From fbea1e607c99358734fd420e268cbebef5c6a429 Mon Sep 17 00:00:00 2001
From: Richard Thier <magosit@outlook.hu>
Date: Tue, 16 Aug 2022 11:44:34 +0200
Subject: [PATCH] factored out internal_array_separate(..) to check if it has
 the errors or not

---
 space_partitioning_sort/spsort.h | 60 ++++++++++++++++++++------------
 1 file changed, 38 insertions(+), 22 deletions(-)

diff --git a/space_partitioning_sort/spsort.h b/space_partitioning_sort/spsort.h
index ae29733..31804e0 100644
--- a/space_partitioning_sort/spsort.h
+++ b/space_partitioning_sort/spsort.h
@@ -72,6 +72,41 @@ inline uint32_t internal_mid(uint32_t low, uint32_t high) {
 /** Sort using space-partitioning - does recursive re-pivoting */
 inline void spsort(uint32_t *t, int n, int m = 32);
 
+struct lr {
+	int left;
+	int right;
+};
+
+inline struct lr internal_array_separate(uint32_t *t, int n, uint32_t low, uint32_t mid, uint32_t high) {
+	// Init left-right "write head" indices
+	int left = 0;
+	int right = n - 1;
+	uint32_t current = t[left];
+	bool current_is_left = true;
+
+	// Separate to the ends of the array (in-place)
+	for(int i = 0; i < n; ++i) {
+		if(current < mid) {
+			const auto tmp = t[left];
+			t[left++] = current;
+			current = current_is_left ? t[left] : tmp;
+			current_is_left = true;
+
+		} else {
+			const auto tmp = t[right];
+			t[right--] = current;
+			current = tmp;
+			current = !current_is_left ? t[right] : tmp;
+			current_is_left = false;
+		}
+	}
+
+	struct lr eler;
+	eler.left = left;
+	eler.right = right;
+
+	return eler;
+}
 
 // TODO: [spsort] In-place variant that looks like a quicksort-kind-of-thing:
 //       - I realized that in-placing make this similar to quicksort actually
@@ -98,28 +133,9 @@ inline void internal_spsort(uint32_t *t, int n, int m, uint32_t low, uint32_t mi
 		binsertion_sort(t, n);
 	}
 
-	// Init left-right "write head" indices
-	int left = 0;
-	int right = n - 1;
-	uint32_t current = t[left];
-	bool current_is_left = true;
-
-	// Separate to the ends of the array (in-place)
-	for(int i = 0; i < n; ++i) {
-		if(current < mid) {
-			const auto tmp = t[left];
-			t[left++] = current;
-			current = current_is_left ? t[left] : tmp;
-			current_is_left = true;
-
-		} else {
-			const auto tmp = t[right];
-			t[right--] = current;
-			current = tmp;
-			current = !current_is_left ? t[right] : tmp;
-			current_is_left = false;
-		}
-	}
+	struct lr eler = internal_array_separate(t, n, low, mid, high);
+	auto left = eler.left;
+	auto right = eler.right;
 
 	auto lefts = left;
 	auto rights = right - left;