diff options
| -rw-r--r-- | src/base/SConscript | 1 | ||||
| -rw-r--r-- | src/base/bitfield.cc | 67 | ||||
| -rw-r--r-- | src/base/bitfield.hh | 38 |
3 files changed, 104 insertions, 2 deletions
diff --git a/src/base/SConscript b/src/base/SConscript index 74a248be0..1ca0e35bc 100644 --- a/src/base/SConscript +++ b/src/base/SConscript @@ -34,6 +34,7 @@ if env['CP_ANNOTATE']: SimObject('CPA.py') Source('cp_annotate.cc') Source('atomicio.cc') +Source('bitfield.cc') Source('bigint.cc') Source('bitmap.cc') Source('callback.cc') diff --git a/src/base/bitfield.cc b/src/base/bitfield.cc new file mode 100644 index 000000000..0650a8c18 --- /dev/null +++ b/src/base/bitfield.cc @@ -0,0 +1,67 @@ +/* + * Copyright (c) 2017 ARM Limited + * All rights reserved + * + * The license below extends only to copyright in the software and shall + * not be construed as granting a license to any other intellectual + * property including but not limited to intellectual property relating + * to a hardware implementation of the functionality of the software + * licensed hereunder. You may use the software subject to the license + * terms below provided that you ensure that this notice is replicated + * unmodified and in its entirety in all distributions of the software, + * modified or unmodified, in source code or in binary form. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer; + * redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution; + * neither the name of the copyright holders nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * Authors: Giacomo Travaglini + */ + +#include "base/bitfield.hh" + +/** Lookup table used for High Speed bit reversing */ +const uint8_t reverseLookUpTable[] = +{ + 0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, + 0x30, 0xB0, 0x70, 0xF0, 0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, + 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, 0x04, 0x84, 0x44, 0xC4, + 0x24, 0xA4, 0x64, 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, + 0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC, + 0x3C, 0xBC, 0x7C, 0xFC, 0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, + 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2, 0x0A, 0x8A, 0x4A, 0xCA, + 0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA, + 0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, 0x16, 0x96, 0x56, 0xD6, + 0x36, 0xB6, 0x76, 0xF6, 0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, + 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE, 0x01, 0x81, 0x41, 0xC1, + 0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1, + 0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9, + 0x39, 0xB9, 0x79, 0xF9, 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, + 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5, 0x0D, 0x8D, 0x4D, 0xCD, + 0x2D, 0xAD, 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD, + 0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3, + 0x33, 0xB3, 0x73, 0xF3, 0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, + 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB, 0x07, 0x87, 0x47, 0xC7, + 0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, + 0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, 0x1F, 0x9F, 0x5F, 0xDF, + 0x3F, 0xBF, 0x7F, 0xFF +}; diff --git a/src/base/bitfield.hh b/src/base/bitfield.hh index 885b42288..23c8b4b12 100644 --- a/src/base/bitfield.hh +++ b/src/base/bitfield.hh @@ -39,12 +39,19 @@ * * Authors: Steve Reinhardt * Nathan Binkert + * Giacomo Travaglini */ #ifndef __BASE_BITFIELD_HH__ #define __BASE_BITFIELD_HH__ #include <inttypes.h> +#include <cassert> +#include <cstddef> +#include <type_traits> + +/** Lookup table used for High Speed bit reversing */ +extern const uint8_t reverseLookUpTable[]; /** * Generate a 64-bit mask of 'nbits' 1s, right justified. @@ -55,8 +62,6 @@ mask(int nbits) return (nbits == 64) ? (uint64_t)-1LL : (1ULL << nbits) - 1; } - - /** * Extract the bitfield from position 'first' to 'last' (inclusive) * from 'val' and right justify it. MSB is numbered 63, LSB is 0. @@ -155,6 +160,35 @@ replaceBits(T& val, int bit, B bit_val) { val = insertBits(val, bit, bit, bit_val); } + +/** + * Takes a variable lenght word and returns the mirrored version + * (Bit by bit, LSB=>MSB). + * + * algorithm from + * http://graphics.stanford.edu/~seander/bithacks.html + * #ReverseBitsByLookupTable + * + * @param val: variable lenght word + * @param size: number of bytes to mirror + * @return mirrored word + */ +template <class T> +T +reverseBits(T val, std::size_t size = sizeof(T)) +{ + static_assert(std::is_integral<T>::value, "Expecting an integer type"); + + assert(size <= sizeof(T)); + + T output = 0; + for (auto byte = 0; byte < size; byte++, val >>= 8) { + output = (output << 8) | reverseLookUpTable[val & 0xFF]; + } + + return output; +} + /** * Returns the bit position of the MSB that is set in the input */ |