/* qsort -- qsort interface implemented by faster quicksort. J. L. Bentley and M. D. McIlroy, SPE 23 (1993) 1249-1265. Copyright 1993, John Wiley. */ /*assume sizeof(long) is a power of 2 */ #define SWAPINIT(a, es) swaptype = \ (a-(char*)0 | es) % sizeof(long) ? 2 : es > sizeof(long); #define swapcode(TYPE, parmi, parmj, n) { \ register TYPE *pi = (TYPE *) (parmi); \ register TYPE *pj = (TYPE *) (parmj); \ do { \ register TYPE t = *pi; \ *pi++ = *pj; \ *pj++ = t; \ } while ((n -= sizeof(TYPE)) > 0); \ } #include static void swapfunc(char *a, char *b, size_t n, int swaptype) { if (swaptype <= 1) swapcode(long, a, b, n) else swapcode(char, a, b, n) } #define swap(a, b) \ if (swaptype == 0) { \ t = *(long*)(a); \ *(long*)(a) = *(long*)(b); \ *(long*)(b) = t; \ } else \ swapfunc(a, b, es, swaptype) #define PVINIT(pv, pm) \ if (swaptype != 0) { pv = a; swap(pv, pm); } \ else { pv = (char*)&v; *(long*)pv = *(long*)pm; } #define vecswap(a, b, n) if (n > 0) swapfunc(a, b, n, swaptype) #define min(x, y) ((x)<=(y) ? (x) : (y)) static char *med3(char *a, char *b, char *c, int (*cmp)()) { return cmp(a, b) < 0 ? (cmp(b, c) < 0 ? b : cmp(a, c) < 0 ? c : a) : (cmp(b, c) > 0 ? b : cmp(a, c) > 0 ? c : a); } void qsort(char *a, size_t n, size_t es, int (*cmp)()) { char *pa, *pb, *pc, *pd, *pl, *pm, *pn, *pv; int r, swaptype; long t, v; size_t s; SWAPINIT(a, es); if (n < 7) { /* Insertion sort on smallest arrays */ for (pm = a + es; pm < a + n*es; pm += es) for (pl = pm; pl > a && cmp(pl-es, pl) > 0; pl -= es) swap(pl, pl-es); return; } pm = a + (n/2)*es; /* Small arrays, middle element */ if (n > 7) { pl = a; pn = a + (n-1)*es; if (n > 40) { /* Big arrays, pseudomedian of 9 */ s = (n/8)*es; pl = med3(pl, pl+s, pl+2*s, cmp); pm = med3(pm-s, pm, pm+s, cmp); pn = med3(pn-2*s, pn-s, pn, cmp); } pm = med3(pl, pm, pn, cmp); /* Mid-size, med of 3 */ } PVINIT(pv, pm); /* pv points to partition value */ pa = pb = a; pc = pd = a + (n-1)*es; for (;;) { while (pb <= pc && (r = cmp(pb, pv)) <= 0) { if (r == 0) { swap(pa, pb); pa += es; } pb += es; } while (pb <= pc && (r = cmp(pc, pv)) >= 0) { if (r == 0) { swap(pc, pd); pd -= es; } pc -= es; } if (pb > pc) break; swap(pb, pc); pb += es; pc -= es; } pn = a + n*es; s = min(pa-a, pb-pa ); vecswap(a, pb-s, s); s = min(pd-pc, pn-pd-es); vecswap(pb, pn-s, s); if ((s = pb-pa) > es) qsort(a, s/es, es, cmp); if ((s = pd-pc) > es) qsort(pn-s, s/es, es, cmp); }