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stdlib: Move insertion sort out qsort

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Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
This commit is contained in:
Adhemerval Zanella 2023-10-03 09:22:47 -03:00
parent 21d30c774c
commit a035a9857e
1 changed files with 54 additions and 47 deletions
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101
stdlib/qsort.c
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@ -111,6 +111,58 @@ typedef struct
#define STACK_NOT_EMPTY (stack < top)
static inline void
insertion_sort_qsort_partitions (void *const pbase, size_t total_elems,
size_t size, enum swap_type_t swap_type,
__compar_d_fn_t cmp, void *arg)
{
char *base_ptr = (char *) pbase;
char *const end_ptr = &base_ptr[size * (total_elems - 1)];
char *tmp_ptr = base_ptr;
#define min(x, y) ((x) < (y) ? (x) : (y))
const size_t max_thresh = MAX_THRESH * size;
char *thresh = min(end_ptr, base_ptr + max_thresh);
char *run_ptr;
/* Find smallest element in first threshold and place it at the
array's beginning. This is the smallest array element,
and the operation speeds up insertion sort's inner loop. */
for (run_ptr = tmp_ptr + size; run_ptr <= thresh; run_ptr += size)
if (cmp (run_ptr, tmp_ptr, arg) < 0)
tmp_ptr = run_ptr;
if (tmp_ptr != base_ptr)
do_swap (tmp_ptr, base_ptr, size, swap_type);
/* Insertion sort, running from left-hand-side up to right-hand-side. */
run_ptr = base_ptr + size;
while ((run_ptr += size) <= end_ptr)
{
tmp_ptr = run_ptr - size;
while (cmp (run_ptr, tmp_ptr, arg) < 0)
tmp_ptr -= size;
tmp_ptr += size;
if (tmp_ptr != run_ptr)
{
char *trav;
trav = run_ptr + size;
while (--trav >= run_ptr)
{
char c = *trav;
char *hi, *lo;
for (hi = lo = trav; (lo -= size) >= tmp_ptr; hi = lo)
*hi = *lo;
*hi = c;
}
}
}
}
/* Order size using quicksort. This implementation incorporates
four optimizations discussed in Sedgewick:
@ -257,51 +309,6 @@ _quicksort (void *const pbase, size_t total_elems, size_t size,
for partitions below MAX_THRESH size. BASE_PTR points to the beginning
of the array to sort, and END_PTR points at the very last element in
the array (*not* one beyond it!). */
#define min(x, y) ((x) < (y) ? (x) : (y))
{
char *const end_ptr = &base_ptr[size * (total_elems - 1)];
char *tmp_ptr = base_ptr;
char *thresh = min(end_ptr, base_ptr + max_thresh);
char *run_ptr;
/* Find smallest element in first threshold and place it at the
array's beginning. This is the smallest array element,
and the operation speeds up insertion sort's inner loop. */
for (run_ptr = tmp_ptr + size; run_ptr <= thresh; run_ptr += size)
if ((*cmp) ((void *) run_ptr, (void *) tmp_ptr, arg) < 0)
tmp_ptr = run_ptr;
if (tmp_ptr != base_ptr)
do_swap (tmp_ptr, base_ptr, size, swap_type);
/* Insertion sort, running from left-hand-side up to right-hand-side. */
run_ptr = base_ptr + size;
while ((run_ptr += size) <= end_ptr)
{
tmp_ptr = run_ptr - size;
while ((*cmp) ((void *) run_ptr, (void *) tmp_ptr, arg) < 0)
tmp_ptr -= size;
tmp_ptr += size;
if (tmp_ptr != run_ptr)
{
char *trav;
trav = run_ptr + size;
while (--trav >= run_ptr)
{
char c = *trav;
char *hi, *lo;
for (hi = lo = trav; (lo -= size) >= tmp_ptr; hi = lo)
*hi = *lo;
*hi = c;
}
}
}
}
insertion_sort_qsort_partitions (pbase, total_elems, size, swap_type, cmp,
arg);
}