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Modify unpack_vlcs() so that there are fewer dereferences through the 

main (heavily iterated) loop.

Originally committed as revision 19934 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Mike Melanson 2009-09-21 01:37:50 +00:00
parent 40461e54ce
commit ee3d7f5852
1 changed files with 15 additions and 9 deletions
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24
libavcodec/vp3.c
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@ -1035,9 +1035,15 @@ static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
int zero_run = 0;
DCTELEM coeff = 0;
Vp3Fragment *fragment;
uint8_t *perm= s->scantable.permutated;
int bits_to_get;
/* local references to structure members to avoid repeated deferences */
uint8_t *perm= s->scantable.permutated;
int *coded_fragment_list = s->coded_fragment_list;
Vp3Fragment *all_fragments = s->all_fragments;
uint8_t *coeff_counts = s->coeff_counts;
VLC_TYPE (*vlc_table)[2] = table->table;
if ((first_fragment >= s->fragment_count) ||
(last_fragment >= s->fragment_count)) {
@ -1047,15 +1053,15 @@ static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
}
for (i = first_fragment; i <= last_fragment; i++) {
int fragment_num = s->coded_fragment_list[i];
int fragment_num = coded_fragment_list[i];
if (s->coeff_counts[fragment_num] > coeff_index)
if (coeff_counts[fragment_num] > coeff_index)
continue;
fragment = &s->all_fragments[fragment_num];
fragment = &all_fragments[fragment_num];
if (!eob_run) {
/* decode a VLC into a token */
token = get_vlc2(gb, table->table, 5, 3);
token = get_vlc2(gb, vlc_table, 5, 3);
/* use the token to get a zero run, a coefficient, and an eob run */
if (token <= 6) {
eob_run = eob_run_base[token];
@ -1076,16 +1082,16 @@ static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
}
if (!eob_run) {
s->coeff_counts[fragment_num] += zero_run;
if (s->coeff_counts[fragment_num] < 64){
coeff_counts[fragment_num] += zero_run;
if (coeff_counts[fragment_num] < 64){
fragment->next_coeff->coeff= coeff;
fragment->next_coeff->index= perm[s->coeff_counts[fragment_num]++]; //FIXME perm here already?
fragment->next_coeff->index= perm[coeff_counts[fragment_num]++]; //FIXME perm here already?
fragment->next_coeff->next= s->next_coeff;
s->next_coeff->next=NULL;
fragment->next_coeff= s->next_coeff++;
}
} else {
s->coeff_counts[fragment_num] |= 128;
coeff_counts[fragment_num] |= 128;
eob_run--;
}
}