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* bd/qsort: compat: Add simplified merge sort implementation from glibc
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Original file line number | Diff line number | Diff line change |
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#include "../git-compat-util.h" | ||
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/* | ||
* A merge sort implementation, simplified from the qsort implementation | ||
* by Mike Haertel, which is a part of the GNU C Library. | ||
*/ | ||
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static void msort_with_tmp(void *b, size_t n, size_t s, | ||
int (*cmp)(const void *, const void *), | ||
char *t) | ||
{ | ||
char *tmp; | ||
char *b1, *b2; | ||
size_t n1, n2; | ||
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if (n <= 1) | ||
return; | ||
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n1 = n / 2; | ||
n2 = n - n1; | ||
b1 = b; | ||
b2 = (char *)b + (n1 * s); | ||
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msort_with_tmp(b1, n1, s, cmp, t); | ||
msort_with_tmp(b2, n2, s, cmp, t); | ||
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tmp = t; | ||
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while (n1 > 0 && n2 > 0) { | ||
if (cmp(b1, b2) <= 0) { | ||
memcpy(tmp, b1, s); | ||
tmp += s; | ||
b1 += s; | ||
--n1; | ||
} else { | ||
memcpy(tmp, b2, s); | ||
tmp += s; | ||
b2 += s; | ||
--n2; | ||
} | ||
} | ||
if (n1 > 0) | ||
memcpy(tmp, b1, n1 * s); | ||
memcpy(b, t, (n - n2) * s); | ||
} | ||
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void git_qsort(void *b, size_t n, size_t s, | ||
int (*cmp)(const void *, const void *)) | ||
{ | ||
const size_t size = n * s; | ||
char buf[1024]; | ||
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if (size < sizeof(buf)) { | ||
/* The temporary array fits on the small on-stack buffer. */ | ||
msort_with_tmp(b, n, s, cmp, buf); | ||
} else { | ||
/* It's somewhat large, so malloc it. */ | ||
char *tmp = malloc(size); | ||
msort_with_tmp(b, n, s, cmp, tmp); | ||
free(tmp); | ||
} | ||
} |
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