diff options
| -rw-r--r-- | bench.c | 2 | ||||
| -rw-r--r-- | glibc_msort.c | 309 | ||||
| -rw-r--r-- | glibc_qsort.c | 249 | ||||
| -rw-r--r-- | musl_qsort.c | 2 | ||||
| -rw-r--r-- | sorters.c | 4 | ||||
| -rw-r--r-- | sorters.h | 4 |
6 files changed, 566 insertions, 4 deletions
@@ -28,7 +28,7 @@ static int compare(const void *a, const void *b) #define CMP_WIDTH 12 #define MS_WIDTH 6 -#define SORT_WIDTH 10 +#define SORT_WIDTH 16 #define GEN_WIDTH (CMP_WIDTH + MS_WIDTH + 1) #define SIZE_WIDTH 10 diff --git a/glibc_msort.c b/glibc_msort.c new file mode 100644 index 0000000..e35f477 --- /dev/null +++ b/glibc_msort.c @@ -0,0 +1,309 @@ +/* An alternative to qsort, with an identical interface. + This file is part of the GNU C Library. + Copyright (C) 1992-2014 Free Software Foundation, Inc. + Written by Mike Haertel, September 1988. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +/* minor modifications made to compile in the qsort_bench tree rather than the glibc tree */ + +#include <alloca.h> +#include <stdint.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <errno.h> + +#include "sorters.h" + +#define __alloca(n) alloca(n) +#define __sysconf(n) sysconf(n) +#define atomic_write_barrier() do { } while(0) +#define __set_errno(e) do { errno = (e); } while(0) + +static inline void *__mempcpy(void * restrict dest, const void * restrict src, size_t n) +{ + memcpy(dest, src, n); + return ((char *) dest) + n; +} + +struct msort_param +{ + size_t s; + size_t var; + cmpfun cmp; + char *t; +}; + +static void +msort_with_tmp (const struct msort_param *p, void *b, size_t n) +{ + char *b1, *b2; + size_t n1, n2; + + if (n <= 1) + return; + + n1 = n / 2; + n2 = n - n1; + b1 = b; + b2 = (char *) b + (n1 * p->s); + + msort_with_tmp (p, b1, n1); + msort_with_tmp (p, b2, n2); + + char *tmp = p->t; + const size_t s = p->s; + cmpfun cmp = p->cmp; + switch (p->var) + { + case 0: + while (n1 > 0 && n2 > 0) + { + if ((*cmp) (b1, b2) <= 0) + { + *(uint32_t *) tmp = *(uint32_t *) b1; + b1 += sizeof (uint32_t); + --n1; + } + else + { + *(uint32_t *) tmp = *(uint32_t *) b2; + b2 += sizeof (uint32_t); + --n2; + } + tmp += sizeof (uint32_t); + } + break; + case 1: + while (n1 > 0 && n2 > 0) + { + if ((*cmp) (b1, b2) <= 0) + { + *(uint64_t *) tmp = *(uint64_t *) b1; + b1 += sizeof (uint64_t); + --n1; + } + else + { + *(uint64_t *) tmp = *(uint64_t *) b2; + b2 += sizeof (uint64_t); + --n2; + } + tmp += sizeof (uint64_t); + } + break; + case 2: + while (n1 > 0 && n2 > 0) + { + unsigned long *tmpl = (unsigned long *) tmp; + unsigned long *bl; + + tmp += s; + if ((*cmp) (b1, b2) <= 0) + { + bl = (unsigned long *) b1; + b1 += s; + --n1; + } + else + { + bl = (unsigned long *) b2; + b2 += s; + --n2; + } + while (tmpl < (unsigned long *) tmp) + *tmpl++ = *bl++; + } + break; + case 3: + while (n1 > 0 && n2 > 0) + { + if ((*cmp) (*(const void **) b1, *(const void **) b2) <= 0) + { + *(void **) tmp = *(void **) b1; + b1 += sizeof (void *); + --n1; + } + else + { + *(void **) tmp = *(void **) b2; + b2 += sizeof (void *); + --n2; + } + tmp += sizeof (void *); + } + break; + default: + while (n1 > 0 && n2 > 0) + { + if ((*cmp) (b1, b2) <= 0) + { + tmp = (char *) __mempcpy (tmp, b1, s); + b1 += s; + --n1; + } + else + { + tmp = (char *) __mempcpy (tmp, b2, s); + b2 += s; + --n2; + } + } + break; + } + + if (n1 > 0) + memcpy (tmp, b1, n1 * s); + memcpy (b, p->t, (n - n2) * s); +} + + +void +glibc_mergesort (void *b, size_t n, size_t s, cmpfun cmp) +{ + size_t size = n * s; + char *tmp = NULL; + struct msort_param p; + + /* For large object sizes use indirect sorting. */ + if (s > 32) + size = 2 * n * sizeof (void *) + s; + + if (size < 