http://snippets.dzone.com/posts Sun, 18 May 2008 07:07:28 GMT DZone Snippets: bitfields code http://snippets.dzone.com/posts/show/2070 // C# does not provide the ability to set a field within a byte to a value. <br />// It has the ability to set individual bits, but if you are accessing hardware <br />// you may need to set fields within bytes - no way jose. Until now! <br /> <br /><code> <br />/// <summary> <br />/// SetField is used to set a certain set of bits to the value specified. <br />/// </summary> <br />/// <param name="input">byte in which to set the field</param> <br />/// <param name="value">value to set field to</param> <br />/// <param name="location">bit number within byte where field begins</param> <br />/// <param name="noBits">field size</param> <br />private void SetField(ref long input, long value, byte location, int noBits) <br />{ <br /> int size = 1; <br /> if ((location > 31) || (location < 0)) <br /> throw new Exception("location out of range: " + location); <br /> if ((noBits > 31) || (noBits <= 0)) <br /> throw new Exception("noBits out of range: " + noBits); <br /> if (noBits > 1) size = size << noBits; <br /> if ((value < 0) || (value > size)) <br /> throw new Exception("value out of range: " + value); <br /> value = value << location; <br /> if (value < 0) <br /> throw new Exception("value out of range after shifting to field location: " + value); <br /> input = (input | value); <br />} <br /></code> <br /> <br />Test: <br /><code> <br />using System; <br /> <br />namespace testApp <br />{ <br /> /// <summary> <br /> /// Summary description for Class1. <br /> /// </summary> <br /> class Class1 <br /> { <br /> /// <summary> <br /> /// The main entry point for the application. <br /> /// </summary> <br /> [STAThread] <br /> static void Main(string[] args) <br /> { <br /> Class1 t = new Class1(); <br /> long i = 2; // <br /> Console.WriteLine(t.ConvertByteToBinaryString(i)); <br /> t.SetField(ref i,5,8,4); <br /> Console.WriteLine(t.ConvertByteToBinaryString(i)); <br /> } <br /> /// <summary> <br /> /// SetField is used to set a certain set of bits to the value specified. <br /> /// </summary> <br /> /// <param name="input">byte in which to set the field</param> <br /> /// <param name="value">value to set field to</param> <br /> /// <param name="location">bit number within byte where field begins</param> <br /> /// <param name="noBits">field size</param> <br /> private void SetField(ref long input, long value, byte location, int noBits) <br /> { <br /> int size = 1; <br /> if ((location > 31) || (location < 0)) <br /> throw new Exception("location out of range: " + location); <br /> if ((noBits > 31) || (noBits <= 0)) <br /> throw new Exception("noBits out of range: " + noBits); <br /> if (noBits > 1) size = size << noBits; <br /> if ((value < 0) || (value > size)) <br /> throw new Exception("value out of range: " + value); <br /> value = value << location; <br /> if (value < 0) <br /> throw new Exception("value out of range after shifting to field location: " + value); <br /> input = (input | value); <br /> } <br /> /// <summary> <br /> /// Format integer as a binary string with spaces between every 4 bits <br /> /// </summary> <br /> /// <param name="input">integer to format</param> <br /> /// <returns>string of the form "0000 0000 0000 0000 0000 0110 0001 1000"</returns> <br /> private string ConvertByteToBinaryString(long input) <br /> { <br /> string result = null; <br /> string bitstring = null; <br /> for(int i=31;i>=0;i--) <br /> { <br /> if (((input >> i) & 1) == 1) result = "1"; <br /> else result = "0"; <br /> bitstring += result; <br /> if ((i>0) && ((i)%4)==0) <br /> { <br /> bitstring += " "; <br /> } <br /> } <br /> return bitstring; <br /> } <br /> } <br />} <br /></code> <br /> <br />Output from test: <br />C:\>testApp.exe <br />0000 0000 0000 0000 0000 0000 0000 0010 <br />0000 0000 0000 0000 0000 0101 0000 0010 <br />C:\> <br /> Thu, 18 May 2006 20:08:49 GMT http://snippets.dzone.com/posts/show/2070 ocorpening (Owen Corpening)