release/src/router/libxml2/timsort.h

   1 /*
   2  * taken from https://github.com/swenson/sort
   3  * Kept as is for the moment to be able to apply upstream patches for that
   4  * code, currently used only to speed up XPath node sorting, see xpath.c
   5  */
   6
   7 /*
   8  * All code in this header, unless otherwise specified, is hereby licensed under the MIT Public License:
   9
  10 Copyright (c) 2010 Christopher Swenson
  11
  12 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
  13
  14 The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
  15
  16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  17 */
  18
  19 #include <stdlib.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #ifdef HAVE_STDINT_H
  23 #include <stdint.h>
  24 #else
  25 #ifdef HAVE_INTTYPES_H
  26 #include <inttypes.h>
  27 #elif defined(WIN32)
  28 typedef __int64 int64_t;
  29 typedef unsigned __int64 uint64_t;
  30 #endif
  31 #endif
  32
  33 #ifndef MK_UINT64
  34 #if defined(WIN32) && defined(_MSC_VER) && _MSC_VER < 1300
  35 #define MK_UINT64(x) ((uint64_t)(x))
  36 #else
  37 #define MK_UINT64(x) x##ULL
  38 #endif
  39 #endif
  40
  41 #ifndef MAX
  42 #define MAX(x,y) (((x) > (y) ? (x) : (y)))
  43 #endif
  44 #ifndef MIN
  45 #define MIN(x,y) (((x) < (y) ? (x) : (y)))
  46 #endif
  47
  48 int compute_minrun(uint64_t);
  49
  50 #ifndef CLZ
  51 #if defined(__GNUC__) && ((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ > 3))
  52 #define CLZ __builtin_clzll
  53 #else
  54
  55 int clzll(uint64_t);
  56
  57 /* adapted from Hacker's Delight */
  58 int clzll(uint64_t x) /* {{{ */
  59 {
  60   int n;
  61
  62   if (x == 0) return(64);
  63   n = 0;
  64   if (x <= 0x00000000FFFFFFFFL) {n = n + 32; x = x << 32;}
  65   if (x <= 0x0000FFFFFFFFFFFFL) {n = n + 16; x = x << 16;}
  66   if (x <= 0x00FFFFFFFFFFFFFFL) {n = n + 8; x = x << 8;}
  67   if (x <= 0x0FFFFFFFFFFFFFFFL) {n = n + 4; x = x << 4;}
  68   if (x <= 0x3FFFFFFFFFFFFFFFL) {n = n + 2; x = x << 2;}
  69   if (x <= 0x7FFFFFFFFFFFFFFFL) {n = n + 1;}
  70   return n;
  71 }
  72 /* }}} */
  73
  74 #define CLZ clzll
  75 #endif
  76 #endif
  77
  78 int compute_minrun(uint64_t size) /* {{{ */
  79 {
  80   const int top_bit = 64 - CLZ(size);
  81   const int shift = MAX(top_bit, 6) - 6;
  82   const int minrun = size >> shift;
  83   const uint64_t mask = (MK_UINT64(1) << shift) - 1;
  84   if (mask & size) return minrun + 1;
  85   return minrun;
  86 }
  87 /* }}} */
  88
  89 #ifndef SORT_NAME
  90 #error "Must declare SORT_NAME"
  91 #endif
  92
  93 #ifndef SORT_TYPE
  94 #error "Must declare SORT_TYPE"
  95 #endif
  96
  97 #ifndef SORT_CMP
  98 #define SORT_CMP(x, y)  ((x) < (y) ? -1 : ((x) == (y) ? 0 : 1))
  99 #endif
 100
 101
 102 #define SORT_SWAP(x,y) {SORT_TYPE __SORT_SWAP_t = (x); (x) = (y); (y) = __SORT_SWAP_t;}
 103
 104 #define SORT_CONCAT(x, y) x ## _ ## y
 105 #define SORT_MAKE_STR1(x, y) SORT_CONCAT(x,y)
 106 #define SORT_MAKE_STR(x) SORT_MAKE_STR1(SORT_NAME,x)
 107
 108 #define BINARY_INSERTION_FIND  SORT_MAKE_STR(binary_insertion_find)
 109 #define BINARY_INSERTION_SORT_START SORT_MAKE_STR(binary_insertion_sort_start)
 110 #define BINARY_INSERTION_SORT  SORT_MAKE_STR(binary_insertion_sort)
 111 #define REVERSE_ELEMENTS       SORT_MAKE_STR(reverse_elements)
 112 #define COUNT_RUN              SORT_MAKE_STR(count_run)
 113 #define CHECK_INVARIANT        SORT_MAKE_STR(check_invariant)
 114 #define TIM_SORT               SORT_MAKE_STR(tim_sort)
 115 #define TIM_SORT_RESIZE        SORT_MAKE_STR(tim_sort_resize)
 116 #define TIM_SORT_MERGE         SORT_MAKE_STR(tim_sort_merge)
 117 #define TIM_SORT_COLLAPSE      SORT_MAKE_STR(tim_sort_collapse)
