BITS, 2);
} else { } else {
code = get_vlc2(&s->gb, rv_dc_chrom.table, DC_VLC_BITS, 2); code = get_vlc2(&s->gb, rv_dc_chrom, DC_VLC_BITS, 2);
if (code < 0) { if (code < 0) {
av_log(s->avctx, AV_LOG_ERROR, "chroma dc error\n"); av_log(s->avctx, AV_LOG_ERROR, "chroma dc error\n");
return -1; return -1;
@ -306,7 +306,8 @@ static int rv20_decode_picture_header(RVDecContext *rv, int whole_size)
return s->mb_width * s->mb_height - mb_pos; return s->mb_width * s->mb_height - mb_pos;
} }
static av_cold void rv10_build_vlc(VLC *vlc, const uint16_t len_count[15], static av_cold void rv10_build_vlc(VLCElem vlc[], int table_size,
const uint16_t len_count[15],
const uint8_t sym_rl[][2], int sym_rl_elems) const uint8_t sym_rl[][2], int sym_rl_elems)
{ {
uint16_t syms[MAX_VLC_ENTRIES]; uint16_t syms[MAX_VLC_ENTRIES];
@ -323,32 +324,26 @@ static av_cold void rv10_build_vlc(VLC *vlc, const uint16_t len_count[15],
for (unsigned tmp = nb_lens + len_count[i]; nb_lens < tmp; nb_lens++) for (unsigned tmp = nb_lens + len_count[i]; nb_lens < tmp; nb_lens++)
lens[nb_lens] = i + 2; lens[nb_lens] = i + 2;
av_assert1(nb_lens == nb_syms); av_assert1(nb_lens == nb_syms);
ff_vlc_init_from_lengths(vlc, DC_VLC_BITS, nb_lens, lens, 1, ff_vlc_init_table_from_lengths(vlc, table_size, DC_VLC_BITS, nb_lens,
syms, 2, 2, 0, VLC_INIT_STATIC_OVERLONG, NULL); lens, 1, syms, 2, 2, 0, 0);
} }
static av_cold void rv10_init_static(void) static av_cold void rv10_init_static(void)
{ {
static VLCElem table[1472 + 992]; rv10_build_vlc(rv_dc_lum, FF_ARRAY_ELEMS(rv_dc_lum), rv_lum_len_count,
rv_dc_lum.table = table;
rv_dc_lum.table_allocated = 1472;
rv10_build_vlc(&rv_dc_lum, rv_lum_len_count,
rv_sym_run_len, FF_ARRAY_ELEMS(rv_sym_run_len)); rv_sym_run_len, FF_ARRAY_ELEMS(rv_sym_run_len));
for (int i = 0; i < 1 << (DC_VLC_BITS - 7 /* Length of skip prefix */); i++) { for (int i = 0; i < 1 << (DC_VLC_BITS - 7 /* Length of skip prefix */); i++) {
/* All codes beginning with 0x7F have the same length and value. /* All codes beginning with 0x7F have the same length and value.
* Modifying the table directly saves us the useless subtables. */ * Modifying the table directly saves us the useless subtables. */
rv_dc_lum.table[(0x7F << (DC_VLC_BITS - 7)) + i].sym = 255; rv_dc_lum[(0x7F << (DC_VLC_BITS - 7)) + i].sym = 255;
rv_dc_lum.table[(0x7F << (DC_VLC_BITS - 7)) + i].len = 18; rv_dc_lum[(0x7F << (DC_VLC_BITS - 7)) + i].len = 18;
} }
rv_dc_chrom.table = &table[1472]; rv10_build_vlc(rv_dc_chrom, FF_ARRAY_ELEMS(rv_dc_chrom), rv_chrom_len_count,
rv_dc_chrom.table_allocated = 992;
rv10_build_vlc(&rv_dc_chrom, rv_chrom_len_count,
rv_sym_run_len, FF_ARRAY_ELEMS(rv_sym_run_len) - 2); rv_sym_run_len, FF_ARRAY_ELEMS(rv_sym_run_len) - 2);
for (int i = 0; i < 1 << (DC_VLC_BITS - 9 /* Length of skip prefix */); i++) { for (int i = 0; i < 1 << (DC_VLC_BITS - 9 /* Length of skip prefix */); i++) {
/* Same as above. */ /* Same as above. */
rv_dc_chrom.table[(0x1FE << (DC_VLC_BITS - 9)) + i].sym = 255; rv_dc_chrom[(0x1FE << (DC_VLC_BITS - 9)) + i].sym = 255;
rv_dc_chrom.table[(0x1FE << (DC_VLC_BITS - 9)) + i].len = 18; rv_dc_chrom[(0x1FE << (DC_VLC_BITS - 9)) + i].len = 18;
} }
} }