3 * Copyright (c) 1991-2001, Larry Wall
5 * You may distribute under the terms of either the GNU General Public
6 * License or the Artistic License, as specified in the README file.
11 * ...they shuffled back towards the rear of the line. 'No, not at the
12 * rear!' the slave-driver shouted. 'Three files up. And stay there...
16 #define PERL_IN_PP_SORT_C
19 static I32 sortcv(pTHX_ SV *a, SV *b);
20 static I32 sortcv_stacked(pTHX_ SV *a, SV *b);
21 static I32 sortcv_xsub(pTHX_ SV *a, SV *b);
22 static I32 sv_ncmp(pTHX_ SV *a, SV *b);
23 static I32 sv_i_ncmp(pTHX_ SV *a, SV *b);
24 static I32 amagic_ncmp(pTHX_ SV *a, SV *b);
25 static I32 amagic_i_ncmp(pTHX_ SV *a, SV *b);
26 static I32 amagic_cmp(pTHX_ SV *a, SV *b);
27 static I32 amagic_cmp_locale(pTHX_ SV *a, SV *b);
29 #define sv_cmp_static Perl_sv_cmp
30 #define sv_cmp_locale_static Perl_sv_cmp_locale
32 #define SORTHINTS(hintsvp) \
34 (hintsvp = hv_fetch(GvHV(PL_hintgv), "SORT", 4, FALSE))) ? \
35 (I32)SvIV(*hintsvp) : 0)
38 * The mergesort implementation is by Peter M. Mcilroy <pmcilroy@lucent.com>.
40 * The original code was written in conjunction with BSD Computer Software
41 * Research Group at University of California, Berkeley.
43 * See also: "Optimistic Merge Sort" (SODA '92)
45 * The integration to Perl is by John P. Linderman <jpl@research.att.com>.
47 * The code can be distributed under the same terms as Perl itself.
52 #include <sys/types.h>
56 #define New(ID,VAR,N,TYPE) VAR=(TYPE *)malloc((N)*sizeof(TYPE))
57 #define Safefree(VAR) free(VAR)
58 typedef int (*SVCOMPARE_t) (pTHX_ SV*, SV*);
59 #endif /* TESTHARNESS */
61 typedef char * aptr; /* pointer for arithmetic on sizes */
62 typedef SV * gptr; /* pointers in our lists */
64 /* Binary merge internal sort, with a few special mods
65 ** for the special perl environment it now finds itself in.
67 ** Things that were once options have been hotwired
68 ** to values suitable for this use. In particular, we'll always
69 ** initialize looking for natural runs, we'll always produce stable
70 ** output, and we'll always do Peter McIlroy's binary merge.
73 /* Pointer types for arithmetic and storage and convenience casts */
75 #define APTR(P) ((aptr)(P))
76 #define GPTP(P) ((gptr *)(P))
77 #define GPPP(P) ((gptr **)(P))
80 /* byte offset from pointer P to (larger) pointer Q */
81 #define BYTEOFF(P, Q) (APTR(Q) - APTR(P))
83 #define PSIZE sizeof(gptr)
85 /* If PSIZE is power of 2, make PSHIFT that power, if that helps */
88 #define PNELEM(P, Q) (BYTEOFF(P,Q) >> (PSHIFT))
89 #define PNBYTE(N) ((N) << (PSHIFT))
90 #define PINDEX(P, N) (GPTP(APTR(P) + PNBYTE(N)))
92 /* Leave optimization to compiler */
93 #define PNELEM(P, Q) (GPTP(Q) - GPTP(P))
94 #define PNBYTE(N) ((N) * (PSIZE))
95 #define PINDEX(P, N) (GPTP(P) + (N))
98 /* Pointer into other corresponding to pointer into this */
99 #define POTHER(P, THIS, OTHER) GPTP(APTR(OTHER) + BYTEOFF(THIS,P))
101 #define FROMTOUPTO(src, dst, lim) do *dst++ = *src++; while(src<lim)
104 /* Runs are identified by a pointer in the auxilliary list.
105 ** The pointer is at the start of the list,
106 ** and it points to the start of the next list.
107 ** NEXT is used as an lvalue, too.
110 #define NEXT(P) (*GPPP(P))
113 /* PTHRESH is the minimum number of pairs with the same sense to justify
114 ** checking for a run and extending it. Note that PTHRESH counts PAIRS,
115 ** not just elements, so PTHRESH == 8 means a run of 16.
120 /* RTHRESH is the number of elements in a run that must compare low
121 ** to the low element from the opposing run before we justify
122 ** doing a binary rampup instead of single stepping.
123 ** In random input, N in a row low should only happen with
124 ** probability 2^(1-N), so we can risk that we are dealing
125 ** with orderly input without paying much when we aren't.
132 ** Overview of algorithm and variables.
133 ** The array of elements at list1 will be organized into runs of length 2,
134 ** or runs of length >= 2 * PTHRESH. We only try to form long runs when
135 ** PTHRESH adjacent pairs compare in the same way, suggesting overall order.
137 ** Unless otherwise specified, pair pointers address the first of two elements.
139 ** b and b+1 are a pair that compare with sense ``sense''.
140 ** b is the ``bottom'' of adjacent pairs that might form a longer run.
142 ** p2 parallels b in the list2 array, where runs are defined by
145 ** t represents the ``top'' of the adjacent pairs that might extend
146 ** the run beginning at b. Usually, t addresses a pair
147 ** that compares with opposite sense from (b,b+1).
148 ** However, it may also address a singleton element at the end of list1,
149 ** or it may be equal to ``last'', the first element beyond list1.
151 ** r addresses the Nth pair following b. If this would be beyond t,
152 ** we back it off to t. Only when r is less than t do we consider the
153 ** run long enough to consider checking.
155 ** q addresses a pair such that the pairs at b through q already form a run.
156 ** Often, q will equal b, indicating we only are sure of the pair itself.
157 ** However, a search on the previous cycle may have revealed a longer run,
158 ** so q may be greater than b.