 118
 119 #define TIM_SORT_RUN_T         SORT_MAKE_STR(tim_sort_run_t)
 120 #define TEMP_STORAGE_T         SORT_MAKE_STR(temp_storage_t)
 121
 122 typedef struct {
 123   int64_t start;
 124   int64_t length;
 125 } TIM_SORT_RUN_T;
 126
 127 void BINARY_INSERTION_SORT(SORT_TYPE *dst, const size_t size);
 128 void TIM_SORT(SORT_TYPE *dst, const size_t size);
 129
 130 /* Function used to do a binary search for binary insertion sort */
 131 static int64_t BINARY_INSERTION_FIND(SORT_TYPE *dst, const SORT_TYPE x, const size_t size)
 132 {
 133   int64_t l, c, r;
 134   SORT_TYPE lx;
 135   SORT_TYPE cx;
 136   l = 0;
 137   r = size - 1;
 138   c = r >> 1;
 139   lx = dst[l];
 140
 141   /* check for beginning conditions */
 142   if (SORT_CMP(x, lx) < 0)
 143     return 0;
 144   else if (SORT_CMP(x, lx) == 0)
 145   {
 146     int64_t i = 1;
 147     while (SORT_CMP(x, dst[i]) == 0) i++;
 148     return i;
 149   }
 150
 151   cx = dst[c];
 152   while (1)
 153   {
 154     const int val = SORT_CMP(x, cx);
 155     if (val < 0)
 156     {
 157       if (c - l <= 1) return c;
 158       r = c;
 159     }
 160     else if (val > 0)
 161     {
 162       if (r - c <= 1) return c + 1;
 163       l = c;
 164       lx = cx;
 165     }
 166     else
 167     {
 168       do
 169       {
 170         cx = dst[++c];
 171       } while (SORT_CMP(x, cx) == 0);
 172       return c;
 173     }
 174     c = l + ((r - l) >> 1);
 175     cx = dst[c];
 176   }
 177 }
 178
 179 /* Binary insertion sort, but knowing that the first "start" entries are sorted.  Used in timsort. */
 180 static void BINARY_INSERTION_SORT_START(SORT_TYPE *dst, const size_t start, const size_t size)
 181 {
 182   int64_t i;
 183   for (i = start; i < (int64_t) size; i++)
 184   {
 185     int64_t j;
 186     SORT_TYPE x;
 187     int64_t location;
 188     /* If this entry is already correct, just move along */
 189     if (SORT_CMP(dst[i - 1], dst[i]) <= 0) continue;
 190
 191     /* Else we need to find the right place, shift everything over, and squeeze in */
 192     x = dst[i];
 193     location = BINARY_INSERTION_FIND(dst, x, i);
 194     for (j = i - 1; j >= location; j--)
 195     {
 196       dst[j + 1] = dst[j];
 197     }
 198     dst[location] = x;
 199   }
 200 }
 201
 202 /* Binary insertion sort */
 203 void BINARY_INSERTION_SORT(SORT_TYPE *dst, const size_t size)
 204 {
 205   BINARY_INSERTION_SORT_START(dst, 1, size);
 206 }
 207
 208 /* timsort implementation, based on timsort.txt */
 209
 210 static void REVERSE_ELEMENTS(SORT_TYPE *dst, int64_t start, int64_t end)
 211 {
 212   while (1)
 213   {
 214     if (start >= end) return;
 215     SORT_SWAP(dst[start], dst[end]);
 216     start++;
 217     end--;
 218   }
 219 }
 220
 221 static int64_t COUNT_RUN(SORT_TYPE *dst, const int64_t start, const size_t size)
 222 {
 223   int64_t curr;
 224   if (size - start == 1) return 1;
 225   if (start >= (int64_t) size - 2)
 226   {
 227     if (SORT_CMP(dst[size - 2], dst[size - 1]) > 0)
 228       SORT_SWAP(dst[size - 2], dst[size - 1]);
 229     return 2;
 230   }
 231
 232   curr = start + 2;
 233
 234   if (SORT_CMP(dst[start], dst[start + 1]) <= 0)
 235   {
 236     /* increasing run */
 237     while (1)
 238     {
 239       if (curr == (int64_t) size - 1) break;
 240       if (SORT_CMP(dst[curr - 1], dst[curr]) > 0) break;
 241       curr++;
 242     }
 243     return curr - start;
 244   }
 245   else
 246   {
 247     /* decreasing run */
 248     while (1)
 249     {
 250       if (curr == (int64_t) size - 1) break;
 251       if (SORT_CMP(dst[curr - 1], dst[curr]) <= 0) break;
 252       curr++;
