diff options
Diffstat (limited to 'stdlib')
| -rw-r--r-- | stdlib/msort.c | 408 | ||||
| -rw-r--r-- | stdlib/qsort.c | 15 |
2 files changed, 58 insertions, 365 deletions
diff --git a/stdlib/msort.c b/stdlib/msort.c index 7d21c10..3668370 100644 --- a/stdlib/msort.c +++ b/stdlib/msort.c @@ -1,9 +1,7 @@ /* An alternative to qsort, with an identical interface. This file is part of the GNU C Library. - Copyright (C) 1992, 1995-1997, 1999, 2000, 2001, 2002 - Free Software Foundation, Inc. - Original Implementation by Mike Haertel, September 1988. - Towers of Hanoi Mergesort by Roger Sayle, January 2002. + Copyright (C) 1992, 1995-1997, 1999, 2000, 2001 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 @@ -21,372 +19,70 @@ 02111-1307 USA. */ #include <alloca.h> -#include <limits.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <memcopy.h> #include <errno.h> - -/* Check whether pointer P is aligned for access by type T. */ -#define TYPE_ALIGNED(P,T) (((char *) (P) - (char *) 0) % __alignof__ (T) == 0) - - -static int hanoi_sort (char *b, size_t n, size_t s, - __compar_fn_t cmp, char *t); -static int hanoi_sort_int (int *b, size_t n, - __compar_fn_t cmp, int *t); -#if INT_MAX != LONG_MAX -static int hanoi_sort_long (long int *b, size_t n, - __compar_fn_t cmp, long int *t); -#endif static void msort_with_tmp (void *b, size_t n, size_t s, - __compar_fn_t cmp, void *t); - - -/* This routine implements "Towers of Hanoi Mergesort". The algorithm - sorts the n elements of size s pointed to by array b using comparison - function cmp. The argument t points to a suitable temporary buffer. - If the return value is zero, the sorted array is returned in b, and - for non-zero return values the sorted array is returned in t. */ -static int -hanoi_sort (char *b, size_t n, size_t s, __compar_fn_t cmp, char *t) -{ - size_t n1, n2; - char *b1,*b2; - char *t1,*t2; - char *s1,*s2; - size_t size; - int result; - char *ptr; - - if (n <= 1) - return 0; - - if (n == 2) - { - b2 = b + s; - if ((*cmp) (b, b2) <= 0) - return 0; - memcpy (__mempcpy (t, b2, s), b, s); - return 1; - } - - n1 = n/2; - n2 = n - n1; - /* n1 < n2! */ - - size = n1 * s; - b1 = b; - b2 = b + size; - - t1 = t; - t2 = t + size; - - /* Recursively call hanoi_sort to sort the two halves of the array. - Depending upon the return values, determine the values s1 and s2 - the locations of the two sorted subarrays, ptr, the location to - contain the sorted array and result, the return value for this - function. Note that "ptr = result? t : b". */ - if (hanoi_sort (b1, n1, s, cmp, t1)) - { - if (hanoi_sort (b2, n2, s, cmp, t2)) - { - result = 0; - ptr = b; - s1 = t1; - s2 = t2; - } - else - { - result = 0; - ptr = b; - s1 = t1; - s2 = b2; - } - } - else - { - if (hanoi_sort (b2, n2, s, cmp, t2)) - { - result = 1; - ptr = t; - s1 = b1; - s2 = t2; - } - else - { - result = 1; - ptr = t; - s1 = b1; - s2 = b2; - } - } + __compar_fn_t cmp, char *t); - /* Merge the two sorted arrays s1 and s2 of n1 and n2 elements - respectively, placing the result in ptr. On entry, n1 > 0 - && n2 > 0, and with each iteration either n1 or n2 is decreased - until either reaches zero, and the loop terminates via return. */ - for (;;) - { - if ((*cmp) (s1, s2) <= 0) - { - ptr = (char *) __mempcpy (ptr, s1, s); - s1 += s; - --n1; - if (n1 == 0) - { - if (ptr != s2) - memcpy (ptr, s2, n2 * s); - return result; - } - } - else - { - ptr = (char *) __mempcpy (ptr, s2, s); - s2 += s; - --n2; - if (n2 == 0) - { - memcpy (ptr, s1, n1 * s); - return result; - } - } - } -} - - -/* This routine is a variant of hanoi_sort that is optimized for the - case where items to be sorted are the size of ints, and both b and - t are suitably aligned. The parameter s in not needed as it is - known to be sizeof(int). */ -static int -hanoi_sort_int (int *b, size_t n, __compar_fn_t cmp, int *t) -{ - size_t n1, n2; - int *b1,*b2; - int *t1,*t2; - int *s1,*s2; - int result; - int *ptr; - - if (n <= 1) - return 0; - - if (n == 2) - { - if ((*cmp) (b, b + 1) <= 0) - return 0; - t[0] = b[1]; - t[1] = b[0]; - return 1; - } - - n1 = n/2; - n2 = n - n1; - /* n1 < n2! */ - - b1 = b; - b2 = b + n1; - - t1 = t; - t2 = t + n1; - - /* Recursively call hanoi_sort_int to sort the two halves. */ - if (hanoi_sort_int (b1, n1, cmp, t1)) - { - if (hanoi_sort_int (b2, n2, cmp, t2)) - { - result = 0; - ptr = b; - s1 = t1; - s2 = t2; - } - else - { - result = 0; - ptr = b; - s1 = t1; - s2 = b2; - } - } - else - { - if (hanoi_sort_int (b2, n2, cmp, t2)) - { - result = 1; - ptr = t; - s1 = b1; - s2 = t2; - } - else - { - result = 1; - ptr = t; - s1 = b1; - s2 = b2; - } - } - - /* Merge n1 elements from s1 and n2 elements from s2 into ptr. */ - for (;;) - { - if ((*cmp) (s1, s2) <= 0) - { - *ptr++ = *s1++; - --n1; - if (n1 == 0) - { - if (ptr != s2) - memcpy (ptr, s2, n2 * sizeof (int)); - return result; - } - } - else - { - *ptr++ = *s2++; - --n2; - if (n2 == 0) - { - memcpy (ptr, s1, n1 * sizeof (int)); - return result; - } - } - } -} - - -#if INT_MAX != LONG_MAX -/* This routine is a variant of hanoi_sort that is optimized for the - case where items to be sorted are the size of longs, and both b and - t are suitably aligned. The parameter s in not needed as it is - known to be sizeof(long). In case sizeof(int)== sizeof(long) we - do not need this code since it would be the same as hanoi_sort_int. */ -static int -hanoi_sort_long (long int *b, size_t n, __compar_fn_t cmp, long int *t) +static void +msort_with_tmp (void *b, size_t n, size_t s, __compar_fn_t cmp, + char *t) { + char *tmp; + char *b1, *b2; size_t n1, n2; - long int *b1,*b2; - long int *t1,*t2; - long int *s1,*s2; - int result; - long int *ptr; if (n <= 1) - return 0; - - if (n == 2) - { - if ((*cmp) (b, b + 1) <= 0) - return 0; - t[0] = b[1]; - t[1] = b[0]; - return 1; - } + return; - n1 = n/2; + n1 = n / 2; n2 = n - n1; - /* n1 < n2! */ - b1 = b; - b2 = b + n1; - - t1 = t; - t2 = t + n1; - - /* Recursively call hanoi_sort_long to sort the two halves. */ - if (hanoi_sort_long (b1, n1, cmp, t1)) - { - if (hanoi_sort_long (b2, n2, cmp, t2)) - { - result = 0; - ptr = b; - s1 = t1; - s2 = t2; - } - else - { - result = 0; - ptr = b; - s1 = t1; - s2 = b2; - } - } + b2 = (char *) b + (n1 * s); + + msort_with_tmp (b1, n1, s, cmp, t); + msort_with_tmp (b2, n2, s, cmp, t); + + tmp = t; + + if (s == OPSIZ && (b1 - (char *) 0) % OPSIZ == 0) + /* We are operating on aligned words. Use direct word stores. */ + while (n1 > 0 && n2 > 0) + { + if ((*cmp) (b1, b2) <= 0) + { + --n1; + *((op_t *) tmp)++ = *((op_t *) b1)++; + } + else + { + --n2; + *((op_t *) tmp)++ = *((op_t *) b2)++; + } + } else - { - if (hanoi_sort_long (b2, n2, cmp, t2)) - { - result = 1; - ptr = t; - s1 = b1; - s2 = t2; - } - else - { - result = 1; - ptr = t; - s1 = b1; - s2 = b2; - } - } - - /* Merge n1 elements from s1 and n2 elements from s2 into ptr. */ - for (;;) - { - if ((*cmp) (s1, s2) <= 0) - { - *ptr++ = *s1++; - --n1; - if (n1 == 0) - { - if (ptr != s2) - memcpy (ptr, s2, n2 * sizeof (long)); - return result; - } - } - else - { - *ptr++ = *s2++; - --n2; - if (n2 == 0) - { - memcpy (ptr, s1, n1 * sizeof (long)); - return result; - } - } - } -} -#endif - - -/* This routine preserves the original interface to msort_with_tmp and - determines which variant of hanoi_sort to call, based upon item size - and alignment. */ - -static void -msort_with_tmp (void *b, size_t n, size_t s, __compar_fn_t cmp, void *t) -{ - const size_t size = n * s; - - if (s == sizeof (int) && TYPE_ALIGNED (b, int)) - { - if (hanoi_sort_int (b, n, cmp, t)) - memcpy (b, t, size); - } -#if INT_MAX != LONG_MAX - else if (s == sizeof (long int) && TYPE_ALIGNED (b, long int)) - { - if (hanoi_sort_long (b, n, cmp, t)) - memcpy (b, t, size); - } -#endif - else - { - /* Call the generic implementation. */ - if (hanoi_sort (b, n, s, cmp, t)) - memcpy (b, t, size); - } + 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; + } + } + if (n1 > 0) + memcpy (tmp, b1, n1 * s); + memcpy (b, t, (n - n2) * s); } void @@ -397,7 +93,7 @@ qsort (void *b, size_t n, size_t s, __compar_fn_t cmp) if (size < 1024) { void *buf = __alloca (size); - + /* The temporary array is small, so put it on the stack. */ msort_with_tmp (b, n, s, cmp, buf); } @@ -434,7 +130,7 @@ qsort (void *b, size_t n, size_t s, __compar_fn_t cmp) measured in bytes. */ /* If the memory requirements are too high don't allocate memory. */ - if ((long int) (size / pagesize) > phys_pages) + if (size / pagesize > phys_pages) _quicksort (b, n, s, cmp); else { diff --git a/stdlib/qsort.c b/stdlib/qsort.c index 512277a..1ac268b 100644 --- a/stdlib/qsort.c +++ b/stdlib/qsort.c @@ -92,9 +92,6 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, { register char *base_ptr = (char *) pbase; - /* Allocating SIZE bytes for a pivot buffer facilitates a better - algorithm below since we can do comparisons directly on the pivot. */ - char *pivot_buffer = (char *) __alloca (size); const size_t max_thresh = MAX_THRESH * size; if (total_elems == 0) @@ -113,8 +110,6 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, char *left_ptr; char *right_ptr; - char *pivot = pivot_buffer; - /* 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 @@ -132,8 +127,6 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, if ((*cmp) ((void *) mid, (void *) lo) < 0) SWAP (mid, lo, size); jump_over:; - memcpy (pivot, mid, size); - pivot = pivot_buffer; left_ptr = lo + size; right_ptr = hi - size; @@ -143,15 +136,19 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, that this algorithm runs much faster than others. */ do { - while ((*cmp) ((void *) left_ptr, (void *) pivot) < 0) + while ((*cmp) ((void *) left_ptr, (void *) mid) < 0) left_ptr += size; - while ((*cmp) ((void *) pivot, (void *) right_ptr) < 0) + 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; } |