summaryrefslogtreecommitdiffstats
path: root/application/basilisk/components/translation/cld2/internal/cldutil_shared.cc
blob: f111473afa6eabb4e7d2c0fc900fbab70cbf3dba (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
// 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)
//

#include "cldutil_shared.h"
#include <string>

#include "cld2tablesummary.h"
#include "integral_types.h"
#include "port.h"
#include "utf8statetable.h"

namespace CLD2 {

// 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).


// Indicator bits for leading/trailing space around quad/octagram
// NOTE: 4444 bits are chosen to flip constant bits in hash of four chars of
// 1-, 2-, or 3-bytes each.
static const uint32 kPreSpaceIndicator =  0x00004444;
static const uint32 kPostSpaceIndicator = 0x44440000;

// Little-endian masks for 0..24 bytes picked up as uint32's
static const uint32 kWordMask0[4] = {
  0xFFFFFFFF, 0x000000FF, 0x0000FFFF, 0x00FFFFFF
};

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


// 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      //
//----------------------------------------------------------------------------//

// Design principles for these hash functions
// - Few operations
// - Handle 1-, 2-, and 3-byte UTF-8 scripts, ignoring intermixing except in
//   Latin script expect 1- and 2-byte mixtures.
// - Last byte of each character has about 5 bits of information
// - Spread good bits around so they can interact in at least two ways
//   with other characters
// - Use add for additional mixing thorugh carries

// CJK Three-byte bigram
//   ....dddd..cccccc..bbbbbb....aaaa
//   ..................ffffff..eeeeee
// make
//   ....dddd..cccccc..bbbbbb....aaaa
//   000....dddd..cccccc..bbbbbb....a
//   ..................ffffff..eeeeee
//   ffffff..eeeeee000000000000000000
//
// CJK Four-byte bigram
//   ..dddddd..cccccc....bbbb....aaaa
//   ..hhhhhh..gggggg....ffff....eeee
// make
//   ..dddddd..cccccc....bbbb....aaaa
//   000..dddddd..cccccc....bbbb....a
//   ..hhhhhh..gggggg....ffff....eeee
//   ..ffff....eeee000000000000000000

// BIGRAM
// Pick up 1..8 bytes and hash them via mask/shift/add. NO pre/post
// OVERSHOOTS up to 3 bytes
// For runtime use of tables
// Does X86 unaligned loads
uint32 BiHashV2(const char* word_ptr, int bytecount) {
  if (bytecount == 0) {return 0;}
  const uint32* word_ptr32 = reinterpret_cast<const uint32*>(word_ptr);
  uint32 word0, word1;
  if (bytecount <= 4) {
    word0 = UNALIGNED_LOAD32(word_ptr32) & kWordMask0[bytecount & 3];
    word0 = word0 ^ (word0 >> 3);
    return word0;
  }
  // Else do 8 bytes
  word0 = UNALIGNED_LOAD32(word_ptr32);
  word0 = word0 ^ (word0 >> 3);
  word1 = UNALIGNED_LOAD32(word_ptr32 + 1) & kWordMask0[bytecount & 3];
  word1 = word1 ^ (word1 << 18);
  return word0 + word1;
}

//
// Ascii-7 One-byte chars
//   ...ddddd...ccccc...bbbbb...aaaaa
// make
//   ...ddddd...ccccc...bbbbb...aaaaa
//   000...ddddd...ccccc...bbbbb...aa
//
// Latin 1- and 2-byte chars
//   ...ddddd...ccccc...bbbbb...aaaaa
//   ...................fffff...eeeee
// make
//   ...ddddd...ccccc...bbbbb...aaaaa
//   000...ddddd...ccccc...bbbbb...aa
//   ...................fffff...eeeee
//   ...............fffff...eeeee0000
//
// Non-CJK Two-byte chars
//   ...ddddd...........bbbbb........
//   ...hhhhh...........fffff........
// make
//   ...ddddd...........bbbbb........
//   000...ddddd...........bbbbb.....
//   ...hhhhh...........fffff........
//   hhhh...........fffff........0000
//
// Non-CJK Three-byte chars
//   ...........ccccc................
//   ...................fffff........
//   ...lllll...................iiiii
// make
//   ...........ccccc................
//   000...........ccccc.............
//   ...................fffff........
//   ...............fffff........0000
//   ...lllll...................iiiii
//   .lllll...................iiiii00
//

