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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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26
src/utils/huffman_utils.c
View File

@ -91,7 +91,8 @@ static int BuildHuffmanTable(HuffmanCode* const root_table, int root_bits,
assert(code_lengths_size != 0);
assert(code_lengths != NULL);
assert(root_table != NULL);
assert((root_table != NULL && sorted != NULL) ||
(root_table == NULL && sorted == NULL));
assert(root_bits > 0);
// Build histogram of code lengths.
@ -120,16 +121,22 @@ static int BuildHuffmanTable(HuffmanCode* const root_table, int root_bits,
for (symbol = 0; symbol < code_lengths_size; ++symbol) {
const int symbol_code_length = code_lengths[symbol];
if (code_lengths[symbol] > 0) {
sorted[offset[symbol_code_length]++] = symbol;
if (sorted != NULL) {
sorted[offset[symbol_code_length]++] = symbol;
} else {
offset[symbol_code_length]++;
}
}
}
// Special case code with only one value.
if (offset[MAX_ALLOWED_CODE_LENGTH] == 1) {
HuffmanCode code;
code.bits = 0;
code.value = (uint16_t)sorted[0];
ReplicateValue(table, 1, total_size, code);
if (sorted != NULL) {
HuffmanCode code;
code.bits = 0;
code.value = (uint16_t)sorted[0];
ReplicateValue(table, 1, total_size, code);
}
return total_size;
}
@ -151,6 +158,7 @@ static int BuildHuffmanTable(HuffmanCode* const root_table, int root_bits,
if (num_open < 0) {
return 0;
}
if (root_table == NULL) continue;
for (; count[len] > 0; --count[len]) {
HuffmanCode code;
code.bits = (uint8_t)len;
@ -169,6 +177,7 @@ static int BuildHuffmanTable(HuffmanCode* const root_table, int root_bits,
if (num_open < 0) {
return 0;
}
if (root_table == NULL) continue;
for (; count[len] > 0; --count[len]) {
HuffmanCode code;
if ((key & mask) != low) {
@ -206,7 +215,10 @@ int VP8LBuildHuffmanTable(HuffmanCode* const root_table, int root_bits,
const int code_lengths[], int code_lengths_size) {
int total_size;
assert(code_lengths_size <= MAX_CODE_LENGTHS_SIZE);
if (code_lengths_size <= SORTED_SIZE_CUTOFF) {
if (root_table == NULL) {
total_size = BuildHuffmanTable(NULL, root_bits,
code_lengths, code_lengths_size, NULL);
} else if (code_lengths_size <= SORTED_SIZE_CUTOFF) {
// use local stack-allocated array.
uint16_t sorted[SORTED_SIZE_CUTOFF];
total_size = BuildHuffmanTable(root_table, root_bits,

2
src/utils/huffman_utils.h
View File

@ -78,6 +78,8 @@ void VP8LHtreeGroupsFree(HTreeGroup* const htree_groups);
// the huffman table.
// Returns built table size or 0 in case of error (invalid tree or
// memory error).
// If root_table is NULL, it returns 0 if a lookup cannot be built, something
// > 0 otherwise (but not the table size).
int VP8LBuildHuffmanTable(HuffmanCode* const root_table, int root_bits,
const int code_lengths[], int code_lengths_size);