 253     }
 254     /* reverse in-place */
 255     REVERSE_ELEMENTS(dst, start, curr - 1);
 256     return curr - start;
 257   }
 258 }
 259
 260 #define PUSH_NEXT() do {\
 261 len = COUNT_RUN(dst, curr, size);\
 262 run = minrun;\
 263 if (run < minrun) run = minrun;\
 264 if (run > (int64_t) size - curr) run = size - curr;\
 265 if (run > len)\
 266 {\
 267   BINARY_INSERTION_SORT_START(&dst[curr], len, run);\
 268   len = run;\
 269 }\
 270 {\
 271 run_stack[stack_curr].start = curr;\
 272 run_stack[stack_curr].length = len;\
 273 stack_curr++;\
 274 }\
 275 curr += len;\
 276 if (curr == (int64_t) size)\
 277 {\
 278   /* finish up */ \
 279   while (stack_curr > 1) \
 280   { \
 281     TIM_SORT_MERGE(dst, run_stack, stack_curr, store); \
 282     run_stack[stack_curr - 2].length += run_stack[stack_curr - 1].length; \
 283     stack_curr--; \
 284   } \
 285   if (store->storage != NULL)\
 286   {\
 287     free(store->storage);\
 288     store->storage = NULL;\
 289   }\
 290   return;\
 291 }\
 292 }\
 293 while (0)
 294
 295 static int CHECK_INVARIANT(TIM_SORT_RUN_T *stack, const int stack_curr)
 296 {
 297   int64_t A, B, C;
 298   if (stack_curr < 2) return 1;
 299   if (stack_curr == 2)
 300   {
 301     const int64_t A1 = stack[stack_curr - 2].length;
 302     const int64_t B1 = stack[stack_curr - 1].length;
 303     if (A1 <= B1) return 0;
 304     return 1;
 305   }
 306   A = stack[stack_curr - 3].length;
 307   B = stack[stack_curr - 2].length;
 308   C = stack[stack_curr - 1].length;
 309   if ((A <= B + C) || (B <= C)) return 0;
 310   return 1;
 311 }
 312
 313 typedef struct {
 314   size_t alloc;
 315   SORT_TYPE *storage;
 316 } TEMP_STORAGE_T;
 317
 318
 319 static void TIM_SORT_RESIZE(TEMP_STORAGE_T *store, const size_t new_size)
 320 {
 321   if (store->alloc < new_size)
 322   {
 323     SORT_TYPE *tempstore = (SORT_TYPE *)realloc(store->storage, new_size * sizeof(SORT_TYPE));
 324     if (tempstore == NULL)
 325     {
 326       fprintf(stderr, "Error allocating temporary storage for tim sort: need %lu bytes", sizeof(SORT_TYPE) * new_size);
 327       exit(1);
 328     }
 329     store->storage = tempstore;
 330     store->alloc = new_size;
 331   }
 332 }
 333
 334 static void TIM_SORT_MERGE(SORT_TYPE *dst, const TIM_SORT_RUN_T *stack, const int stack_curr, TEMP_STORAGE_T *store)
 335 {
 336   const int64_t A = stack[stack_curr - 2].length;
 337   const int64_t B = stack[stack_curr - 1].length;
 338   const int64_t curr = stack[stack_curr - 2].start;
 339   SORT_TYPE *storage;
 340   int64_t i, j, k;
 341
 342   TIM_SORT_RESIZE(store, MIN(A, B));
 343   storage = store->storage;
 344
 345   /* left merge */
 346   if (A < B)
 347   {
 348     memcpy(storage, &dst[curr], A * sizeof(SORT_TYPE));
 349     i = 0;
 350     j = curr + A;
 351
 352     for (k = curr; k < curr + A + B; k++)
 353     {
 354       if ((i < A) && (j < curr + A + B))
 355       {
 356         if (SORT_CMP(storage[i], dst[j]) <= 0)
 357           dst[k] = storage[i++];
 358         else
 359           dst[k] = dst[j++];
 360       }
 361       else if (i < A)
 362       {
 363         dst[k] = storage[i++];
 364       }
 365       else
 366         dst[k] = dst[j++];
 367     }
 368   }
 369   /* right merge */
 370   else
 371   {
 372     memcpy(storage, &dst[curr + A], B * sizeof(SORT_TYPE));
 373     i = B - 1;
 374     j = curr + A - 1;
 375
 376     for (k = curr + A + B - 1; k >= curr; k--)
 377     {
 378       if ((i >= 0) && (j >= curr))
 379       {
 380           if (SORT_CMP(dst[j], storage[i]) > 0)
 381             dst[k] = dst[j--];
 382           else
 383             dst[k] = storage[i--];
