BankedArray.cc revision 11321:02e930db812d
1/* 2 * Copyright (c) 2012 Advanced Micro Devices, Inc. 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 * Author: Brad Beckmann 29 * 30 */ 31 32#include "base/intmath.hh" 33#include "mem/ruby/structures/BankedArray.hh" 34#include "mem/ruby/system/RubySystem.hh" 35 36BankedArray::BankedArray(unsigned int banks, Cycles accessLatency, 37 unsigned int startIndexBit, RubySystem *rs) 38 : m_ruby_system(rs) 39{ 40 this->banks = banks; 41 this->accessLatency = accessLatency; 42 this->startIndexBit = startIndexBit; 43 44 if (banks != 0) { 45 bankBits = floorLog2(banks); 46 } 47 48 busyBanks.resize(banks); 49} 50 51bool 52BankedArray::tryAccess(int64_t idx) 53{ 54 if (accessLatency == 0) 55 return true; 56 57 unsigned int bank = mapIndexToBank(idx); 58 assert(bank < banks); 59 60 if (busyBanks[bank].endAccess >= curTick()) { 61 return false; 62 } 63 64 return true; 65} 66 67void 68BankedArray::reserve(int64_t idx) 69{ 70 if (accessLatency == 0) 71 return; 72 73 unsigned int bank = mapIndexToBank(idx); 74 assert(bank < banks); 75 76 if (busyBanks[bank].endAccess >= curTick()) { 77 if (busyBanks[bank].startAccess == curTick() && 78 busyBanks[bank].idx == idx) { 79 // this is the same reservation (can happen when 80 // e.g., reserve the same resource for read and write) 81 return; // OK 82 } else { 83 panic("BankedArray reservation error"); 84 } 85 } 86 87 busyBanks[bank].idx = idx; 88 busyBanks[bank].startAccess = curTick(); 89 busyBanks[bank].endAccess = curTick() + 90 (accessLatency-1) * m_ruby_system->clockPeriod(); 91} 92 93unsigned int 94BankedArray::mapIndexToBank(int64_t idx) 95{ 96 if (banks == 1) { 97 return 0; 98 } 99 return idx % banks; 100} 101