Spartan6Bitstream.hpp

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// Torc - Copyright 2011-2013 University of Southern California.  All Rights Reserved.
// $HeadURL$
// $Id$

// This program is free software: you can redistribute it and/or modify it under the terms of the 
// GNU General Public License as published by the Free Software Foundation, either version 3 of the 
// License, or (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
// without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See 
// the GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License along with this program.  If 
// not, see <http://www.gnu.org/licenses/>.

/// \file
/// \brief Header for the Spartan6Bitstream class.

#ifndef TORC_BITSTREAM_SPARTAN6BITSTREAM_HPP
#define TORC_BITSTREAM_SPARTAN6BITSTREAM_HPP

#include <boost/cstdint.hpp>
#include "torc/bitstream/Bitstream.hpp"
#include "torc/bitstream/Spartan6Packet.hpp"

namespace torc {
namespace bitstream {

namespace bitstream { class Spartan6BitstreamUnitTest; }

    /// \brief Spartan-class bitstream.
    class Spartan6Bitstream : virtual public Bitstream, public Spartan6PacketVector, 
        public Spartan6PacketConstants {
        friend class torc::bitstream::bitstream::Spartan6BitstreamUnitTest;
    protected:
    // typedefs
        /// \brief Imported type name.
        typedef boost::uint16_t uint16_t;
        typedef boost::uint32_t uint32_t;
    // inner classes
        /// \brief CRC class for the Spartan6 architecture.
        struct CRC {
            /// \brief Length of the CRC calculation.
            enum { eLen = 22 };
            /// \brief CRC calculation bits.
            uint8_t mBits[eLen];
            /// \brief CRC calculation value.
            uint32_t mValue;
            /// \brief Default constructor.
            CRC(void) { reset(); }
            /// \brief Function to clear the CRC calculation.
            void reset(void) { for(int32_t i = 0; i < eLen; i++) mBits[i] = 0; mValue = 0; }
            /// \brief Update the CRC with new data.
            void update(uint32_t inAddress, uint32_t inWord) {
                uint8_t input[eLen];
                uint8_t next[eLen];
                // initialize the input with the current register address and data word
                for(int32_t i = 21, mask = 0x20; i >= 16; i--, mask >>= 1) 
                    input[i] = (inAddress & mask) ? 1 : 0;
                for(int32_t i = 15, mask = 0x8000; i >= 0; i--, mask >>= 1) 
                    input[i] = (inWord & mask) ? 1 : 0;
                // update the CRC
                for(int32_t i = 21; i >= 16; i--) next[i] = mBits[i - 1] ^ input[i];
                next[15] = mBits[14] ^ input[15] ^ mBits[21];
                for(int32_t i = 14; i >= 13; i--) next[i] = mBits[i - 1] ^ input[i];
                next[12] = mBits[11] ^ input[12] ^ mBits[21];
                for(int32_t i = 11; i >= 8; i--) next[i] = mBits[i - 1] ^ input[i];
                next[7] = mBits[6] ^ input[7] ^ mBits[21];
                for(int32_t i = 6; i >= 1; i--) next[i] = mBits[i - 1] ^ input[i];
                next[0] = input[0] ^ mBits[21];
                // copy the updated bits into place
                mValue = 0;
                for(int32_t i = 0, mask = 1; i < eLen; i++, mask <<= 1) {
                    mBits[i] = next[i];
                    mValue |= mBits[i] ? mask : 0;
                }
            }
            /// \brief Index operator.
            uint8_t& operator[] (int i) { return mBits[i]; }
            /// \brief Cast operator to return the CRC as an integer.
            operator uint32_t (void) const { return mValue; }
        };
    // members
    public:
    // constructors
        /// \brief Basic constructor.
        Spartan6Bitstream(void) : Bitstream(), Spartan6PacketVector(), Spartan6PacketConstants() {}
    // functions
        /// \brief Read bitstream packets from a stream.
        /// \note This function should be called after the bitstream header has been read.
        virtual void readPackets(std::istream& inStream);
        /// \brief Write bitstream packets to a stream.
        virtual void writePackets(std::ostream& inStream);
        /// \brief Preflight the packets.
        virtual void preflightPackets(void);
        /// \brief Update the header packet length.
        virtual void updatePacketLength(void);
    };

} // namespace bitstream
} // namespace torc

#endif // TORC_BITSTREAM_SPARTAN6BITSTREAM_HPP