double ZopfliCalculateBlockSize(const unsigned short* litlens,
const unsigned short* dists,
size_t lstart, size_t lend, int btype) {
size_t ll_counts[288];
size_t d_counts[32];
unsigned ll_lengths[288];
unsigned d_lengths[32];
double result = 3; /*bfinal and btype bits*/
assert(btype == 1 || btype == 2); /* This is not for uncompressed blocks. */
if(btype == 1) {
GetFixedTree(ll_lengths, d_lengths);
} else {
ZopfliLZ77Counts(litlens, dists, lstart, lend, ll_counts, d_counts);
ZopfliCalculateBitLengths(ll_counts, 288, 15, ll_lengths);
ZopfliCalculateBitLengths(d_counts, 32, 15, d_lengths);
PatchDistanceCodesForBuggyDecoders(d_lengths);
result += CalculateTreeSize(ll_lengths, d_lengths, ll_counts, d_counts);
}
result += CalculateBlockSymbolSize(
ll_lengths, d_lengths, litlens, dists, lstart, lend);
return result;
}
/*
Calculates the bit lengths for the symbols for dynamic blocks. Chooses bit
lengths that give the smallest size of tree encoding + encoding of all the
symbols to have smallest output size. This are not necessarily the ideal Huffman
bit lengths.
*/
static void GetDynamicLengths(const unsigned short* litlens,
const unsigned short* dists,
size_t lstart, size_t lend,
unsigned* ll_lengths, unsigned* d_lengths) {
size_t ll_counts[288];
size_t d_counts[32];
ZopfliLZ77Counts(litlens, dists, lstart, lend, ll_counts, d_counts);
OptimizeHuffmanForRle(288, ll_counts);
OptimizeHuffmanForRle(32, d_counts);
ZopfliCalculateBitLengths(ll_counts, 288, 15, ll_lengths);
ZopfliCalculateBitLengths(d_counts, 32, 15, d_lengths);
PatchDistanceCodesForBuggyDecoders(d_lengths);
}
