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From: Adhemerval Zanella <azanella@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc] stdlib: Move insertion sort out qsort Date: Tue, 31 Oct 2023 17:23:50 +0000 (GMT) [thread overview] Message-ID: <20231031172350.659B938582AC@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a035a9857e11faf16ed021b5e80faf215262afd1 commit a035a9857e11faf16ed021b5e80faf215262afd1 Author: Adhemerval Zanella <adhemerval.zanella@linaro.org> Date: Tue Oct 3 09:22:47 2023 -0300 stdlib: Move insertion sort out qsort Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com> Diff: --- stdlib/qsort.c | 101 ++++++++++++++++++++++++++++++--------------------------- 1 file changed, 54 insertions(+), 47 deletions(-) diff --git a/stdlib/qsort.c b/stdlib/qsort.c index 072ccdfb95..5691249a9b 100644 --- a/stdlib/qsort.c +++ b/stdlib/qsort.c @@ -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); }
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