ras.hh revision 6226:f1076450ab2b
1/* 2 * Copyright (c) 2004-2005 The Regents of The University of Michigan 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are 7 * met: redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer; 9 * redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution; 12 * neither the name of the copyright holders nor the names of its 13 * contributors may be used to endorse or promote products derived from 14 * this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * Authors: Kevin Lim 29 */ 30 31#ifndef __CPU_O3_RAS_HH__ 32#define __CPU_O3_RAS_HH__ 33 34#include <vector> 35 36#include "base/types.hh" 37 38/** Return address stack class, implements a simple RAS. */ 39class ReturnAddrStack 40{ 41 public: 42 /** Creates a return address stack, but init() must be called prior to 43 * use. 44 */ 45 ReturnAddrStack() {} 46 47 /** Initializes RAS with a specified number of entries. 48 * @param numEntries Number of entries in the RAS. 49 */ 50 void init(unsigned numEntries); 51 52 void reset(); 53 54 /** Returns the top address on the RAS. */ 55 Addr top() 56 { return addrStack[tos]; } 57 58 /** Returns the index of the top of the RAS. */ 59 unsigned topIdx() 60 { return tos; } 61 62 /** Pushes an address onto the RAS. */ 63 void push(const Addr &return_addr); 64 65 /** Pops the top address from the RAS. */ 66 void pop(); 67 68 /** Changes index to the top of the RAS, and replaces the top address with 69 * a new target. 70 * @param top_entry_idx The index of the RAS that will now be the top. 71 * @param restored_target The new target address of the new top of the RAS. 72 */ 73 void restore(unsigned top_entry_idx, const Addr &restored_target); 74 75 bool empty() { return usedEntries == 0; } 76 77 bool full() { return usedEntries == numEntries; } 78 private: 79 /** Increments the top of stack index. */ 80 inline void incrTos() 81 { if (++tos == numEntries) tos = 0; } 82 83 /** Decrements the top of stack index. */ 84 inline void decrTos() 85 { tos = (tos == 0 ? numEntries - 1 : tos - 1); } 86 87 /** The RAS itself. */ 88 std::vector<Addr> addrStack; 89 90 /** The number of entries in the RAS. */ 91 unsigned numEntries; 92 93 /** The number of used entries in the RAS. */ 94 unsigned usedEntries; 95 96 /** The top of stack index. */ 97 unsigned tos; 98}; 99 100#endif // __CPU_O3_RAS_HH__ 101