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Speedups for unused Huffman groups.

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If we know a Huffman group is unused, do not build
it: just check that it is valid.

Change-Id: Ie8223fe1afa1e769085a23ab92e730edd9060176
This commit is contained in:
Vincent Rabaud
2019-03-11 16:53:06 +01:00
parent 01ac46bae6
commit 067031eaed
3 changed files with 82 additions and 71 deletions
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125
src/dec/vp8l_dec.c
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@ -362,12 +362,8 @@ static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
VP8LMetadata* const hdr = &dec->hdr_;
uint32_t* huffman_image = NULL;
HTreeGroup* htree_groups = NULL;
// When reading htrees, some might be unused, as the format allows it.
// We will still read them but put them in this htree_group_bogus.
HTreeGroup htree_group_bogus;
HuffmanCode* huffman_tables = NULL;
HuffmanCode* huffman_tables_bogus = NULL;
HuffmanCode* next = NULL;
HuffmanCode* huffman_table = NULL;
int num_htree_groups = 1;
int num_htree_groups_max = 1;
int max_alphabet_size = 0;
@ -418,12 +414,6 @@ static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
if (*mapped_group == -1) *mapped_group = num_htree_groups++;
huffman_image[i] = *mapped_group;
}
huffman_tables_bogus = (HuffmanCode*)WebPSafeMalloc(
table_size, sizeof(*huffman_tables_bogus));
if (huffman_tables_bogus == NULL) {
dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
goto Error;
}
} else {
num_htree_groups = num_htree_groups_max;
}
@ -453,63 +443,71 @@ static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
goto Error;
}
next = huffman_tables;
huffman_table = huffman_tables;
for (i = 0; i < num_htree_groups_max; ++i) {
// If the index "i" is unused in the Huffman image, read the coefficients
// but store them to a bogus htree_group.
const int is_bogus = (mapping != NULL && mapping[i] == -1);
HTreeGroup* const htree_group =
is_bogus ? &htree_group_bogus :
&htree_groups[(mapping == NULL) ? i : mapping[i]];
HuffmanCode** const htrees = htree_group->htrees;
HuffmanCode* huffman_tables_i = is_bogus ? huffman_tables_bogus : next;
int size;
int total_size = 0;
int is_trivial_literal = 1;
int max_bits = 0;
for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) {
int alphabet_size = kAlphabetSize[j];
htrees[j] = huffman_tables_i;
if (j == 0 && color_cache_bits > 0) {
alphabet_size += 1 << color_cache_bits;
}
size =
ReadHuffmanCode(alphabet_size, dec, code_lengths, huffman_tables_i);
if (size == 0) {
goto Error;
}
if (is_trivial_literal && kLiteralMap[j] == 1) {
is_trivial_literal = (huffman_tables_i->bits == 0);
}
total_size += huffman_tables_i->bits;
huffman_tables_i += size;
if (j <= ALPHA) {
int local_max_bits = code_lengths[0];
int k;
for (k = 1; k < alphabet_size; ++k) {
if (code_lengths[k] > local_max_bits) {
local_max_bits = code_lengths[k];
}
// If the index "i" is unused in the Huffman image, just make sure the
// coefficients are valid but do not store them.
if (mapping != NULL && mapping[i] == -1) {
for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) {
int alphabet_size = kAlphabetSize[j];
if (j == 0 && color_cache_bits > 0) {
alphabet_size += (1 << color_cache_bits);
}
// Passing in NULL so that nothing gets filled.
if (!ReadHuffmanCode(alphabet_size, dec, code_lengths, NULL)) {
goto Error;
}
max_bits += local_max_bits;
}
}
if (!is_bogus) next = huffman_tables_i;
htree_group->is_trivial_literal = is_trivial_literal;
htree_group->is_trivial_code = 0;
if (is_trivial_literal) {
const int red = htrees[RED][0].value;
const int blue = htrees[BLUE][0].value;
const int alpha = htrees[ALPHA][0].value;
htree_group->literal_arb = ((uint32_t)alpha << 24) | (red << 16) | blue;
if (total_size == 0 && htrees[GREEN][0].value < NUM_LITERAL_CODES) {
htree_group->is_trivial_code = 1;
htree_group->literal_arb |= htrees[GREEN][0].value << 8;
} else {
HTreeGroup* const htree_group =
&htree_groups[(mapping == NULL) ? i : mapping[i]];
HuffmanCode** const htrees = htree_group->htrees;
int size;
int total_size = 0;
int is_trivial_literal = 1;
int max_bits = 0;
for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) {
int alphabet_size = kAlphabetSize[j];
htrees[j] = huffman_table;
if (j == 0 && color_cache_bits > 0) {
alphabet_size += (1 << color_cache_bits);
}
size = ReadHuffmanCode(alphabet_size, dec, code_lengths, huffman_table);
if (size == 0) {
goto Error;
}
if (is_trivial_literal && kLiteralMap[j] == 1) {
is_trivial_literal = (huffman_table->bits == 0);
}
total_size += huffman_table->bits;
huffman_table += size;
if (j <= ALPHA) {
int local_max_bits = code_lengths[0];
int k;
for (k = 1; k < alphabet_size; ++k) {
if (code_lengths[k] > local_max_bits) {
local_max_bits = code_lengths[k];
}
}
max_bits += local_max_bits;
}
}
htree_group->is_trivial_literal = is_trivial_literal;
htree_group->is_trivial_code = 0;
if (is_trivial_literal) {
const int red = htrees[RED][0].value;
const int blue = htrees[BLUE][0].value;
const int alpha = htrees[ALPHA][0].value;
htree_group->literal_arb = ((uint32_t)alpha << 24) | (red << 16) | blue;
if (total_size == 0 && htrees[GREEN][0].value < NUM_LITERAL_CODES) {
htree_group->is_trivial_code = 1;
htree_group->literal_arb |= htrees[GREEN][0].value << 8;
}
}
htree_group->use_packed_table =
!htree_group->is_trivial_code && (max_bits < HUFFMAN_PACKED_BITS);
if (htree_group->use_packed_table) BuildPackedTable(htree_group);
}
htree_group->use_packed_table =
!htree_group->is_trivial_code && (max_bits < HUFFMAN_PACKED_BITS);
if (htree_group->use_packed_table) BuildPackedTable(htree_group);
}
ok = 1;
@ -521,7 +519,6 @@ static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
Error:
WebPSafeFree(code_lengths);
WebPSafeFree(huffman_tables_bogus);
WebPSafeFree(mapping);
if (!ok) {
WebPSafeFree(huffman_image);