bitfield.hh revision 4244
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 353386Sgblack@eecs.umich.edu#include <inttypes.h> 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/** 623814Ssaidi@eecs.umich.edu * Mask off the given bits in place like bits() but without shifting. 633814Ssaidi@eecs.umich.edu * msb = 63, lsb = 0 643814Ssaidi@eecs.umich.edu */ 653814Ssaidi@eecs.umich.edutemplate <class T> 663814Ssaidi@eecs.umich.eduinline 673814Ssaidi@eecs.umich.eduT 683814Ssaidi@eecs.umich.edumbits(T val, int first, int last) 693814Ssaidi@eecs.umich.edu{ 703814Ssaidi@eecs.umich.edu return val & (mask(first+1) & ~mask(last)); 713814Ssaidi@eecs.umich.edu} 723814Ssaidi@eecs.umich.edu 734070Ssaidi@eecs.umich.eduinline uint64_t 744070Ssaidi@eecs.umich.edumask(int first, int last) 754070Ssaidi@eecs.umich.edu{ 764070Ssaidi@eecs.umich.edu return mbits((uint64_t)-1LL, first, last); 774070Ssaidi@eecs.umich.edu} 784070Ssaidi@eecs.umich.edu 793814Ssaidi@eecs.umich.edu/** 802SN/A * Sign-extend an N-bit value to 64 bits. 812SN/A */ 822SN/Atemplate <int N> 832SN/Ainline 842SN/Aint64_t 852SN/Asext(uint64_t val) 862SN/A{ 872SN/A int sign_bit = bits(val, N-1, N-1); 882SN/A return sign_bit ? (val | ~mask(N)) : val; 892SN/A} 902SN/A 913422Sgblack@eecs.umich.edu/** 923422Sgblack@eecs.umich.edu * Return val with bits first to last set to bit_val 933422Sgblack@eecs.umich.edu */ 943422Sgblack@eecs.umich.edutemplate <class T, class B> 953422Sgblack@eecs.umich.eduinline 963422Sgblack@eecs.umich.eduT 973422Sgblack@eecs.umich.eduinsertBits(T val, int first, int last, B bit_val) 983422Sgblack@eecs.umich.edu{ 993422Sgblack@eecs.umich.edu T bmask = mask(first - last + 1) << last; 1003422Sgblack@eecs.umich.edu return ((bit_val << last) & bmask) | (val & ~bmask); 1013422Sgblack@eecs.umich.edu} 1023422Sgblack@eecs.umich.edu 1033422Sgblack@eecs.umich.edu/** 1043422Sgblack@eecs.umich.edu * A convenience function to replace bits first to last of val with bit_val 1053422Sgblack@eecs.umich.edu * in place. 1063422Sgblack@eecs.umich.edu */ 1073422Sgblack@eecs.umich.edutemplate <class T, class B> 1083422Sgblack@eecs.umich.eduinline 1093422Sgblack@eecs.umich.eduvoid 1103422Sgblack@eecs.umich.edureplaceBits(T& val, int first, int last, B bit_val) 1113422Sgblack@eecs.umich.edu{ 1123422Sgblack@eecs.umich.edu val = insertBits(val, first, last, bit_val); 1133422Sgblack@eecs.umich.edu} 1143422Sgblack@eecs.umich.edu 1154103Ssaidi@eecs.umich.edu/** 1164103Ssaidi@eecs.umich.edu * Returns the bit position of the MSB that is set in the input 1174103Ssaidi@eecs.umich.edu */ 1184103Ssaidi@eecs.umich.eduinline 1194103Ssaidi@eecs.umich.eduint 1204103Ssaidi@eecs.umich.edufindMsbSet(uint64_t val) { 1214103Ssaidi@eecs.umich.edu int msb = 0; 1224103Ssaidi@eecs.umich.edu if (!val) 1234103Ssaidi@eecs.umich.edu return 0; 1244244Ssaidi@eecs.umich.edu if (bits(val, 63,32)) { msb += 32; val >>= 32; } 1254244Ssaidi@eecs.umich.edu if (bits(val, 31,16)) { msb += 16; val >>= 16; } 1264244Ssaidi@eecs.umich.edu if (bits(val, 15,8)) { msb += 8; val >>= 8; } 1274244Ssaidi@eecs.umich.edu if (bits(val, 7,4)) { msb += 4; val >>= 4; } 1284244Ssaidi@eecs.umich.edu if (bits(val, 3,2)) { msb += 2; val >>= 2; } 1294244Ssaidi@eecs.umich.edu if (bits(val, 1,1)) { msb += 1; } 1304103Ssaidi@eecs.umich.edu return msb; 1314103Ssaidi@eecs.umich.edu} 1324103Ssaidi@eecs.umich.edu 1334103Ssaidi@eecs.umich.edu 1344103Ssaidi@eecs.umich.edu 1351112SN/A#endif // __BASE_BITFIELD_HH__ 136