160 ** p is used to work back from a candidate r, trying to reach q,
161 ** which would mean b through r would be a run. If we discover such a run,
162 ** we start q at r and try to push it further towards t.
163 ** If b through r is NOT a run, we detect the wrong order at (p-1,p).
164 ** In any event, after the check (if any), we have two main cases.
166 ** 1) Short run. b <= q < p <= r <= t.
167 ** b through q is a run (perhaps trivial)
168 ** q through p are uninteresting pairs
169 ** p through r is a run
171 ** 2) Long run. b < r <= q < t.
172 ** b through q is a run (of length >= 2 * PTHRESH)
174 ** Note that degenerate cases are not only possible, but likely.
175 ** For example, if the pair following b compares with opposite sense,
176 ** then b == q < p == r == t.
181 dynprep(pTHX_ gptr *list1, gptr *list2, size_t nmemb, SVCOMPARE_t cmp)
184 register gptr *b, *p, *q, *t, *p2;
185 register gptr c, *last, *r;
189 last = PINDEX(b, nmemb);
190 sense = (cmp(aTHX_ *b, *(b+1)) > 0);
191 for (p2 = list2; b < last; ) {
192 /* We just started, or just reversed sense.
193 ** Set t at end of pairs with the prevailing sense.
195 for (p = b+2, t = p; ++p < last; t = ++p) {
196 if ((cmp(aTHX_ *t, *p) > 0) != sense) break;
199 /* Having laid out the playing field, look for long runs */
201 p = r = b + (2 * PTHRESH);
202 if (r >= t) p = r = t; /* too short to care about */
204 while (((cmp(aTHX_ *(p-1), *p) > 0) == sense) &&
207 /* b through r is a (long) run.
208 ** Extend it as far as possible.
211 while (((p += 2) < t) &&
212 ((cmp(aTHX_ *(p-1), *p) > 0) == sense)) q = p;
213 r = p = q + 2; /* no simple pairs, no after-run */
216 if (q > b) { /* run of greater than 2 at b */
219 /* pick up singleton, if possible */
222 ((cmp(aTHX_ *(p-1), *p) > 0) == sense))
223 savep = r = p = q = last;
224 p2 = NEXT(p2) = p2 + (p - b);
225 if (sense) while (b < --p) {
232 while (q < p) { /* simple pairs */
233 p2 = NEXT(p2) = p2 + 2;
240 if (((b = p) == t) && ((t+1) == last)) {
252 /* Overview of bmerge variables:
254 ** list1 and list2 address the main and auxiliary arrays.
255 ** They swap identities after each merge pass.
256 ** Base points to the original list1, so we can tell if
257 ** the pointers ended up where they belonged (or must be copied).
259 ** When we are merging two lists, f1 and f2 are the next elements
260 ** on the respective lists. l1 and l2 mark the end of the lists.
261 ** tp2 is the current location in the merged list.
263 ** p1 records where f1 started.
264 ** After the merge, a new descriptor is built there.
266 ** p2 is a ``parallel'' pointer in (what starts as) descriptor space.
267 ** It is used to identify and delimit the runs.
269 ** In the heat of determining where q, the greater of the f1/f2 elements,
270 ** belongs in the other list, b, t and p, represent bottom, top and probe
271 ** locations, respectively, in the other list.
272 ** They make convenient temporary pointers in other places.
276 S_mergesortsv(pTHX_ gptr *list1, size_t nmemb, SVCOMPARE_t cmp)
280 register gptr *f1, *f2, *t, *b, *p, *tp2, *l1, *l2, *q;
281 gptr *aux, *list2, *p2, *last;
285 if (nmemb <= 1) return; /* sorted trivially */
286 New(799,list2,nmemb,gptr); /* allocate auxilliary array */
288 dynprep(aTHX_ list1, list2, nmemb, cmp);
289 last = PINDEX(list2, nmemb);
290 while (NEXT(list2) != last) {
291 /* More than one run remains. Do some merging to reduce runs. */
293 for (tp2 = p2 = list2; p2 != last;) {
294 /* The new first run begins where the old second list ended.
295 ** Use the p2 ``parallel'' pointer to identify the end of the run.
299 f2 = l1 = POTHER(t, list2, list1);
300 if (t != last) t = NEXT(t);
301 l2 = POTHER(t, list2, list1);
303 while (f1 < l1 && f2 < l2) {
304 /* If head 1 is larger than head 2, find ALL the elements
305 ** in list 2 strictly less than head1, write them all,
306 ** then head 1. Then compare the new heads, and repeat,
307 ** until one or both lists are exhausted.
309 ** In all comparisons (after establishing
310 ** which head to merge) the item to merge
311 ** (at pointer q) is the first operand of
312 ** the comparison. When we want to know
313 ** if ``q is strictly less than the other'',
316 ** because stability demands that we treat equality
317 ** as high when q comes from l2, and as low when
318 ** q was from l1. So we ask the question by doing
319 ** cmp(q, other) <= sense
320 ** and make sense == 0 when equality should look low,
321 ** and -1 when equality should look high.
325 if (cmp(aTHX_ *f1, *f2) <= 0) {
326 q = f2; b = f1; t = l1;
329 q = f1; b = f2; t = l2;
336 ** Leave t at something strictly
337 ** greater than q (or at the end of the list),
338 ** and b at something strictly less than q.
340 for (i = 1, run = 0 ;;) {
341 if ((p = PINDEX(b, i)) >= t) {
343 if (((p = PINDEX(t, -1)) > b) &&
344 (cmp(aTHX_ *q, *p) <= sense))
348 } else if (cmp(aTHX_ *q, *p) <= sense) {
352 if (++run >= RTHRESH) i += i;
356 /* q is known to follow b and must be inserted before t.
357 ** Increment b, so the range of possibilities is [b,t).
358 ** Round binary split down, to favor early appearance.
359 ** Adjust b and t until q belongs just before t.
