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fixes #932, and partially also fixes #921

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This commit is contained in:
Dennis Luxen 2014-02-25 12:50:08 +01:00
parent 4b94f1fa83
commit 2b010811d8
1 changed files with 39 additions and 29 deletions
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68
Algorithms/IteratorBasedCRC32.h
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@ -25,34 +25,54 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef ITERATORBASEDCRC32_H_
#define ITERATORBASEDCRC32_H_
#ifndef ITERATOR_BASED_CRC32_H
#define ITERATOR_BASED_CRC32_H
#include "../Util/SimpleLogger.h"
#include <boost/crc.hpp> // for boost::crc_32_type
#include <iostream>
#if defined(__x86_64__)
#include <cpuid.h>
#else
#include <boost/crc.hpp> // for boost::crc_32_type
inline void __get_cpuid(
int param,
unsigned *eax,
unsigned *ebx,
unsigned *ecx,
unsigned *edx
) { *ecx = 0; }
#endif
template<class ContainerT>
class IteratorbasedCRC32 {
private:
typedef typename ContainerT::iterator IteratorType;
unsigned crc;
typedef boost::crc_optimal<32, 0x1EDC6F41, 0x0, 0x0, true, true> my_crc_32_type;
typedef unsigned (IteratorbasedCRC32::*CRC32CFunctionPtr)(char *str, unsigned len, unsigned crc);
CRC32CFunctionPtr crc_function;
unsigned SoftwareBasedCRC32(char *str, unsigned len, unsigned ){
#if !defined(__x86_64__)
boost::crc_optimal<32, 0x1EDC6F41, 0x0, 0x0, true, true> CRC32_processor;
#endif
unsigned SoftwareBasedCRC32(char *str, unsigned len, unsigned ){
#if !defined(__x86_64__)
CRC32_processor.process_bytes( str, len);
return CRC32_processor.checksum();
#else
return 0;
#endif
}
unsigned SSE42BasedCRC32( char *str, unsigned len, unsigned crc){
// adapted from http://byteworm.com/2010/10/13/crc32/
unsigned SSE42BasedCRC32( char *str, unsigned len, unsigned){
#if defined(__x86_64__)
unsigned q=len/sizeof(unsigned),
r=len%sizeof(unsigned),
*p=(unsigned*)str/*, crc*/;
unsigned q = len/sizeof(unsigned);
unsigned r = len%sizeof(unsigned);
unsigned *p = (unsigned*)str;
//crc=0;
while (q--) {
@ -77,25 +97,17 @@ private:
return crc;
}
#if defined(__x86_64__)
unsigned cpuid(unsigned functionInput){
unsigned eax;
unsigned ebx;
unsigned ecx;
unsigned edx;
asm("cpuid" : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx) : "a" (functionInput));
inline unsigned cpuid() const {
unsigned eax, ebx, ecx, edx;
// on X64 this calls hardware cpuid(.) instr. otherwise a dummy impl.
__get_cpuid( 1, &eax, &ebx, &ecx, &edx );
return ecx;
}
#endif
CRC32CFunctionPtr DetectNativeCRC32Support(){
#if defined(__x86_64__)
static const int SSE42_BIT = 20;
unsigned ecx = cpuid(1);
bool has_SSE42 = ecx & (1 << SSE42_BIT);
#else
bool has_SSE42 = false;
#endif
static const int SSE42_BIT = 0x00100000;
const unsigned ecx = cpuid();
const bool has_SSE42 = ecx & SSE42_BIT;
if (has_SSE42) {
SimpleLogger().Write() << "using hardware based CRC32 computation";
return &IteratorbasedCRC32::SSE42BasedCRC32; //crc32 hardware accelarated;
@ -104,23 +116,21 @@ private:
return &IteratorbasedCRC32::SoftwareBasedCRC32; //crc32cSlicingBy8;
}
}
CRC32CFunctionPtr crc_function;
public:
IteratorbasedCRC32(): crc(0) {
crc_function = DetectNativeCRC32Support();
}
// virtual ~IteratorbasedCRC32() { }
unsigned operator()( IteratorType iter, const IteratorType end) {
unsigned crc = 0;
while(iter != end) {
char * data = reinterpret_cast<char*>(&(*iter) );
crc =((*this).*(crc_function))(data, sizeof(typename ContainerT::value_type*), crc);
crc =((*this).*(crc_function))(data, sizeof(typename ContainerT::value_type), crc);
++iter;
}
return crc;
}
};
#endif /* ITERATORBASEDCRC32_H_ */
#endif /* ITERATOR_BASED_CRC32_H */