From 3df745afcfd51da1a18a18f5960c7e5db65e1730 Mon Sep 17 00:00:00 2001
From: Exxion <exxion191@gmail.com>
Date: Tue, 12 Apr 2022 17:17:57 -0400
Subject: [PATCH] Fast macro-based heapsort (#32381)

---
 __DEFINES/sort.dm | 33 +++++++++++++++++++++++++++++++++
 vgstation13.dme   |  1 +
 2 files changed, 34 insertions(+)
 create mode 100644 __DEFINES/sort.dm

diff --git a/__DEFINES/sort.dm b/__DEFINES/sort.dm
new file mode 100644
index 00000000000..792d555fdaa
--- /dev/null
+++ b/__DEFINES/sort.dm
@@ -0,0 +1,33 @@
+#define SIFT_DOWN(L, comparison, n, i) do { \
+var/SIFT_DOWN_largest = i; \
+var/SIFT_DOWN_i; \
+do { \
+	SIFT_DOWN_i = SIFT_DOWN_largest; \
+	var/SIFT_DOWN_l = 2 * SIFT_DOWN_largest; \
+	var/SIFT_DOWN_r = SIFT_DOWN_l + 1; \
+	if(SIFT_DOWN_l <= n) { \
+		if(comparison(L[SIFT_DOWN_l], L[SIFT_DOWN_largest])) { \
+			SIFT_DOWN_largest = SIFT_DOWN_l; \
+		} \
+		if((SIFT_DOWN_r <= n) && comparison(L[SIFT_DOWN_r], L[SIFT_DOWN_largest])) { \
+			SIFT_DOWN_largest = SIFT_DOWN_r; \
+		} \
+	} \
+	L.Swap(SIFT_DOWN_i, SIFT_DOWN_largest); \
+} while(SIFT_DOWN_largest != SIFT_DOWN_i);} while(FALSE)
+
+#define SORT(L, comparison) do { \
+var/SORT_N = L.len; \
+for(var/SORT_i in round(SORT_N / 2) to 1 step -1) { \
+	SIFT_DOWN(L, comparison, SORT_N, SORT_i); \
+} \
+for(var/SORT_i in SORT_N to 2 step -1) { \
+	L.Swap(1, SORT_i); \
+	SIFT_DOWN(L, comparison, SORT_i - 1, 1); \
+}} while(FALSE)
+
+#define GREATER(a, b) (a > b)
+#define LESS(a, b) (a < b)
+
+#define SORT_ASC(L) SORT(L, GREATER)
+#define SORT_DSC(L) SORT(L, LESS)
diff --git a/vgstation13.dme b/vgstation13.dme
index 22686290e3d..b8f487bacb6 100644
--- a/vgstation13.dme
+++ b/vgstation13.dme
@@ -66,6 +66,7 @@
 #include "__DEFINES\silicon.dm"
 #include "__DEFINES\simple_animal_defines.dm"
 #include "__DEFINES\snow.dm"
+#include "__DEFINES\sort.dm"
 #include "__DEFINES\spell_defines.dm"
 #include "__DEFINES\striketeam_defines.dm"
 #include "__DEFINES\stylesheet.dm"