int_sqrt: Improve 3x faster integer sqrt.

Result on 10,000,000 call.
Old:
sqrt(12345689) = 3513
real	0m0.768s
user	0m0.760s
sys	0m0.004s

New:
sqrt(12345689) = 3513
real	0m0.222s
user	0m0.224s
sys	0m0.000s

Signed-off-by: engstk <eng.stk@sapo.pt>

1 files changed, 13 insertions, 15 deletions

diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c
index 0814f0762..5c3916d09 100644
--- a/lib/int_sqrt.c
+++ b/lib/int_sqrt.c
@@ -14,34 +14,32 @@
  *
  * A very rough approximation to the sqrt() function.
  */
-unsigned long int_sqrt(unsigned long x)
+inline unsigned long int_sqrt(unsigned long x)
 {
-	unsigned long tmp;
-	unsigned long place;
-	unsigned long root;
-	unsigned long remainder;
+	register unsigned long tmp;
+	register unsigned long place;
+	register unsigned long root = 0;
 
 	if (x <= 1)
 		return x;
 
-	root = 0;
-	remainder = x;
 	place = 1UL << (BITS_PER_LONG - 2);
-	
-	while (place > remainder)  
+
+	do{
 		place >>= 2;
+	}while(place > x);
 
-	while (place != 0) {
+	do {
 		tmp = root + place;
+		root >>= 1;
 
-		if (remainder >= tmp) 
+		if (x >= tmp)
 		{
-			remainder -= tmp;
-			root += (place << 1);
+			x -= tmp;
+			root += place;
 		}
-		root >>= 1;
 		place >>= 2;
-	}
+	}while (place != 0);
 
 	return root;
 }