// ----------------------------------------------------------------------------
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// ----------------------------------------------------------------------------
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// Debug Unit memory cache: definition
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// Debug Unit memory cache: definition
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// Copyright (C) 2008 Embecosm Limited <info@embecosm.com>
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// Copyright (C) 2008 Embecosm Limited <info@embecosm.com>
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// Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>
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// Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>
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// This file is part of the GDB interface to the cycle accurate model of the
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// This file is part of the GDB interface to the cycle accurate model of the
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// OpenRISC 1000 based system-on-chip, ORPSoC, built using Verilator.
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// OpenRISC 1000 based system-on-chip, ORPSoC, built using Verilator.
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// This program is free software: you can redistribute it and/or modify it
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// This program is free software: you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License as published by
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// under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or (at your
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// the Free Software Foundation, either version 3 of the License, or (at your
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// option) any later version.
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// option) any later version.
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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// License for more details.
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// License for more details.
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// You should have received a copy of the GNU Lesser General Public License
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// You should have received a copy of the GNU Lesser General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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// ----------------------------------------------------------------------------
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// ----------------------------------------------------------------------------
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// $Id: MemCache.h 326 2009-03-07 16:47:31Z jeremy $
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// $Id: MemCache.h 326 2009-03-07 16:47:31Z jeremy $
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#ifndef MEM_CACHE__H
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#ifndef MEM_CACHE__H
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#define MEM_CACHE__H
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#define MEM_CACHE__H
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#include <stdint.h>
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#include <stdint.h>
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//! Module for cacheing memory accesses by the debug unit
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//! Module for cacheing memory accesses by the debug unit
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//! Memory reads and writes through the Debug Unit via JTAG are time
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//! Memory reads and writes through the Debug Unit via JTAG are time
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//! consuming - of the order of 1000 CPU clock cycles. However when the
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//! consuming - of the order of 1000 CPU clock cycles. However when the
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//! processor is stalled the values cannot change, other than through the
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//! processor is stalled the values cannot change, other than through the
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//! debug unit, so it makes sense to cache values.
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//! debug unit, so it makes sense to cache values.
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//! Cacheing the entire memory is too much (it does need to be cleared when
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//! Cacheing the entire memory is too much (it does need to be cleared when
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//! the processor is unstalled. This class provides a cacheing function using
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//! the processor is unstalled. This class provides a cacheing function using
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//! a closed hash table.
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//! a closed hash table.
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//! In the event of a clash on write, the old value is replaced by the new
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//! In the event of a clash on write, the old value is replaced by the new
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//! value.
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//! value.
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class MemCache
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class MemCache {
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{
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public:
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public:
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// Constructor and destructor
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// Constructor and destructor
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MemCache (int _tableSize = 1009);
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MemCache(int _tableSize = 1009);
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~MemCache ();
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~MemCache();
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// Functions
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// Functions
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void clear ();
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void clear ();
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void write (uint32_t addr,
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void write(uint32_t addr, uint32_t value);
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uint32_t value);
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bool read(uint32_t addr, uint32_t & value);
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bool read (uint32_t addr,
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uint32_t &value);
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private:
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private:
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//! The size of the hash table. A prime number is a good choice.
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//! The size of the hash table. A prime number is a good choice.
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int tableSize;
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int tableSize;
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// The hash table, keyed by address. Done as three parallel vectors,
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// The hash table, keyed by address. Done as three parallel vectors,
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// allowing unambiguous clearing by use of memset for efficiency.
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// allowing unambiguous clearing by use of memset for efficiency.
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bool *tabIsValid;
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bool *tabIsValid;
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uint32_t *tabKeyAddr;
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uint32_t *tabKeyAddr;
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uint32_t *tabValue;
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uint32_t *tabValue;
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}; // MemCache ()
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}; // MemCache ()
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#endif // MEM_CACHE__H
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#endif // MEM_CACHE__H
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