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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include "zc4_posting_header.h"
#include "zc4_posting_params.h"
#include <vespa/searchlib/bitcompression/compression.h>
namespace search::diskindex {
Zc4PostingHeader::Zc4PostingHeader()
: _has_more(false),
_doc_id_k(K_VALUE_ZCPOSTING_LASTDOCID),
_num_docs(0u),
_doc_ids_size(0u),
_l1_skip_size(0u),
_l2_skip_size(0u),
_l3_skip_size(0u),
_l4_skip_size(0u),
_features_size(0u),
_last_doc_id(0)
{
}
void
Zc4PostingHeader::read(bitcompression::DecodeContext64Base &decode_context, const Zc4PostingParams ¶ms)
{
using EC = bitcompression::FeatureEncodeContext<true>;
_num_docs = decode_context.decode_exp_golomb(K_VALUE_ZCPOSTING_NUMDOCS) + 1;
bool has_more = (_num_docs >= params._min_chunk_docs) ? (decode_context.readBits(1) != 0) : false;
_doc_id_k = params._dynamic_k ? EC::calcDocIdK((_has_more || has_more) ? 1 : _num_docs, params._doc_id_limit) : K_VALUE_ZCPOSTING_LASTDOCID;
if (_num_docs < params._min_skip_docs && !_has_more) {
_doc_ids_size = 0;
_l1_skip_size = 0;
_l2_skip_size = 0;
_l3_skip_size = 0;
_l4_skip_size = 0;
_features_size = 0;
_last_doc_id = 0;
} else {
_doc_ids_size = decode_context.decode_exp_golomb(K_VALUE_ZCPOSTING_DOCIDSSIZE) + 1;
_l1_skip_size = decode_context.decode_exp_golomb(K_VALUE_ZCPOSTING_L1SKIPSIZE);
_l2_skip_size = (_l1_skip_size != 0) ? decode_context.decode_exp_golomb(K_VALUE_ZCPOSTING_L2SKIPSIZE) : 0;
_l3_skip_size = (_l2_skip_size != 0) ? decode_context.decode_exp_golomb(K_VALUE_ZCPOSTING_L3SKIPSIZE) : 0;
_l4_skip_size = (_l3_skip_size != 0) ? decode_context.decode_exp_golomb(K_VALUE_ZCPOSTING_L4SKIPSIZE) : 0;
_features_size = params._encode_features ? decode_context.decode_exp_golomb(K_VALUE_ZCPOSTING_FEATURESSIZE) : 0;
_last_doc_id = params._doc_id_limit - 1 - decode_context.decode_exp_golomb(_doc_id_k);
decode_context.align(8);
}
_has_more = has_more;
}
}
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