364 p = PINDEX(b, (PNELEM(b, t) - 1) / 2);
365 if (cmp(aTHX_ *q, *p) <= sense) {
371 /* Copy all the strictly low elements */
374 FROMTOUPTO(f2, tp2, t);
377 FROMTOUPTO(f1, tp2, t);
383 /* Run out remaining list */
385 if (f2 < l2) FROMTOUPTO(f2, tp2, l2);
386 } else FROMTOUPTO(f1, tp2, l1);
387 p1 = NEXT(p1) = POTHER(tp2, list2, list1);
392 last = PINDEX(list2, nmemb);
395 last = PINDEX(list1, nmemb);
396 FROMTOUPTO(list1, list2, last);
403 * The quicksort implementation was derived from source code contributed
406 * NOTE: this code was derived from Tom Horsley's qsort replacement
407 * and should not be confused with the original code.
410 /* Copyright (C) Tom Horsley, 1997. All rights reserved.
412 Permission granted to distribute under the same terms as perl which are
415 This program is free software; you can redistribute it and/or modify
416 it under the terms of either:
418 a) the GNU General Public License as published by the Free
419 Software Foundation; either version 1, or (at your option) any
422 b) the "Artistic License" which comes with this Kit.
424 Details on the perl license can be found in the perl source code which
425 may be located via the www.perl.com web page.
427 This is the most wonderfulest possible qsort I can come up with (and
428 still be mostly portable) My (limited) tests indicate it consistently
429 does about 20% fewer calls to compare than does the qsort in the Visual
430 C++ library, other vendors may vary.
432 Some of the ideas in here can be found in "Algorithms" by Sedgewick,
433 others I invented myself (or more likely re-invented since they seemed
434 pretty obvious once I watched the algorithm operate for a while).
436 Most of this code was written while watching the Marlins sweep the Giants
437 in the 1997 National League Playoffs - no Braves fans allowed to use this
438 code (just kidding :-).
440 I realize that if I wanted to be true to the perl tradition, the only
441 comment in this file would be something like:
443 ...they shuffled back towards the rear of the line. 'No, not at the
444 rear!' the slave-driver shouted. 'Three files up. And stay there...
446 However, I really needed to violate that tradition just so I could keep
447 track of what happens myself, not to mention some poor fool trying to
448 understand this years from now :-).
451 /* ********************************************************** Configuration */
453 #ifndef QSORT_ORDER_GUESS
454 #define QSORT_ORDER_GUESS 2 /* Select doubling version of the netBSD trick */
457 /* QSORT_MAX_STACK is the largest number of partitions that can be stacked up for
458 future processing - a good max upper bound is log base 2 of memory size
459 (32 on 32 bit machines, 64 on 64 bit machines, etc). In reality can
460 safely be smaller than that since the program is taking up some space and
461 most operating systems only let you grab some subset of contiguous
462 memory (not to mention that you are normally sorting data larger than
463 1 byte element size :-).
465 #ifndef QSORT_MAX_STACK
466 #define QSORT_MAX_STACK 32
469 /* QSORT_BREAK_EVEN is the size of the largest partition we should insertion sort.
470 Anything bigger and we use qsort. If you make this too small, the qsort
471 will probably break (or become less efficient), because it doesn't expect
472 the middle element of a partition to be the same as the right or left -
473 you have been warned).
475 #ifndef QSORT_BREAK_EVEN
476 #define QSORT_BREAK_EVEN 6
479 /* QSORT_PLAY_SAFE is the size of the largest partition we're willing
480 to go quadratic on. We innoculate larger partitions against
481 quadratic behavior by shuffling them before sorting. This is not
482 an absolute guarantee of non-quadratic behavior, but it would take
483 staggeringly bad luck to pick extreme elements as the pivot
484 from randomized data.
486 #ifndef QSORT_PLAY_SAFE
487 #define QSORT_PLAY_SAFE 255
490 /* ************************************************************* Data Types */
492 /* hold left and right index values of a partition waiting to be sorted (the
493 partition includes both left and right - right is NOT one past the end or
496 struct partition_stack_entry {
499 #ifdef QSORT_ORDER_GUESS
500 int qsort_break_even;
504 /* ******************************************************* Shorthand Macros */
506 /* Note that these macros will be used from inside the qsort function where
507 we happen to know that the variable 'elt_size' contains the size of an
508 array element and the variable 'temp' points to enough space to hold a
509 temp element and the variable 'array' points to the array being sorted
510 and 'compare' is the pointer to the compare routine.
512 Also note that there are very many highly architecture specific ways
513 these might be sped up, but this is simply the most generally portable
514 code I could think of.
517 /* Return < 0 == 0 or > 0 as the value of elt1 is < elt2, == elt2, > elt2
519 #define qsort_cmp(elt1, elt2) \
520 ((*compare)(aTHX_ array[elt1], array[elt2]))
522 #ifdef QSORT_ORDER_GUESS
523 #define QSORT_NOTICE_SWAP swapped++;
525 #define QSORT_NOTICE_SWAP
528 /* swaps contents of array elements elt1, elt2.
530 #define qsort_swap(elt1, elt2) \
533 temp = array[elt1]; \
534 array[elt1] = array[elt2]; \
535 array[elt2] = temp; \
538 /* rotate contents of elt1, elt2, elt3 such that elt1 gets elt2, elt2 gets
539 elt3 and elt3 gets elt1.
