The Tor Browser: browser/components/translation/cld2/internal/cldutil.cc@6474c204b198 (annotated)

browser/components/translation/cld2/internal/cldutil.cc@6474c204b198 (annotated)

browser/components/translation/cld2/internal/cldutil.cc

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 // Copyright 2013 Google Inc. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 //
 // Author: dsites@google.com (Dick Sites)
 // Updated 2014.01 for dual table lookup
 //
 #include "cldutil.h"
 #include <string>
 #include "cld2tablesummary.h"
 #include "integral_types.h"
 #include "port.h"
 #include "utf8statetable.h"
 namespace CLD2 {
 // Caller supplies the right tables in scoringcontext
 // Runtime routines for hashing, looking up, and scoring
 // unigrams (CJK), bigrams (CJK), quadgrams, and octagrams.
 // Unigrams and bigrams are for CJK languages only, including simplified/
 // traditional Chinese, Japanese, Korean, Vietnamese Han characters, and
 // Zhuang Han characters. Surrounding spaces are not considered.
 // Quadgrams and octagrams for for non-CJK and include two bits indicating
 // preceding and trailing spaces (word boundaries).
 static const int kMinCJKUTF8CharBytes = 3;
 static const int kMinGramCount = 3;
 static const int kMaxGramCount = 16;
 static const int UTFmax = 4;        // Max number of bytes in a UTF-8 character
   // 1 to skip ASCII space, vowels AEIOU aeiou and UTF-8 continuation bytes 80-BF
   static const uint8 kSkipSpaceVowelContinue[256] = {
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,1,0,0,0,1,0,0, 0,1,0,0,0,0,0,1, 0,0,0,0,0,1,0,0, 0,0,0,0,0,0,0,0,
 ,1,0,0,0,1,0,0, 0,1,0,0,0,0,0,1, 0,0,0,0,0,1,0,0, 0,0,0,0,0,0,0,0,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
   };
   // 1 to skip ASCII space, and UTF-8 continuation bytes 80-BF
   static const uint8 kSkipSpaceContinue[256] = {
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
   };
   // Always advances one UTF-8 character
   static const uint8 kAdvanceOneChar[256] = {
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2,
 ,3,3,3,3,3,3,3, 3,3,3,3,3,3,3,3, 4,4,4,4,4,4,4,4, 4,4,4,4,4,4,4,4,
   };
   // Advances *only* on space (or illegal byte)
   static const uint8 kAdvanceOneCharSpace[256] = {
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
   };
 // Routines to access a hash table of <key:wordhash, value:probs> pairs
 // Buckets have 4-byte wordhash for sizes < 32K buckets, but only
 // 2-byte wordhash for sizes >= 32K buckets, with other wordhash bits used as
 // bucket subscript.
 // Probs is a packed: three languages plus a subscript for probability table
 // Buckets have all the keys together, then all the values.Key array never
 // crosses a cache-line boundary, so no-match case takes exactly one cache miss.
 // Match case may sometimes take an additional cache miss on value access.
 //
 // Other possibilites include 5 or 10 6-byte entries plus pad to make 32 or 64
 // byte buckets with single cache miss.
 // Or 2-byte key and 6-byte value, allowing 5 languages instead  of three.
