/*- * Copyright (c) 1992, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ # include # include # include #define min(a, b) (a) < (b) ? a : b /* * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". */ int VVarArray::Med3( int a, int b, int c ) const { return Compare(a, b) < 0 ? (Compare(b, c) < 0 ? b : (Compare(a, c) < 0 ? c : a )) : (Compare(b, c) > 0 ? b : (Compare(a, c) < 0 ? a : c )); } void VVarArray::Sort( int a, int n ) { int pa, pb, pc, pd, pl, pm, pn; int r, swap_cnt; loop: swap_cnt = 0; /* For small n, do insertion sort. */ if (n < 7) { for (pm = a + 1; pm < a + n; ++pm) for (pl = pm; pl > a && Compare(pl - 1, pl) > 0; --pl) Swap(pl, pl - 1); return; } /* Pick the median */ /* With a large enough sample, we pick the middle of three */ pm = a + n / 2; if (n > 7) { pl = a; pn = a + n - 1; if (n > 40) { int d = n / 8; pl = Med3( pl, pl + d, pl + 2 * d ); pm = Med3( pm - d, pm, pm + d ); pn = Med3( pn - 2 * d, pn - d, pn ); } pm = Med3( pl, pm, pn ); } /* Do it */ Swap(a, pm); pa = pb = a + 1; pc = pd = a + n - 1; for (;;) { while (pb <= pc && (r = Compare(pb, a)) <= 0) { if( !r ) { swap_cnt = 1; Swap( pa++, pb ); } ++pb; } while (pb <= pc && (r = Compare(pc, a)) >= 0) { if( !r ) { swap_cnt = 1; Swap( pc, pd-- ); } --pc; } if (pb > pc) break; swap_cnt = 1; Swap( pb++, pc-- ); } pn = a + n; r = min(pa - a, pb - pa); Swap(a, pb - r, r); r = min(pd - pc, pn - pd - 1); Swap(pb, pn - r, r); /* Switch to insertion sort */ /* This is not in the Bentley paper, but saves time for already */ /* sorted data. This used to be before the vecswaps, but that */ /* was wrong. */ if (swap_cnt == 0) { for (pm = a + 1; pm < a + n; ++pm) { for (pl = pm; pl > a && Compare(pl - 1, pl) > 0; --pl) Swap(pl, pl - 1); /* Be prudent: swap_cnt can be zero if the data is */ /* unsorted to either side of the median, but just */ /* happens to be partitioned properly about the */ /* median. You don't want to risk an insertion sort */ /* on a large body of data, so we bail back to qsort if */ /* we're moving data too far. */ if( ( swap_cnt += ( pm - pl ) ) > 1024 ) goto recurse; } return; } recurse: /* Recurse */ if ((r = pb - pa) > 1) Sort( a, r ); /* Iterate rather than recurse to save stack space */ if ((r = pd - pc) > 1) { a = pn - r; n = r; goto loop; } }