bitfield.hh revision 6215
12SN/A/* 21762SN/A * Copyright (c) 2003-2005 The Regents of The University of Michigan 32SN/A * All rights reserved. 42SN/A * 52SN/A * Redistribution and use in source and binary forms, with or without 62SN/A * modification, are permitted provided that the following conditions are 72SN/A * met: redistributions of source code must retain the above copyright 82SN/A * notice, this list of conditions and the following disclaimer; 92SN/A * redistributions in binary form must reproduce the above copyright 102SN/A * notice, this list of conditions and the following disclaimer in the 112SN/A * documentation and/or other materials provided with the distribution; 122SN/A * neither the name of the copyright holders nor the names of its 132SN/A * contributors may be used to endorse or promote products derived from 142SN/A * this software without specific prior written permission. 152SN/A * 162SN/A * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 172SN/A * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 182SN/A * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 192SN/A * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 202SN/A * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 212SN/A * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 222SN/A * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 232SN/A * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 242SN/A * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 252SN/A * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 262SN/A * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 272665Ssaidi@eecs.umich.edu * 282665Ssaidi@eecs.umich.edu * Authors: Steve Reinhardt 292665Ssaidi@eecs.umich.edu * Nathan Binkert 302SN/A */ 312SN/A 321112SN/A#ifndef __BASE_BITFIELD_HH__ 331112SN/A#define __BASE_BITFIELD_HH__ 342SN/A 356215Snate@binkert.org#include "base/types.hh" 362SN/A 372SN/A/** 382SN/A * Generate a 64-bit mask of 'nbits' 1s, right justified. 392SN/A */ 402SN/Ainline uint64_t 412SN/Amask(int nbits) 422SN/A{ 432SN/A return (nbits == 64) ? (uint64_t)-1LL : (1ULL << nbits) - 1; 442SN/A} 452SN/A 462SN/A 474070Ssaidi@eecs.umich.edu 482SN/A/** 492SN/A * Extract the bitfield from position 'first' to 'last' (inclusive) 502SN/A * from 'val' and right justify it. MSB is numbered 63, LSB is 0. 512SN/A */ 522SN/Atemplate <class T> 532SN/Ainline 542SN/AT 552SN/Abits(T val, int first, int last) 562SN/A{ 572SN/A int nbits = first - last + 1; 582SN/A return (val >> last) & mask(nbits); 592SN/A} 602SN/A 612SN/A/** 624661Sksewell@umich.edu * Extract the bit from this position from 'val' and right justify it. 634661Sksewell@umich.edu */ 644661Sksewell@umich.edutemplate <class T> 654661Sksewell@umich.eduinline 664661Sksewell@umich.eduT 674661Sksewell@umich.edubits(T val, int bit) 684661Sksewell@umich.edu{ 694661Sksewell@umich.edu return bits(val, bit, bit); 704661Sksewell@umich.edu} 714661Sksewell@umich.edu 724661Sksewell@umich.edu/** 733814Ssaidi@eecs.umich.edu * Mask off the given bits in place like bits() but without shifting. 