From ef55dc925fd82cd5811108ae59bdac532470eb11 Mon Sep 17 00:00:00 2001
From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Date: Fri, 7 Mar 2025 16:12:42 +0100
Subject: [PATCH 01/17] avcodec/vlc: Merge VLCElem and RL_VLC_ELEM
It will simplify creating RL-VLCs (which until now used
a stack-based VLC as temporary buffer).
Notice that there would be another option to merge them, namely:
struct VLCElem {
union {
VLCBaseType sym;
int16_t level;
};
int8_t len;
uint8_t run;
};
The main difference to the current patch is that this would change
the type of the length field of VLCElem to int8_t from int16_t.
It turns out that that this would entail additional sign extensions
on ppc, see https://godbolt.org/z/behWYEYE7. I have therefore refrained
from doing so, although it would make the patch simpler.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
libavcodec/cfhd.h | 2 +-
libavcodec/cfhddata.c | 10 +++++-----
libavcodec/dvdec.c | 12 ++++++------
libavcodec/get_bits.h | 6 +++---
libavcodec/mpeg12.c | 2 +-
libavcodec/rl.c | 2 +-
libavcodec/vlc.h | 22 +++++++++++++++-------
7 files changed, 32 insertions(+), 24 deletions(-)
diff --git a/libavcodec/cfhd.h b/libavcodec/cfhd.h
index 9b09c91262..586d3360b6 100644
--- a/libavcodec/cfhd.h
+++ b/libavcodec/cfhd.h
@@ -98,7 +98,7 @@ enum CFHDParam {
typedef struct CFHD_RL_VLC_ELEM {
int16_t level;
- int8_t len;
+ int8_t len8;
uint16_t run;
} CFHD_RL_VLC_ELEM;
diff --git a/libavcodec/cfhddata.c b/libavcodec/cfhddata.c
index a3948a14ca..72b14baf27 100644
--- a/libavcodec/cfhddata.c
+++ b/libavcodec/cfhddata.c
@@ -136,22 +136,22 @@ static av_cold int cfhd_init_vlc(CFHD_RL_VLC_ELEM out[], unsigned out_size,
/** Similar to dv.c, generate signed VLC tables **/
for (unsigned i = j = 0; i < table_size; i++, j++) {
- tmp[j].len = table_vlc[i].len;
+ tmp[j].len8 = table_vlc[i].len;
tmp[j].run = table_vlc[i].run;
tmp[j].level = table_vlc[i].level;
/* Don't include the zero level nor escape bits */
if (table_vlc[i].level && table_vlc[i].run) {
- tmp[j].len++;
+ tmp[j].len8++;
j++;
- tmp[j].len = table_vlc[i].len + 1;
+ tmp[j].len8 = table_vlc[i].len + 1;
tmp[j].run = table_vlc[i].run;
tmp[j].level = -table_vlc[i].level;
}
}
ret = ff_vlc_init_from_lengths(&vlc, VLC_BITS, j,
- &tmp[0].len, sizeof(tmp[0]),
+ &tmp[0].len8, sizeof(tmp[0]),
NULL, 0, 0, 0, 0, logctx);
if (ret < 0)
return ret;
@@ -169,7 +169,7 @@ static av_cold int cfhd_init_vlc(CFHD_RL_VLC_ELEM out[], unsigned out_size,
run = tmp[code].run;
level = tmp[code].level;
}
- out[i].len = len;
+ out[i].len8 = len;
out[i].level = level;
out[i].run = run;
}
diff --git a/libavcodec/dvdec.c b/libavcodec/dvdec.c
index 8297b6d2f3..242708c70a 100644
--- a/libavcodec/dvdec.c
+++ b/libavcodec/dvdec.c
@@ -159,15 +159,15 @@ static av_cold void dv_init_static(void)
/* it's faster to include sign bit in a generic VLC parsing scheme */
for (i = 0, j = 0; i < NB_DV_VLC; i++, j++) {
- tmp[j].len = ff_dv_vlc_len[i];
+ tmp[j].len8 = ff_dv_vlc_len[i];
tmp[j].run = ff_dv_vlc_run[i];
tmp[j].level = ff_dv_vlc_level[i];
if (ff_dv_vlc_level[i]) {
- tmp[j].len++;
+ tmp[j].len8++;
j++;
- tmp[j].len = ff_dv_vlc_len[i] + 1;
+ tmp[j].len8 = ff_dv_vlc_len[i] + 1;
tmp[j].run = ff_dv_vlc_run[i];
tmp[j].level = -ff_dv_vlc_level[i];
}
@@ -176,7 +176,7 @@ static av_cold void dv_init_static(void)
/* NOTE: as a trick, we use the fact the no codes are unused
* to accelerate the parsing of partial codes */
