yaffs_qsort.c 3.1 KB

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  1. // SPDX-License-Identifier: BSD-3-Clause
  2. /*
  3. * Copyright (c) 1992, 1993
  4. * The Regents of the University of California. All rights reserved.
  5. */
  6. #include "yportenv.h"
  7. #include <sort.h>
  8. /* #include <linux/string.h> */
  9. /*
  10. * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  11. */
  12. #define swapcode(TYPE, parmi, parmj, n) do { \
  13. long i = (n) / sizeof(TYPE); \
  14. register TYPE *pi = (TYPE *) (parmi); \
  15. register TYPE *pj = (TYPE *) (parmj); \
  16. do { \
  17. register TYPE t = *pi; \
  18. *pi++ = *pj; \
  19. *pj++ = t; \
  20. } while (--i > 0); \
  21. } while (0)
  22. #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  23. es % sizeof(long) ? 2 : es == sizeof(long) ? 0 : 1;
  24. static inline void
  25. swapfunc(char *a, char *b, int n, int swaptype)
  26. {
  27. if (swaptype <= 1)
  28. swapcode(long, a, b, n);
  29. else
  30. swapcode(char, a, b, n);
  31. }
  32. #define yswap(a, b) do { \
  33. if (swaptype == 0) { \
  34. long t = *(long *)(a); \
  35. *(long *)(a) = *(long *)(b); \
  36. *(long *)(b) = t; \
  37. } else \
  38. swapfunc(a, b, es, swaptype); \
  39. } while (0)
  40. #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
  41. static inline char *
  42. med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
  43. {
  44. return cmp(a, b) < 0 ?
  45. (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a))
  46. : (cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c));
  47. }
  48. #ifndef min
  49. #define min(a, b) (((a) < (b)) ? (a) : (b))
  50. #endif
  51. void
  52. yaffs_qsort(void *aa, size_t n, size_t es,
  53. int (*cmp)(const void *, const void *))
  54. {
  55. char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
  56. int d, r, swaptype, swap_cnt;
  57. register char *a = aa;
  58. loop: SWAPINIT(a, es);
  59. swap_cnt = 0;
  60. if (n < 7) {
  61. for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
  62. for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
  63. pl -= es)
  64. yswap(pl, pl - es);
  65. return;
  66. }
  67. pm = (char *)a + (n / 2) * es;
  68. if (n > 7) {
  69. pl = (char *)a;
  70. pn = (char *)a + (n - 1) * es;
  71. if (n > 40) {
  72. d = (n / 8) * es;
  73. pl = med3(pl, pl + d, pl + 2 * d, cmp);
  74. pm = med3(pm - d, pm, pm + d, cmp);
  75. pn = med3(pn - 2 * d, pn - d, pn, cmp);
  76. }
  77. pm = med3(pl, pm, pn, cmp);
  78. }
  79. yswap(a, pm);
  80. pa = pb = (char *)a + es;
  81. pc = pd = (char *)a + (n - 1) * es;
  82. for (;;) {
  83. while (pb <= pc && (r = cmp(pb, a)) <= 0) {
  84. if (r == 0) {
  85. swap_cnt = 1;
  86. yswap(pa, pb);
  87. pa += es;
  88. }
  89. pb += es;
  90. }
  91. while (pb <= pc && (r = cmp(pc, a)) >= 0) {
  92. if (r == 0) {
  93. swap_cnt = 1;
  94. yswap(pc, pd);
  95. pd -= es;
  96. }
  97. pc -= es;
  98. }
  99. if (pb > pc)
  100. break;
  101. yswap(pb, pc);
  102. swap_cnt = 1;
  103. pb += es;
  104. pc -= es;
  105. }
  106. if (swap_cnt == 0) { /* Switch to insertion sort */
  107. for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
  108. for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
  109. pl -= es)
  110. yswap(pl, pl - es);
  111. return;
  112. }
  113. pn = (char *)a + n * es;
  114. r = min(pa - (char *)a, pb - pa);
  115. vecswap(a, pb - r, r);
  116. r = min((long)(pd - pc), (long)(pn - pd - es));
  117. vecswap(pb, pn - r, r);
  118. r = pb - pa;
  119. if (r > es)
  120. yaffs_qsort(a, r / es, es, cmp);
  121. r = pd - pc;
  122. if (r > es) {
  123. /* Iterate rather than recurse to save stack space */
  124. a = pn - r;
  125. n = r / es;
  126. goto loop;
  127. }
  128. /* yaffs_qsort(pn - r, r / es, es, cmp);*/
  129. }