// QUADGRAM
// Pick up 1..12 bytes plus pre/post space and hash them via mask/shift/add
// OVERSHOOTS up to 3 bytes
// For runtime use of tables
// Does X86 unaligned loads
uint32 QuadHashV2Mix(const char* word_ptr, int bytecount, uint32 prepost) {
  const uint32* word_ptr32 = reinterpret_cast<const uint32*>(word_ptr);
  uint32 word0, word1, word2;
  if (bytecount <= 4) {
    word0 = UNALIGNED_LOAD32(word_ptr32) & kWordMask0[bytecount & 3];
    word0 = word0 ^ (word0 >> 3);
    return word0 ^ prepost;
  } else if (bytecount <= 8) {
    word0 = UNALIGNED_LOAD32(word_ptr32);
    word0 = word0 ^ (word0 >> 3);
    word1 = UNALIGNED_LOAD32(word_ptr32 + 1) & kWordMask0[bytecount & 3];
    word1 = word1 ^ (word1 << 4);
    return (word0 ^ prepost) + word1;
  }
  // else do 12 bytes
  word0 = UNALIGNED_LOAD32(word_ptr32);
  word0 = word0 ^ (word0 >> 3);
  word1 = UNALIGNED_LOAD32(word_ptr32 + 1);
  word1 = word1 ^ (word1 << 4);
  word2 = UNALIGNED_LOAD32(word_ptr32 + 2) & kWordMask0[bytecount & 3];
  word2 = word2 ^ (word2 << 2);
  return (word0 ^ prepost) + word1 + word2;
}


// QUADGRAM wrapper with surrounding spaces
// Pick up 1..12 bytes plus pre/post space and hash them via mask/shift/add
// UNDERSHOOTS 1 byte, OVERSHOOTS up to 3 bytes
// For runtime use of tables
uint32 QuadHashV2(const char* word_ptr, int bytecount) {
  if (bytecount == 0) {return 0;}
  uint32 prepost = 0;
  if (word_ptr[-1] == ' ') {prepost |= kPreSpaceIndicator;}
  if (word_ptr[bytecount] == ' ') {prepost |= kPostSpaceIndicator;}
  return QuadHashV2Mix(word_ptr, bytecount, prepost);
}

// QUADGRAM wrapper with surrounding underscores (offline use)
// Pick up 1..12 bytes plus pre/post '_' and hash them via mask/shift/add
// OVERSHOOTS up to 3 bytes
// For offline construction of tables
uint32 QuadHashV2Underscore(const char* word_ptr, int bytecount) {
  if (bytecount == 0) {return 0;}
  const char* local_word_ptr = word_ptr;
  int local_bytecount = bytecount;
  uint32 prepost = 0;
  if (local_word_ptr[0] == '_') {
    prepost |= kPreSpaceIndicator;
    ++local_word_ptr;
    --local_bytecount;
  }
  if (local_word_ptr[local_bytecount - 1] == '_') {
    prepost |= kPostSpaceIndicator;
    --local_bytecount;
  }
  return QuadHashV2Mix(local_word_ptr, local_bytecount, prepost);
}


