## Mercurial > hg > CbC > CbC_gcc

### view libbacktrace/sort.c @ 158:494b0b89df80 default tip

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author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
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date | Mon, 25 May 2020 18:13:55 +0900 |

parents | 1830386684a0 |

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/* sort.c -- Sort without allocating memory Copyright (C) 2012-2020 Free Software Foundation, Inc. Written by Ian Lance Taylor, Google. 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) The name of the author may not be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 "config.h" #include <stddef.h> #include <sys/types.h> #include "backtrace.h" #include "internal.h" /* The GNU glibc version of qsort allocates memory, which we must not do if we are invoked by a signal handler. So provide our own sort. */ static void swap (char *a, char *b, size_t size) { size_t i; for (i = 0; i < size; i++, a++, b++) { char t; t = *a; *a = *b; *b = t; } } void backtrace_qsort (void *basearg, size_t count, size_t size, int (*compar) (const void *, const void *)) { char *base = (char *) basearg; size_t i; size_t mid; tail_recurse: if (count < 2) return; /* The symbol table and DWARF tables, which is all we use this routine for, tend to be roughly sorted. Pick the middle element in the array as our pivot point, so that we are more likely to cut the array in half for each recursion step. */ swap (base, base + (count / 2) * size, size); mid = 0; for (i = 1; i < count; i++) { if ((*compar) (base, base + i * size) > 0) { ++mid; if (i != mid) swap (base + mid * size, base + i * size, size); } } if (mid > 0) swap (base, base + mid * size, size); /* Recurse with the smaller array, loop with the larger one. That ensures that our maximum stack depth is log count. */ if (2 * mid < count) { backtrace_qsort (base, mid, size, compar); base += (mid + 1) * size; count -= mid + 1; goto tail_recurse; } else { backtrace_qsort (base + (mid + 1) * size, count - (mid + 1), size, compar); count = mid; goto tail_recurse; } }