Message ID | 20231003122251.3325435-5-adhemerval.zanella@linaro.org |
---|---|
State | Accepted |
Commit | d097f3c79be55d646d86efb7ce876bf84d5ebe4e |
Headers | show |
Series | Use introsort for qsort | expand |
On Tue, Oct 3, 2023 at 7:23 AM Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote: > > --- > stdlib/qsort.c | 35 +++++++++++++++++++++++------------ > 1 file changed, 23 insertions(+), 12 deletions(-) > > diff --git a/stdlib/qsort.c b/stdlib/qsort.c > index 5691249a9b..80706b3357 100644 > --- a/stdlib/qsort.c > +++ b/stdlib/qsort.c > @@ -100,15 +100,28 @@ typedef struct > char *hi; > } stack_node; > > -/* The next 4 #defines implement a very fast in-line stack abstraction. */ > /* The stack needs log (total_elements) entries (we could even subtract > log(MAX_THRESH)). Since total_elements has type size_t, we get as > upper bound for log (total_elements): > bits per byte (CHAR_BIT) * sizeof(size_t). */ > -#define STACK_SIZE (CHAR_BIT * sizeof (size_t)) > -#define PUSH(low, high) ((void) ((top->lo = (low)), (top->hi = (high)), ++top)) > -#define POP(low, high) ((void) (--top, (low = top->lo), (high = top->hi))) > -#define STACK_NOT_EMPTY (stack < top) > +enum { STACK_SIZE = CHAR_BIT * sizeof (size_t) }; > + > +static inline stack_node * > +push (stack_node *top, char *lo, char *hi) > +{ > + top->lo = lo; > + top->hi = hi; > + return ++top; > +} > + > +static inline stack_node * > +pop (stack_node *top, char **lo, char **hi) > +{ > + --top; > + *lo = top->lo; > + *hi = top->hi; > + return top; > +} > > > static inline void > @@ -212,11 +225,9 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, > char *lo = base_ptr; > char *hi = &lo[size * (total_elems - 1)]; > stack_node stack[STACK_SIZE]; > - stack_node *top = stack; > - > - PUSH (NULL, NULL); > + stack_node *top = stack + 1; > > - while (STACK_NOT_EMPTY) > + while (stack < top) > { > char *left_ptr; > char *right_ptr; > @@ -281,7 +292,7 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, > { > if ((size_t) (hi - left_ptr) <= max_thresh) > /* Ignore both small partitions. */ > - POP (lo, hi); > + top = pop (top, &lo, &hi); > else > /* Ignore small left partition. */ > lo = left_ptr; > @@ -292,13 +303,13 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, > else if ((right_ptr - lo) > (hi - left_ptr)) > { > /* Push larger left partition indices. */ > - PUSH (lo, right_ptr); > + top = push (top, lo, right_ptr); > lo = left_ptr; > } > else > { > /* Push larger right partition indices. */ > - PUSH (left_ptr, hi); > + top = push (top, left_ptr, hi); > hi = right_ptr; > } > } > -- > 2.34.1 > LGTM Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
diff --git a/stdlib/qsort.c b/stdlib/qsort.c index 5691249a9b..80706b3357 100644 --- a/stdlib/qsort.c +++ b/stdlib/qsort.c @@ -100,15 +100,28 @@ typedef struct char *hi; } stack_node; -/* The next 4 #defines implement a very fast in-line stack abstraction. */ /* The stack needs log (total_elements) entries (we could even subtract log(MAX_THRESH)). Since total_elements has type size_t, we get as upper bound for log (total_elements): bits per byte (CHAR_BIT) * sizeof(size_t). */ -#define STACK_SIZE (CHAR_BIT * sizeof (size_t)) -#define PUSH(low, high) ((void) ((top->lo = (low)), (top->hi = (high)), ++top)) -#define POP(low, high) ((void) (--top, (low = top->lo), (high = top->hi))) -#define STACK_NOT_EMPTY (stack < top) +enum { STACK_SIZE = CHAR_BIT * sizeof (size_t) }; + +static inline stack_node * +push (stack_node *top, char *lo, char *hi) +{ + top->lo = lo; + top->hi = hi; + return ++top; +} + +static inline stack_node * +pop (stack_node *top, char **lo, char **hi) +{ + --top; + *lo = top->lo; + *hi = top->hi; + return top; +} static inline void @@ -212,11 +225,9 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, char *lo = base_ptr; char *hi = &lo[size * (total_elems - 1)]; stack_node stack[STACK_SIZE]; - stack_node *top = stack; - - PUSH (NULL, NULL); + stack_node *top = stack + 1; - while (STACK_NOT_EMPTY) + while (stack < top) { char *left_ptr; char *right_ptr; @@ -281,7 +292,7 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, { if ((size_t) (hi - left_ptr) <= max_thresh) /* Ignore both small partitions. */ - POP (lo, hi); + top = pop (top, &lo, &hi); else /* Ignore small left partition. */ lo = left_ptr; @@ -292,13 +303,13 @@ _quicksort (void *const pbase, size_t total_elems, size_t size, else if ((right_ptr - lo) > (hi - left_ptr)) { /* Push larger left partition indices. */ - PUSH (lo, right_ptr); + top = push (top, lo, right_ptr); lo = left_ptr; } else { /* Push larger right partition indices. */ - PUSH (left_ptr, hi); + top = push (top, left_ptr, hi); hi = right_ptr; } }