 //------------------------------------------------------------------------------
 //----------------------------------------------------------------------------//
 // Hashing groups of 1/2/4/8 letters, perhaps with spaces or underscores      //
 //----------------------------------------------------------------------------//
 //----------------------------------------------------------------------------//
 // Scoring single groups of letters                                           //
 //----------------------------------------------------------------------------//
 // BIGRAM, QUADGRAM, OCTAGRAM score one => tote
 // Input: 4-byte entry of 3 language numbers and one probability subscript, plus
 //  an accumulator tote. (language 0 means unused entry)
 // Output: running sums in tote updated
 void ProcessProbV2Tote(uint32 probs, Tote* tote) {
   uint8 prob123 = (probs >> 0) & 0xff;
   const uint8* prob123_entry = LgProb2TblEntry(prob123);
   uint8 top1 = (probs >> 8) & 0xff;
   if (top1 > 0) {tote->Add(top1, LgProb3(prob123_entry, 0));}
   uint8 top2 = (probs >> 16) & 0xff;
   if (top2 > 0) {tote->Add(top2, LgProb3(prob123_entry, 1));}
   uint8 top3 = (probs >> 24) & 0xff;
   if (top3 > 0) {tote->Add(top3, LgProb3(prob123_entry, 2));}
 }
 // Return score for a particular per-script language, or zero
 int GetLangScore(uint32 probs, uint8 pslang) {
   uint8 prob123 = (probs >> 0) & 0xff;
   const uint8* prob123_entry = LgProb2TblEntry(prob123);
   int retval = 0;
   uint8 top1 = (probs >> 8) & 0xff;
   if (top1 == pslang) {retval += LgProb3(prob123_entry, 0);}
   uint8 top2 = (probs >> 16) & 0xff;
   if (top2 == pslang) {retval += LgProb3(prob123_entry, 1);}
   uint8 top3 = (probs >> 24) & 0xff;
   if (top3 == pslang) {retval += LgProb3(prob123_entry, 2);}
   return retval;
 }
 //----------------------------------------------------------------------------//
 // Routines to accumulate probabilities                                       //
 //----------------------------------------------------------------------------//
 // BIGRAM, using hash table, always advancing by 1 char
 // Caller supplies table, such as &kCjkBiTable_obj or &kGibberishTable_obj
 // Score all bigrams in isrc, using languages that have bigrams (CJK)
 // Return number of bigrams that hit in the hash table
 int DoBigramScoreV3(const CLD2TableSummary* bigram_obj,
                          const char* isrc, int srclen, Tote* chunk_tote) {
   int hit_count = 0;
   const char* src = isrc;
   // Hashtable-based CJK bigram lookup
   const uint8* usrc = reinterpret_cast<const uint8*>(src);
   const uint8* usrclimit1 = usrc + srclen - UTFmax;
   while (usrc < usrclimit1) {
     int len = kAdvanceOneChar[usrc[0]];
     int len2 = kAdvanceOneChar[usrc[len]] + len;
     if ((kMinCJKUTF8CharBytes * 2) <= len2) {      // Two CJK chars possible
       // Lookup and score this bigram
       // Always ignore pre/post spaces
       uint32 bihash = BiHashV2(reinterpret_cast<const char*>(usrc), len2);
       uint32 probs = QuadHashV3Lookup4(bigram_obj, bihash);
       // Now go indirect on the subscript
       probs = bigram_obj->kCLDTableInd[probs &
         ~bigram_obj->kCLDTableKeyMask];
       // Process the bigram
       if (probs != 0) {
         ProcessProbV2Tote(probs, chunk_tote);
         ++hit_count;
       }
     }
     usrc += len;  // Advance by one char
   }
   return hit_count;
 }
 // Score up to 64KB of a single script span in one pass
 // Make a dummy entry off the end to calc length of last span
 // Return offset of first unused input byte
 int GetUniHits(const char* text,
                      int letter_offset, int letter_limit,
                      ScoringContext* scoringcontext,
                      ScoringHitBuffer* hitbuffer) {
   const char* isrc = &text[letter_offset];
   const char* src = isrc;
   // Limit is end, which has extra 20 20 20 00 past len
   const char* srclimit = &text[letter_limit];
   // Local copies
   const UTF8PropObj* unigram_obj =
     scoringcontext->scoringtables->unigram_obj;
   int next_base = hitbuffer->next_base;
   int next_base_limit = hitbuffer->maxscoringhits;
   // Visit all unigrams
   if (src[0] == ' ') {++src;}   // skip any initial space
   while (src < srclimit) {
     const uint8* usrc = reinterpret_cast<const uint8*>(src);
     int len = kAdvanceOneChar[usrc[0]];
     src += len;
     // Look up property of one UTF-8 character and advance over it.