ff_vlc_init_from_lengths(&dv_vlc, TEX_VLC_BITS, j,
- &tmp[0].len, sizeof(tmp[0]),
+ &tmp[0].len8, sizeof(tmp[0]),
NULL, 0, 0, 0, VLC_INIT_USE_STATIC, NULL);
av_assert1(dv_vlc.table_size == 1664);
@@ -193,7 +193,7 @@ static av_cold void dv_init_static(void)
run = tmp[code].run + 1;
level = tmp[code].level;
}
- dv_rl_vlc[i].len = len;
+ dv_rl_vlc[i].len8 = len;
dv_rl_vlc[i].level = level;
dv_rl_vlc[i].run = run;
}
@@ -301,7 +301,7 @@ static void dv_decode_ac(GetBitContext *gb, BlockInfo *mb, int16_t *block)
pos, SHOW_UBITS(re, gb, 16), re_index);
/* our own optimized GET_RL_VLC */
index = NEG_USR32(re_cache, TEX_VLC_BITS);
- vlc_len = dv_rl_vlc[index].len;
+ vlc_len = dv_rl_vlc[index].len8;
if (vlc_len < 0) {
index = NEG_USR32((unsigned) re_cache << TEX_VLC_BITS, -vlc_len) +
dv_rl_vlc[index].level;
diff --git a/libavcodec/get_bits.h b/libavcodec/get_bits.h
index 39d8e5bc1e..1954296569 100644
--- a/libavcodec/get_bits.h
+++ b/libavcodec/get_bits.h
@@ -594,7 +594,7 @@ static inline const uint8_t *align_get_bits(GetBitContext *s)
\
index = SHOW_UBITS(name, gb, bits); \
level = table[index].level; \
- n = table[index].len; \
+ n = table[index].len8; \
\
if (max_depth > 1 && n < 0) { \
SKIP_BITS(name, gb, bits); \
@@ -606,7 +606,7 @@ static inline const uint8_t *align_get_bits(GetBitContext *s)
\
index = SHOW_UBITS(name, gb, nb_bits) + level; \
level = table[index].level; \
- n = table[index].len; \
+ n = table[index].len8; \
if (max_depth > 2 && n < 0) { \
LAST_SKIP_BITS(name, gb, nb_bits); \
if (need_update) { \
@@ -616,7 +616,7 @@ static inline const uint8_t *align_get_bits(GetBitContext *s)
\
index = SHOW_UBITS(name, gb, nb_bits) + level; \
level = table[index].level; \
- n = table[index].len; \
+ n = table[index].len8; \
} \
} \
run = table[index].run; \
diff --git a/libavcodec/mpeg12.c b/libavcodec/mpeg12.c
index 444ea83f3c..0d4a36be04 100644
--- a/libavcodec/mpeg12.c
+++ b/libavcodec/mpeg12.c
@@ -119,7 +119,7 @@ av_cold void ff_init_2d_vlc_rl(const uint16_t table_vlc[][2], RL_VLC_ELEM rl_vlc
level = table_level[code];
}
}
- rl_vlc[i].len = len;
+ rl_vlc[i].len8 = len;
rl_vlc[i].level = level;
rl_vlc[i].run = run;
}
diff --git a/libavcodec/rl.c b/libavcodec/rl.c
index a78242d488..b45cf117c1 100644
--- a/libavcodec/rl.c
+++ b/libavcodec/rl.c
@@ -118,7 +118,7 @@ av_cold void ff_rl_init_vlc(RLTable *rl, unsigned static_size)
if (code >= rl->last) run += 192;
}
}
- rl->rl_vlc[q][i].len = len;
+ rl->rl_vlc[q][i].len8 = len;
rl->rl_vlc[q][i].level = level;
rl->rl_vlc[q][i].run = run;
}
diff --git a/libavcodec/vlc.h b/libavcodec/vlc.h
index bf7b0e65b4..7eecd9651f 100644
--- a/libavcodec/vlc.h
+++ b/libavcodec/vlc.h
@@ -30,9 +30,23 @@
typedef int16_t VLCBaseType;
typedef struct VLCElem {
- VLCBaseType sym, len;
+ union {
+ /// The struct is for use as ordinary VLC (with get_vlc2())
+ struct {
+ VLCBaseType sym;
+ VLCBaseType len;
+ };
+ /// This struct is for use as run-length VLC (with GET_RL_VLC)
+ struct {
+ int16_t level;
+ int8_t len8;
+ uint8_t run;
+ };
+ };
} VLCElem;
+typedef VLCElem RL_VLC_ELEM;
+
typedef struct VLC {
int bits;
VLCElem *table;
@@ -53,12 +67,6 @@ typedef struct VLC_MULTI {
int table_size, table_allocated;
} VLC_MULTI;
-typedef struct RL_VLC_ELEM {
- int16_t level;
- int8_t len;
- uint8_t run;
-} RL_VLC_ELEM;
-
#define vlc_init(vlc, nb_bits, nb_codes, \
bits, bits_wrap, bits_size, \
codes, codes_wrap, codes_size, \
--
2.45.2