summaryrefslogtreecommitdiff
path: root/libguile/hash.c
blob: 11a35c2cb88e9800a0736321fa74f907cd19385d (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
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
/* Copyright 1995-1997,2000-2001,2003-2004,2006,2008-2015,2017-2018,2020
     Free Software Foundation, Inc.

   This file is part of Guile.

   Guile is free software: you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as published
   by the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   Guile is distributed in the hope that it will be useful, but WITHOUT
   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
   License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with Guile.  If not, see
   <https://www.gnu.org/licenses/>.  */




#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#ifdef HAVE_WCHAR_H
#include <wchar.h>
#endif

#include <math.h>
#include <string.h>
#include <unistr.h>

#include "chars.h"
#include "foreign.h"
#include "gsubr.h"
#include "keywords.h"
#include "numbers.h"
#include "pairs.h"
#include "ports.h"
#include "strings.h"
#include "struct.h"
#include "symbols.h"
#include "syntax.h"
#include "vectors.h"

#include "hash.h"




#ifndef floor
extern double floor();
#endif


/* This hash function is originally from
   http://burtleburtle.net/bob/c/lookup3.c by Bob Jenkins, May 2006,
   Public Domain.  No warranty.  */

#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
#define mix(a,b,c) \
{ \
  a -= c;  a ^= rot(c, 4);  c += b; \
  b -= a;  b ^= rot(a, 6);  a += c; \
  c -= b;  c ^= rot(b, 8);  b += a; \
  a -= c;  a ^= rot(c,16);  c += b; \
  b -= a;  b ^= rot(a,19);  a += c; \
  c -= b;  c ^= rot(b, 4);  b += a; \
}

#define final(a,b,c) \
{ \
  c ^= b; c -= rot(b,14); \
  a ^= c; a -= rot(c,11); \
  b ^= a; b -= rot(a,25); \
  c ^= b; c -= rot(b,16); \
  a ^= c; a -= rot(c,4);  \
  b ^= a; b -= rot(a,14); \
  c ^= b; c -= rot(b,24); \
}

#define JENKINS_LOOKUP3_HASHWORD2(k, length, ret)                       \
  do {                                                                  \
    uint32_t a, b, c;                                                   \
                                                                        \
    /* Set up the internal state.  */                                   \
    a = b = c = 0xdeadbeef + ((uint32_t)(length<<2)) + 47;              \
                                                                        \
    /* Handle most of the key.  */                                      \
    while (length > 3)                                                  \
      {                                                                 \
        a += k[0];                                                      \
        b += k[1];                                                      \
        c += k[2];                                                      \
        mix (a, b, c);                                                  \
        length -= 3;                                                    \
        k += 3;                                                         \
      }                                                                 \
                                                                        \
    /* Handle the last 3 elements.  */                                  \
    switch(length) /* All the case statements fall through.  */         \
      {                                                                 \
      case 3 : c += k[2];                                               \
      case 2 : b += k[1];                                               \
      case 1 : a += k[0];                                               \
        final (a, b, c);                                                \
      case 0:     /* case 0: nothing left to add */                     \
        break;                                                          \
      }                                                                 \
                                                                        \
    /* Scheme can access symbol-hash, which exposes this value.  For    \
       cross-compilation reasons, we ensure that the high 32 bits of    \
       the hash on a 64-bit system are equal to the hash on a 32-bit    \
       system.  The low 32 bits just add more entropy.  */              \
    if (sizeof (ret) == 8)                                              \
      ret = (((unsigned long) c) << 32) | b;                            \
    else                                                                \
      ret = c;                                                          \
  } while (0)


static unsigned long
narrow_string_hash (const uint8_t *str, size_t len)
{
  unsigned long ret;
  JENKINS_LOOKUP3_HASHWORD2 (str, len, ret);
  ret >>= 2; /* Ensure that it fits in a fixnum.  */
  return ret;
}

static unsigned long
wide_string_hash (const scm_t_wchar *str, size_t len)
{
  unsigned long ret;
  JENKINS_LOOKUP3_HASHWORD2 (str, len, ret);
  ret >>= 2; /* Ensure that it fits in a fixnum.  */
  return ret;
}

unsigned long
scm_i_string_hash (SCM str)
{
  size_t len = scm_i_string_length (str);

  if (scm_i_is_narrow_string (str))
    return narrow_string_hash ((const uint8_t *) scm_i_string_chars (str),
                               len);
  else
    return wide_string_hash (scm_i_string_wide_chars (str), len);
}

unsigned long 
scm_i_locale_string_hash (const char *str, size_t len)
{
  return scm_i_string_hash (scm_from_locale_stringn (str, len));
}

unsigned long 
scm_i_latin1_string_hash (const char *str, size_t len)
{
  if (len == (size_t) -1)
    len = strlen (str);

  return narrow_string_hash ((const uint8_t *) str, len);
}

/* A tricky optimization, but probably worth it.  */
unsigned long 
scm_i_utf8_string_hash (const char *str, size_t len)
{
  const uint8_t *end, *ustr = (const uint8_t *) str;
  unsigned long ret;