// OCTAGRAM
// Pick up 1..24 bytes plus pre/post space and hash them via mask/shift/add
// UNDERSHOOTS 1 byte, OVERSHOOTS up to 3 bytes
//
// The low 32 bits follow the pattern from above, tuned to different scripts
// The high 8 bits are a simple sum of all bytes, shifted by 0/1/2/3 bits each
// For runtime use of tables V3
// Does X86 unaligned loads
uint64 OctaHash40Mix(const char* word_ptr, int bytecount, uint64 prepost) {
  const uint32* word_ptr32 = reinterpret_cast<const uint32*>(word_ptr);
  uint64 word0;
  uint64 word1;
  uint64 sum;

  if (word_ptr[-1] == ' ') {prepost |= kPreSpaceIndicator;}
  if (word_ptr[bytecount] == ' ') {prepost |= kPostSpaceIndicator;}
  switch ((bytecount - 1) >> 2) {
  case 0:       // 1..4 bytes
    word0 = UNALIGNED_LOAD32(word_ptr32) & kWordMask0[bytecount & 3];
    sum = word0;
    word0 = word0 ^ (word0 >> 3);
    break;
  case 1:       // 5..8 bytes
    word0 = UNALIGNED_LOAD32(word_ptr32);
    sum = word0;
    word0 = word0 ^ (word0 >> 3);
    word1 = UNALIGNED_LOAD32(word_ptr32 + 1) & kWordMask0[bytecount & 3];
    sum += word1;
    word1 = word1 ^ (word1 << 4);
    word0 += word1;
    break;
  case 2:       // 9..12 bytes
    word0 = UNALIGNED_LOAD32(word_ptr32);
    sum = word0;
    word0 = word0 ^ (word0 >> 3);
    word1 = UNALIGNED_LOAD32(word_ptr32 + 1);
    sum += word1;
    word1 = word1 ^ (word1 << 4);
    word0 += word1;
    word1 = UNALIGNED_LOAD32(word_ptr32 + 2) & kWordMask0[bytecount & 3];
    sum += word1;
    word1 = word1 ^ (word1 << 2);
    word0 += word1;
    break;
  case 3:       // 13..16 bytes
    word0 =UNALIGNED_LOAD32(word_ptr32);
    sum = word0;
    word0 = word0 ^ (word0 >> 3);
    word1 = UNALIGNED_LOAD32(word_ptr32 + 1);
    sum += word1;
    word1 = word1 ^ (word1 << 4);
    word0 += word1;
    word1 = UNALIGNED_LOAD32(word_ptr32 + 2);
    sum += word1;
    word1 = word1 ^ (word1 << 2);
    word0 += word1;
    word1 = UNALIGNED_LOAD32(word_ptr32 + 3) & kWordMask0[bytecount & 3];
    sum += word1;
    word1 = word1 ^ (word1 >> 8);
    word0 += word1;
    break;
  case 4:       // 17..20 bytes
    word0 = UNALIGNED_LOAD32(word_ptr32);
    sum = word0;
    word0 = word0 ^ (word0 >> 3);
    word1 = UNALIGNED_LOAD32(word_ptr32 + 1);
    sum += word1;
    word1 = word1 ^ (word1 << 4);
    word0 += word1;
    word1 = UNALIGNED_LOAD32(word_ptr32 + 2);
    sum += word1;
    word1 = word1 ^ (word1 << 2);
    word0 += word1;
    word1 = UNALIGNED_LOAD32(word_ptr32 + 3);
    sum += word1;
    word1 = word1 ^ (word1 >> 8);
    word0 += word1;
    word1 = UNALIGNED_LOAD32(word_ptr32 + 4) & kWordMask0[bytecount & 3];
    sum += word1;
    word1 = word1 ^ (word1 >> 4);
    word0 += word1;
    break;
  default:      // 21..24 bytes and higher (ignores beyond 24)
    word0 = UNALIGNED_LOAD32(word_ptr32);
    sum = word0;
    word0 = word0 ^ (word0 >> 3);
    word1 = UNALIGNED_LOAD32(word_ptr32 + 1);
    sum += word1;
    word1 = word1 ^ (word1 << 4);
    word0 += word1;
    word1 = UNALIGNED_LOAD32(word_ptr32 + 2);
    sum += word1;
    word1 = word1 ^ (word1 << 2);
    word0 += word1;
    word1 = UNALIGNED_LOAD32(word_ptr32 + 3);
    sum += word1;
    word1 = word1 ^ (word1 >> 8);
    word0 += word1;
    word1 = UNALIGNED_LOAD32(word_ptr32 + 4);
    sum += word1;
    word1 = word1 ^ (word1 >> 4);
    word0 += word1;
    word1 = UNALIGNED_LOAD32(word_ptr32 + 5) & kWordMask0[bytecount & 3];
    sum += word1;
    word1 = word1 ^ (word1 >> 6);
    word0 += word1;
    break;
  }