1024) + /* The temporary array is small, so put it on the stack. */ + p.t = __alloca (size); + else + { + /* We should avoid allocating too much memory since this might + have to be backed up by swap space. */ + static long int phys_pages; + static int pagesize; + + if (pagesize == 0) + { + phys_pages = __sysconf (_SC_PHYS_PAGES); + + if (phys_pages == -1) + /* Error while determining the memory size. So let's + assume there is enough memory. Otherwise the + implementer should provide a complete implementation of + the `sysconf' function. */ + phys_pages = (long int) (~0ul >> 1); + + /* The following determines that we will never use more than + a quarter of the physical memory. */ + phys_pages /= 4; + + /* Make sure phys_pages is written to memory. */ + atomic_write_barrier (); + + pagesize = __sysconf (_SC_PAGESIZE); + } + + /* Just a comment here. We cannot compute + phys_pages * pagesize + and compare the needed amount of memory against this value. + The problem is that some systems might have more physical + memory then can be represented with a `size_t' value (when + measured in bytes. */ + + /* If the memory requirements are too high don't allocate memory. */ + if (size / pagesize > (size_t) phys_pages) + { + glibc_quicksort (b, n, s, cmp); + return; + } + + /* It's somewhat large, so malloc it. */ + int save = errno; + tmp = malloc (size); + __set_errno (save); + if (tmp == NULL) + { + /* Couldn't get space, so use the slower algorithm + that doesn't need a temporary array. */ + glibc_quicksort (b, n, s, cmp); + return; + } + p.t = tmp; + } + + p.s = s; + p.var = 4; + p.cmp = cmp; + + if (s > 32) + { + /* Indirect sorting. */ + char *ip = (char *) b; + void **tp = (void **) (p.t + n * sizeof (void *)); + void **t = tp; + void *tmp_storage = (void *) (tp + n); + + while ((void *) t < tmp_storage) + { + *t++ = ip; + ip += s; + } + p.s = sizeof (void *); + p.var = 3; + msort_with_tmp (&p, p.t + n * sizeof (void *), n); + + /* tp[0] .. tp[n - 1] is now sorted, copy around entries of + the original array. Knuth vol. 3 (2nd ed.) exercise 5.2-10. */ + char *kp; + size_t i; + for (i = 0, ip = (char *) b; i < n; i++, ip += s) + if ((kp = tp[i]) != ip) + { + size_t j = i; + char *jp = ip; + memcpy (tmp_storage, ip, s); + + do + { + size_t k = (kp - (char *) b) / s; + tp[j] = jp; + memcpy (jp, kp, s); + j = k; + jp = kp; + kp = tp[k]; + } + while (kp != ip); + + tp[j] = jp; + memcpy (jp, tmp_storage, s); + } + } + else + { + if ((s & (sizeof (uint32_t) - 1)) == 0 + && ((char *) b - (char *) 0) % __alignof__ (uint32_t) == 0) + { + if (s == sizeof (uint32_t)) + p.var = 0; + else if (s == sizeof (uint64_t) + && ((char *) b - (char *) 0) % __alignof__ (uint64_t) == 0) + p.var = 1; + else if ((s & (sizeof (unsigned long) - 1)) == 0 + && ((char *) b - (char *) 0) + % __alignof__ (unsigned long) == 0) + p.var = 2; + } + msort_with_tmp (&p, b, n); + } + free (tmp); +} diff --git a/glibc_qsort.c b/glibc_qsort.c new file mode 100644 index 0000000..ed7baf7 --- /dev/null +++ b/glibc_qsort.c @@ -0,0 +1,249 @@ +/* Copyright (C) 1991-2014 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Written by Douglas C. Schmidt (schmidt@ics.uci.edu). + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +/* If you consider tuning this algorithm, you should consult first: + Engineering a sort function; Jon Bentley and M. Douglas McIlroy; + Software - Practice and Experience; Vol. 23 (11), 1249-1265, 1993. */ + +#include <limits.h> +#include <stdlib.h> +#include <string.h> + +#include "sorters.h" + +/* Byte-wise swap two items of size SIZE. */ +#define SWAP(a, b, size) \ + do \ + { \ + size_t __size = (size); \ + char *__a = (a), *__b = (b); \ + do \ + { \ + char __tmp = *__a; \ + *__a++ = *__b; \ + *__b++ = __tmp; \ + } while (--__size > 0); \ + } while (0) + +/* Discontinue quicksort algorithm when partition gets below this size. + This particular magic number was chosen to work best on a Sun 4/260. */ +#define MAX_THRESH 4 + +/* Stack node declarations used to store unfulfilled partition obligations. */ +typedef struct + { + char *lo; + char *hi; + } stack_node; + +/* The next 4 #defines implement a very fast in-line stack abstraction. */ +/* The stack needs log (total_elements) entries (we could even subtract + log(MAX_THRESH)). Since total_elements has type size_t, we get as + upper bound for log (total_elements): + bits per byte (CHAR_BIT) * sizeof(size_t). */ +#define STACK_SIZE (CHAR_BIT * sizeof(size_t)) +#define PUSH(low, high) ((void) ((top->lo = (low)), (top->hi = (high)), ++top)) +#define POP(low, high) ((void) (--top, (low = top->lo), (high = top->hi))) +#define STACK_NOT_EMPTY (stack < top) + + +/* Order size using quicksort. This implementation incorporates + four optimizations discussed in Sedgewick: + + 1. Non-recursive, using an explicit stack of pointer that store the + next array partition to sort. To save time, this maximum amount + of space required to store an array of SIZE_MAX is allocated on the + stack. Assuming a 32-bit (64 bit) integer for size_t, this needs + only 32 * sizeof(stack_node) == 256 bytes (for 64 bit: 1024 bytes). + Pretty cheap, actually. + + 2. Chose the pivot element using a median-of-three decision tree. + This reduces the probability of selecting a bad pivot value and + eliminates certain extraneous comparisons. + + 3. Only quicksorts TOTAL_ELEMS / MAX_THRESH partitions, leaving + insertion sort to order the MAX_THRESH items within each partition. + This is a big win, since insertion sort is faster for small, mostly + sorted array segments. + + 4. The larger of the two sub-partitions is always pushed onto the + stack first, with the algorithm then concentrating on the + smaller partition. This *guarantees* no more than log (total_elems) + stack size is needed (actually O(1) in this case)! */ + +void +glibc_quicksort (void *pbase, size_t total_elems, size_t size, cmpfun cmp) +{ + char *base_ptr = (char *) pbase; + + const size_t max_thresh = MAX_THRESH * size; + + if (total_elems == 0) + /* Avoid lossage with unsigned arithmetic below. */ + return; + + if (total_elems > MAX_THRESH) + { + char *lo = base_ptr; + char *hi = &lo[size * (total_elems - 1)]; + stack_node stack[STACK_SIZE]; + stack_node *top = stack; + + PUSH (NULL, NULL); + + while (STACK_NOT_EMPTY) + { + char *left_ptr; + char *right_ptr; + + /* Select median value from among LO, MID, and HI. Rearrange + LO and HI so the three values are sorted. This lowers the + probability of picking a pathological pivot value and + skips a comparison for both the LEFT_PTR and RIGHT_PTR in + the while loops. */ + + char *mid = lo + size * ((hi - lo) / size >> 1); + + if ((*cmp) ((void *) mid, (void *) lo) < 0) + SWAP (mid, lo, size); + if ((*cmp) ((void *) hi, (void *) mid) < 0) + SWAP (mid, hi, size); + else + goto jump_over; + if ((*cmp) ((void *) mid, (void *) lo) < 0) + SWAP (mid, lo, size); + jump_over:; + + left_ptr = lo + size; + right_ptr = hi - size; + + /* Here's the famous ``collapse the walls'' section of quicksort. + Gotta like those tight inner loops! They are the main reason + that this algorithm runs much faster than others. */ + do + { + while ((*cmp) ((void *) left_ptr, (void *) mid) < 0) + left_ptr += size; + + while ((*cmp) ((void *) mid, (void *) right_ptr) < 0) + right_ptr -= size; + + if (left_ptr < right_ptr) + { + SWAP (left_ptr, right_ptr, size); + if (mid == left_ptr) + mid = right_ptr; + else if (mid == right_ptr) + mid = left_ptr; + left_ptr += size; + right_ptr -= size; + } + else if (left_ptr == right_ptr) + { + left_ptr += size; + right_ptr -= size; + break; + } + } + while (left_ptr <= right_ptr); + + /* Set up pointers for next iteration. First determine whether + left and right partitions are below the threshold size. If so, + ignore one or both. Otherwise, push the larger partition's + bounds on the stack and continue sorting the smaller one. */ + + if ((size_t) (right_ptr - lo) <= max_thresh) + { + if ((size_t) (hi - left_ptr) <= max_thresh) + /* Ignore both small partitions. */ + POP (lo, hi); + else + /* Ignore small left partition. */ + lo = left_ptr; + } + else if ((size_t) (hi - left_ptr) <= max_thresh) + /* Ignore small right partition. */ + hi = right_ptr; + else if ((right_ptr - lo) > (hi - left_ptr)) + { + /* Push larger left partition indices. */ + PUSH (lo, right_ptr); + lo = left_ptr; + } + else + { + /* Push larger right partition indices. */ + PUSH (left_ptr, hi); + hi = right_ptr; + } + } + } + + /* Once the BASE_PTR array is partially sorted by quicksort the rest + is completely sorted using insertion sort, since this is efficient + for partitions below MAX_THRESH size. BASE_PTR points to the beginning + of the array to sort, and END_PTR points at the very last element in + the array (*not* one beyond it!). */ + +#define min(x, y) ((x) < (y) ? (x) : (y)) + + { + char *const end_ptr = &base_ptr[size * (total_elems - 1)]; + char *tmp_ptr = base_ptr; + char *thresh = min(end_ptr, base_ptr + max_thresh); + char *run_ptr; + + /* Find smallest element in first threshold and place it at the + array's beginning. This is the smallest array element, + and the operation speeds up insertion sort's inner loop. */ + + for (run_ptr = tmp_ptr + size; run_ptr <= thresh; run_ptr += size) + if ((*cmp) ((void *) run_ptr, (void *) tmp_ptr) < 0) + tmp_ptr = run_ptr; + + if (tmp_ptr != base_ptr) + SWAP (tmp_ptr, base_ptr, size); + + /* Insertion sort, running from left-hand-side up to right-hand-side. */ + + run_ptr = base_ptr + size; + while ((run_ptr += size) <= end_ptr) + { + tmp_ptr = run_ptr - size; + while ((*cmp) ((void *) run_ptr, (void *) tmp_ptr) < 0) + tmp_ptr -= size; + + tmp_ptr += size; + if (tmp_ptr != run_ptr) + { + char *trav; + + trav = run_ptr + size; + while (--trav >= run_ptr) + { + char c = *trav; + char *hi, *lo; + + for (hi = lo = trav; (lo -= size) >= tmp_ptr; hi = lo) + *hi = *lo; + *hi = c; + } + } + } + } +} diff --git a/musl_qsort.c b/musl_qsort.c index 21a39bd..3792aa1 100644 --- a/musl_qsort.c +++ b/musl_qsort.c @@ -154,7 +154,7 @@ static void trinkle(unsigned char *head, size_t width, cmpfun cmp, size_t pp[2], } } -void qsort_musl(void *base, size_t nel, size_t width, cmpfun cmp) +void musl_qsort(void *base, size_t nel, size_t width, cmpfun cmp) { size_t lp[12*sizeof(size_t)]; size_t i, size = width * nel; @@ -1,6 +1,8 @@ #include "sorters.h" const struct sorter sorters[] = { - { .name = "musl", .func = qsort_musl }, + { .name = "glibc quicksort", .func = glibc_quicksort }, + { .name = "glibc mergesort", .func = glibc_mergesort }, + { .name = "musl", .func = musl_qsort }, { 0 } }; @@ -3,7 +3,9 @@ typedef int (*cmpfun)(const void *, const void *); typedef void (*sorter)(void *, size_t, size_t, cmpfun); -void qsort_musl(void *, size_t, size_t, cmpfun); +void musl_qsort(void *, size_t, size_t, cmpfun); +void glibc_quicksort(void *, size_t, size_t, cmpfun); +void glibc_mergesort(void *, size_t, size_t, cmpfun); extern const struct sorter { const char *name; |