From 5a71deda15f15f3658bc22db9cc71767a851d17e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20T=C5=AFma?= <tumic@cbox.cz>
Date: Tue, 22 Oct 2024 09:06:09 +0200
Subject: [PATCH] Optimization

---
 src/map/dem.cpp | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/map/dem.cpp b/src/map/dem.cpp
index fa3b8920..28e45ba5 100644
--- a/src/map/dem.cpp
+++ b/src/map/dem.cpp
@@ -23,12 +23,20 @@
 
 static unsigned int isqrt(unsigned int x)
 {
-	unsigned int r = 0;
+	unsigned int l = 0;
+	unsigned int m;
+	unsigned int r = x + 1;
 
-	while ((r + 1) * (r + 1) <= x)
-		r++;
+	while (l != r - 1) {
+		m = (l + r) / 2;
 
-	return r;
+		if (m * m <= x)
+			l = m;
+		else
+			r = m;
+	}
+
+	return l;
 }
 
 static double interpolate(double dx, double dy, double p0, double p1, double p2,