mirror of
https://github.com/moses-smt/mosesdecoder.git
synced 2024-09-11 11:25:40 +03:00
132 lines
5.5 KiB
C++
132 lines
5.5 KiB
C++
#include "lm/trie.hh"
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#include "lm/bhiksha.hh"
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#include "util/bit_packing.hh"
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#include "util/exception.hh"
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#include "util/sorted_uniform.hh"
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#include <cassert>
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namespace lm {
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namespace ngram {
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namespace trie {
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namespace {
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class KeyAccessor {
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public:
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KeyAccessor(const void *base, uint64_t key_mask, uint8_t key_bits, uint8_t total_bits)
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: base_(reinterpret_cast<const uint8_t*>(base)), key_mask_(key_mask), key_bits_(key_bits), total_bits_(total_bits) {}
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typedef uint64_t Key;
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Key operator()(uint64_t index) const {
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return util::ReadInt57(base_, index * static_cast<uint64_t>(total_bits_), key_bits_, key_mask_);
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}
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private:
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const uint8_t *const base_;
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const WordIndex key_mask_;
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const uint8_t key_bits_, total_bits_;
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};
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bool FindBitPacked(const void *base, uint64_t key_mask, uint8_t key_bits, uint8_t total_bits, uint64_t begin_index, uint64_t end_index, const uint64_t max_vocab, const uint64_t key, uint64_t &at_index) {
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KeyAccessor accessor(base, key_mask, key_bits, total_bits);
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if (!util::BoundedSortedUniformFind<uint64_t, KeyAccessor, util::PivotSelect<sizeof(WordIndex)>::T>(accessor, begin_index - 1, (uint64_t)0, end_index, max_vocab, key, at_index)) return false;
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return true;
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}
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} // namespace
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uint64_t BitPacked::BaseSize(uint64_t entries, uint64_t max_vocab, uint8_t remaining_bits) {
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uint8_t total_bits = util::RequiredBits(max_vocab) + remaining_bits;
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// Extra entry for next pointer at the end.
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// +7 then / 8 to round up bits and convert to bytes
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// +sizeof(uint64_t) so that ReadInt57 etc don't go segfault.
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// Note that this waste is O(order), not O(number of ngrams).
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return ((1 + entries) * total_bits + 7) / 8 + sizeof(uint64_t);
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}
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void BitPacked::BaseInit(void *base, uint64_t max_vocab, uint8_t remaining_bits) {
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util::BitPackingSanity();
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word_bits_ = util::RequiredBits(max_vocab);
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word_mask_ = (1ULL << word_bits_) - 1ULL;
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if (word_bits_ > 57) UTIL_THROW(util::Exception, "Sorry, word indices more than " << (1ULL << 57) << " are not implemented. Edit util/bit_packing.hh and fix the bit packing functions.");
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total_bits_ = word_bits_ + remaining_bits;
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base_ = static_cast<uint8_t*>(base);
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insert_index_ = 0;
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max_vocab_ = max_vocab;
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}
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template <class Bhiksha> uint64_t BitPackedMiddle<Bhiksha>::Size(uint8_t quant_bits, uint64_t entries, uint64_t max_vocab, uint64_t max_ptr, const Config &config) {
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return Bhiksha::Size(entries + 1, max_ptr, config) + BaseSize(entries, max_vocab, quant_bits + Bhiksha::InlineBits(entries + 1, max_ptr, config));
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}
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template <class Bhiksha> BitPackedMiddle<Bhiksha>::BitPackedMiddle(void *base, uint8_t quant_bits, uint64_t entries, uint64_t max_vocab, uint64_t max_next, const BitPacked &next_source, const Config &config) :
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BitPacked(),
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quant_bits_(quant_bits),
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// If the offset of the method changes, also change TrieSearch::UpdateConfigFromBinary.
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bhiksha_(base, entries + 1, max_next, config),
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next_source_(&next_source) {
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if (entries + 1 >= (1ULL << 57) || (max_next >= (1ULL << 57))) UTIL_THROW(util::Exception, "Sorry, this does not support more than " << (1ULL << 57) << " n-grams of a particular order. Edit util/bit_packing.hh and fix the bit packing functions.");
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BaseInit(reinterpret_cast<uint8_t*>(base) + Bhiksha::Size(entries + 1, max_next, config), max_vocab, quant_bits_ + bhiksha_.InlineBits());
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}
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template <class Bhiksha> util::BitAddress BitPackedMiddle<Bhiksha>::Insert(WordIndex word) {
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assert(word <= word_mask_);
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uint64_t at_pointer = insert_index_ * total_bits_;
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util::WriteInt57(base_, at_pointer, word_bits_, word);
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at_pointer += word_bits_;
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util::BitAddress ret(base_, at_pointer);
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at_pointer += quant_bits_;
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uint64_t next = next_source_->InsertIndex();
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bhiksha_.WriteNext(base_, at_pointer, insert_index_, next);
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++insert_index_;
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return ret;
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}
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template <class Bhiksha> util::BitAddress BitPackedMiddle<Bhiksha>::Find(WordIndex word, NodeRange &range, uint64_t &pointer) const {
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uint64_t at_pointer;
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if (!FindBitPacked(base_, word_mask_, word_bits_, total_bits_, range.begin, range.end, max_vocab_, word, at_pointer)) {
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return util::BitAddress(NULL, 0);
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}
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pointer = at_pointer;
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at_pointer *= total_bits_;
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at_pointer += word_bits_;
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bhiksha_.ReadNext(base_, at_pointer + quant_bits_, pointer, total_bits_, range);
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return util::BitAddress(base_, at_pointer);
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}
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template <class Bhiksha> void BitPackedMiddle<Bhiksha>::FinishedLoading(uint64_t next_end, const Config &config) {
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// Write at insert_index. . .
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uint64_t last_next_write = insert_index_ * total_bits_ +
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// at the offset where the next pointers are stored.
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(total_bits_ - bhiksha_.InlineBits());
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bhiksha_.WriteNext(base_, last_next_write, insert_index_, next_end);
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bhiksha_.FinishedLoading(config);
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}
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util::BitAddress BitPackedLongest::Insert(WordIndex index) {
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assert(index <= word_mask_);
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uint64_t at_pointer = insert_index_ * total_bits_;
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util::WriteInt57(base_, at_pointer, word_bits_, index);
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at_pointer += word_bits_;
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++insert_index_;
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return util::BitAddress(base_, at_pointer);
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}
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util::BitAddress BitPackedLongest::Find(WordIndex word, const NodeRange &range) const {
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uint64_t at_pointer;
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if (!FindBitPacked(base_, word_mask_, word_bits_, total_bits_, range.begin, range.end, max_vocab_, word, at_pointer)) return util::BitAddress(NULL, 0);
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at_pointer = at_pointer * total_bits_ + word_bits_;
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return util::BitAddress(base_, at_pointer);
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}
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template class BitPackedMiddle<DontBhiksha>;
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template class BitPackedMiddle<ArrayBhiksha>;
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} // namespace trie
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} // namespace ngram
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} // namespace lm
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