     // Updates usrc and len (bad interface design), hence increment above
     int propval = UTF8GenericPropertyBigOneByte(unigram_obj, &usrc, &len);
     if (propval > 0) {
       // Save indirect subscript for later scoring; 1 or 2 langprobs
       int indirect_subscr = propval;
       hitbuffer->base[next_base].offset = src - text;     // Offset in text
       hitbuffer->base[next_base].indirect = indirect_subscr;
       ++next_base;
     }
     if (next_base >= next_base_limit) {break;}
   }
   hitbuffer->next_base = next_base;
   // Make a dummy entry off the end to calc length of last span
   int dummy_offset = src - text;
   hitbuffer->base[hitbuffer->next_base].offset = dummy_offset;
   hitbuffer->base[hitbuffer->next_base].indirect = 0;
   return src - text;
 }
 // Score up to 64KB of a single script span, doing both delta-bi and
 // distinct bis in one pass
 void GetBiHits(const char* text,
                      int letter_offset, int letter_limit,
                      ScoringContext* scoringcontext,
                      ScoringHitBuffer* hitbuffer) {
   const char* isrc = &text[letter_offset];
   const char* src = isrc;
   // Limit is end
   const char* srclimit1 = &text[letter_limit];
   // Local copies
   const CLD2TableSummary* deltabi_obj =
     scoringcontext->scoringtables->deltabi_obj;
   const CLD2TableSummary* distinctbi_obj =
     scoringcontext->scoringtables->distinctbi_obj;
   int next_delta = hitbuffer->next_delta;
   int next_delta_limit = hitbuffer->maxscoringhits;
   int next_distinct = hitbuffer->next_distinct;
   // We can do 2 inserts per loop, so -1
   int next_distinct_limit = hitbuffer->maxscoringhits - 1;
   while (src < srclimit1) {
     const uint8* usrc = reinterpret_cast<const uint8*>(src);
     int len = kAdvanceOneChar[usrc[0]];
     int len2 = kAdvanceOneChar[usrc[len]] + len;
     if ((kMinCJKUTF8CharBytes * 2) <= len2) {      // Two CJK chars possible
       // Lookup and this bigram and save <offset, indirect>
       uint32 bihash = BiHashV2(src, len2);
       uint32 probs = QuadHashV3Lookup4(deltabi_obj, bihash);
       // Now go indirect on the subscript
       if (probs != 0) {
         // Save indirect subscript for later scoring; 1 langprob
         int indirect_subscr = probs & ~deltabi_obj->kCLDTableKeyMask;
         hitbuffer->delta[next_delta].offset = src - text;
         hitbuffer->delta[next_delta].indirect = indirect_subscr;
         ++next_delta;
       }
       // Lookup this distinct bigram and save <offset, indirect>
       probs = QuadHashV3Lookup4(distinctbi_obj, bihash);
       if (probs != 0) {
         int indirect_subscr = probs & ~distinctbi_obj->kCLDTableKeyMask;
         hitbuffer->distinct[next_distinct].offset = src - text;
         hitbuffer->distinct[next_distinct].indirect = indirect_subscr;
         ++next_distinct;
       }
     }
     src += len;  // Advance by one char (not two)
     // Almost always srclimit hit first
     if (next_delta >= next_delta_limit) {break;}
     if (next_distinct >= next_distinct_limit) {break;}
   }
   hitbuffer->next_delta = next_delta;
   hitbuffer->next_distinct = next_distinct;
   // Make a dummy entry off the end to calc length of last span
   int dummy_offset = src - text;
   hitbuffer->delta[hitbuffer->next_delta].offset = dummy_offset;
   hitbuffer->delta[hitbuffer->next_delta].indirect = 0;
   hitbuffer->distinct[hitbuffer->next_distinct].offset = dummy_offset;
   hitbuffer->distinct[hitbuffer->next_distinct].indirect = 0;
 }
 // Score up to 64KB of a single script span in one pass
 // Make a dummy entry off the end to calc length of last span
 // Return offset of first unused input byte
 int GetQuadHits(const char* text,
                      int letter_offset, int letter_limit,
                      ScoringContext* scoringcontext,
                      ScoringHitBuffer* hitbuffer) {
   const char* isrc = &text[letter_offset];
   const char* src = isrc;
   // Limit is end, which has extra 20 20 20 00 past len
   const char* srclimit = &text[letter_limit];
   // Local copies
   const CLD2TableSummary* quadgram_obj =
     scoringcontext->scoringtables->quadgram_obj;
   const CLD2TableSummary* quadgram_obj2 =
     scoringcontext->scoringtables->quadgram_obj2;
   int next_base = hitbuffer->next_base;
   int next_base_limit = hitbuffer->maxscoringhits;
