feat: Added IsInteger method in Fixed64.cs and Fixed64.Extensions.cs (#21)

* feat: Added IsInteger method in Fixed64.cs and Fixed64.Extensions.cs

* fix: using MAX_SHIFTED_AMOUNT_UI instead of uint.MaxValue

Author: ltomazetto

src/FixedMathSharp/Fixed64.Extensions.cs

@@ -16,6 +16,13 @@ public static int Sign(this Fixed64 value)
             return Fixed64.Sign(value);
         }
 
+        /// <inheritdoc cref="Fixed64.IsInteger(Fixed64)" />
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static bool IsInteger(this Fixed64 value)
+        {
+            return Fixed64.IsInteger(value);
+        }
+        
         /// <inheritdoc cref="FixedMath.Squared(Fixed64)" />
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Fixed64 Squared(this Fixed64 value)

src/FixedMathSharp/Fixed64.cs

@@ -150,6 +150,15 @@ public static int Sign(Fixed64 value)
             // Return the sign of the value, optimizing for branchless comparison
             return value.m_rawValue < 0 ? -1 : (value.m_rawValue > 0 ? 1 : 0);
         }
+        
+        /// <summary>
+        /// Returns true if the number has no decimal part (i.e., if the number is equivalent to an integer) and False otherwise. 
+        /// </summary>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static bool IsInteger(Fixed64 value)
+        {
+            return ((ulong)value.m_rawValue & FixedMath.MAX_SHIFTED_AMOUNT_UI) == 0;
+        }
 
         #endregion
 

tests/FixedMathSharp.Tests/Fixed64.Tests.cs

@@ -190,5 +190,44 @@ public void Subtract_OverflowProtection_ReturnsMinValue()
         }
 
         #endregion
+        
+        #region Test: Operations
+
+        [Fact]
+        public void IsInteger_PositiveInteger_ReturnsTrue()
+        {
+            var a = new Fixed64(42);
+            Assert.True(a.IsInteger());
+        }
+
+        [Fact]
+        public void IsInteger_NegativeInteger_ReturnsTrue()
+        {
+            var a = new Fixed64(-42);
+            Assert.True(a.IsInteger());
+        }
+
+        [Fact]
+        public void IsInteger_WhenZero_ReturnsTrue()
+        {
+            var a = Fixed64.Zero;
+            Assert.True(a.IsInteger());
+        }
+
+        [Fact]
+        public void IsInteger_PositiveDecimal_ReturnsFalse()
+        {
+            var a = new Fixed64(4.2);
+            Assert.False(a.IsInteger());
+        }
+
+        [Fact]
+        public void IsInteger_NegativeDecimal_ReturnsFalse()
+        {
+            var a = new Fixed64(-4.2);
+            Assert.False(a.IsInteger());
+        }
+
+        #endregion
     }
 }