541 #define qsort_rotate(elt1, elt2, elt3) \
544 temp = array[elt1]; \
545 array[elt1] = array[elt2]; \
546 array[elt2] = array[elt3]; \
547 array[elt3] = temp; \
550 /* ************************************************************ Debug stuff */
557 return; /* good place to set a breakpoint */
560 #define qsort_assert(t) (void)( (t) || (break_here(), 0) )
567 int (*compare)(const void * elt1, const void * elt2),
568 int pc_left, int pc_right, int u_left, int u_right)
572 qsort_assert(pc_left <= pc_right);
573 qsort_assert(u_right < pc_left);
574 qsort_assert(pc_right < u_left);
575 for (i = u_right + 1; i < pc_left; ++i) {
576 qsort_assert(qsort_cmp(i, pc_left) < 0);
578 for (i = pc_left; i < pc_right; ++i) {
579 qsort_assert(qsort_cmp(i, pc_right) == 0);
581 for (i = pc_right + 1; i < u_left; ++i) {
582 qsort_assert(qsort_cmp(pc_right, i) < 0);
586 #define qsort_all_asserts(PC_LEFT, PC_RIGHT, U_LEFT, U_RIGHT) \
587 doqsort_all_asserts(array, num_elts, elt_size, compare, \
588 PC_LEFT, PC_RIGHT, U_LEFT, U_RIGHT)
592 #define qsort_assert(t) ((void)0)
594 #define qsort_all_asserts(PC_LEFT, PC_RIGHT, U_LEFT, U_RIGHT) ((void)0)
598 /* ****************************************************************** qsort */
600 STATIC void /* the standard unstable (u) quicksort (qsort) */
601 S_qsortsvu(pTHX_ SV ** array, size_t num_elts, SVCOMPARE_t compare)
605 struct partition_stack_entry partition_stack[QSORT_MAX_STACK];
606 int next_stack_entry = 0;
610 #ifdef QSORT_ORDER_GUESS
611 int qsort_break_even;
615 /* Make sure we actually have work to do.
621 /* Innoculate large partitions against quadratic behavior */
622 if (num_elts > QSORT_PLAY_SAFE) {
623 register size_t n, j;
625 for (n = num_elts, q = array; n > 1; ) {
633 /* Setup the initial partition definition and fall into the sorting loop
636 part_right = (int)(num_elts - 1);
637 #ifdef QSORT_ORDER_GUESS
638 qsort_break_even = QSORT_BREAK_EVEN;
640 #define qsort_break_even QSORT_BREAK_EVEN
643 if ((part_right - part_left) >= qsort_break_even) {
644 /* OK, this is gonna get hairy, so lets try to document all the
645 concepts and abbreviations and variables and what they keep
648 pc: pivot chunk - the set of array elements we accumulate in the
649 middle of the partition, all equal in value to the original
650 pivot element selected. The pc is defined by:
652 pc_left - the leftmost array index of the pc
653 pc_right - the rightmost array index of the pc
655 we start with pc_left == pc_right and only one element
656 in the pivot chunk (but it can grow during the scan).
658 u: uncompared elements - the set of elements in the partition
659 we have not yet compared to the pivot value. There are two
660 uncompared sets during the scan - one to the left of the pc
661 and one to the right.
663 u_right - the rightmost index of the left side's uncompared set
664 u_left - the leftmost index of the right side's uncompared set
666 The leftmost index of the left sides's uncompared set
667 doesn't need its own variable because it is always defined
668 by the leftmost edge of the whole partition (part_left). The
669 same goes for the rightmost edge of the right partition
672 We know there are no uncompared elements on the left once we
673 get u_right < part_left and no uncompared elements on the
674 right once u_left > part_right. When both these conditions
675 are met, we have completed the scan of the partition.
677 Any elements which are between the pivot chunk and the
678 uncompared elements should be less than the pivot value on
679 the left side and greater than the pivot value on the right
680 side (in fact, the goal of the whole algorithm is to arrange
681 for that to be true and make the groups of less-than and
682 greater-then elements into new partitions to sort again).
684 As you marvel at the complexity of the code and wonder why it
685 has to be so confusing. Consider some of the things this level
688 Once I do a compare, I squeeze every ounce of juice out of it. I
689 never do compare calls I don't have to do, and I certainly never
692 I also never swap any elements unless I can prove there is a
693 good reason. Many sort algorithms will swap a known value with
694 an uncompared value just to get things in the right place (or
695 avoid complexity :-), but that uncompared value, once it gets
696 compared, may then have to be swapped again. A lot of the
697 complexity of this code is due to the fact that it never swaps
698 anything except compared values, and it only swaps them when the
699 compare shows they are out of position.
701 int pc_left, pc_right;
706 pc_left = ((part_left + part_right) / 2);
708 u_right = pc_left - 1;
709 u_left = pc_right + 1;
711 /* Qsort works best when the pivot value is also the median value
712 in the partition (unfortunately you can't find the median value
713 without first sorting :-), so to give the algorithm a helping
714 hand, we pick 3 elements and sort them and use the median value
715 of that tiny set as the pivot value.
717 Some versions of qsort like to use the left middle and right as
718 the 3 elements to sort so they can insure the ends of the
719 partition will contain values which will stop the scan in the
720 compare loop, but when you have to call an arbitrarily complex
721 routine to do a compare, its really better to just keep track of
722 array index values to know when you hit the edge of the
723 partition and avoid the extra compare. An even better reason to
724 avoid using a compare call is the fact that you can drop off the
725 edge of the array if someone foolishly provides you with an
726 unstable compare function that doesn't always provide consistent
729 So, since it is simpler for us to compare the three adjacent
730 elements in the middle of the partition, those are the ones we
731 pick here (conveniently pointed at by u_right, pc_left, and
732 u_left). The values of the left, center, and right elements
733 are refered to as l c and r in the following comments.
736 #ifdef QSORT_ORDER_GUESS
739 s = qsort_cmp(u_right, pc_left);
742 s = qsort_cmp(pc_left, u_left);
743 /* if l < c, c < r - already in order - nothing to do */
745 /* l < c, c == r - already in order, pc grows */
747 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
749 /* l < c, c > r - need to know more */
750 s = qsort_cmp(u_right, u_left);
752 /* l < c, c > r, l < r - swap c & r to get ordered */
753 qsort_swap(pc_left, u_left);
754 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
756 /* l < c, c > r, l == r - swap c&r, grow pc */
757 qsort_swap(pc_left, u_left);
759 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
761 /* l < c, c > r, l > r - make lcr into rlc to get ordered */
762 qsort_rotate(pc_left, u_right, u_left);
763 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
768 s = qsort_cmp(pc_left, u_left);
770 /* l == c, c < r - already in order, grow pc */
772 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
774 /* l == c, c == r - already in order, grow pc both ways */
777 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
779 /* l == c, c > r - swap l & r, grow pc */
780 qsort_swap(u_right, u_left);
782 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
786 s = qsort_cmp(pc_left, u_left);
788 /* l > c, c < r - need to know more */
789 s = qsort_cmp(u_right, u_left);
791 /* l > c, c < r, l < r - swap l & c to get ordered */
792 qsort_swap(u_right, pc_left);
793 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
795 /* l > c, c < r, l == r - swap l & c, grow pc */
796 qsort_swap(u_right, pc_left);
798 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
800 /* l > c, c < r, l > r - rotate lcr into crl to order */
801 qsort_rotate(u_right, pc_left, u_left);
802 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
805 /* l > c, c == r - swap ends, grow pc */
806 qsort_swap(u_right, u_left);
808 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
810 /* l > c, c > r - swap ends to get in order */
811 qsort_swap(u_right, u_left);
812 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
815 /* We now know the 3 middle elements have been compared and
816 arranged in the desired order, so we can shrink the uncompared
821 qsort_all_asserts(pc_left, pc_right, u_left, u_right);
823 /* The above massive nested if was the simple part :-). We now have
824 the middle 3 elements ordered and we need to scan through the
825 uncompared sets on either side, swapping elements that are on
826 the wrong side or simply shuffling equal elements around to get
827 all equal elements into the pivot chunk.