  sum += (sum >> 17);             // extra 1-bit shift for bytes 2 & 3
  sum += (sum >> 9);              // extra 1-bit shift for bytes 1 & 3
  sum = (sum & 0xff) << 32;
  return (word0 ^ prepost) + sum;
}

// OCTAGRAM wrapper with surrounding spaces
// Pick up 1..24 bytes plus pre/post space and hash them via mask/shift/add
// UNDERSHOOTS 1 byte, OVERSHOOTS up to 3 bytes
//
// The low 32 bits follow the pattern from above, tuned to different scripts
// The high 8 bits are a simple sum of all bytes, shifted by 0/1/2/3 bits each
// For runtime use of tables V3
uint64 OctaHash40(const char* word_ptr, int bytecount) {
  if (bytecount == 0) {return 0;}
  uint64 prepost = 0;
  if (word_ptr[-1] == ' ') {prepost |= kPreSpaceIndicator;}
  if (word_ptr[bytecount] == ' ') {prepost |= kPostSpaceIndicator;}
  return OctaHash40Mix(word_ptr, bytecount, prepost);
}


// OCTAGRAM wrapper with surrounding underscores (offline use)
// Pick up 1..24 bytes plus pre/post space and hash them via mask/shift/add
// UNDERSHOOTS 1 byte, OVERSHOOTS up to 3 bytes
//
// The low 32 bits follow the pattern from above, tuned to different scripts
// The high 8 bits are a simple sum of all bytes, shifted by 0/1/2/3 bits each
// For offline construction of tables
uint64 OctaHash40underscore(const char* word_ptr, int bytecount) {
  if (bytecount == 0) {return 0;}
  const char* local_word_ptr = word_ptr;
  int local_bytecount = bytecount;
  uint64 prepost = 0;
  if (local_word_ptr[0] == '_') {
    prepost |= kPreSpaceIndicator;
    ++local_word_ptr;
    --local_bytecount;
  }
  if (local_word_ptr[local_bytecount - 1] == '_') {
    prepost |= kPostSpaceIndicator;
    --local_bytecount;
  }
  return OctaHash40Mix(local_word_ptr, local_bytecount, prepost);
}

// Hash a consecutive pair of tokens/words A B
// Old: hash is B - A, which gives too many false hits on one-char diffs
// Now: rotate(A,13) + B
uint64 PairHash(uint64 worda_hash, uint64 wordb_hash) {
   return ((worda_hash >> 13) | (worda_hash << (64 - 13))) + wordb_hash;
}




//----------------------------------------------------------------------------//
// Finding groups of 1/2/4/8 letters                                          //
//----------------------------------------------------------------------------//

// src points to a letter. Find the byte length of a unigram starting there.
int UniLen(const char* src) {
  const char* src_end = src;
  src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
  return src_end - src;
}

// src points to a letter. Find the byte length of a bigram starting there.
int BiLen(const char* src) {
  const char* src_end = src;
  src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
  src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
  return src_end - src;
}

// src points to a letter. Find the byte length of a quadgram starting there.
int QuadLen(const char* src) {
  const char* src_end = src;
  src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
  src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
  src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
  src_end += kAdvanceOneCharButSpace[(uint8)src_end[0]];
  return src_end - src;
}

// src points to a letter. Find the byte length of an octagram starting there.
int OctaLen(const char* src) {
  const char* src_end = src;
  int charcount = 0;
  while (src_end[0] != ' ') {
    src_end += UTF8OneCharLen(src);
    ++charcount;
    if (charcount == 8) {break;}
  }
  return src_end - src;
}

}       // End namespace CLD2