  /* The length of the string in characters.  This name corresponds to
     Jenkins' original name.  */
  size_t length;

  uint32_t a, b, c, u32;

  if (len == (size_t) -1)
    len = strlen (str);

  end = ustr + len;

  if (u8_check (ustr, len) != NULL)
    /* Invalid UTF-8; punt.  */
    return scm_i_string_hash (scm_from_utf8_stringn (str, len));

  length = u8_strnlen (ustr, len);

  /* Set up the internal state.  */
  a = b = c = 0xdeadbeef + ((uint32_t)(length<<2)) + 47;

  /* Handle most of the key.  */
  while (length > 3)
    {
      ustr += u8_mbtouc_unsafe (&u32, ustr, end - ustr);
      a += u32;
      ustr += u8_mbtouc_unsafe (&u32, ustr, end - ustr);
      b += u32;
      ustr += u8_mbtouc_unsafe (&u32, ustr, end - ustr);
      c += u32;
      mix (a, b, c);
      length -= 3;
    }

  /* Handle the last 3 elements's.  */
  ustr += u8_mbtouc_unsafe (&u32, ustr, end - ustr);
  a += u32;
  if (--length)
    {
      ustr += u8_mbtouc_unsafe (&u32, ustr, end - ustr);
      b += u32;
      if (--length)
        {
          ustr += u8_mbtouc_unsafe (&u32, ustr, end - ustr);
          c += u32;
        }
    }

  final (a, b, c);

  if (sizeof (unsigned long) == 8)
    ret = (((unsigned long) c) << 32) | b;
  else
    ret = c;

  ret >>= 2; /* Ensure that it fits in a fixnum.  */
  return ret;
}

static unsigned long scm_raw_ihashq (scm_t_bits key);
static unsigned long scm_raw_ihash (SCM obj, size_t depth);

/* Return the hash of struct OBJ.  Traverse OBJ's fields to compute the
   result, unless DEPTH is zero.  Assumes that OBJ is a struct.  */
static unsigned long
scm_i_struct_hash (SCM obj, size_t depth)
{
  size_t struct_size, field_num;
  unsigned long hash;

  struct_size = SCM_STRUCT_SIZE (obj);

  hash = scm_raw_ihashq (SCM_UNPACK (SCM_STRUCT_VTABLE (obj)));
  if (depth > 0)
    {
      for (field_num = 0; field_num < struct_size; field_num++)
        if (SCM_STRUCT_FIELD_IS_UNBOXED (obj, field_num))
          hash ^= scm_raw_ihashq (SCM_STRUCT_DATA_REF (obj, field_num));
        else
          hash ^= scm_raw_ihash (SCM_STRUCT_SLOT_REF (obj, field_num),
                                 depth / 2);
    }

  return hash;
}

/* Thomas Wang's integer hasher, from
   http://www.cris.com/~Ttwang/tech/inthash.htm.  */
static unsigned long
scm_raw_ihashq (scm_t_bits key)
{
  if (sizeof (key) < 8)
    {
      key = (key ^ 61) ^ (key >> 16);
      key = key + (key << 3);
      key = key ^ (key >> 4);
      key = key * 0x27d4eb2d;
      key = key ^ (key >> 15);
    }
  else
    {
      key = (~key) + (key << 21); // key = (key << 21) - key - 1;
      key = key ^ (key >> 24);
      key = (key + (key << 3)) + (key << 8); // key * 265
      key = key ^ (key >> 14);
      key = (key + (key << 2)) + (key << 4); // key * 21
      key = key ^ (key >> 28);
      key = key + (key << 31);
    }
  key >>= 2; /* Ensure that it fits in a fixnum.  */
  return key;
}

/* `depth' is used to limit recursion. */
static unsigned long
scm_raw_ihash (SCM obj, size_t depth)
{
  if (SCM_IMP (obj))
    return scm_raw_ihashq (SCM_UNPACK (obj));

  switch (SCM_TYP7(obj))
    {
      /* FIXME: do better for structs, variables, ...  Also the hashes
         are currently associative, which ain't the right thing.  */
    case scm_tc7_smob:
      return scm_raw_ihashq (SCM_TYP16 (obj));
    case scm_tc7_number:
      if (scm_is_integer (obj))
        {
          SCM n = SCM_I_MAKINUM (SCM_MOST_POSITIVE_FIXNUM);
          if (scm_is_inexact (obj))
            obj = scm_inexact_to_exact (obj);
          return scm_raw_ihashq (scm_to_ulong (scm_modulo (obj, n)));
        }
      else
        return scm_i_string_hash (scm_number_to_string (obj, scm_from_int (10)));
    case scm_tc7_string:
      return scm_i_string_hash (obj);
    case scm_tc7_symbol:
      return scm_i_symbol_hash (obj);
    case scm_tc7_keyword:
      return SCM_I_KEYWORD_HASH (obj);
    case scm_tc7_pointer:
      return scm_raw_ihashq ((uintptr_t) SCM_POINTER_VALUE (obj));
    case scm_tc7_wvect:
    case scm_tc7_vector:
      {
	size_t len = SCM_SIMPLE_VECTOR_LENGTH (obj);
        size_t i = depth / 2;
        unsigned long h = scm_raw_ihashq (SCM_CELL_WORD_0 (obj));
        if (len)
          while (i--)
            h ^= scm_raw_ihash (scm_c_vector_ref (obj, h % len), i);
        return h;
      }
    case scm_tc7_syntax:
      {
        unsigned long h;
        h = scm_raw_ihash (scm_syntax_expression (obj), depth);
        h ^= scm_raw_ihash (scm_syntax_wrap (obj), depth);
        h ^= scm_raw_ihash (scm_syntax_module (obj), depth);
        return h;
      }

