function to get float sign bit

mikera · Dec 21, 2012 · 378d9ba · 378d9ba
1 parent d4f1dd7
commit 378d9ba
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diff --git a/src/main/java/mikera/util/Bits.java b/src/main/java/mikera/util/Bits.java
@@ -428,6 +428,13 @@ public static String toBinaryString(int a) {
 		return new String(chars);
 	}
 
+	/**
+	 * Gets the sign bit of a floating point value
+	 */
+	public static int signBit(float f) {
+		return (Float.floatToIntBits(f)>>>31);
+	}
+
 	/**
 	 * Creates a long value out of high and low integer components
 	 * 

diff --git a/src/test/java/mikera/util/TestBits.java b/src/test/java/mikera/util/TestBits.java
@@ -150,6 +150,13 @@ public class TestBits {
 		assertEquals(1,Bits.parity(0x0100F000));
 	}
 
+	@Test public void testFloatSign() {
+		assertEquals(0,Bits.signBit(1.0f));
+		assertEquals(1,Bits.signBit(-1.0f));
+		assertEquals(0,Bits.signBit(Float.POSITIVE_INFINITY));
+		assertEquals(1,Bits.signBit(Float.NEGATIVE_INFINITY));
+	}
+
 	@Test public void testRoll() {
 		assertEquals(0xFFF0000F,Bits.rollLeft(0x0000FFFF,20));
 		assertEquals(0xFFF0000F,Bits.rollLeft(0x0000FFFF,52));