86 lines
2.5 KiB
C++
86 lines
2.5 KiB
C++
/*
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open source routing machine
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Copyright (C) Dennis Luxen, others 2010
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU AFFERO General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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or see http://www.gnu.org/licenses/agpl.txt.
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*/
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#include "CRC32.h"
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CRC32::CRC32() : crc(0) {
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crcFunction = detectBestCRC32C();
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}
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unsigned CRC32::SoftwareBasedCRC32(char *str, unsigned len, unsigned ) {
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boost::crc_optimal<32, 0x1EDC6F41, 0x0, 0x0, true, true> CRC32_Processor;
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CRC32_Processor.process_bytes( str, len);
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return CRC32_Processor.checksum();
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}
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unsigned CRC32::SSEBasedCRC32( char *str, unsigned len, unsigned crc) {
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unsigned q=len/sizeof(unsigned),
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r=len%sizeof(unsigned),
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*p=(unsigned*)str/*, crc*/;
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//crc=0;
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while (q--) {
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__asm__ __volatile__(
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".byte 0xf2, 0xf, 0x38, 0xf1, 0xf1;"
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:"=S"(crc)
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:"0"(crc), "c"(*p)
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);
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++p;
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}
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str=(char*)p;
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while (r--) {
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__asm__ __volatile__(
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".byte 0xf2, 0xf, 0x38, 0xf1, 0xf1;"
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:"=S"(crc)
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:"0"(crc), "c"(*str)
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);
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++str;
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}
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return crc;
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}
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CRC32::CRC32CFunctionPtr CRC32::detectBestCRC32C() {
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static const int SSE42_BIT = 20;
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unsigned ecx = cpuid(1);
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bool hasSSE42 = ecx & (1 << SSE42_BIT);
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if (hasSSE42) {
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SimpleLogger().Write() << "using hardware base sse computation";
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return &CRC32::SSEBasedCRC32; //crc32 hardware accelarated;
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} else {
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SimpleLogger().Write() << "using software base sse computation";
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return &CRC32::SoftwareBasedCRC32; //crc32cSlicingBy8;
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}
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}
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unsigned CRC32::cpuid(unsigned functionInput) {
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unsigned eax;
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unsigned ebx;
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unsigned ecx;
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unsigned edx;
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asm("cpuid" : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx) : "a" (functionInput));
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return ecx;
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}
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unsigned CRC32::operator()(char *str, unsigned len){
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crc =((*this).*(crcFunction))(str, len, crc);
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return crc;
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}
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