Add SetBit method to modify one bit of a byte

tianke3477 · Aug 15, 2023 · 2ec7322 · 2ec7322
1 parent a8ef47b
commit 2ec7322
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diff --git a/S7.Net.UnitTest/ConvertersUnitTest.cs b/S7.Net.UnitTest/ConvertersUnitTest.cs
@@ -24,5 +24,21 @@ public void T00_TestSelectBit()
             Assert.IsFalse(dummyByte.SelectBit(7));
 
         }
+
+        [TestMethod]
+        public void T01_TestSetBit()
+        {
+            byte dummyByte = 0xAA; // 1010 1010
+            dummyByte.SetBit(0, true);
+            dummyByte.SetBit(1, false);
+            dummyByte.SetBit(2, true);
+            dummyByte.SetBit(3, false);
+            Assert.AreEqual<byte>(dummyByte, 0xA5);// 1010 0101
+            dummyByte.SetBit(4, true);
+            dummyByte.SetBit(5, true);
+            dummyByte.SetBit(6, true);
+            dummyByte.SetBit(7, true);
+            Assert.AreEqual<byte>(dummyByte, 0xF5);// 1111 0101
+        }
     }
 }
diff --git a/S7.Net/Conversion.cs b/S7.Net/Conversion.cs
@@ -151,6 +151,51 @@ public static bool SelectBit(this byte data, int bitPosition)
             return (result != 0);
         }
 
+        /// <summary>
+        /// Helper to set a bit value to the given byte at the bit index.
+        /// </summary>
+        /// <param name="data"></param>
+        /// <param name="bitPosition"></param>
+        /// <param name="value"></param>
+        public static void SetBit(this ref byte data, int bitPosition, bool value)
+        {
+            if (bitPosition < 0 || bitPosition > 7)
+            {
+                return;
+            }
+
+            if (value)
+            {
+                switch (bitPosition)
+                {
+                    case 0: data |= 0x01; return;
+                    case 1: data |= 0x02; return;
+                    case 2: data |= 0x04; return;
+                    case 3: data |= 0x08; return;
+                    case 4: data |= 0x10; return;
+                    case 5: data |= 0x20; return;
+                    case 6: data |= 0x40; return;
+                    case 7: data |= 0x80; return;
+                    default: return;
+                }
+            }
+            else
+            {
+                switch (bitPosition)
+                {
+                    case 0: data &= 0xFE; return;
+                    case 1: data &= 0xFD; return;
+                    case 2: data &= 0xFB; return;
+                    case 3: data &= 0xF7; return;
+                    case 4: data &= 0xEF; return;
+                    case 5: data &= 0xDF; return;
+                    case 6: data &= 0xBF; return;
+                    case 7: data &= 0x7F; return;
+                    default: return;
+                }
+            }
+        }
+
         /// <summary>
         /// Converts from ushort value to short value; it's used to retrieve negative values from words
         /// </summary>