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#include "../git-compat-util.h"
/*
* A merge sort implementation, simplified from the qsort implementation
* by Mike Haertel, which is a part of the GNU C Library.
* Added context pointer, safety checks and return value.
*/
static void msort_with_tmp(void *b, size_t n, size_t s,
int (*cmp)(const void *, const void *, void *),
char *t, void *ctx)
{
char *tmp;
char *b1, *b2;
size_t n1, n2;
if (n <= 1)
return;
n1 = n / 2;
n2 = n - n1;
b1 = b;
b2 = (char *)b + (n1 * s);
msort_with_tmp(b1, n1, s, cmp, t, ctx);
msort_with_tmp(b2, n2, s, cmp, t, ctx);
tmp = t;
while (n1 > 0 && n2 > 0) {
if (cmp(b1, b2, ctx) <= 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);
}
int git_qsort_s(void *b, size_t n, size_t s,
int (*cmp)(const void *, const void *, void *), void *ctx)
{
const size_t size = st_mult(n, s);
char buf[1024];
if (!n)
return 0;
if (!b || !cmp)
return -1;
if (size < sizeof(buf)) {
/* The temporary array fits on the small on-stack buffer. */
msort_with_tmp(b, n, s, cmp, buf, ctx);
} else {
/* It's somewhat large, so malloc it. */
char *tmp = xmalloc(size);
msort_with_tmp(b, n, s, cmp, tmp, ctx);
free(tmp);
}
return 0;
}
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