831 int still_work_on_left;
832 int still_work_on_right;
834 /* Scan the uncompared values on the left. If I find a value
835 equal to the pivot value, move it over so it is adjacent to
836 the pivot chunk and expand the pivot chunk. If I find a value
837 less than the pivot value, then just leave it - its already
838 on the correct side of the partition. If I find a greater
839 value, then stop the scan.
841 while ((still_work_on_left = (u_right >= part_left))) {
842 s = qsort_cmp(u_right, pc_left);
847 if (pc_left != u_right) {
848 qsort_swap(u_right, pc_left);
854 qsort_assert(u_right < pc_left);
855 qsort_assert(pc_left <= pc_right);
856 qsort_assert(qsort_cmp(u_right + 1, pc_left) <= 0);
857 qsort_assert(qsort_cmp(pc_left, pc_right) == 0);
860 /* Do a mirror image scan of uncompared values on the right
862 while ((still_work_on_right = (u_left <= part_right))) {
863 s = qsort_cmp(pc_right, u_left);
868 if (pc_right != u_left) {
869 qsort_swap(pc_right, u_left);
875 qsort_assert(u_left > pc_right);
876 qsort_assert(pc_left <= pc_right);
877 qsort_assert(qsort_cmp(pc_right, u_left - 1) <= 0);
878 qsort_assert(qsort_cmp(pc_left, pc_right) == 0);
881 if (still_work_on_left) {
882 /* I know I have a value on the left side which needs to be
883 on the right side, but I need to know more to decide
884 exactly the best thing to do with it.
886 if (still_work_on_right) {
887 /* I know I have values on both side which are out of
888 position. This is a big win because I kill two birds
889 with one swap (so to speak). I can advance the
890 uncompared pointers on both sides after swapping both
891 of them into the right place.
893 qsort_swap(u_right, u_left);
896 qsort_all_asserts(pc_left, pc_right, u_left, u_right);
898 /* I have an out of position value on the left, but the
899 right is fully scanned, so I "slide" the pivot chunk
900 and any less-than values left one to make room for the
901 greater value over on the right. If the out of position
902 value is immediately adjacent to the pivot chunk (there
903 are no less-than values), I can do that with a swap,
904 otherwise, I have to rotate one of the less than values
905 into the former position of the out of position value
906 and the right end of the pivot chunk into the left end
910 if (pc_left == u_right) {
911 qsort_swap(u_right, pc_right);
912 qsort_all_asserts(pc_left, pc_right-1, u_left, u_right-1);
914 qsort_rotate(u_right, pc_left, pc_right);
915 qsort_all_asserts(pc_left, pc_right-1, u_left, u_right-1);
920 } else if (still_work_on_right) {
921 /* Mirror image of complex case above: I have an out of
922 position value on the right, but the left is fully
923 scanned, so I need to shuffle things around to make room
924 for the right value on the left.
927 if (pc_right == u_left) {
928 qsort_swap(u_left, pc_left);
929 qsort_all_asserts(pc_left+1, pc_right, u_left+1, u_right);
931 qsort_rotate(pc_right, pc_left, u_left);
932 qsort_all_asserts(pc_left+1, pc_right, u_left+1, u_right);
937 /* No more scanning required on either side of partition,
938 break out of loop and figure out next set of partitions
944 /* The elements in the pivot chunk are now in the right place. They
945 will never move or be compared again. All I have to do is decide
946 what to do with the stuff to the left and right of the pivot
949 Notes on the QSORT_ORDER_GUESS ifdef code:
951 1. If I just built these partitions without swapping any (or
952 very many) elements, there is a chance that the elements are
953 already ordered properly (being properly ordered will
954 certainly result in no swapping, but the converse can't be
957 2. A (properly written) insertion sort will run faster on
958 already ordered data than qsort will.
960 3. Perhaps there is some way to make a good guess about
961 switching to an insertion sort earlier than partition size 6
962 (for instance - we could save the partition size on the stack
963 and increase the size each time we find we didn't swap, thus
964 switching to insertion sort earlier for partitions with a
965 history of not swapping).
967 4. Naturally, if I just switch right away, it will make
968 artificial benchmarks with pure ascending (or descending)
969 data look really good, but is that a good reason in general?
973 #ifdef QSORT_ORDER_GUESS
975 #if QSORT_ORDER_GUESS == 1
976 qsort_break_even = (part_right - part_left) + 1;
978 #if QSORT_ORDER_GUESS == 2
979 qsort_break_even *= 2;
981 #if QSORT_ORDER_GUESS == 3
982 int prev_break = qsort_break_even;
983 qsort_break_even *= qsort_break_even;
984 if (qsort_break_even < prev_break) {
985 qsort_break_even = (part_right - part_left) + 1;
989 qsort_break_even = QSORT_BREAK_EVEN;
993 if (part_left < pc_left) {
994 /* There are elements on the left which need more processing.