 384       }
 385       else if (i >= 0)
 386         dst[k] = storage[i--];
 387       else
 388         dst[k] = dst[j--];
 389     }
 390   }
 391 }
 392
 393 static int TIM_SORT_COLLAPSE(SORT_TYPE *dst, TIM_SORT_RUN_T *stack, int stack_curr, TEMP_STORAGE_T *store, const size_t size)
 394 {
 395   while (1)
 396   {
 397     int64_t A, B, C;
 398     /* if the stack only has one thing on it, we are done with the collapse */
 399     if (stack_curr <= 1) break;
 400     /* if this is the last merge, just do it */
 401     if ((stack_curr == 2) &&
 402         (stack[0].length + stack[1].length == (int64_t) size))
 403     {
 404       TIM_SORT_MERGE(dst, stack, stack_curr, store);
 405       stack[0].length += stack[1].length;
 406       stack_curr--;
 407       break;
 408     }
 409     /* check if the invariant is off for a stack of 2 elements */
 410     else if ((stack_curr == 2) && (stack[0].length <= stack[1].length))
 411     {
 412       TIM_SORT_MERGE(dst, stack, stack_curr, store);
 413       stack[0].length += stack[1].length;
 414       stack_curr--;
 415       break;
 416     }
 417     else if (stack_curr == 2)
 418       break;
 419
 420     A = stack[stack_curr - 3].length;
 421     B = stack[stack_curr - 2].length;
 422     C = stack[stack_curr - 1].length;
 423
 424     /* check first invariant */
 425     if (A <= B + C)
 426     {
 427       if (A < C)
 428       {
 429         TIM_SORT_MERGE(dst, stack, stack_curr - 1, store);
 430         stack[stack_curr - 3].length += stack[stack_curr - 2].length;
 431         stack[stack_curr - 2] = stack[stack_curr - 1];
 432         stack_curr--;
 433       }
 434       else
 435       {
 436         TIM_SORT_MERGE(dst, stack, stack_curr, store);
 437         stack[stack_curr - 2].length += stack[stack_curr - 1].length;
 438         stack_curr--;
 439       }
 440     }
 441     /* check second invariant */
 442     else if (B <= C)
 443     {
 444       TIM_SORT_MERGE(dst, stack, stack_curr, store);
 445       stack[stack_curr - 2].length += stack[stack_curr - 1].length;
 446       stack_curr--;
 447     }
 448     else
 449       break;
 450   }
 451   return stack_curr;
 452 }
 453
 454 void TIM_SORT(SORT_TYPE *dst, const size_t size)
 455 {
 456   int minrun;
 457   TEMP_STORAGE_T _store, *store;
 458   TIM_SORT_RUN_T run_stack[128];
 459   int stack_curr = 0;
 460   int64_t len, run;
 461   int64_t curr = 0;
 462
 463   if (size < 64)
 464   {
 465     BINARY_INSERTION_SORT(dst, size);
 466     return;
 467   }
 468
 469   /* compute the minimum run length */
 470   minrun = compute_minrun(size);
 471
 472   /* temporary storage for merges */
 473   store = &_store;
 474   store->alloc = 0;
 475   store->storage = NULL;
 476
 477   PUSH_NEXT();
 478   PUSH_NEXT();
 479   PUSH_NEXT();
 480
 481   while (1)
 482   {
 483     if (!CHECK_INVARIANT(run_stack, stack_curr))
 484     {
 485       stack_curr = TIM_SORT_COLLAPSE(dst, run_stack, stack_curr, store, size);
 486       continue;
 487     }
 488     PUSH_NEXT();
 489   }
 490 }
 491
 492 #undef SORT_CONCAT
 493 #undef SORT_MAKE_STR1
 494 #undef SORT_MAKE_STR
 495 #undef SORT_NAME
 496 #undef SORT_TYPE
 497 #undef SORT_CMP
 498 #undef TEMP_STORAGE_T
 499 #undef TIM_SORT_RUN_T
 500 #undef PUSH_NEXT
 501 #undef SORT_SWAP
 502 #undef SORT_CONCAT
 503 #undef SORT_MAKE_STR1
 504 #undef SORT_MAKE_STR
 505 #undef BINARY_INSERTION_FIND
 506 #undef BINARY_INSERTION_SORT_START
 507 #undef BINARY_INSERTION_SORT
 508 #undef REVERSE_ELEMENTS
 509 #undef COUNT_RUN
 510 #undef TIM_SORT
 511 #undef TIM_SORT_RESIZE
 512 #undef TIM_SORT_COLLAPSE
 513 #undef TIM_SORT_RUN_T
 514 #undef TEMP_STORAGE_T