743814Ssaidi@eecs.umich.edu * msb = 63, lsb = 0 753814Ssaidi@eecs.umich.edu */ 763814Ssaidi@eecs.umich.edutemplate <class T> 773814Ssaidi@eecs.umich.eduinline 783814Ssaidi@eecs.umich.eduT 793814Ssaidi@eecs.umich.edumbits(T val, int first, int last) 803814Ssaidi@eecs.umich.edu{ 813814Ssaidi@eecs.umich.edu return val & (mask(first+1) & ~mask(last)); 823814Ssaidi@eecs.umich.edu} 833814Ssaidi@eecs.umich.edu 844070Ssaidi@eecs.umich.eduinline uint64_t 854070Ssaidi@eecs.umich.edumask(int first, int last) 864070Ssaidi@eecs.umich.edu{ 874070Ssaidi@eecs.umich.edu return mbits((uint64_t)-1LL, first, last); 884070Ssaidi@eecs.umich.edu} 894070Ssaidi@eecs.umich.edu 903814Ssaidi@eecs.umich.edu/** 912SN/A * Sign-extend an N-bit value to 64 bits. 922SN/A */ 932SN/Atemplate <int N> 942SN/Ainline 952SN/Aint64_t 962SN/Asext(uint64_t val) 972SN/A{ 982SN/A int sign_bit = bits(val, N-1, N-1); 992SN/A return sign_bit ? (val | ~mask(N)) : val; 1002SN/A} 1012SN/A 1023422Sgblack@eecs.umich.edu/** 1033422Sgblack@eecs.umich.edu * Return val with bits first to last set to bit_val 1043422Sgblack@eecs.umich.edu */ 1053422Sgblack@eecs.umich.edutemplate <class T, class B> 1063422Sgblack@eecs.umich.eduinline 1073422Sgblack@eecs.umich.eduT 1083422Sgblack@eecs.umich.eduinsertBits(T val, int first, int last, B bit_val) 1093422Sgblack@eecs.umich.edu{ 1104425Ssaidi@eecs.umich.edu T t_bit_val = bit_val; 1113422Sgblack@eecs.umich.edu T bmask = mask(first - last + 1) << last; 1124425Ssaidi@eecs.umich.edu return ((t_bit_val << last) & bmask) | (val & ~bmask); 1133422Sgblack@eecs.umich.edu} 1143422Sgblack@eecs.umich.edu 1153422Sgblack@eecs.umich.edu/** 1164661Sksewell@umich.edu * Overloaded for access to only one bit in value 1174661Sksewell@umich.edu */ 1184661Sksewell@umich.edutemplate <class T, class B> 1194661Sksewell@umich.eduinline 1204661Sksewell@umich.eduT 1214661Sksewell@umich.eduinsertBits(T val, int bit, B bit_val) 1224661Sksewell@umich.edu{ 1234661Sksewell@umich.edu return insertBits(val, bit, bit, bit_val); 1244661Sksewell@umich.edu} 1254661Sksewell@umich.edu 1264661Sksewell@umich.edu/** 1273422Sgblack@eecs.umich.edu * A convenience function to replace bits first to last of val with bit_val 1283422Sgblack@eecs.umich.edu * in place. 1293422Sgblack@eecs.umich.edu */ 1303422Sgblack@eecs.umich.edutemplate <class T, class B> 1313422Sgblack@eecs.umich.eduinline 1323422Sgblack@eecs.umich.eduvoid 1333422Sgblack@eecs.umich.edureplaceBits(T& val, int first, int last, B bit_val) 1343422Sgblack@eecs.umich.edu{ 1353422Sgblack@eecs.umich.edu val = insertBits(val, first, last, bit_val); 1363422Sgblack@eecs.umich.edu} 1373422Sgblack@eecs.umich.edu 1384661Sksewell@umich.edu/** Overloaded function to allow to access only 1 bit*/ 1394661Sksewell@umich.edutemplate <class T, class B> 1404661Sksewell@umich.eduinline 1414661Sksewell@umich.eduvoid 1424661Sksewell@umich.edureplaceBits(T& val, int bit, B bit_val) 1434661Sksewell@umich.edu{ 1444661Sksewell@umich.edu val = insertBits(val, bit, bit, bit_val); 1454661Sksewell@umich.edu} 1464103Ssaidi@eecs.umich.edu/** 1474103Ssaidi@eecs.umich.edu * Returns the bit position of the MSB that is set in the input 1484103Ssaidi@eecs.umich.edu */ 1494103Ssaidi@eecs.umich.eduinline 1504103Ssaidi@eecs.umich.eduint 1514103Ssaidi@eecs.umich.edufindMsbSet(uint64_t val) { 1524103Ssaidi@eecs.umich.edu int msb = 0; 1534103Ssaidi@eecs.umich.edu if (!val) 1544103Ssaidi@eecs.umich.edu return 0; 1554244Ssaidi@eecs.umich.edu if (bits(val, 63,32)) { msb += 32; val >>= 32; } 1564244Ssaidi@eecs.umich.edu if (bits(val, 31,16)) { msb += 16; val >>= 16; } 1574244Ssaidi@eecs.umich.edu if (bits(val, 15,8)) { msb += 8; val >>= 8; } 1584244Ssaidi@eecs.umich.edu if (bits(val, 7,4)) { msb += 4; val >>= 4; } 1594244Ssaidi@eecs.umich.edu if (bits(val, 3,2)) { msb += 2; val >>= 2; } 1604244Ssaidi@eecs.umich.edu if (bits(val, 1,1)) { msb += 1; } 1614103Ssaidi@eecs.umich.edu return msb; 1624103Ssaidi@eecs.umich.edu} 1634103Ssaidi@eecs.umich.edu 1641112SN/A#endif // __BASE_BITFIELD_HH__ 165