995 Check the right as well before deciding what to do.
997 if (pc_right < part_right) {
998 /* We have two partitions to be sorted. Stack the biggest one
999 and process the smallest one on the next iteration. This
1000 minimizes the stack height by insuring that any additional
1001 stack entries must come from the smallest partition which
1002 (because it is smallest) will have the fewest
1003 opportunities to generate additional stack entries.
1005 if ((part_right - pc_right) > (pc_left - part_left)) {
1006 /* stack the right partition, process the left */
1007 partition_stack[next_stack_entry].left = pc_right + 1;
1008 partition_stack[next_stack_entry].right = part_right;
1009 #ifdef QSORT_ORDER_GUESS
1010 partition_stack[next_stack_entry].qsort_break_even = qsort_break_even;
1012 part_right = pc_left - 1;
1014 /* stack the left partition, process the right */
1015 partition_stack[next_stack_entry].left = part_left;
1016 partition_stack[next_stack_entry].right = pc_left - 1;
1017 #ifdef QSORT_ORDER_GUESS
1018 partition_stack[next_stack_entry].qsort_break_even = qsort_break_even;
1020 part_left = pc_right + 1;
1022 qsort_assert(next_stack_entry < QSORT_MAX_STACK);
1025 /* The elements on the left are the only remaining elements
1026 that need sorting, arrange for them to be processed as the
1029 part_right = pc_left - 1;
1031 } else if (pc_right < part_right) {
1032 /* There is only one chunk on the right to be sorted, make it
1033 the new partition and loop back around.
1035 part_left = pc_right + 1;
1037 /* This whole partition wound up in the pivot chunk, so
1038 we need to get a new partition off the stack.
1040 if (next_stack_entry == 0) {
1041 /* the stack is empty - we are done */
1045 part_left = partition_stack[next_stack_entry].left;
1046 part_right = partition_stack[next_stack_entry].right;
1047 #ifdef QSORT_ORDER_GUESS
1048 qsort_break_even = partition_stack[next_stack_entry].qsort_break_even;
1052 /* This partition is too small to fool with qsort complexity, just
1053 do an ordinary insertion sort to minimize overhead.
1056 /* Assume 1st element is in right place already, and start checking
1057 at 2nd element to see where it should be inserted.
1059 for (i = part_left + 1; i <= part_right; ++i) {
1061 /* Scan (backwards - just in case 'i' is already in right place)
1062 through the elements already sorted to see if the ith element
1063 belongs ahead of one of them.
1065 for (j = i - 1; j >= part_left; --j) {
1066 if (qsort_cmp(i, j) >= 0) {
1067 /* i belongs right after j
1074 /* Looks like we really need to move some things
1078 for (k = i - 1; k >= j; --k)
1079 array[k + 1] = array[k];
1084 /* That partition is now sorted, grab the next one, or get out
1085 of the loop if there aren't any more.
1088 if (next_stack_entry == 0) {
1089 /* the stack is empty - we are done */
1093 part_left = partition_stack[next_stack_entry].left;
1094 part_right = partition_stack[next_stack_entry].right;
1095 #ifdef QSORT_ORDER_GUESS
1096 qsort_break_even = partition_stack[next_stack_entry].qsort_break_even;
1101 /* Believe it or not, the array is sorted at this point! */
1105 #define SMALLSORT (200)
1108 /* Stabilize what is, presumably, an otherwise unstable sort method.
1109 * We do that by allocating (or having on hand) an array of pointers
1110 * that is the same size as the original array of elements to be sorted.
1111 * We initialize this parallel array with the addresses of the original
1112 * array elements. This indirection can make you crazy.
1113 * Some pictures can help. After initializing, we have
1117 * | | --------------> | | ------> first element to be sorted
1119 * | | --------------> | | ------> second element to be sorted
1121 * | | --------------> | | ------> third element to be sorted
1125 * | | --------------> | | ------> n-1st element to be sorted
1127 * | | --------------> | | ------> n-th element to be sorted
1130 * During the sort phase, we leave the elements of list1 where they are,
1131 * and sort the pointers in the indirect array in the same order determined
1132 * by the original comparison routine on the elements pointed to.
1133 * Because we don't move the elements of list1 around through
1134 * this phase, we can break ties on elements that compare equal
1135 * using their address in the list1 array, ensuring stabilty.
1136 * This leaves us with something looking like
1140 * | | --+ +---> | | ------> first element to be sorted
1142 * | | --|-------|---> | | ------> second element to be sorted
1144 * | | --|-------+ +-> | | ------> third element to be sorted
1147 * +----+ | | | | +----+
1148 * | | ---|-+ | +--> | | ------> n-1st element to be sorted
1150 * | | ---+ +----> | | ------> n-th element to be sorted
1153 * where the i-th element of the indirect array points to the element
1154 * that should be i-th in the sorted array. After the sort phase,
1155 * we have to put the elements of list1 into the places
1156 * dictated by the indirect array.
1159 static SVCOMPARE_t RealCmp;
1162 cmpindir(pTHX_ gptr a, gptr b)
1165 gptr *ap = (gptr *)a;
1166 gptr *bp = (gptr *)b;
1168 if ((sense = RealCmp(aTHX_ *ap, *bp)) == 0)
1169 sense = (ap > bp) ? 1 : ((ap < bp) ? -1 : 0);
1174 S_qsortsv(pTHX_ gptr *list1, size_t nmemb, SVCOMPARE_t cmp)
1178 if (SORTHINTS(hintsvp) & HINT_SORT_FAST)
1179 S_qsortsvu(aTHX_ list1, nmemb, cmp);
1181 register gptr **pp, *q;
1182 register size_t n, j, i;
1183 gptr *small[SMALLSORT], **indir, tmp;
1184 SVCOMPARE_t savecmp;
1185 if (nmemb <= 1) return; /* sorted trivially */
1187 /* Small arrays can use the stack, big ones must be allocated */
1188 if (nmemb <= SMALLSORT) indir = small;
1189 else { New(1799, indir, nmemb, gptr *); }
1191 /* Copy pointers to original array elements into indirect array */
1192 for (n = nmemb, pp = indir, q = list1; n--; ) *pp++ = q++;
1194 savecmp = RealCmp; /* Save current comparison routine, if any */
1195 RealCmp = cmp; /* Put comparison routine where cmpindir can find it */
1197 /* sort, with indirection */
1198 S_qsortsvu(aTHX_ (gptr *)indir, nmemb, cmpindir);
1202 for (n = nmemb; n--; ) {
1203 /* Assert A: all elements of q with index > n are already
1204 * in place. This is vacuosly true at the start, and we
1205 * put element n where it belongs below (if it wasn't
1206 * already where it belonged). Assert B: we only move
1207 * elements that aren't where they belong,
1208 * so, by A, we never tamper with elements above n.