   // Run a little cache of last quad hits to catch overly-repetitive "text"
   // We don't care if we miss a couple repetitions at scriptspan boundaries
   int next_prior_quadhash = 0;
   uint32 prior_quadhash[2] = {0, 0};
   // Visit all quadgrams
   if (src[0] == ' ') {++src;}   // skip any initial space
   while (src < srclimit) {
     // Find one quadgram
     const char* src_end = src;
     src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
     src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
     const char* src_mid = src_end;
     src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
     src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
     int len = src_end - src;
     // Hash the quadgram
     uint32 quadhash = QuadHashV2(src, len);
     // Filter out recent repeats
     if ((quadhash != prior_quadhash[0]) && (quadhash != prior_quadhash[1])) {
       // Look up this quadgram and save <offset, indirect>
       uint32 indirect_flag = 0;   // For dual tables
       const CLD2TableSummary* hit_obj = quadgram_obj;
       uint32 probs = QuadHashV3Lookup4(quadgram_obj, quadhash);
       if ((probs == 0) && (quadgram_obj2->kCLDTableSize != 0)) {
         // Try lookup in dual table if not found in first one
         // Note: we need to know later which of two indirect tables to use.
         indirect_flag = 0x80000000u;
         hit_obj = quadgram_obj2;
         probs = QuadHashV3Lookup4(quadgram_obj2, quadhash);
       }
       if (probs != 0) {
         // Round-robin two entries of actual hits
         prior_quadhash[next_prior_quadhash] = quadhash;
         next_prior_quadhash = (next_prior_quadhash + 1) & 1;
         // Save indirect subscript for later scoring; 1 or 2 langprobs
         int indirect_subscr = probs & ~hit_obj->kCLDTableKeyMask;
         hitbuffer->base[next_base].offset = src - text;     // Offset in text
         // Flip the high bit for table2
         hitbuffer->base[next_base].indirect = indirect_subscr | indirect_flag;
         ++next_base;
       }
     }
     // Advance: all the way past word if at end-of-word, else 2 chars
     if (src_end[0] == ' ') {
       src = src_end;
     } else {
       src = src_mid;
     }
     // Skip over space at end of word, or ASCII vowel in middle of word
     // Use kAdvanceOneCharSpace instead to get rid of vowel hack
     if (src < srclimit) {
       src += kAdvanceOneCharSpaceVowel[(uint8)src[0]];
     } else {
       // Advancing by 4/8/16 can overshoot, but we are about to exit anyway
       src = srclimit;
     }
     if (next_base >= next_base_limit) {break;}
   }
   hitbuffer->next_base = next_base;
   // Make a dummy entry off the end to calc length of last span
   int dummy_offset = src - text;
   hitbuffer->base[hitbuffer->next_base].offset = dummy_offset;
   hitbuffer->base[hitbuffer->next_base].indirect = 0;
   return src - text;
 }
 // inputs:
 //  const tables
 //  const char* isrc, int srclen (in sscriptbuffer)
 // intermediates:
 //  vector of octa <offset, probs>   (which need indirect table to decode)
 //  vector of distinct <offset, probs>   (which need indirect table to decode)
 // Score up to 64KB of a single script span, doing both delta-octa and
 // distinct words in one pass
 void GetOctaHits(const char* text,
                      int letter_offset, int letter_limit,
                      ScoringContext* scoringcontext,
                      ScoringHitBuffer* hitbuffer) {
   const char* isrc = &text[letter_offset];
   const char* src = isrc;
   // Limit is end+1, to include extra space char (0x20) off the end
   const char* srclimit = &text[letter_limit + 1];
   // Local copies
   const CLD2TableSummary* deltaocta_obj =
     scoringcontext->scoringtables->deltaocta_obj;
   int next_delta = hitbuffer->next_delta;
   int next_delta_limit = hitbuffer->maxscoringhits;
   const CLD2TableSummary* distinctocta_obj =
     scoringcontext->scoringtables->distinctocta_obj;
   int next_distinct = hitbuffer->next_distinct;
   // We can do 2 inserts per loop, so -1
   int next_distinct_limit = hitbuffer->maxscoringhits - 1;
   // Run a little cache of last octa hits to catch overly-repetitive "text"
   // We don't care if we miss a couple repetitions at scriptspan boundaries
   int next_prior_octahash = 0;
   uint64 prior_octahash[2] = {0, 0};
