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[/] [openrisc/] [trunk/] [orpsocv2/] [bench/] [sysc/] [include/] [MemCache.h] - Rev 348
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// ---------------------------------------------------------------------------- // Debug Unit memory cache: definition // Copyright (C) 2008 Embecosm Limited <info@embecosm.com> // Contributor Jeremy Bennett <jeremy.bennett@embecosm.com> // This file is part of the GDB interface to the cycle accurate model of the // OpenRISC 1000 based system-on-chip, ORPSoC, built using Verilator. // This program is free software: you can redistribute it and/or modify it // under the terms of the GNU Lesser 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 Lesser General Public // License for more details. // You should have received a copy of the GNU Lesser General Public License // along with this program. If not, see <http://www.gnu.org/licenses/>. // ---------------------------------------------------------------------------- // $Id: MemCache.h 326 2009-03-07 16:47:31Z jeremy $ #ifndef MEM_CACHE__H #define MEM_CACHE__H #include <stdint.h> //! Module for cacheing memory accesses by the debug unit //! Memory reads and writes through the Debug Unit via JTAG are time //! consuming - of the order of 1000 CPU clock cycles. However when the //! processor is stalled the values cannot change, other than through the //! debug unit, so it makes sense to cache values. //! Cacheing the entire memory is too much (it does need to be cleared when //! the processor is unstalled. This class provides a cacheing function using //! a closed hash table. //! In the event of a clash on write, the old value is replaced by the new //! value. class MemCache { public: // Constructor and destructor MemCache (int _tableSize = 1009); ~MemCache (); // Functions void clear (); void write (uint32_t addr, uint32_t value); bool read (uint32_t addr, uint32_t &value); private: //! The size of the hash table. A prime number is a good choice. int tableSize; // The hash table, keyed by address. Done as three parallel vectors, // allowing unambiguous clearing by use of memset for efficiency. bool *tabIsValid; uint32_t *tabKeyAddr; uint32_t *tabValue; }; // MemCache () #endif // MEM_CACHE__H
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