1210 j = pp[n] - q; /* This sets j so that q[j] is
1211 * at pp[n]. *pp[j] belongs in
1212 * q[j], by construction.
1214 if (n != j) { /* all's well if n == j */
1215 tmp = q[j]; /* save what's in q[j] */
1217 q[j] = *pp[j]; /* put *pp[j] where it belongs */
1218 i = pp[j] - q; /* the index in q of the element
1220 pp[j] = q + j; /* this is ok now */
1221 } while ((j = i) != n);
1222 /* There are only finitely many (nmemb) addresses
1224 * So we must eventually revisit an index we saw before.
1225 * Suppose the first revisited index is k != n.
1226 * An index is visited because something else belongs there.
1227 * If we visit k twice, then two different elements must
1228 * belong in the same place, which cannot be.
1229 * So j must get back to n, the loop terminates,
1230 * and we put the saved element where it belongs.
1232 q[n] = tmp; /* put what belongs into
1233 * the n-th element */
1237 /* free iff allocated */
1238 if (indir != small) { Safefree(indir); }
1239 /* restore prevailing comparison routine */
1247 Sort an array. Here is an example:
1249 sortsv(AvARRAY(av), av_len(av)+1, Perl_sv_cmp_locale);
1255 Perl_sortsv(pTHX_ SV **array, size_t nmemb, SVCOMPARE_t cmp)
1257 void (*sortsvp)(pTHX_ SV **array, size_t nmemb, SVCOMPARE_t cmp) =
1262 if ((hints = SORTHINTS(hintsvp))) {
1263 if (hints & HINT_SORT_QUICKSORT)
1264 sortsvp = S_qsortsv;
1266 if (hints & HINT_SORT_MERGESORT)
1267 sortsvp = S_mergesortsv;
1269 sortsvp = S_mergesortsv;
1273 sortsvp(aTHX_ array, nmemb, cmp);
1278 dSP; dMARK; dORIGMARK;
1280 SV **myorigmark = ORIGMARK;
1286 OP* nextop = PL_op->op_next;
1287 I32 overloading = 0;
1288 bool hasargs = FALSE;
1291 if (gimme != G_ARRAY) {
1297 SAVEVPTR(PL_sortcop);
1298 if (PL_op->op_flags & OPf_STACKED) {
1299 if (PL_op->op_flags & OPf_SPECIAL) {
1300 OP *kid = cLISTOP->op_first->op_sibling; /* pass pushmark */
1301 kid = kUNOP->op_first; /* pass rv2gv */
1302 kid = kUNOP->op_first; /* pass leave */
1303 PL_sortcop = kid->op_next;
1304 stash = CopSTASH(PL_curcop);
1307 cv = sv_2cv(*++MARK, &stash, &gv, 0);
1308 if (cv && SvPOK(cv)) {
1310 char *proto = SvPV((SV*)cv, n_a);
1311 if (proto && strEQ(proto, "$$")) {
1315 if (!(cv && CvROOT(cv))) {
1316 if (cv && CvXSUB(cv)) {
1320 SV *tmpstr = sv_newmortal();
1321 gv_efullname3(tmpstr, gv, Nullch);
1322 DIE(aTHX_ "Undefined sort subroutine \"%s\" called",
1326 DIE(aTHX_ "Undefined subroutine in sort");
1331 PL_sortcop = (OP*)cv;
1333 PL_sortcop = CvSTART(cv);
1334 SAVEVPTR(CvROOT(cv)->op_ppaddr);
1335 CvROOT(cv)->op_ppaddr = PL_ppaddr[OP_NULL];
1337 SAVEVPTR(PL_curpad);
1338 PL_curpad = AvARRAY((AV*)AvARRAY(CvPADLIST(cv))[1]);
1343 PL_sortcop = Nullop;
1344 stash = CopSTASH(PL_curcop);
1347 up = myorigmark + 1;
1348 while (MARK < SP) { /* This may or may not shift down one here. */
1350 if ((*up = *++MARK)) { /* Weed out nulls. */
1352 if (!PL_sortcop && !SvPOK(*up)) {
1357 (void)sv_2pv(*up, &n_a);
1362 max = --up - myorigmark;
1367 bool oldcatch = CATCH_GET;
1373 PUSHSTACKi(PERLSI_SORT);
1374 if (!hasargs && !is_xsub) {
1375 if (PL_sortstash != stash || !PL_firstgv || !PL_secondgv) {
1376 SAVESPTR(PL_firstgv);
1377 SAVESPTR(PL_secondgv);
1378 PL_firstgv = gv_fetchpv("a", TRUE, SVt_PV);
1379 PL_secondgv = gv_fetchpv("b", TRUE, SVt_PV);
1380 PL_sortstash = stash;
1382 #ifdef USE_5005THREADS
1383 sv_lock((SV *)PL_firstgv);
1384 sv_lock((SV *)PL_secondgv);
1386 SAVESPTR(GvSV(PL_firstgv));
1387 SAVESPTR(GvSV(PL_secondgv));
1390 PUSHBLOCK(cx, CXt_NULL, PL_stack_base);
1391 if (!(PL_op->op_flags & OPf_SPECIAL)) {
1392 cx->cx_type = CXt_SUB;
1393 cx->blk_gimme = G_SCALAR;
1396 (void)SvREFCNT_inc(cv); /* in preparation for POPSUB */
1398 PL_sortcxix = cxstack_ix;
1400 if (hasargs && !is_xsub) {
1401 /* This is mostly copied from pp_entersub */
