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/*++
Module Name:
GenericFile_map.cpp
Abstract:
Generic IO class for SNAP that can map an input file.
Authors:
Bill Bolosky, September, 2014
Environment:
User mode service.
Revision History:
--*/
#include "stdafx.h"
#include "GenericFile_map.h"
#include "Error.h"
#include "exit.h"
GenericFile_map *GenericFile_map::open(const char *filename)
{
size_t fileSize = QueryFileSize(filename);
if (0 == fileSize) {
return new GenericFile_map(NULL, NULL, 0);
}
void *contents;
MemoryMappedFile *mappedFile = OpenMemoryMappedFile(filename, 0, fileSize, &contents);
return new GenericFile_map(mappedFile, contents, fileSize);
}
GenericFile_map::GenericFile_map(MemoryMappedFile *i_mappedFile, void *i_contents, size_t i_fileSize) : mappedFile(i_mappedFile), contents((const char *)i_contents), fileSize(i_fileSize), GenericFile_Blob(i_contents, i_fileSize)
{
}
void
GenericFile_map::close()
{
if (NULL != mappedFile) {
CloseMemoryMappedFile(mappedFile);
mappedFile = NULL;
GenericFile_Blob::close();
}
}
GenericFile_map::~GenericFile_map()
{
close();
}
_int64
GenericFile_map::prefetch()
{
if (NULL == mappedFile) {
return 0;
}
AdviseMemoryMappedFilePrefetch(mappedFile);
int pageSize = getpagesize();
_int64 total = 0;
for (size_t offset = 0; offset < fileSize / sizeof (_int64); offset += 4 ) {
total += ((_int64 *)contents)[offset];
}
return total; // We're returning this just to keep the compiler from optimizing away the whole thing.
}
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