f4609b896f
This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because there is some breakage in the git build related to the netrc credentials helper which someone has taken care of in nixpkgs. The stable channel is not used for anything other than git, so this should be fine. Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb
62 lines
1.2 KiB
C
62 lines
1.2 KiB
C
#include "git-compat-util.h"
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/*
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* A merge sort implementation, simplified from the qsort implementation
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* by Mike Haertel, which is a part of the GNU C Library.
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*/
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static void msort_with_tmp(void *b, size_t n, size_t s,
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int (*cmp)(const void *, const void *),
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char *t)
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{
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char *tmp;
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char *b1, *b2;
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size_t n1, n2;
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if (n <= 1)
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return;
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n1 = n / 2;
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n2 = n - n1;
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b1 = b;
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b2 = (char *)b + (n1 * s);
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msort_with_tmp(b1, n1, s, cmp, t);
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msort_with_tmp(b2, n2, s, cmp, t);
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tmp = t;
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while (n1 > 0 && n2 > 0) {
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if (cmp(b1, b2) <= 0) {
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memcpy(tmp, b1, s);
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tmp += s;
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b1 += s;
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--n1;
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} else {
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memcpy(tmp, b2, s);
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tmp += s;
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b2 += s;
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--n2;
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}
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}
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if (n1 > 0)
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memcpy(tmp, b1, n1 * s);
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memcpy(b, t, (n - n2) * s);
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}
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void git_stable_qsort(void *b, size_t n, size_t s,
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int (*cmp)(const void *, const void *))
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{
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const size_t size = st_mult(n, s);
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char buf[1024];
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if (size < sizeof(buf)) {
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/* The temporary array fits on the small on-stack buffer. */
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msort_with_tmp(b, n, s, cmp, buf);
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} else {
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/* It's somewhat large, so malloc it. */
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char *tmp = xmalloc(size);
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msort_with_tmp(b, n, s, cmp, tmp);
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free(tmp);
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}
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}
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