1402 AV *av = (AV*)PL_curpad[0];
1404 #ifndef USE_5005THREADS
1405 cx->blk_sub.savearray = GvAV(PL_defgv);
1406 GvAV(PL_defgv) = (AV*)SvREFCNT_inc(av);
1407 #endif /* USE_5005THREADS */
1408 cx->blk_sub.oldcurpad = PL_curpad;
1409 cx->blk_sub.argarray = av;
1411 sortsv((myorigmark+1), max,
1412 is_xsub ? sortcv_xsub : hasargs ? sortcv_stacked : sortcv);
1414 POPBLOCK(cx,PL_curpm);
1415 PL_stack_sp = newsp;
1417 CATCH_SET(oldcatch);
1422 MEXTEND(SP, 20); /* Can't afford stack realloc on signal. */
1423 sortsv(ORIGMARK+1, max,
1424 (PL_op->op_private & OPpSORT_NUMERIC)
1425 ? ( (PL_op->op_private & OPpSORT_INTEGER)
1426 ? ( overloading ? amagic_i_ncmp : sv_i_ncmp)
1427 : ( overloading ? amagic_ncmp : sv_ncmp))
1428 : ( IN_LOCALE_RUNTIME
1431 : sv_cmp_locale_static)
1432 : ( overloading ? amagic_cmp : sv_cmp_static)));
1433 if (PL_op->op_private & OPpSORT_REVERSE) {
1434 SV **p = ORIGMARK+1;
1435 SV **q = ORIGMARK+max;
1445 PL_stack_sp = ORIGMARK + max;
1450 sortcv(pTHX_ SV *a, SV *b)
1452 I32 oldsaveix = PL_savestack_ix;
1453 I32 oldscopeix = PL_scopestack_ix;
1455 GvSV(PL_firstgv) = a;
1456 GvSV(PL_secondgv) = b;
1457 PL_stack_sp = PL_stack_base;
1460 if (PL_stack_sp != PL_stack_base + 1)
1461 Perl_croak(aTHX_ "Sort subroutine didn't return single value");
1462 if (!SvNIOKp(*PL_stack_sp))
1463 Perl_croak(aTHX_ "Sort subroutine didn't return a numeric value");
1464 result = SvIV(*PL_stack_sp);
1465 while (PL_scopestack_ix > oldscopeix) {
1468 leave_scope(oldsaveix);
1473 sortcv_stacked(pTHX_ SV *a, SV *b)
1475 I32 oldsaveix = PL_savestack_ix;
1476 I32 oldscopeix = PL_scopestack_ix;
1480 #ifdef USE_5005THREADS
1481 av = (AV*)PL_curpad[0];
1483 av = GvAV(PL_defgv);
1486 if (AvMAX(av) < 1) {
1487 SV** ary = AvALLOC(av);
1488 if (AvARRAY(av) != ary) {
1489 AvMAX(av) += AvARRAY(av) - AvALLOC(av);
1490 SvPVX(av) = (char*)ary;
1492 if (AvMAX(av) < 1) {
1495 SvPVX(av) = (char*)ary;
1502 PL_stack_sp = PL_stack_base;
1505 if (PL_stack_sp != PL_stack_base + 1)
1506 Perl_croak(aTHX_ "Sort subroutine didn't return single value");
1507 if (!SvNIOKp(*PL_stack_sp))
1508 Perl_croak(aTHX_ "Sort subroutine didn't return a numeric value");
1509 result = SvIV(*PL_stack_sp);
1510 while (PL_scopestack_ix > oldscopeix) {
1513 leave_scope(oldsaveix);
1518 sortcv_xsub(pTHX_ SV *a, SV *b)
1521 I32 oldsaveix = PL_savestack_ix;
1522 I32 oldscopeix = PL_scopestack_ix;
1524 CV *cv=(CV*)PL_sortcop;
1532 (void)(*CvXSUB(cv))(aTHX_ cv);
1533 if (PL_stack_sp != PL_stack_base + 1)
1534 Perl_croak(aTHX_ "Sort subroutine didn't return single value");
1535 if (!SvNIOKp(*PL_stack_sp))
1536 Perl_croak(aTHX_ "Sort subroutine didn't return a numeric value");
1537 result = SvIV(*PL_stack_sp);
1538 while (PL_scopestack_ix > oldscopeix) {
1541 leave_scope(oldsaveix);
1547 sv_ncmp(pTHX_ SV *a, SV *b)
1551 return nv1 < nv2 ? -1 : nv1 > nv2 ? 1 : 0;
1555 sv_i_ncmp(pTHX_ SV *a, SV *b)
1559 return iv1 < iv2 ? -1 : iv1 > iv2 ? 1 : 0;
1561 #define tryCALL_AMAGICbin(left,right,meth,svp) STMT_START { \
1563 if (PL_amagic_generation) { \
1564 if (SvAMAGIC(left)||SvAMAGIC(right))\
1565 *svp = amagic_call(left, \
1573 amagic_ncmp(pTHX_ register SV *a, register SV *b)
1576 tryCALL_AMAGICbin(a,b,ncmp,&tmpsv);
1581 I32 i = SvIVX(tmpsv);
1591 return sv_ncmp(aTHX_ a, b);
1595 amagic_i_ncmp(pTHX_ register SV *a, register SV *b)
1598 tryCALL_AMAGICbin(a,b,ncmp,&tmpsv);
1603 I32 i = SvIVX(tmpsv);
1613 return sv_i_ncmp(aTHX_ a, b);
1617 amagic_cmp(pTHX_ register SV *str1, register SV *str2)
1620 tryCALL_AMAGICbin(str1,str2,scmp,&tmpsv);
1625 I32 i = SvIVX(tmpsv);
1635 return sv_cmp(str1, str2);
1639 amagic_cmp_locale(pTHX_ register SV *str1, register SV *str2)
1642 tryCALL_AMAGICbin(str1,str2,scmp,&tmpsv);
1647 I32 i = SvIVX(tmpsv);
1657 return sv_cmp_locale(str1, str2);