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tune CCarray.sort_generic

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Simon Cruanes 2015-10-24 00:13:02 +02:00
parent 3b1922671e
commit 2608fc90bb
1 changed files with 62 additions and 67 deletions
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129
src/core/CCArray.ml
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@ -663,13 +663,13 @@ module SortGeneric(A : MONO_ARRAY) = struct
let seed_ = [|123456|]
type state = {
rand: Rand.t; (* random state *)
cmp: A.elt -> A.elt -> int;
mutable l: int; (* left pointer *)
mutable g: int; (* right pointer *)
mutable k: int;
}
let rand_idx_ rand i j = i + Rand.int rand (j-i)
let swap_ a i j =
if i=j then ()
else (
@ -678,74 +678,69 @@ module SortGeneric(A : MONO_ARRAY) = struct
A.set a j tmp
)
let rec insert_ ~cmp a i k =
if k<i then ()
else if cmp (A.get a k) (A.get a (k+1)) > 0 then (
swap_ a k (k+1);
insert_ ~cmp a i (k-1)
)
(* recursive part of insertion sort *)
let rec sort_insertion_rec ~cmp a i j k =
if k<j then (
insert_ ~cmp a i (k-1);
sort_insertion_rec ~cmp a i j (k+1)
)
(* insertion sort, for small slices *)
let sort_insertion ~cmp a i j =
if j-i > 1 then sort_insertion_rec ~cmp a i j (i+1)
let rand_idx_ ~st i j =
i + Rand.int st.rand (j-i)
(* sort slice.
There is a chance that the two pivots are equal, but it's unlikely. *)
let rec sort_slice_ ~st a i j =
if j-i>16 then (
st.l <- i;
st.g <- j-1;
st.k <- i;
(* choose pivots *)
let p = A.get a (rand_idx_ ~st i j) in
let q = A.get a (rand_idx_ ~st i j) in
(* invariant: st.p <= st.q, swap them otherwise *)
let p, q = if st.cmp p q > 0 then q, p else p, q in
while st.k <= st.g do
let cur = A.get a st.k in
if st.cmp cur p < 0 then (
(* insert in leftmost band *)
if st.k <> st.l then swap_ a st.k st.l;
st.l <- st.l + 1
) else if st.cmp cur q > 0 then (
(* insert in rightmost band *)
while st.k < st.g && st.cmp (A.get a st.g) q > 0 do
st.g <- st.g - 1
done;
swap_ a st.k st.g;
st.g <- st.g - 1;
(* the element swapped from the right might be in the first situation.
that is, < p (we know it's <= q already) *)
if st.cmp (A.get a st.k) p < 0 then (
let sort ~cmp a =
let rec insert_ a i k =
if k<i then ()
else if cmp (A.get a k) (A.get a (k+1)) > 0 then (
swap_ a k (k+1);
insert_ a i (k-1)
)
in
(* recursive part of insertion sort *)
let rec sort_insertion_rec a i j k =
if k<j then (
insert_ a i (k-1);
sort_insertion_rec a i j (k+1)
)
in
(* insertion sort, for small slices *)
let sort_insertion a i j =
if j-i > 1 then sort_insertion_rec a i j (i+1)
in
let rand = Rand.make seed_ in
(* sort slice.
There is a chance that the two pivots are equal, but it's unlikely. *)
let rec sort_slice_ ~st a i j =
if j-i>10 then (
st.l <- i;
st.g <- j-1;
st.k <- i;
(* choose pivots *)
let p = A.get a (rand_idx_ rand i j) in
let q = A.get a (rand_idx_ rand i j) in
(* invariant: st.p <= st.q, swap them otherwise *)
let p, q = if cmp p q > 0 then q, p else p, q in
while st.k <= st.g do
let cur = A.get a st.k in
if cmp cur p < 0 then (
(* insert in leftmost band *)
if st.k <> st.l then swap_ a st.k st.l;
st.l <- st.l + 1
)
);
st.k <- st.k + 1
done;
(* save values before recursing *)
let l = st.l and g = st.g and sort_middle = st.cmp p q < 0 in
sort_slice_ ~st a i l;
if sort_middle then sort_slice_ ~st a l (g+1);
sort_slice_ ~st a (g+1) j;
) else sort_insertion ~cmp:st.cmp a i j
let sort ~cmp a =
) else if cmp cur q > 0 then (
(* insert in rightmost band *)
while st.k < st.g && cmp (A.get a st.g) q > 0 do
st.g <- st.g - 1
done;
swap_ a st.k st.g;
st.g <- st.g - 1;
(* the element swapped from the right might be in the first situation.
that is, < p (we know it's <= q already) *)
if cmp (A.get a st.k) p < 0 then (
if st.k <> st.l then swap_ a st.k st.l;
st.l <- st.l + 1
)
);
st.k <- st.k + 1
done;
(* save values before recursing *)
let l = st.l and g = st.g and sort_middle = cmp p q < 0 in
sort_slice_ ~st a i l;
if sort_middle then sort_slice_ ~st a l (g+1);
sort_slice_ ~st a (g+1) j;
) else sort_insertion a i j
in
if A.length a > 0 then (
let st = {
rand=Rand.make seed_; cmp;
l=0; g=A.length a; k=0;
} in
let st = { l=0; g=A.length a; k=0; } in
sort_slice_ ~st a 0 (A.length a)
)
end