   // Score all words truncated to 8 characters
   int charcount = 0;
   // Skip any initial space
   if (src[0] == ' ') {++src;}
   // Begin the first word
   const char* prior_word_start = src;
   const char* word_start = src;
   const char* word_end = word_start;
   while (src < srclimit) {
     // Terminate previous word or continue current word
     if (src[0] == ' ') {
       int len = word_end - word_start;
       // Hash the word
       uint64 wordhash40 = OctaHash40(word_start, len);
       uint32 probs;
       // Filter out recent repeats. Unlike quads, we update even if no hit,
       // so we can get hits on same word if separated by non-hit words
       if ((wordhash40 != prior_octahash[0]) &&
           (wordhash40 != prior_octahash[1])) {
         // Round-robin two entries of words
         prior_octahash[next_prior_octahash] = wordhash40;
         next_prior_octahash = 1 - next_prior_octahash;    // Alternates 0,1,0,1
         // (1) Lookup distinct word PAIR. For a pair, we want an asymmetrical
         // function of the two word hashs. For words A B C, B-A and C-B are good
         // enough and fast. We use the same table as distinct single words
         // Do not look up a pair of identical words -- all pairs hash to zero
         // Both 1- and 2-word distinct lookups are in distinctocta_obj now
         // Do this first, because it has the lowest offset
         uint64 tmp_prior_hash = prior_octahash[next_prior_octahash];
         if ((tmp_prior_hash != 0) && (tmp_prior_hash != wordhash40)) {
           uint64 pair_hash = PairHash(tmp_prior_hash, wordhash40);
           probs = OctaHashV3Lookup4(distinctocta_obj, pair_hash);
           if (probs != 0) {
             int indirect_subscr = probs & ~distinctocta_obj->kCLDTableKeyMask;
             hitbuffer->distinct[next_distinct].offset = prior_word_start - text;
             hitbuffer->distinct[next_distinct].indirect = indirect_subscr;
             ++next_distinct;
           }
         }
         // (2) Lookup this distinct word and save <offset, indirect>
         probs = OctaHashV3Lookup4(distinctocta_obj, wordhash40);
         if (probs != 0) {
           int indirect_subscr = probs & ~distinctocta_obj->kCLDTableKeyMask;
           hitbuffer->distinct[next_distinct].offset = word_start - text;
           hitbuffer->distinct[next_distinct].indirect = indirect_subscr;
           ++next_distinct;
         }
         // (3) Lookup this word and save <offset, indirect>
         probs = OctaHashV3Lookup4(deltaocta_obj, wordhash40);
         if (probs != 0) {
           // Save indirect subscript for later scoring; 1 langprob
           int indirect_subscr = probs & ~deltaocta_obj->kCLDTableKeyMask;
           hitbuffer->delta[next_delta].offset = word_start - text;
           hitbuffer->delta[next_delta].indirect = indirect_subscr;
           ++next_delta;
         }
       }
       // Begin the next word
       charcount = 0;
       prior_word_start = word_start;
       word_start = src + 1;   // Over the space
       word_end = word_start;
     } else {
       ++charcount;
     }
     // Advance to next char
     src += UTF8OneCharLen(src);
     if (charcount <= 8) {
       word_end = src;
     }
     // Almost always srclimit hit first
     if (next_delta >= next_delta_limit) {break;}
     if (next_distinct >= next_distinct_limit) {break;}
   }
   hitbuffer->next_delta = next_delta;
   hitbuffer->next_distinct = next_distinct;
   // Make a dummy entry off the end to calc length of last span
   int dummy_offset = src - text;
   hitbuffer->delta[hitbuffer->next_delta].offset = dummy_offset;
   hitbuffer->delta[hitbuffer->next_delta].indirect = 0;
   hitbuffer->distinct[hitbuffer->next_distinct].offset = dummy_offset;
   hitbuffer->distinct[hitbuffer->next_distinct].indirect = 0;
 }
 //----------------------------------------------------------------------------//
 // Reliability calculations, for single language and between languages        //
 //----------------------------------------------------------------------------//
 // Return reliablity of result 0..100 for top two scores
 // delta==0 is 0% reliable, delta==fully_reliable_thresh is 100% reliable
 // (on a scale where +1 is a factor of  2 ** 1.6 = 3.02)
 // Threshold is uni/quadgram increment count, bounded above and below.
