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Diffstat (limited to 'gcc-4.2.1-5666.3/libiberty/sort.c')
| -rw-r--r-- | gcc-4.2.1-5666.3/libiberty/sort.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/gcc-4.2.1-5666.3/libiberty/sort.c b/gcc-4.2.1-5666.3/libiberty/sort.c new file mode 100644 index 000000000..3738dd733 --- /dev/null +++ b/gcc-4.2.1-5666.3/libiberty/sort.c @@ -0,0 +1,186 @@ +/* Sorting algorithms. + Copyright (C) 2000 Free Software Foundation, Inc. + Contributed by Mark Mitchell <mark@codesourcery.com>. + +This file is part of GNU CC. + +GNU CC is free software; you can redistribute it and/or modify it +under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU CC 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 +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU CC; see the file COPYING. If not, write to +the Free Software Foundation, 51 Franklin Street - Fifth Floor, +Boston, MA 02110-1301, USA. */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif +#include "libiberty.h" +#include "sort.h" +#ifdef HAVE_LIMITS_H +#include <limits.h> +#endif +#ifdef HAVE_SYS_PARAM_H +#include <sys/param.h> +#endif +#ifdef HAVE_STDLIB_H +#include <stdlib.h> +#endif +#ifdef HAVE_STRING_H +#include <string.h> +#endif + +#ifndef UCHAR_MAX +#define UCHAR_MAX ((unsigned char)(-1)) +#endif + +/* POINTERS and WORK are both arrays of N pointers. When this + function returns POINTERS will be sorted in ascending order. */ + +void sort_pointers (size_t n, void **pointers, void **work) +{ + /* The type of a single digit. This can be any unsigned integral + type. When changing this, DIGIT_MAX should be changed as + well. */ + typedef unsigned char digit_t; + + /* The maximum value a single digit can have. */ +#define DIGIT_MAX (UCHAR_MAX + 1) + + /* The Ith entry is the number of elements in *POINTERSP that have I + in the digit on which we are currently sorting. */ + unsigned int count[DIGIT_MAX]; + /* Nonzero if we are running on a big-endian machine. */ + int big_endian_p; + size_t i; + size_t j; + + /* The algorithm used here is radix sort which takes time linear in + the number of elements in the array. */ + + /* The algorithm here depends on being able to swap the two arrays + an even number of times. */ + if ((sizeof (void *) / sizeof (digit_t)) % 2 != 0) + abort (); + + /* Figure out the endianness of the machine. */ + for (i = 0, j = 0; i < sizeof (size_t); ++i) + { + j *= (UCHAR_MAX + 1); + j += i; + } + big_endian_p = (((char *)&j)[0] == 0); + + /* Move through the pointer values from least significant to most + significant digits. */ + for (i = 0; i < sizeof (void *) / sizeof (digit_t); ++i) + { + digit_t *digit; + digit_t *bias; + digit_t *top; + unsigned int *countp; + void **pointerp; + + /* The offset from the start of the pointer will depend on the + endianness of the machine. */ + if (big_endian_p) + j = sizeof (void *) / sizeof (digit_t) - i; + else + j = i; + + /* Now, perform a stable sort on this digit. We use counting + sort. */ + memset (count, 0, DIGIT_MAX * sizeof (unsigned int)); + + /* Compute the address of the appropriate digit in the first and + one-past-the-end elements of the array. On a little-endian + machine, the least-significant digit is closest to the front. */ + bias = ((digit_t *) pointers) + j; + top = ((digit_t *) (pointers + n)) + j; + + /* Count how many there are of each value. At the end of this + loop, COUNT[K] will contain the number of pointers whose Ith + digit is K. */ + for (digit = bias; + digit < top; + digit += sizeof (void *) / sizeof (digit_t)) + ++count[*digit]; + + /* Now, make COUNT[K] contain the number of pointers whose Ith + digit is less than or equal to K. */ + for (countp = count + 1; countp < count + DIGIT_MAX; ++countp) + *countp += countp[-1]; + + /* Now, drop the pointers into their correct locations. */ + for (pointerp = pointers + n - 1; pointerp >= pointers; --pointerp) + work[--count[((digit_t *) pointerp)[j]]] = *pointerp; + + /* Swap WORK and POINTERS so that POINTERS contains the sorted + array. */ + pointerp = pointers; + pointers = work; + work = pointerp; + } +} + +/* Everything below here is a unit test for the routines in this + file. */ + +#ifdef UNIT_TEST + +#include <stdio.h> + +void *xmalloc (size_t n) +{ + return malloc (n); +} + +int main (int argc, char **argv) +{ + int k; + int result; + size_t i; + void **pointers; + void **work; + + if (argc > 1) + k = atoi (argv[1]); + else + k = 10; + + pointers = XNEWVEC (void*, k); + work = XNEWVEC (void*, k); + + for (i = 0; i < k; ++i) + { + pointers[i] = (void *) random (); + printf ("%x\n", pointers[i]); + } + + sort_pointers (k, pointers, work); + + printf ("\nSorted\n\n"); + + result = 0; + + for (i = 0; i < k; ++i) + { + printf ("%x\n", pointers[i]); + if (i > 0 && (char*) pointers[i] < (char*) pointers[i - 1]) + result = 1; + } + + free (pointers); + free (work); + + return result; +} + +#endif |