      /* The following tc7s have no 'equal?' implementation.  Thus, just
         fall back to 'hashq'.  */
    case scm_tc7_variable:
    case scm_tc7_hashtable:
    case scm_tc7_fluid:
    case scm_tc7_dynamic_state:
    case scm_tc7_frame:
    case scm_tc7_atomic_box:
    case scm_tc7_program:
    case scm_tc7_vm_cont:
    case scm_tc7_weak_set:
    case scm_tc7_weak_table:
    case scm_tc7_port:
      return scm_raw_ihashq (SCM_UNPACK (obj));

    case scm_tcs_cons_imcar: 
    case scm_tcs_cons_nimcar:
      if (depth)
        return (scm_raw_ihash (SCM_CAR (obj), depth / 2)
                ^ scm_raw_ihash (SCM_CDR (obj), depth / 2));
      else
        return scm_raw_ihashq (scm_tc3_cons);
    case scm_tcs_struct:
      return scm_i_struct_hash (obj, depth);
    default:
      return scm_raw_ihashq (SCM_CELL_WORD_0 (obj));
    }
}




unsigned long
scm_ihashq (SCM obj, unsigned long n)
{
  return scm_raw_ihashq (SCM_UNPACK (obj)) % n;
}


SCM_DEFINE (scm_hashq, "hashq", 2, 0, 0,
           (SCM key, SCM size),
	    "Determine a hash value for @var{key} that is suitable for\n"
	    "lookups in a hashtable of size @var{size}, where @code{eq?} is\n"
	    "used as the equality predicate.  The function returns an\n"
	    "integer in the range 0 to @var{size} - 1.  Note that\n"
	    "@code{hashq} may use internal addresses.  Thus two calls to\n"
	    "hashq where the keys are @code{eq?} are not guaranteed to\n"
	    "deliver the same value if the key object gets garbage collected\n"
	    "in between.  This can happen, for example with symbols:\n"
	    "@code{(hashq 'foo n) (gc) (hashq 'foo n)} may produce two\n"
	    "different values, since @code{foo} will be garbage collected.")
#define FUNC_NAME s_scm_hashq
{
  unsigned long sz = scm_to_unsigned_integer (size, 1, ULONG_MAX);
  return scm_from_ulong (scm_ihashq (key, sz));
}
#undef FUNC_NAME





unsigned long
scm_ihashv (SCM obj, unsigned long n)
{
  if (SCM_NUMP(obj))
    return scm_raw_ihash (obj, 10) % n;
  else
    return scm_raw_ihashq (SCM_UNPACK (obj)) % n;
}


SCM_DEFINE (scm_hashv, "hashv", 2, 0, 0,
           (SCM key, SCM size),
	    "Determine a hash value for @var{key} that is suitable for\n"
	    "lookups in a hashtable of size @var{size}, where @code{eqv?} is\n"
	    "used as the equality predicate.  The function returns an\n"
	    "integer in the range 0 to @var{size} - 1.  Note that\n"
	    "@code{(hashv key)} may use internal addresses.  Thus two calls\n"
	    "to hashv where the keys are @code{eqv?} are not guaranteed to\n"
	    "deliver the same value if the key object gets garbage collected\n"
	    "in between.  This can happen, for example with symbols:\n"
	    "@code{(hashv 'foo n) (gc) (hashv 'foo n)} may produce two\n"
	    "different values, since @code{foo} will be garbage collected.")
#define FUNC_NAME s_scm_hashv
{
  unsigned long sz = scm_to_unsigned_integer (size, 1, ULONG_MAX);
  return scm_from_ulong (scm_ihashv (key, sz));
}
#undef FUNC_NAME





unsigned long
scm_ihash (SCM obj, unsigned long n)
{
  return (unsigned long) scm_raw_ihash (obj, 10) % n;
}

SCM_DEFINE (scm_hash, "hash", 2, 0, 0,
           (SCM key, SCM size),
	    "Determine a hash value for @var{key} that is suitable for\n"
	    "lookups in a hashtable of size @var{size}, where @code{equal?}\n"
	    "is used as the equality predicate.  The function returns an\n"
	    "integer in the range 0 to @var{size} - 1.")
#define FUNC_NAME s_scm_hash
{
  unsigned long sz = scm_to_unsigned_integer (size, 1, ULONG_MAX);
  return scm_from_ulong (scm_ihash (key, sz));
}
#undef FUNC_NAME





void
scm_init_hash ()
{
#include "hash.x"
}