 //
 // Requiring a factor of 3 improvement (e.g. +1 log base 3)
 // for each scored quadgram is too stringent, so I've backed this off to a
 // factor of 2 (e.g. +5/8 log base 3).
 //
 // I also somewhat lowered the Min/MaxGramCount limits above
 //
 // Added: if fewer than 8 quads/unis, max reliability is 12*n percent
 //
 int ReliabilityDelta(int value1, int value2, int gramcount) {
   int max_reliability_percent = 100;
   if (gramcount < 8) {
     max_reliability_percent = 12 * gramcount;
   }
   int fully_reliable_thresh = (gramcount * 5) >> 3;     // see note above
   if (fully_reliable_thresh < kMinGramCount) {          // Fully = 3..16
     fully_reliable_thresh = kMinGramCount;
   } else if (fully_reliable_thresh > kMaxGramCount) {
     fully_reliable_thresh = kMaxGramCount;
   }
   int delta = value1 - value2;
   if (delta >= fully_reliable_thresh) {return max_reliability_percent;}
   if (delta <= 0) {return 0;}
   return minint(max_reliability_percent,
                      (100 * delta) / fully_reliable_thresh);
 }
 // Return reliablity of result 0..100 for top score vs. expected mainsteam score
 // Values are score per 1024 bytes of input
 // ratio = max(top/mainstream, mainstream/top)
 // ratio > 4.0 is 0% reliable, <= 2.0 is 100% reliable
 // Change: short-text word scoring can give unusually good results.
 //  Let top exceed mainstream by 4x at 50% reliable
 //
 // dsites April 2010: These could be tightened up. It would be
 // reasonable with newer data and round-robin table allocation to start ramping
 // down at mean * 1.5 and mean/1.5, while letting mean*2 and mean/2 pass,
 // but just barely.
 //
 // dsites March 2013: Tightened up a bit.
 static const double kRatio100 = 1.5;
 static const double kRatio0 = 4.0;
 int ReliabilityExpected(int actual_score_1kb, int expected_score_1kb) {
   if (expected_score_1kb == 0) {return 100;}    // No reliability data available yet
   if (actual_score_1kb == 0) {return 0;}        // zero score = unreliable
   double ratio;
   if (expected_score_1kb > actual_score_1kb) {
     ratio = (1.0 * expected_score_1kb) / actual_score_1kb;
   } else {
     ratio = (1.0 * actual_score_1kb) / expected_score_1kb;
   }
   // Ratio 1.0 .. 1.5 scores 100%
   // Ratio 2.0 scores 80%
   // Linear decline, to ratio 4.0 scores 0%
   if (ratio <= kRatio100) {return 100;}
   if (ratio > kRatio0) {return 0;}
   int percent_good = 100.0 * (kRatio0 - ratio) / (kRatio0 - kRatio100);
   return percent_good;
 }
 // Create a langprob packed value from its parts.
 // qprob is quantized [0..12]
 // We use Latn script to represent any RTypeMany language
 uint32 MakeLangProb(Language lang, int qprob) {
   uint32 pslang = PerScriptNumber(ULScript_Latin, lang);
   uint32 retval = (pslang << 8) | kLgProbV2TblBackmap[qprob];
   return retval;
 }
 }       // End namespace CLD2

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browser/components/translation/cld2/internal/cldutil.cc@6474c204b198 (annotated)

browser/components/translation/cld2/internal/cldutil.cc