From 4aefda6f17c1e4e8f9dba03e5f6be20ba673727a Mon Sep 17 00:00:00 2001
From: Michael Moon <triffid.hunter@gmail.com>
Date: Thu, 24 Feb 2011 18:49:28 +1100
Subject: [PATCH] added integer square root algorithm for future use

---
 dda.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/dda.c b/dda.c
index 03fbff8..6a3f470 100644
--- a/dda.c
+++ b/dda.c
@@ -100,6 +100,25 @@ uint32_t approx_distance_3( uint32_t dx, uint32_t dy, uint32_t dz )
 	return (( approx + 512 ) >> 10 );
 }
 
+// courtesy of http://www.embedded-systems.com/98/9802fe2.htm
+uint16_t int_sqrt(uint32_t a) {
+	uint32_t rem = 0;
+	uint32_t root = 0;
+	for (uint16_t i = 0; i < 16; i++) {
+		root <<= 1;
+		rem = ((rem << 2) + (a >> 30));
+		a <<= 2;
+		root++;
+		if (root <= rem) {
+			rem -= root;
+			root++;
+		}
+		else
+			root--;
+	}
+	return (uint16_t) ((root >> 1) & 0xFFFFL);
+}
+
 // this is an ultra-crude pseudo-logarithm routine, such that:
 // 2 ^ msbloc(v) >= v
 const uint8_t	msbloc (uint32_t v) {