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[/] [a-z80/] [trunk/] [tools/] [z80_pla_checker/] [source/] [ClassPLAEntry.cs] - Blame information for rev 3

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Line No. Rev Author Line
1 3 gdevic
´╗┐using System;
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namespace z80_pla_checker
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{
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    /// 
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    /// This class defines a single PLA entry and the operations on it
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    /// 
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    public class ClassPlaEntry
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    {
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        // IX/IY Modifiers
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        [FlagsAttribute]
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        public enum Modifier
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        {
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            IXY0 = (1 << 6),                    // IX or IY flag is reset
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            IXY1 = (1 << 5),                    // IX or IY flag is set
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            NHALT = (1 << 4),                   // Not in HALT state
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            ALU  = (1 << 3),                    // ALU operation
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            XX = (1 << 2),                      // Regular instruction
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            CB = (1 << 1),                      // CB instruction table modifier
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            ED = (1 << 0)                       // ED instruction table modifier
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        };
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        private int prefix;                         // Modifier bitfield
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        private int opcode;                         // Opcode bitfield
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        private bool duplicate;                     // This entry is a duplicate
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        public bool IsDuplicate() { return duplicate; }
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        public int N { get; private set; }          // Ordinal number of this entry, or the entry ID
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        public string Comment { get; private set; } // PLA line description / comment text
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        public string Raw { get; private set; }     // Raw line as-is
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        public bool Ignored = false;                // This entry can optionally be ignored
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        /// 
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        /// PLA entry class constructor
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        /// Accepts the init string which should contain a line from the PLA master table.
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        /// Various fields from that line are read into this class.
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        /// 
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        public bool Init(string init)
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        {
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            try
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            {
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                Raw = init;
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                char[] delimiterChars = { '\t' };
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                string[] w = init.Split(delimiterChars);
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                // Example of an input line:
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                // w[0]                    w[1] w[2] w[3]     w[4]
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                // ....1.. 1.1........1.11.  D   63  00xxx110 ld r,*
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                // Mark a duplicate
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                duplicate = w[1].Contains("D");
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                // Read the 7 bits of the prefix
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                for (int i = 0; i < 7; i++)
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                    if (w[0][6-i] == '1') prefix |= (1 << i);
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                // Read 16 bits of the opcode mask
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                for (int i = 0; i < 16; i++)
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                    if (w[0][23 - i] == '1') opcode |= (1 << i);
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                N = Convert.ToInt32(w[2]);
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                Comment = w[4];
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                return true;
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            }
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            catch (Exception ex)
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            {
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                ClassLog.Log("ClassPlaEntry: Can't parse line: " + init);
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                ClassLog.Log(ex.Message);
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            }
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            return false;
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        }
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        /// 
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        /// Matches a given opcode to this PLA line. Returns empty string if not a match
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        /// or PLA number and mnemonic if there is a match. Duplicates are ignored.
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        /// 
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        public string Match(Modifier modifier, Byte instr)
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        {
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            if (duplicate) return string.Empty;
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            // Check the modifiers against the prefix bitfield.
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            if ((((int)modifier) & prefix) != prefix)
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                return string.Empty;
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            // Check each opcode bit
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            // If any bit in the opcode map is 1, the instruction needs to be "0" or "1"
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            for (int i = 0; i < 8; i++)
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            {
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                int testbit = (instr >> i) & 1;
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                int test1 = (opcode >> (i * 2)) & 1;
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                int test0 = (opcode >> (i * 2 + 1)) & 1;
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                if (test1 == 1 && testbit != 1) return string.Empty;
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                if (test0 == 1 && testbit != 0) return string.Empty;
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            }
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            return string.Format("[{0}] {1}", N, Comment);
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        }
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        /// 
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        /// Return a PLA entry suitable to use in a System Verilog compare statement
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        /// 
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        public string GetBitstream()
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        {
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            // Write out these bits in order; they can be 1 or don't care (X)
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            string bitstream = "";
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            // Create 7 bits of the prefix
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            for (int i = 6; i >= 0; i--)
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                bitstream += (prefix & (1 << i))==0 ? "X" : "1";
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            bitstream += "_";
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            // Followed by the 8 bits of the opcode mask
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            for (int i = 7; i >= 0; i--)
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            {
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                string code = "X";
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                int test1 = (opcode >> (i * 2)) & 1;
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                int test0 = (opcode >> (i * 2 + 1)) & 1;
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                if (test1 == 1)
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                    code = "1";
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                if (test0 == 1)
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                    code = "0";
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                bitstream += code;
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            }
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            return bitstream;
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        }
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    }
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}

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